WorldWideScience

Sample records for investigating hippocampal sharp

  1. Caffeine Increases Hippocampal Sharp Waves in Vitro.

    Science.gov (United States)

    Watanabe, Yusuke; Ikegaya, Yuji

    2017-01-01

    Caffeine promotes memory consolidation. Memory consolidation is thought to depend at least in part on hippocampal sharp waves (SWs). In the present study, we investigated the effect of bath-application of caffeine in spontaneously occurring SWs in mouse acute hippocampal slices. Caffeine induced an about 100% increase in the event frequency of SWs at concentrations of 60 and 200 µM. The effect of caffeine was reversible after washout of caffeine and was mimicked by an adenosine A 1 receptor antagonist, but not by an A 2A receptor antagonist. Caffeine increased SWs even in dentate-CA3 mini-slices without the CA2 regions, in which adenosine A 1 receptors are abundantly expressed in the hippocampus. Thus, caffeine facilitates SWs by inhibiting adenosine A 1 receptors in the hippocampal CA3 region or the dentate gyrus.

  2. Serotonin dependent masking of hippocampal sharp wave ripples.

    Science.gov (United States)

    ul Haq, Rizwan; Anderson, Marlene L; Hollnagel, Jan-Oliver; Worschech, Franziska; Sherkheli, Muhammad Azahr; Behrens, Christoph J; Heinemann, Uwe

    2016-02-01

    Sharp wave ripples (SPW-Rs) are thought to play an important role in memory consolidation. By rapid replay of previously stored information during slow wave sleep and consummatory behavior, they result from the formation of neural ensembles during a learning period. Serotonin (5-HT), suggested to be able to modify SPW-Rs, can affect many neurons simultaneously by volume transmission and alter network functions in an orchestrated fashion. In acute slices from dorsal hippocampus, SPW-Rs can be induced by repeated high frequency stimulation that induces long-lasting LTP. We used this model to study SPW-R appearance and modulation by 5-HT. Although stimulation in presence of 5-HT permitted LTP induction, SPW-Rs were "masked"--but appeared after 5-HT wash-out. This SPW-R masking was dose dependent with 100 nM 5-HT being sufficient--if the 5-HT re-uptake inhibitor citalopram was present. Fenfluramine, a serotonin releaser, could also mask SPW-Rs. Masking was due to 5-HT1A and 5-HT2A/C receptor activation. Neither membrane potential nor membrane conductance changes in pyramidal cells caused SPW-R blockade since both remained unaffected by combining 5-HT and citalopram. Moreover, 10 and 30 μM 5-HT mediated SPW-R masking preceded neuronal hyperpolarization and involved reduced presynaptic transmitter release. 5-HT, as well as a 5-HT1A agonist, augmented paired pulse facilitation and affected the coefficient of variance. Spontaneous SPW-Rs in mice hippocampal slices were also masked by 5-HT and fenfluramine. While neuronal ensembles can acquire long lasting LTP during higher 5-HT levels, lower 5-HT levels enable neural ensembles to replay previously stored information and thereby permit memory consolidation memory. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Sharp wave/ripple network oscillations and learning-associated hippocampal maps.

    Science.gov (United States)

    Csicsvari, Jozsef; Dupret, David

    2014-02-05

    Sharp wave/ripple (SWR, 150-250 Hz) hippocampal events have long been postulated to be involved in memory consolidation. However, more recent work has investigated SWRs that occur during active waking behaviour: findings that suggest that SWRs may also play a role in cell assembly strengthening or spatial working memory. Do such theories of SWR function apply to animal learning? This review discusses how general theories linking SWRs to memory-related function may explain circuit mechanisms related to rodent spatial learning and to the associated stabilization of new cognitive maps.

  4. Choline-mediated modulation of hippocampal sharp wave-ripple complexes in vitro.

    Science.gov (United States)

    Fischer, Viktoria; Both, Martin; Draguhn, Andreas; Egorov, Alexei V

    2014-06-01

    The cholinergic system is critically involved in the modulation of cognitive functions, including learning and memory. Acetylcholine acts through muscarinic (mAChRs) and nicotinic receptors (nAChRs), which are both abundantly expressed in the hippocampus. Previous evidence indicates that choline, the precursor and degradation product of Acetylcholine, can itself activate nAChRs and thereby affects intrinsic and synaptic neuronal functions. Here, we asked whether the cellular actions of choline directly affect hippocampal network activity. Using mouse hippocampal slices we found that choline efficiently suppresses spontaneously occurring sharp wave-ripple complexes (SPW-R) and can induce gamma oscillations. In addition, choline reduces synaptic transmission between hippocampal subfields CA3 and CA1. Surprisingly, these effects are mediated by activation of both mAChRs and α7-containing nAChRs. Most nicotinic effects became only apparent after local, fast application of choline, indicating rapid desensitization kinetics of nAChRs. Effects were still present following block of choline uptake and are, therefore, likely because of direct actions of choline at the respective receptors. Together, choline turns out to be a potent regulator of patterned network activity within the hippocampus. These actions may be of importance for understanding state transitions in normal and pathologically altered neuronal networks. In this study we asked whether choline, the precursor and degradation product of acetylcholine, directly affects hippocampal network activity. Using mouse hippocampal slices we found that choline efficiently suppresses spontaneously occurring sharp wave-ripple complexes (SPW-R). In addition, choline reduces synaptic transmission between hippocampal subfields. These effects are mediated by direct activation of muscarinic as well as nicotinic cholinergic pathways. Together, choline turns out to be a potent regulator of patterned activity within hippocampal

  5. Disrupting neural activity related to awake-state sharp wave-ripple complexes prevents hippocampal learning.

    Science.gov (United States)

    Nokia, Miriam S; Mikkonen, Jarno E; Penttonen, Markku; Wikgren, Jan

    2012-01-01

    Oscillations in hippocampal local-field potentials (LFPs) reflect the crucial involvement of the hippocampus in memory trace formation: theta (4-8 Hz) oscillations and ripples (~200 Hz) occurring during sharp waves are thought to mediate encoding and consolidation, respectively. During sharp wave-ripple complexes (SPW-Rs), hippocampal cell firing closely follows the pattern that took place during the initial experience, most likely reflecting replay of that event. Disrupting hippocampal ripples using electrical stimulation either during training in awake animals or during sleep after training retards spatial learning. Here, adult rabbits were trained in trace eyeblink conditioning, a hippocampus-dependent associative learning task. A bright light was presented to the animals during the inter-trial interval (ITI), when awake, either during SPW-Rs or irrespective of their neural state. Learning was particularly poor when the light was presented following SPW-Rs. While the light did not disrupt the ripple itself, it elicited a theta-band oscillation, a state that does not usually coincide with SPW-Rs. Thus, it seems that consolidation depends on neuronal activity within and beyond the hippocampus taking place immediately after, but by no means limited to, hippocampal SPW-Rs.

  6. Dopamine receptor activation reorganizes neuronal ensembles during hippocampal sharp waves in vitro.

    Directory of Open Access Journals (Sweden)

    Takeyuki Miyawaki

    Full Text Available Hippocampal sharp wave (SW/ripple complexes are thought to contribute to memory consolidation. Previous studies suggest that behavioral rewards facilitate SW occurrence in vivo. However, little is known about the precise mechanism underlying this enhancement. Here, we examined the effect of dopaminergic neuromodulation on spontaneously occurring SWs in acute hippocampal slices. Local field potentials were recorded from the CA1 region. A brief (1 min treatment with dopamine led to a persistent increase in the event frequency and the magnitude of SWs. This effect lasted at least for our recording period of 45 min and did not occur in the presence of a dopamine D1/D5 receptor antagonist. Functional multineuron calcium imaging revealed that dopamine-induced SW augmentation was associated with an enriched repertoire of the firing patterns in SW events, whereas the overall tendency of individual neurons to participate in SWs and the mean number of cells participating in a single SW were maintained. Therefore, dopaminergic activation is likely to reorganize cell assemblies during SWs.

  7. Lamina-specific contribution of glutamatergic and GABAergic potentials to hippocampal sharp wave-ripple complexes.

    Science.gov (United States)

    Schönberger, Jan; Draguhn, Andreas; Both, Martin

    2014-01-01

    The mammalian hippocampus expresses highly organized patterns of neuronal activity which form a neuronal correlate of spatial memories. These memory-encoding neuronal ensembles form on top of different network oscillations which entrain neurons in a state- and experience-dependent manner. The mechanisms underlying activation, timing and selection of participating neurons are incompletely understood. Here we studied the synaptic mechanisms underlying one prominent network pattern called sharp wave-ripple complexes (SPW-R) which are involved in memory consolidation during sleep. We recorded SPW-R with extracellular electrodes along the different layers of area CA1 in mouse hippocampal slices. Contribution of glutamatergic excitation and GABAergic inhibition, respectively, was probed by local application of receptor antagonists into s. radiatum, pyramidale and oriens. Laminar profiles of field potentials show that GABAergic potentials contribute substantially to sharp waves and superimposed ripple oscillations in s. pyramidale. Inhibitory inputs to s. pyramidale and s. oriens are crucial for action potential timing by ripple oscillations, as revealed by multiunit-recordings in the pyramidal cell layer. Glutamatergic afferents, on the other hand, contribute to sharp waves in s. radiatum where they also evoke a fast oscillation at ~200 Hz. Surprisingly, field ripples in s. radiatum are slightly slower than ripples in s. pyramidale, resulting in a systematic shift between dendritic and somatic oscillations. This complex interplay between dendritic excitation and perisomatic inhibition may be responsible for the precise timing of discharge probability during the time course of SPW-R. Together, our data illustrate a complementary role of spatially confined excitatory and inhibitory transmission during highly ordered network patterns in the hippocampus.

  8. Hippocampal sharp wave‐ripple: A cognitive biomarker for episodic memory and planning

    Science.gov (United States)

    2015-01-01

    ABSTRACT Sharp wave ripples (SPW‐Rs) represent the most synchronous population pattern in the mammalian brain. Their excitatory output affects a wide area of the cortex and several subcortical nuclei. SPW‐Rs occur during “off‐line” states of the brain, associated with consummatory behaviors and non‐REM sleep, and are influenced by numerous neurotransmitters and neuromodulators. They arise from the excitatory recurrent system of the CA3 region and the SPW‐induced excitation brings about a fast network oscillation (ripple) in CA1. The spike content of SPW‐Rs is temporally and spatially coordinated by a consortium of interneurons to replay fragments of waking neuronal sequences in a compressed format. SPW‐Rs assist in transferring this compressed hippocampal representation to distributed circuits to support memory consolidation; selective disruption of SPW‐Rs interferes with memory. Recently acquired and pre‐existing information are combined during SPW‐R replay to influence decisions, plan actions and, potentially, allow for creative thoughts. In addition to the widely studied contribution to memory, SPW‐Rs may also affect endocrine function via activation of hypothalamic circuits. Alteration of the physiological mechanisms supporting SPW‐Rs leads to their pathological conversion, “p‐ripples,” which are a marker of epileptogenic tissue and can be observed in rodent models of schizophrenia and Alzheimer's Disease. Mechanisms for SPW‐R genesis and function are discussed in this review. © 2015 The Authors Hippocampus Published by Wiley Periodicals, Inc. PMID:26135716

  9. Downstream effects of hippocampal sharp wave ripple oscillations on medial entorhinal cortex layer V neurons in vitro.

    Science.gov (United States)

    Roth, Fabian C; Beyer, Katinka M; Both, Martin; Draguhn, Andreas; Egorov, Alexei V

    2016-12-01

    The entorhinal cortex (EC) is a critical component of the medial temporal lobe (MTL) memory system. Local networks within the MTL express a variety of state-dependent network oscillations that are believed to organize neuronal activity during memory formation. The peculiar pattern of sharp wave-ripple complexes (SPW-R) entrains neurons by a very fast oscillation at ∼200 Hz in the hippocampal areas CA3 and CA1 and then propagates through the "output loop" into the EC. The precise mechanisms of SPW-R propagation and the resulting cellular input patterns in the mEC are, however, largely unknown. We therefore investigated the activity of layer V (LV) principal neurons of the medial EC (mEC) during SPW-R oscillations in horizontal mouse brain slices. Intracellular recordings in the mEC were combined with extracellular monitoring of propagating network activity. SPW-R in CA1 were regularly followed by negative field potential deflections in the mEC. Propagation of SPW-R activity from CA1 to the mEC was mostly monosynaptic and excitatory, such that synaptic input to mEC LV neurons directly reflected unit activity in CA1. Comparison with propagating network activity from CA3 to CA1 revealed a similar role of excitatory long-range connections for both regions. However, SPW-R-induced activity in CA1 involved strong recruitment of rhythmic synaptic inhibition and corresponding fast field oscillations, in contrast to the mEC. These differences between features of propagating SPW-R emphasize the differential processing of network activity by each local network of the hippocampal output loop. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  10. Investigation of Sharp Injuries in an Educational Hospital, Ahvaz, Iran

    Directory of Open Access Journals (Sweden)

    Sahar Geravandi

    2017-01-01

    Full Text Available Background & Aims of the Study: The Sharp Injuries (SIs are a percutaneous piercing wound caused by a sharp instrument. Needle Sticks and Sharp Injuries (NSSIs can increase the incidence of cases of Hepatitis B, C and HIV. The purpose of this study was to Investigation of the relative frequency of NSSIs in healthcare workers (HCWs in Ahvaz, Iran (Razi hospital over 3-year period (2011–2013. Materials and Methods: A descriptive study during 2011-2013 was conducted on 600 HCWs at Razi Hospital, Ahvaz, Iran. To measure NSSIs, has been diagnosis and categorized based on the National Nosocomial Infections Surveillance (NNIS. Data about health workers’ age, sex, site of NSIs injury, ward of hospitalization and case of needle stick were collected. Descriptive statistical by SPSS version 16 used for analyzed data in this study. Results: According to the results of this study, among all nurses, the maximum cases of NSIs were HCWs. Regarding the finding, recapping needle were found in 34.17%, handling needle in 20.25%, suturing in 16.45%, passing needle in 13.92%, transit disposal in 8.86% and dissembling needle in 6.32% of cases. Findings showed that the most NSIs in Razi Hospital were general surgery, emergency, Intensive Care Unit (ICU, Obstetrics and Gynecology (OBGYN, operating room, orthopedic and infectious diseases wards during 2011-2013. Conclusion: Based on these findings, the number of health care-associated with NSIs between nurses in our study may be due to the shortage of nurses, long working hours during the night shift, fatigue and failure to use an appropriate equipment.

  11. Interplay between Hippocampal Sharp-Wave-Ripple Events and Vicarious Trial and Error Behaviors in Decision Making.

    Science.gov (United States)

    Papale, Andrew E; Zielinski, Mark C; Frank, Loren M; Jadhav, Shantanu P; Redish, A David

    2016-12-07

    Current theories posit that memories encoded during experiences are subsequently consolidated into longer-term storage. Hippocampal sharp-wave-ripple (SWR) events have been linked to this consolidation process during sleep, but SWRs also occur during awake immobility, where their role remains unclear. We report that awake SWR rates at the reward site are inversely related to the prevalence of vicarious trial and error (VTE) behaviors, thought to be involved in deliberation processes. SWR rates were diminished immediately after VTE behaviors and an increase in the rate of SWR events at the reward site predicted a decrease in subsequent VTE behaviors at the choice point. Furthermore, SWR disruptions increased VTE behaviors. These results suggest an inverse relationship between SWRs and VTE behaviors and suggest that awake SWRs and associated planning and memory consolidation mechanisms are engaged specifically in the context of higher levels of behavioral certainty. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Hippocampal sharp wave/ripples during sleep for consolidation of associative memory.

    Directory of Open Access Journals (Sweden)

    Wiâm Ramadan

    Full Text Available The beneficial effect of sleep on memory has been well-established by extensive research on humans, but the neurophysiological mechanisms remain a matter of speculation. This study addresses the hypothesis that the fast oscillations known as ripples recorded in the CA1 region of the hippocampus during slow wave sleep (SWS may provide a physiological substrate for long term memory consolidation. We trained rats in a spatial discrimination task to retrieve palatable reward in three fixed locations. Hippocampal local field potentials and cortical EEG were recorded for 2 h after each daily training session. There was an increase in ripple density during SWS after early training sessions, in both trained rats and in rats randomly rewarded for exploring the maze. In rats learning the place -reward association, there was a striking further significant increase in ripple density correlated with subsequent improvements in behavioral performance as the rat learned the spatial discrimination aspect of the task. The results corroborate others showing an experience-dependent increase in ripple activity and associated ensemble replay after exploratory activity, but in addition, for the first time, reveal a clear further increase in ripple activity related to associative learning based on spatial discrimination.

  13. At clinically relevant concentrations the anaesthetic/amnesic thiopental but not the anticonvulsant phenobarbital interferes with hippocampal sharp wave-ripple complexes

    Directory of Open Access Journals (Sweden)

    Sotiriou Evangelos

    2007-07-01

    Full Text Available Abstract Background Many sedative agents, including anesthetics, produce explicit memory impairment by largely unknown mechanisms. Sharp-wave ripple (SPW-R complexes are network activity thought to represent the neuronal substrate for information transfer from the hippocampal to neocortical circuits, contributing to the explicit memory consolidation. In this study we examined and compared the actions of two barbiturates with distinct amnesic actions, the general anesthetic thiopental and the anticonvulsant phenobarbital, on in vitro SPW-R activity. Results Using an in vitro model of SPW-R activity we found that thiopental (50–200 μM significantly and concentration-dependently reduced the incidence of SPW-R events (it increased the inter-event period by 70–430 %. At the concentration of 25 μM, which clinically produces mild sedation and explicit memory impairment, thiopental significantly reduced the quantity of ripple oscillation (it reduced the number of ripples and the duration of ripple episodes by 20 ± 5%, n = 12, P P P Conclusion We hypothesize that thiopental, by interfering with SPW-R activity, through enhancement of the GABAA receptor-mediated transmission, affects memory processes which involve hippocampal circuit activation. The quantity but not the frequency of ripple oscillation was affected by the drug.

  14. At clinically relevant concentrations the anaesthetic/amnesic thiopental but not the anticonvulsant phenobarbital interferes with hippocampal sharp wave-ripple complexes

    Science.gov (United States)

    Papatheodoropoulos, Costas; Sotiriou, Evangelos; Kotzadimitriou, Dimitrios; Drimala, Panagiota

    2007-01-01

    Background Many sedative agents, including anesthetics, produce explicit memory impairment by largely unknown mechanisms. Sharp-wave ripple (SPW-R) complexes are network activity thought to represent the neuronal substrate for information transfer from the hippocampal to neocortical circuits, contributing to the explicit memory consolidation. In this study we examined and compared the actions of two barbiturates with distinct amnesic actions, the general anesthetic thiopental and the anticonvulsant phenobarbital, on in vitro SPW-R activity. Results Using an in vitro model of SPW-R activity we found that thiopental (50–200 μM) significantly and concentration-dependently reduced the incidence of SPW-R events (it increased the inter-event period by 70–430 %). At the concentration of 25 μM, which clinically produces mild sedation and explicit memory impairment, thiopental significantly reduced the quantity of ripple oscillation (it reduced the number of ripples and the duration of ripple episodes by 20 ± 5%, n = 12, P Phenobarbital significantly accelerated SPWs at 50 and 100 μM whereas it reduced their rate at 200 and 400 μM. Furthermore, it significantly prolonged SPWs, reduced their synchrony and reduced the quantity of ripples only at the clinically very high concentration of 400 μM, reported to affect memory. Conclusion We hypothesize that thiopental, by interfering with SPW-R activity, through enhancement of the GABAA receptor-mediated transmission, affects memory processes which involve hippocampal circuit activation. The quantity but not the frequency of ripple oscillation was affected by the drug. PMID:17672909

  15. Numerical investigation of rarefaction effects in the vicinity of a sharp leading edge

    Science.gov (United States)

    Pan, Shaowu; Gao, Zhenxun; Lee, Chunhian

    2014-12-01

    This paper presents a study of rarefaction effect on hypersonic flow over a sharp leading edge. Both continuum approach and kinetic method: a widely spread commercial Computational Fluid Dynamics-Navior-Stokes-Fourier (CFD-NSF) software - Fluent together with a direct simulation Monte Carlo (DSMC) code developed by the authors are employed for simulation of transition regime with Knudsen number ranging from 0.005 to 0.2. It is found that Fluent can predict the wall fluxes in the case of hypersonic argon flow over the sharp leading edge for the lowest Kn case (Kn = 0.005) in current paper while for other cases it also has a good agreement with DSMC except at the location near the sharp leading edge. Among all of the wall fluxes, it is found that coefficient of pressure is the most sensitive to rarefaction while heat transfer is the least one. A parameter based on translational nonequilibrium and a cut-off value of 0.34 is proposed for continuum breakdown in this paper. The structure of entropy and velocity profile in boundary layer is analyzed. Also, it is found that the ratio of heat transfer coefficient to skin friction coefficient remains uniform along the surface for the four cases in this paper.

  16. Sharps container

    Science.gov (United States)

    Lee, Angelene M. (Inventor)

    1992-01-01

    This invention relates to a system for use in disposing of potentially hazardous items and more particularly a Sharps receptacle for used hypodermic needles and the like. A Sharps container is constructed from lightweight alodined nonmagnetic metal material with a cup member having an elongated tapered shape and length greater than its transverse dimensions. A magnet in the cup member provides for metal retention in the container. A nonmagnetic lid member has an opening and spring biased closure flap member. The flap member is constructed from stainless steel. A Velcro patch on the container permits selective attachment at desired locations.

  17. Gust-Tunnel Investigation of the Effect of a Sharp-Edge Gust on the Flapwise Blade Bending Moments of a Model Helicopter Rotor

    National Research Council Canada - National Science Library

    Maglieri, Domenic

    1955-01-01

    Preliminary investigations have been made in the Langley gust tunnel to determine the effects of a sharp-edge vertical gust on the blade flapwise vibratory bending moments of small model rotors having...

  18. Metabolic therapy for temporal lobe epilepsy in a dish: investigating mechanisms of ketogenic diet using electrophysiological recordings in hippocampal slices

    Directory of Open Access Journals (Sweden)

    Masahito Kawamura

    2016-11-01

    Full Text Available The hippocampus is prone to epileptic seizures and is a key brain region and experimental platform for investigating mechanisms associated with the abnormal neuronal excitability that characterizes a seizure. Accordingly, the hippocampal slice is a common in vitro model to study treatments that may prevent or reduce seizure activity. The ketogenic diet is a metabolic therapy used to treat epilepsy in adults and children for nearly 100 years; it can reduce or eliminate even severe or refractory seizures. New insights into its underlying mechanisms have been revealed by diverse types of electrophysiological recordings in hippocampal slices. Here we review these reports and their relevant mechanistic findings. We acknowledge that a major difficulty in using hippocampal slices is the inability to reproduce precisely the in vivo condition of ketogenic diet feeding in any in vitro preparation, and progress has been made in this in vivo/in vitro transition. Thus far at least three different approaches are reported to reproduce relevant diet effects in the hippocampal slices: (1 direct application of ketone bodies, (2 mimicking the ketogenic diet condition during a whole-cell patch-clamp technique, and (3 reduced glucose incubation of hippocampal slices from ketogenic diet–fed animals. Significant results have been found with each of these methods and provide options for further study into short- and long-term mechanisms including ATP-sensitive potassium channels, vesicular glutamate transporter, pannexin channels and adenosine receptors underlying ketogenic diet and other forms of metabolic therapy.

  19. Metabolic Therapy for Temporal Lobe Epilepsy in a Dish: Investigating Mechanisms of Ketogenic Diet using Electrophysiological Recordings in Hippocampal Slices

    Science.gov (United States)

    Kawamura, Masahito Jr.; Ruskin, David N.; Masino, Susan A.

    2016-01-01

    The hippocampus is prone to epileptic seizures and is a key brain region and experimental platform for investigating mechanisms associated with the abnormal neuronal excitability that characterizes a seizure. Accordingly, the hippocampal slice is a common in vitro model to study treatments that may prevent or reduce seizure activity. The ketogenic diet is a metabolic therapy used to treat epilepsy in adults and children for nearly 100 years; it can reduce or eliminate even severe or refractory seizures. New insights into its underlying mechanisms have been revealed by diverse types of electrophysiological recordings in hippocampal slices. Here we review these reports and their relevant mechanistic findings. We acknowledge that a major difficulty in using hippocampal slices is the inability to reproduce precisely the in vivo condition of ketogenic diet feeding in any in vitro preparation, and progress has been made in this in vivo/in vitro transition. Thus far at least three different approaches are reported to reproduce relevant diet effects in the hippocampal slices: (1) direct application of ketone bodies; (2) mimicking the ketogenic diet condition during a whole-cell patch-clamp technique; and (3) reduced glucose incubation of hippocampal slices from ketogenic diet–fed animals. Significant results have been found with each of these methods and provide options for further study into short- and long-term mechanisms including Adenosine triphosphate (ATP)-sensitive potassium (KATP) channels, vesicular glutamate transporter (VGLUT), pannexin channels and adenosine receptors underlying ketogenic diet and other forms of metabolic therapy. PMID:27847463

  20. Indirect flat-panel detector with avalanche gain: Fundamental feasibility investigation for SHARP-AMFPI (scintillator HARP active matrix flat panel imager)

    International Nuclear Information System (INIS)

    Zhao Wei; Li Dan; Reznik, Alla; Lui, B.J.M.; Hunt, D.C.; Rowlands, J.A.; Ohkawa, Yuji; Tanioka, Kenkichi

    2005-01-01

    An indirect flat-panel imager (FPI) with avalanche gain is being investigated for low-dose x-ray imaging. It is made by optically coupling a structured x-ray scintillator CsI(Tl) to an amorphous selenium (a-Se) avalanche photoconductor called HARP (high-gain avalanche rushing photoconductor). The final electronic image is read out using an active matrix array of thin film transistors (TFT). We call the proposed detector SHARP-AMFPI (scintillator HARP active matrix flat panel imager). The advantage of the SHARP-AMFPI is its programmable gain, which can be turned on during low dose fluoroscopy to overcome electronic noise, and turned off during high dose radiography to avoid pixel saturation. The purpose of this paper is to investigate the important design considerations for SHARP-AMFPI such as avalanche gain, which depends on both the thickness d Se and the applied electric field E Se of the HARP layer. To determine the optimal design parameter and operational conditions for HARP, we measured the E Se dependence of both avalanche gain and optical quantum efficiency of an 8 μm HARP layer. The results were used in a physical model of HARP as well as a linear cascaded model of the FPI to determine the following x-ray imaging properties in both the avalanche and nonavalanche modes as a function of E Se : (1) total gain (which is the product of avalanche gain and optical quantum efficiency); (2) linearity; (3) dynamic range; (4) gain nonuniformity resulting from thickness nonuniformity; and (5) effects of direct x-ray interaction in HARP. Our results showed that a HARP layer thickness of 8 μm can provide adequate avalanche gain and sufficient dynamic range for x-ray imaging applications to permit quantum limited operation over the range of exposures needed for radiography and fluoroscopy

  1. Software design of SHARP

    International Nuclear Information System (INIS)

    Siegel, A.; Tautges, T.; Caceres, A.; Kaushik, D.; Fischer, P.; Palmiotti, G.; Smith, M.; Ragusa, J.

    2007-01-01

    SHARP (Simulation-based High-efficiency Advanced Reactor Prototyping) is a modern suite of codes to simulate the key components of a fast reactor core. The SHARP tool-kit is organized as a collection of modules, each representing the key components of the physics to be modeled - neutron transport, thermal hydraulics, fuel/structure behavior - together with pre and post-processing for geometry definition, mesh generation, visualization, user interface, etc. The physics models are designed to make minimal possible use of lumped parameter models, homogenization, and empirical correlations in favor of more direct solution of the fundamental governing equations, when sufficient computing resources are available. Thus, one of the key design goals is to effectively leverage leadership class computing resources - viz. BG/P and Cray Supercomputers that are on the current trajectory to delivering sustained peta-flops performance. Further, the nature of the physical problem to be investigated will require either strong or weak coupling between some or all of the existing modules (e.g. operator split vs. fully coupled), while multiple implementations of each physics module, representing different algorithms, will also be required (e.g. deterministic versus Monte Carlo) for verification and to explore different physical regimes. Accomplishing these goals in the context of ultra-scalable architectures and multidisciplinary and possibly distributed development teams is a daunting task. In this paper we explain our initial lightweight and loosely coupled framework, its initial design, and a number of current open research questions in this area. (authors)

  2. Sharpening Sharpe Ratios

    OpenAIRE

    William N. Goetzmann; Jonathan E. Ingersoll Jr.; Matthew I. Spiegel; Ivo Welch

    2002-01-01

    It is now well known that the Sharpe ratio and other related reward-to-risk measures may be manipulated with option-like strategies. In this paper we derive the general conditions for achieving the maximum expected Sharpe ratio. We derive static rules for achieving the maximum Sharpe ratio with two or more options, as well as a continuum of derivative contracts. The optimal strategy has a truncated right tail and a fat left tail. We also derive dynamic rules for increasing the Sharpe ratio. O...

  3. Experimental investigation of the effect of a passive porous coating on a hypersonic boundary layer stability on a sharp cone at an angle of attack

    Science.gov (United States)

    Lukashevich, S. V.; Morozov, S. O.; Shiplyuk, A. N.

    2018-03-01

    Experimental investigations are performed to determine the effect of the passive porous coating on the stability of the hypersonic boundary layer on the cone at small angles of attack. Measurements of the pressure disturbances on the cone surface showed that, the increase of the angle of attack leads to decrease of the second-mode amplitude, when the smooth cone side is the windward side. On the leeward side the amplitude of the disturbances increase with the angle of attack until the boundary layer is laminar. It was found that the ultrasonically absorptive coating leads to the energy decrease of the second-mode disturbances on both leeward and windward side of the sharp cone.

  4. Analysis of sharpness increase by image noise

    Science.gov (United States)

    Kurihara, Takehito; Aoki, Naokazu; Kobayashi, Hiroyuki

    2009-02-01

    Motivated by the reported increase in sharpness by image noise, we investigated how noise affects sharpness perception. We first used natural images of tree bark with different amounts of noise to see whether noise enhances sharpness. Although the result showed sharpness decreased as noise amount increased, some observers seemed to perceive more sharpness with increasing noise, while the others did not. We next used 1D and 2D uni-frequency patterns as stimuli in an attempt to reduce such variability in the judgment. The result showed, for higher frequency stimuli, sharpness decreased as the noise amount increased, while sharpness of the lower frequency stimuli increased at a certain noise level. From this result, we thought image noise might reduce sharpness at edges, but be able to improve sharpness of lower frequency component or texture in image. To prove this prediction, we experimented again with the natural image used in the first experiment. Stimuli were made by applying noise separately to edge or to texture part of the image. The result showed noise, when added to edge region, only decreased sharpness, whereas when added to texture, could improve sharpness. We think it is the interaction between noise and texture that sharpens image.

  5. Intracranial investigation of a patient with nodular heterotopia and hippocampal sclerosis: dealing with a dual pathology.

    Science.gov (United States)

    Ladino, Lady Diana; Dash, Chelsea; Wu, Adam; Tellez-Zenteno, Jose Francisco

    2017-06-01

    The pre-operative assessment and surgical management of patients with dual pathology is challenging. We describe a patient with drug-resistant focal epilepsy with hippocampal sclerosis and extensive periventricular nodular heterotopia in the same hemisphere. The semiology, scalp EEG, and imaging were divergent, but the presence of focal interictal and ictal epileptic discharges of the putative ictal onset zone resulted in successful localization of the epileptogenic zone. A less aggressive resection was performed based on intracranial EEG recording. The patient has been seizure-free for three years since resection. Electroclinical hypotheses and challenges in defining the epileptogenic network are discussed.

  6. SHARP User Manual

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Y. Q. [Argonne National Lab. (ANL), Argonne, IL (United States); Shemon, E. R. [Argonne National Lab. (ANL), Argonne, IL (United States); Thomas, J. W. [Argonne National Lab. (ANL), Argonne, IL (United States); Mahadevan, Vijay S. [Argonne National Lab. (ANL), Argonne, IL (United States); Rahaman, Ronald O. [Argonne National Lab. (ANL), Argonne, IL (United States); Solberg, Jerome [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-03-31

    SHARP is an advanced modeling and simulation toolkit for the analysis of nuclear reactors. It is comprised of several components including physical modeling tools, tools to integrate the physics codes for multi-physics analyses, and a set of tools to couple the codes within the MOAB framework. Physics modules currently include the neutronics code PROTEUS, the thermal-hydraulics code Nek5000, and the structural mechanics code Diablo. This manual focuses on performing multi-physics calculations with the SHARP ToolKit. Manuals for the three individual physics modules are available with the SHARP distribution to help the user to either carry out the primary multi-physics calculation with basic knowledge or perform further advanced development with in-depth knowledge of these codes. This manual provides step-by-step instructions on employing SHARP, including how to download and install the code, how to build the drivers for a test case, how to perform a calculation and how to visualize the results. Since SHARP has some specific library and environment dependencies, it is highly recommended that the user read this manual prior to installing SHARP. Verification tests cases are included to check proper installation of each module. It is suggested that the new user should first follow the step-by-step instructions provided for a test problem in this manual to understand the basic procedure of using SHARP before using SHARP for his/her own analysis. Both reference output and scripts are provided along with the test cases in order to verify correct installation and execution of the SHARP package. At the end of this manual, detailed instructions are provided on how to create a new test case so that user can perform novel multi-physics calculations with SHARP. Frequently asked questions are listed at the end of this manual to help the user to troubleshoot issues.

  7. SHARP User Manual

    International Nuclear Information System (INIS)

    Yu, Y. Q.; Shemon, E. R.; Thomas, J. W.; Mahadevan, Vijay S.; Rahaman, Ronald O.; Solberg, Jerome

    2016-01-01

    SHARP is an advanced modeling and simulation toolkit for the analysis of nuclear reactors. It is comprised of several components including physical modeling tools, tools to integrate the physics codes for multi-physics analyses, and a set of tools to couple the codes within the MOAB framework. Physics modules currently include the neutronics code PROTEUS, the thermal-hydraulics code Nek5000, and the structural mechanics code Diablo. This manual focuses on performing multi-physics calculations with the SHARP ToolKit. Manuals for the three individual physics modules are available with the SHARP distribution to help the user to either carry out the primary multi-physics calculation with basic knowledge or perform further advanced development with in-depth knowledge of these codes. This manual provides step-by-step instructions on employing SHARP, including how to download and install the code, how to build the drivers for a test case, how to perform a calculation and how to visualize the results. Since SHARP has some specific library and environment dependencies, it is highly recommended that the user read this manual prior to installing SHARP. Verification tests cases are included to check proper installation of each module. It is suggested that the new user should first follow the step-by-step instructions provided for a test problem in this manual to understand the basic procedure of using SHARP before using SHARP for his/her own analysis. Both reference output and scripts are provided along with the test cases in order to verify correct installation and execution of the SHARP package. At the end of this manual, detailed instructions are provided on how to create a new test case so that user can perform novel multi-physics calculations with SHARP. Frequently asked questions are listed at the end of this manual to help the user to troubleshoot issues.

  8. Almost sharp quantum effects

    International Nuclear Information System (INIS)

    Arias, Alvaro; Gudder, Stan

    2004-01-01

    Quantum effects are represented by operators on a Hilbert space satisfying 0≤A≤I, and sharp quantum effects are represented by projection operators. We say that an effect A is almost sharp if A=PQP for projections P and Q. We give simple characterizations of almost sharp effects. We also characterize effects that can be written as longer products of projections. For generality we first work in the formalism of von Neumann algebras. We then specialize to the full operator algebra B(H) and to finite dimensional Hilbert spaces

  9. SHARP Multiphysics Tutorials

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Y. Q. [Argonne National Lab. (ANL), Argonne, IL (United States); Shemon, E. R. [Argonne National Lab. (ANL), Argonne, IL (United States); Mahadevan, Vijay S. [Argonne National Lab. (ANL), Argonne, IL (United States); Rahaman, Ronald O. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-02-29

    SHARP, developed under the NEAMS Reactor Product Line, is an advanced modeling and simulation toolkit for the analysis of advanced nuclear reactors. SHARP is comprised of three physics modules currently including neutronics, thermal hydraulics, and structural mechanics. SHARP empowers designers to produce accurate results for modeling physical phenomena that have been identified as important for nuclear reactor analysis. SHARP can use existing physics codes and take advantage of existing infrastructure capabilities in the MOAB framework and the coupling driver/solver library, the Coupled Physics Environment (CouPE), which utilizes the widely used, scalable PETSc library. This report aims at identifying the coupled-physics simulation capability of SHARP by introducing the demonstration example called sahex in advance of the SHARP release expected by Mar 2016. sahex consists of 6 fuel pins with cladding, 1 control rod, sodium coolant and an outer duct wall that encloses all the other components. This example is carefully chosen to demonstrate the proof of concept for solving more complex demonstration examples such as EBR II assembly and ABTR full core. The workflow of preparing the input files, running the case and analyzing the results is demonstrated in this report. Moreover, an extension of the sahex model called sahex_core, which adds six homogenized neighboring assemblies to the full heterogeneous sahex model, is presented to test homogenization capabilities in both Nek5000 and PROTEUS. Some primary information on the configuration and build aspects for the SHARP toolkit, which includes capability to auto-download dependencies and configure/install with optimal flags in an architecture-aware fashion, is also covered by this report. A step-by-step instruction is provided to help users to create their cases. Details on these processes will be provided in the SHARP user manual that will accompany the first release.

  10. SHARP Multiphysics Tutorials

    International Nuclear Information System (INIS)

    Yu, Y. Q.; Shemon, E. R.; Mahadevan, Vijay S.; Rahaman, Ronald O.

    2016-01-01

    SHARP, developed under the NEAMS Reactor Product Line, is an advanced modeling and simulation toolkit for the analysis of advanced nuclear reactors. SHARP is comprised of three physics modules currently including neutronics, thermal hydraulics, and structural mechanics. SHARP empowers designers to produce accurate results for modeling physical phenomena that have been identified as important for nuclear reactor analysis. SHARP can use existing physics codes and take advantage of existing infrastructure capabilities in the MOAB framework and the coupling driver/solver library, the Coupled Physics Environment (CouPE), which utilizes the widely used, scalable PETSc library. This report aims at identifying the coupled-physics simulation capability of SHARP by introducing the demonstration example called sahex in advance of the SHARP release expected by Mar 2016. sahex consists of 6 fuel pins with cladding, 1 control rod, sodium coolant and an outer duct wall that encloses all the other components. This example is carefully chosen to demonstrate the proof of concept for solving more complex demonstration examples such as EBR II assembly and ABTR full core. The workflow of preparing the input files, running the case and analyzing the results is demonstrated in this report. Moreover, an extension of the sahex model called sahex c ore, which adds six homogenized neighboring assemblies to the full heterogeneous sahex model, is presented to test homogenization capabilities in both Nek5000 and PROTEUS. Some primary information on the configuration and build aspects for the SHARP toolkit, which includes capability to auto-download dependencies and configure/install with optimal flags in an architecture-aware fashion, is also covered by this report. A step-by-step instruction is provided to help users to create their cases. Details on these processes will be provided in the SHARP user manual that will accompany the first release.

  11. Investigating sub-spine actin dynamics in rat hippocampal neurons with super-resolution optical imaging.

    Directory of Open Access Journals (Sweden)

    Vedakumar Tatavarty

    Full Text Available Morphological changes in dendritic spines represent an important mechanism for synaptic plasticity which is postulated to underlie the vital cognitive phenomena of learning and memory. These morphological changes are driven by the dynamic actin cytoskeleton that is present in dendritic spines. The study of actin dynamics in these spines traditionally has been hindered by the small size of the spine. In this study, we utilize a photo-activation localization microscopy (PALM-based single-molecule tracking technique to analyze F-actin movements with approximately 30-nm resolution in cultured hippocampal neurons. We were able to observe the kinematic (physical motion of actin filaments, i.e., retrograde flow and kinetic (F-actin turn-over dynamics of F-actin at the single-filament level in dendritic spines. We found that F-actin in dendritic spines exhibits highly heterogeneous kinematic dynamics at the individual filament level, with simultaneous actin flows in both retrograde and anterograde directions. At the ensemble level, movements of filaments integrate into a net retrograde flow of approximately 138 nm/min. These results suggest a weakly polarized F-actin network that consists of mostly short filaments in dendritic spines.

  12. Investigating sub-spine actin dynamics in rat hippocampal neurons with super-resolution optical imaging.

    Science.gov (United States)

    Tatavarty, Vedakumar; Kim, Eun-Ji; Rodionov, Vladimir; Yu, Ji

    2009-11-09

    Morphological changes in dendritic spines represent an important mechanism for synaptic plasticity which is postulated to underlie the vital cognitive phenomena of learning and memory. These morphological changes are driven by the dynamic actin cytoskeleton that is present in dendritic spines. The study of actin dynamics in these spines traditionally has been hindered by the small size of the spine. In this study, we utilize a photo-activation localization microscopy (PALM)-based single-molecule tracking technique to analyze F-actin movements with approximately 30-nm resolution in cultured hippocampal neurons. We were able to observe the kinematic (physical motion of actin filaments, i.e., retrograde flow) and kinetic (F-actin turn-over) dynamics of F-actin at the single-filament level in dendritic spines. We found that F-actin in dendritic spines exhibits highly heterogeneous kinematic dynamics at the individual filament level, with simultaneous actin flows in both retrograde and anterograde directions. At the ensemble level, movements of filaments integrate into a net retrograde flow of approximately 138 nm/min. These results suggest a weakly polarized F-actin network that consists of mostly short filaments in dendritic spines.

  13. The SHARP scramjet launcher

    Energy Technology Data Exchange (ETDEWEB)

    Cartland, H.; Fiske, P.; Greenwood, R.; Hargiss, D.; Heston, P.; Hinsey, N.; Hunter, J.; Massey, W.

    1995-01-10

    The worlds largest light gas gun at SHARP (Super High Altitude Research Project) is completed and in the past year has launched 9 scramjets. Typical masses and velocities are 5.9 kg at 2.8 km/sec.and 4.4 kg at 3.1 km/sec. In so doing SHARP launched the first fully functioning, hydrogen burning scramjet at mach 8. The SHARP launcher is unique in having a 4 inch diameter and 155 foot-long barrel. This enables lower acceleration launches than any other system. In addition the facility can deliver high energy projectiles to targets in the open air without having to contain the impact fragments. This allows one to track lethality test debris for several thousand feet.

  14. A microbiological study to investigate the carriage and transmission-potential of Clostridium difficile spores on single-use and reusable sharps containers.

    Science.gov (United States)

    Grimmond, Terry; Neelakanta, Anu; Miller, Barbara; Saiyed, Asif; Gill, Pam; Cadnum, Jennifer; Olmsted, Russell; Donskey, Curtis; Pate, Kimberly; Miller, Katherine

    2018-05-22

    A 2015 study matching use of disposable and reusable sharps containers (DSCs, RSCs) with Clostridium difficile infection (CDI) incidence found a decreased incidence with DSCs. We conducted microbiologic samplings and examined the literature and disease-transmission principles to evaluate the scientific feasibility of such an association. (i) 197 RSCs were sampled for C. difficile at processing facilities; (ii) RSCs were challenged with high C. difficile densities to evaluate efficacy of automated decontamination; and (iii) 50 RSCs and 50 DSCs were sampled in CDI patient rooms in 7 hospitals. Results were coupled with epidemiologic studies, clinical requirements, and chain-of-infection principles, and tests of evidence of disease transmission were applied. C. difficile spores were found on 9 of 197 (4.6%) RSCs prior to processing. Processing completely removed C. difficile. In CDI patient rooms, 4 of 50 RSCs (8.0%) and 8 of 50 DSCs (16.0%) had sub-infective counts of C. difficile (P = .27). DSCs were in permanent wall cabinets; RSCs were removed and decontaminated frequently. With C. difficile bioburden being sub-infective on both DSCs and RSCs, sharps containers being no-touch, and glove removal required after sharps disposal, we found 2 links in the chain of infection to be broken and 5 of 7 tests of evidence to be unmet. We conclude that sharps containers pose no risk of C. difficile transmission. Copyright © 2018 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

  15. Sharp spatially constrained inversion

    DEFF Research Database (Denmark)

    Vignoli, Giulio G.; Fiandaca, Gianluca G.; Christiansen, Anders Vest C A.V.C.

    2013-01-01

    We present sharp reconstruction of multi-layer models using a spatially constrained inversion with minimum gradient support regularization. In particular, its application to airborne electromagnetic data is discussed. Airborne surveys produce extremely large datasets, traditionally inverted...... by using smoothly varying 1D models. Smoothness is a result of the regularization constraints applied to address the inversion ill-posedness. The standard Occam-type regularized multi-layer inversion produces results where boundaries between layers are smeared. The sharp regularization overcomes...... inversions are compared against classical smooth results and available boreholes. With the focusing approach, the obtained blocky results agree with the underlying geology and allow for easier interpretation by the end-user....

  16. Gene Expression Profiling as a Tool to Investigate the Molecular Machinery Activated during Hippocampal Neurodegeneration Induced by Trimethyltin (TMT Administration

    Directory of Open Access Journals (Sweden)

    Maria Concetta Geloso

    2013-08-01

    Full Text Available Trimethyltin (TMT is an organotin compound exhibiting neurotoxicant effects selectively localized in the limbic system and especially marked in the hippocampus, in both experimental animal models and accidentally exposed humans. TMT administration causes selective neuronal death involving either the granular neurons of the dentate gyrus or the pyramidal cells of the Cornu Ammonis, with a different pattern of localization depending on the different species studied or the dosage schedule. TMT is broadly used to realize experimental models of hippocampal neurodegeneration associated with cognitive impairment and temporal lobe epilepsy, though the molecular mechanisms underlying the associated selective neuronal death are still not conclusively clarified. Experimental evidence indicates that TMT-induced neurodegeneration is a complex event involving different pathogenetic mechanisms, probably acting differently in animal and cell models, which include neuroinflammation, intracellular calcium overload, and oxidative stress. Microarray-based, genome-wide expression analysis has been used to investigate the molecular scenario occurring in the TMT-injured brain in different in vivo and in vitro models, producing an overwhelming amount of data. The aim of this review is to discuss and rationalize the state-of-the-art on TMT-associated genome wide expression profiles in order to identify comparable and reproducible data that may allow focusing on significantly involved pathways.

  17. Protective effects of hydroponic Teucrium polium on hippocampal neurodegeneration in ovariectomized rats.

    Science.gov (United States)

    Simonyan, K V; Chavushyan, V A

    2016-10-24

    The hippocampus is a target of ovarian hormones, and is necessary for memory. Ovarian hormone loss is associated with a progressive reduction in synaptic strength and dendritic spine. Teucrium polium has beneficial effects on learning and memory. However, it remains unknown whether Teucrium polium ameliorates hippocampal cells spike activity and morphological impairments induced by estrogen deficiency. In the present study, we investigated the effects of hydroponic Teucrium polium on hippocampal neuronal activity and morpho-histochemistry of bilateral ovariectomized (OVX) rats. Tetanic potentiation or depression with posttetanic potentiation and depression was recorded extracellularly in response to ipsilateral entorhinal cortex high frequency stimulation. In morpho-histochemical study revealing of the activity of Ca 2+ -dependent acid phosphatase was observed. In all groups (sham-operated, sham + Teucrium polium, OVX, OVX + Teucrium polium), most recorded hippocampal neurons at HFS of entorhinal cortex showed TD-PTP responses. After 8 weeks in OVX group an anomalous evoked spike activity was detected (a high percentage of typical areactive units). In OVX + Teucrium polium group a synaptic activity was revealed, indicating prevention OVX-induced degenerative alterations: balance of types of responses was close to norm and areactive units were not recorded. All recorded neurons in sham + Teucrium polium group were characterized by the highest mean frequency background and poststimulus activity. In OVX+ Teucrium polium group the hippocampal cells had recovered their size and shape in CA1 and CA3 field compared with OVX group where hippocampal cells were characterized by a sharp drop in phosphatase activity and there was a complete lack of processes reaction. Thus, Teucrium polium reduced OVX-induce neurodegenerative alterations in entorhinal cortex-hippocamp circuitry and facilitated neuronal survival by modulating activity of neurotransmitters and

  18. Intra- and interregional cortical interactions related to sharp-wave ripples and dentate spikes.

    Science.gov (United States)

    Headley, Drew B; Kanta, Vasiliki; Paré, Denis

    2017-02-01

    The hippocampus generates population events termed sharp-wave ripples (SWRs) and dentate spikes (DSs). While little is known about DSs, SWR-related hippocampal discharges during sleep are thought to replay prior waking activity, reactivating the cortical networks that encoded the initial experience. During slow-wave sleep, such reactivations likely occur during up-states, when most cortical neurons are depolarized. However, most studies have examined the relationship between SWRs and up-states measured in single neocortical regions. As a result, it is currently unclear whether SWRs are associated with particular patterns of widely distributed cortical activity. Additionally, no such investigation has been carried out for DSs. The present study addressed these questions by recording SWRs and DSs from the dorsal hippocampus simultaneously with prefrontal, sensory (visual and auditory), perirhinal, and entorhinal cortices in naturally sleeping rats. We found that SWRs and DSs were associated with up-states in all cortical regions. Up-states coinciding with DSs and SWRs exhibited increased unit activity, power in the gamma band, and intraregional gamma coherence. Unexpectedly, interregional gamma coherence rose much more strongly in relation to DSs than to SWRs. Whereas the increase in gamma coherence was time locked to DSs, that seen in relation to SWRs was not. These observations suggest that SWRs are related to the strength of up-state activation within individual regions throughout the neocortex but not so much to gamma coherence between different regions. Perhaps more importantly, DSs coincided with stronger periods of interregional gamma coherence, suggesting that they play a more important role than previously assumed. Off-line cortico-hippocampal interactions are thought to support memory consolidation. We surveyed the relationship between hippocampal sharp-wave ripples (SWRs) and dentate spikes (DSs) with up-states across multiple cortical regions. SWRs and

  19. Stereological Investigation of the Effects of Treadmill Running Exercise on the Hippocampal Neurons in Middle-Aged APP/PS1 Transgenic Mice.

    Science.gov (United States)

    Chao, Fenglei; Jiang, Lin; Zhang, Yi; Zhou, Chunni; Zhang, Lei; Tang, Jing; Liang, Xin; Qi, Yingqiang; Zhu, Yanqing; Ma, Jing; Tang, Yong

    2018-01-01

    The risk of cognitive decline during Alzheimer's disease (AD) can be reduced if physical activity is maintained; however, the specific neural events underlying this beneficial effect are still uncertain. To quantitatively investigate the neural events underlying the effect of running exercise on middle-aged AD subjects, 12-month-old male APP/PS1 mice were randomly assigned to a control group or running group, and age-matched non-transgenic littermates were used as a wild-type group. AD running group mice were subjected to a treadmill running protocol (regular and moderate intensity) for four months. Spatial learning and memory abilities were assessed using the Morris water maze. Hippocampal amyloid plaques were observed using Thioflavin S staining and immunohistochemistry. Hippocampal volume, number of neurons, and number of newborn cells (BrdU+ cells) in the hippocampus were estimated using stereological techniques, and newborn neurons were observed using double-labelling immunofluorescence. Marked neuronal loss in both the CA1 field and dentate gyrus (DG) and deficits in both the neurogenesis and survival of new neurons in the DG of middle-aged APP/PS1 mice were observed. Running exercise could improve the spatial learning and memory abilities, reduce amyloid plaques in the hippocampi, delay neuronal loss, induce neurogenesis, and promote the survival of newborn neurons in the DG of middle-aged APP/PS1 mice. Exercise-induced protection of neurons and adult neurogenesis within the DG might be part of the important structural basis of the improved spatial learning and memory abilities observed in AD mice.

  20. Computational analysis of network activity and spatial reach of sharp wave-ripples.

    Directory of Open Access Journals (Sweden)

    Sadullah Canakci

    Full Text Available Network oscillations of different frequencies, durations and amplitudes are hypothesized to coordinate information processing and transfer across brain areas. Among these oscillations, hippocampal sharp wave-ripple complexes (SPW-Rs are one of the most prominent. SPW-Rs occurring in the hippocampus are suggested to play essential roles in memory consolidation as well as information transfer to the neocortex. To-date, most of the knowledge about SPW-Rs comes from experimental studies averaging responses from neuronal populations monitored by conventional microelectrodes. In this work, we investigate spatiotemporal characteristics of SPW-Rs and how microelectrode size and distance influence SPW-R recordings using a biophysical model of hippocampus. We also explore contributions from neuronal spikes and synaptic potentials to SPW-Rs based on two different types of network activity. Our study suggests that neuronal spikes from pyramidal cells contribute significantly to ripples while high amplitude sharp waves mainly arise from synaptic activity. Our simulations on spatial reach of SPW-Rs show that the amplitudes of sharp waves and ripples exhibit a steep decrease with distance from the network and this effect is more prominent for smaller area electrodes. Furthermore, the amplitude of the signal decreases strongly with increasing electrode surface area as a result of averaging. The relative decrease is more pronounced when the recording electrode is closer to the source of the activity. Through simulations of field potentials across a high-density microelectrode array, we demonstrate the importance of finding the ideal spatial resolution for capturing SPW-Rs with great sensitivity. Our work provides insights on contributions from spikes and synaptic potentials to SPW-Rs and describes the effect of measurement configuration on LFPs to guide experimental studies towards improved SPW-R recordings.

  1. Experimental investigation on spontaneously active hippocampal cultures recorded by means of high-density MEAs: analysis of the spatial resolution effects

    Directory of Open Access Journals (Sweden)

    Alessandro Maccione

    2010-05-01

    Full Text Available Based on experiments performed with high-resolution Active Pixel Sensor microelectrode arrays (APS-MEAs coupled with spontaneously active hippocampal cultures, this work investigates the spatial resolution effects of the neuroelectronic interface on the analysis of the recorded electrophysiological signals. The adopted methodology consists, first, in recording the spontaneous activity at the highest spatial resolution (inter-electrode separation of 21 µm from the whole array of 4096 microelectrodes. Then, the full resolution dataset is spatially down sampled in order to evaluate the effects on raster plot representation, array-wide spike rate (AWSR, mean firing rate (MFR and mean bursting rate (MBR. Furthermore, the effects of the array-to-network relative position are evaluated by shifting a subset of equally spaced electrodes on the entire recorded area. Results highlight that MFR and MBR are particularly influenced by the spatial resolution provided by the neuroelectronic interface. On high-resolution large MEAs, such analysis better represent the time-based parameterization of the network dynamics. Finally, this work suggest interesting capabilities of high-resolution MEAs for spatial-based analysis in dense and low-dense neuronal preparation for investigating signalling at both local and global neuronal circuitries.

  2. Both oophorectomy and obesity impaired solely hippocampal-dependent memory via increased hippocampal dysfunction.

    Science.gov (United States)

    Mantor, Duangkamol; Pratchayasakul, Wasana; Minta, Wanitchaya; Sutham, Wissuta; Palee, Siripong; Sripetchwandee, Jirapas; Kerdphoo, Sasiwan; Jaiwongkum, Thidarat; Sriwichaiin, Sirawit; Krintratun, Warunsorn; Chattipakorn, Nipon; Chattipakorn, Siriporn C

    2018-04-17

    Our previous study demonstrated that obesity aggravated peripheral insulin resistance and brain dysfunction in the ovariectomized condition. Conversely, the effect of obesity followed by oophorectomy on brain oxidative stress, brain apoptosis, synaptic function and cognitive function, particularly in hippocampal-dependent and hippocampal-independent memory, has not been investigated. Our hypothesis was that oophorectomy aggravated metabolic impairment, brain dysfunction and cognitive impairment in obese rats. Thirty-two female rats were fed with either a normal diet (ND, n = 16) or a high-fat diet (HFD, n = 16) for a total of 20 weeks. At week 13, rats in each group were subdivided into sham and ovariectomized subgroups (n = 8/subgroup). At week 20, all rats were tested for hippocampal-dependent and hippocampal-independent memory by using Morris water maze test (MWM) and Novel objective recognition (NOR) tests, respectively. We found that the obese-insulin resistant condition occurred in sham-HFD-fed rats (HFS), ovariectomized-ND-fed rats (NDO), and ovariectomized-HFD-fed rats (HFO). Increased hippocampal oxidative stress level, increased hippocampal apoptosis, increased hippocampal synaptic dysfunction, decreased hippocampal estrogen level and impaired hippocampal-dependent memory were observed in HFS, NDO, and HFO rats. However, the hippocampal-independent memory, cortical estrogen levels, cortical ROS production, and cortical apoptosis showed no significant difference between groups. These findings suggested that oophorectomy and obesity exclusively impaired hippocampal-dependent memory, possibly via increased hippocampal dysfunction. Nonetheless, oophorectomy did not aggravate these deleterious effects under conditions of obesity. Copyright © 2017. Published by Elsevier Inc.

  3. Abnormalities of hippocampal-cortical connectivity in temporal lobe epilepsy patients with hippocampal sclerosis

    Science.gov (United States)

    Li, Wenjing; He, Huiguang; Lu, Jingjing; Wang, Chunheng; Li, Meng; Lv, Bin; Jin, Zhengyu

    2011-03-01

    Hippocampal sclerosis (HS) is the most common damage seen in the patients with temporal lobe epilepsy (TLE). In the present study, the hippocampal-cortical connectivity was defined as the correlation between the hippocampal volume and cortical thickness at each vertex throughout the whole brain. We aimed to investigate the differences of ipsilateral hippocampal-cortical connectivity between the unilateral TLE-HS patients and the normal controls. In our study, the bilateral hippocampal volumes were first measured in each subject, and we found that the ipsilateral hippocampal volume significantly decreased in the left TLE-HS patients. Then, group analysis showed significant thinner average cortical thickness of the whole brain in the left TLE-HS patients compared with the normal controls. We found significantly increased ipsilateral hippocampal-cortical connectivity in the bilateral superior temporal gyrus, the right cingulate gyrus and the left parahippocampal gyrus of the left TLE-HS patients, which indicated structural vulnerability related to the hippocampus atrophy in the patient group. However, for the right TLE-HS patients, no significant differences were found between the patients and the normal controls, regardless of the ipsilateral hippocampal volume, the average cortical thickness or the patterns of hippocampal-cortical connectivity, which might be related to less atrophies observed in the MRI scans. Our study provided more evidence for the structural abnormalities in the unilateral TLE-HS patients.

  4. Assessment of Sharp Injuries among Cameroonian Dental ...

    African Journals Online (AJOL)

    2010-07-10

    Jul 10, 2010 ... prophylaxis practice and methods of sharps disposal. Results ... training on guidelines adherence, safe recapping and disposal systems. Abstract ... of sharps in oral healthcare delivery and restricted nar- row field of surgery ...

  5. Lacosamide and Levetiracetam Have No Effect on Sharp-Wave Ripple Rate.

    Science.gov (United States)

    Kudlacek, Jan; Chvojka, Jan; Posusta, Antonin; Kovacova, Lubica; Hong, Seung Bong; Weiss, Shennan; Volna, Kamila; Marusic, Petr; Otahal, Jakub; Jiruska, Premysl

    2017-01-01

    Pathological high-frequency oscillations are a novel marker used to improve the delineation of epileptogenic tissue and, hence, the outcome of epilepsy surgery. Their practical clinical utilization is curtailed by the inability to discriminate them from physiological oscillations due to frequency overlap. Although it is well documented that pathological HFOs are suppressed by antiepileptic drugs (AEDs), the effect of AEDs on normal HFOs is not well known. In this experimental study, we have explored whether physiological HFOs (sharp-wave ripples) of hippocampal origin respond to AED treatment. The results show that application of a single dose of levetiracetam or lacosamide does not reduce the rate of sharp-wave ripples. In addition, it seems that these new generation drugs do not negatively affect the cellular and network mechanisms involved in sharp-wave ripple generation, which may provide a plausible explanation for the absence of significant negative effects on cognitive functions of these drugs, particularly on memory.

  6. Sharps injury reduction using a sharps container with enhanced engineering: a 28 hospital nonrandomized intervention and cohort study.

    Science.gov (United States)

    Grimmond, Terry; Bylund, Suzann; Anglea, Candace; Beeke, Lou; Callahan, Angela; Christiansen, Erik; Flewelling, Kelly; McIntosh, Kathleen; Richter, Kay; Vitale, Monica

    2010-12-01

    The decrease in reported sharps injuries (SI) in the United States has markedly slowed. Additional devices and strategies need investigation. Sharps containers are associated with SI, and more than 90% of these injuries are related to container design. This study addresses the hypothesis that containers with enhanced engineering can reduce SI. In a before/after intervention study from 2006 to 2008, we examined the impact of conversion to a sharps container with enhanced engineering (the Device) on SI categories in 14 Ascension Health hospitals (study group). The Device's safety features included large horizontal aperture, sensitive counterbalanced door, large atrium, and passive overfill prevention. Study group results were also compared with a control cohort of 14 contemporaneous size-matched, Ascension Health hospitals (control group). The Device was associated with significant reductions in after-procedure (-30%), disposal-related (-57%), and container-associated (-81%) SI in the study group. No significant reductions occurred in container-associated sharps injuries in the control group. Hospitals using the Device had significantly fewer total SI than control hospitals. Enhanced aperture design can significantly reduce container-associated sharps injuries. Other factors contributing to reduced injuries may include 1-hand deposit, safe closure, hand restriction, and preassembly. These results, from a country where sharps safety devices are widespread, are particularly applicable to countries where safety devices are not extensively used. Copyright © 2010 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

  7. Memory impairment in multiple sclerosis: Relevance of hippocampal activation and hippocampal connectivity

    NARCIS (Netherlands)

    Hulst, H.E.; Schoonheim, M.M.; van Geest, Q.; Uitdehaag, B.M.J.; Barkhof, F.; Geurts, J.J.G.

    2015-01-01

    Background: Memory impairment is frequent in multiple sclerosis (MS), but it is unclear what functional brain changes underlie this cognitive deterioration. Objective: To investigate functional hippocampal activation and connectivity, in relation to memory performance in MS. Methods: Structural and

  8. Asymptotic Sharpness of Bounds on Hypertrees

    Directory of Open Access Journals (Sweden)

    Lin Yi

    2017-08-01

    Full Text Available The hypertree can be defined in many different ways. Katona and Szabó introduced a new, natural definition of hypertrees in uniform hypergraphs and investigated bounds on the number of edges of the hypertrees. They showed that a k-uniform hypertree on n vertices has at most (nk−1$\\left( {\\matrix{n \\cr {k - 1} } } \\right$ edges and they conjectured that the upper bound is asymptotically sharp. Recently, Szabó verified that the conjecture holds by recursively constructing an infinite sequence of k-uniform hypertrees and making complicated analyses for it. In this note we give a short proof of the conjecture by directly constructing a sequence of k-uniform k-hypertrees.

  9. Assessment of sharps waste management practices in a referral ...

    African Journals Online (AJOL)

    hospital (40.8 kg/day) was higher than values reported in district hospitals, but the sharps waste ... Key words: Sharps waste, sharps waste container, overfilled safety box, sharps waste proportion, .... requirements and availability of technology.

  10. Mechanisms of sharp wave initiation and ripple generation.

    Science.gov (United States)

    Schlingloff, Dániel; Káli, Szabolcs; Freund, Tamás F; Hájos, Norbert; Gulyás, Attila I

    2014-08-20

    Replay of neuronal activity during hippocampal sharp wave-ripples (SWRs) is essential in memory formation. To understand the mechanisms underlying the initiation of irregularly occurring SWRs and the generation of periodic ripples, we selectively manipulated different components of the CA3 network in mouse hippocampal slices. We recorded EPSCs and IPSCs to examine the buildup of neuronal activity preceding SWRs and analyzed the distribution of time intervals between subsequent SWR events. Our results suggest that SWRs are initiated through a combined refractory and stochastic mechanism. SWRs initiate when firing in a set of spontaneously active pyramidal cells triggers a gradual, exponential buildup of activity in the recurrent CA3 network. We showed that this tonic excitatory envelope drives reciprocally connected parvalbumin-positive basket cells, which start ripple-frequency spiking that is phase-locked through reciprocal inhibition. The synchronized GABA(A) receptor-mediated currents give rise to a major component of the ripple-frequency oscillation in the local field potential and organize the phase-locked spiking of pyramidal cells. Optogenetic stimulation of parvalbumin-positive cells evoked full SWRs and EPSC sequences in pyramidal cells. Even with excitation blocked, tonic driving of parvalbumin-positive cells evoked ripple oscillations. Conversely, optogenetic silencing of parvalbumin-positive cells interrupted the SWRs or inhibited their occurrence. Local drug applications and modeling experiments confirmed that the activity of parvalbumin-positive perisomatic inhibitory neurons is both necessary and sufficient for ripple-frequency current and rhythm generation. These interneurons are thus essential in organizing pyramidal cell activity not only during gamma oscillation, but, in a different configuration, during SWRs. Copyright © 2014 the authors 0270-6474/14/3411385-14$15.00/0.

  11. Summer High School Apprenticeship Research Program (SHARP)

    Science.gov (United States)

    1997-01-01

    The summer of 1997 will not only be noted by NASA for the mission to Mars by the Pathfinder but also for the 179 brilliant apprentices that participated in the SHARP Program. Apprentice participation increased 17% over last year's total of 153 participants. As indicated by the End-of-the-Program Evaluations, 96% of the programs' participants rated the summer experience from very good to excellent. The SHARP Management Team began the year by meeting in Cocoa Beach, Florida for the annual SHARP Planning Conference. Participants strengthened their Education Division Computer Aided Tracking System (EDCATS) skills, toured the world-renowned Kennedy Space Center, and took a journey into space during the Alien Encounter Exercise. The participants returned to their Centers with the same goals and objectives in mind. The 1997 SHARP Program goals were: (1) Utilize NASA's mission, unique facilities and specialized workforce to provide exposure, education, and enrichment experiences to expand participants' career horizons and inspire excellence in formal education and lifelong learning. (2) Develop and implement innovative education reform initiatives which support NASA's Education Strategic Plan and national education goals. (3) Utilize established statistical indicators to measure the effectiveness of SHARP's program goals. (4) Explore new recruiting methods which target the student population for which SHARP was specifically designed. (5) Increase the number of participants in the program. All of the SHARP Coordinators reported that the goals and objectives for the overall program as well as their individual program goals were achieved. Some of the goals and objectives for the Centers were: (1) To increase the students' awareness of science, mathematics, engineering, and computer technology; (2) To provide students with the opportunity to broaden their career objectives; and (3) To expose students to a variety of enrichment activities. Most of the Center goals and

  12. Knowledge Base Editor (SharpKBE)

    Science.gov (United States)

    Tikidjian, Raffi; James, Mark; Mackey, Ryan

    2007-01-01

    The SharpKBE software provides a graphical user interface environment for domain experts to build and manage knowledge base systems. Knowledge bases can be exported/translated to various target languages automatically, including customizable target languages.

  13. Investigating the Interactive Effects of Sex Steroid Hormones and Brain-Derived Neurotrophic Factor during Adolescence on Hippocampal NMDA Receptor Expression

    Directory of Open Access Journals (Sweden)

    Cushla R. McCarthny

    2018-01-01

    Full Text Available Sex steroid hormones have neuroprotective properties which may be mediated by brain-derived neurotrophic factor (BDNF. This study sought to determine the interactive effects of preadolescent hormone manipulation and BDNF heterozygosity (+/− on hippocampal NMDA-R expression. Wild-type and BDNF+/− mice were gonadectomised, and females received either 17β-estradiol or progesterone treatment, while males received either testosterone or dihydrotestosterone (DHT treatment. Dorsal (DHP and ventral hippocampus (VHP were dissected, and protein expression of GluN1, GluN2A, GluN2B, and PSD-95 was assessed by Western blot analysis. Significant genotype × OVX interactions were found for GluN1 and GluN2 expression within the DHP of female mice, suggesting modulation of select NMDA-R levels by female sex hormones is mediated by BDNF. Furthermore, within the DHP BDNF+/− mice show a hypersensitive response to hormone treatment on GluN2 expression which may result from upstream alterations in TrkB phosphorylation. In contrast to the DHP, the VHP showed no effects of hormone manipulation but significant effects of genotype on NMDA-R expression. Castration had no effect on NMDA-R expression; however, androgen treatment had selective effects on GluN2B. These data show case distinct, interactive roles for sex steroid hormones and BDNF in the regulation of NMDA-R expression that are dependent on dorsal versus ventral hippocampal region.

  14. PEROLD-SHARPE REBALANCING STRATEGIES IN PRACTICE

    Directory of Open Access Journals (Sweden)

    Valentyn Khokhlov

    2016-11-01

    Full Text Available The purpose of this paper is to investigate the different strategies for portfolio rebalanc-ing (buy-and-hold, constant weights, and constant-proportion portfolio insurance (CPPI suggested by Perold and Sharpe in a reallife environment using the actual market data and considering trans-action costs. Methodology. Exchange-traded funds were used to represent asset classes, and actual market prices in 2007-2015 for the ETFs used to conduct the research. The Monte-Carlo simulations were used to generate 400 portfolios over 3 different time horizons in order to get a representative sample. Two actual fee structures were used from the leading U.S. brokerage firms. Results of the portfolio dynamics research show outperformance of CPPI over other strategies on holding periods over 36 months, and on shorter time horizons CPPI and constant weights strategies clearly dominate over buyand- hold strategy. Contrary to the previous conclusions by Perold and Sharpe, there was no definite link between the stock market dynamics or volatility and the preferred strategy. We also see that after a bull market period the CPPI portfolio allocation shifts to 100% equity. The portfolio turnover is typically higher and much more dispersed for CPPI strategy than for constant weights strategy. We also found a strong negative correlation between the CPPI portfolio turnover and the initial equity allocation, whereas for constant weights strategy the turnover is higher at 50% allocation to both stocks and bonds. Practical implications. The strategy choice is shown to be more a matter of the holding period; CPPI seems the best choice over longer periods. Contrary to the widespread perception, our research shows that brokerage fees has not had a material influence on the simulated portfolio performance and, thus, should not be a factor for choosing a strategy. Originality/value. Unlike previous studies in this area that focused on analytical derivation based on sample statistics

  15. Functional imaging of sleep vertex sharp transients.

    Science.gov (United States)

    Stern, John M; Caporro, Matteo; Haneef, Zulfi; Yeh, Hsiang J; Buttinelli, Carla; Lenartowicz, Agatha; Mumford, Jeanette A; Parvizi, Josef; Poldrack, Russell A

    2011-07-01

    The vertex sharp transient (VST) is an electroencephalographic (EEG) discharge that is an early marker of non-REM sleep. It has been recognized since the beginning of sleep physiology research, but its source and function remain mostly unexplained. We investigated VST generation using functional MRI (fMRI). Simultaneous EEG and fMRI were recorded from seven individuals in drowsiness and light sleep. VST occurrences on EEG were modeled with fMRI using an impulse function convolved with a hemodynamic response function to identify cerebral regions correlating to the VSTs. A resulting statistical image was thresholded at Z>2.3. Two hundred VSTs were identified. Significantly increased signal was present bilaterally in medial central, lateral precentral, posterior superior temporal, and medial occipital cortex. No regions of decreased signal were present. The regions are consistent with electrophysiologic evidence from animal models and functional imaging of human sleep, but the results are specific to VSTs. The regions principally encompass the primary sensorimotor cortical regions for vision, hearing, and touch. The results depict a network comprising the presumed VST generator and its associated regions. The associated regions functional similarity for primary sensation suggests a role for VSTs in sensory experience during sleep. Copyright © 2011 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  16. Time-clustering behavior of sharp fluctuation sequences in Chinese stock markets

    International Nuclear Information System (INIS)

    Yuan Ying; Zhuang Xintian; Liu Zhiying; Huang Weiqiang

    2012-01-01

    Sharp fluctuations (in particular, extreme fluctuations) of asset prices have a great impact on financial markets and risk management. Therefore, investigating the time dynamics of sharp fluctuation is a challenge in the financial fields. Using two different representations of the sharp fluctuations (inter-event times and series of counts), the time clustering behavior in the sharp fluctuation sequences of stock markets in China is studied with several statistical tools, including coefficient of variation, Allan Factor, Fano Factor as well as R/S (rescaled range) analysis. All of the empirical results indicate that the time dynamics of the sharp fluctuation sequences can be considered as a fractal process with a high degree of time-clusterization of the events. It can help us to get a better understanding of the nature and dynamics of sharp fluctuation of stock price in stock markets.

  17. Stress, depression and hippocampal damage

    Indian Academy of Sciences (India)

    Amongst the prime targets of stress in the brain is the hippocampus, which has high receptor ... effects on different hippocampal subfields (McEwen 1999). ... disorders, and decreases in hippocampal volume have been observed in patients of ...

  18. A note on trader Sharpe Ratios.

    Science.gov (United States)

    Coates, John M; Page, Lionel

    2009-11-25

    Traders in the financial world are assessed by the amount of money they make and, increasingly, by the amount of money they make per unit of risk taken, a measure known as the Sharpe Ratio. Little is known about the average Sharpe Ratio among traders, but the Efficient Market Hypothesis suggests that traders, like asset managers, should not outperform the broad market. Here we report the findings of a study conducted in the City of London which shows that a population of experienced traders attain Sharpe Ratios significantly higher than the broad market. To explain this anomaly we examine a surrogate marker of prenatal androgen exposure, the second-to-fourth finger length ratio (2D:4D), which has previously been identified as predicting a trader's long term profitability. We find that it predicts the amount of risk taken by traders but not their Sharpe Ratios. We do, however, find that the traders' Sharpe Ratios increase markedly with the number of years they have traded, a result suggesting that learning plays a role in increasing the returns of traders. Our findings present anomalous data for the Efficient Markets Hypothesis.

  19. A note on trader Sharpe Ratios.

    Directory of Open Access Journals (Sweden)

    John M Coates

    Full Text Available Traders in the financial world are assessed by the amount of money they make and, increasingly, by the amount of money they make per unit of risk taken, a measure known as the Sharpe Ratio. Little is known about the average Sharpe Ratio among traders, but the Efficient Market Hypothesis suggests that traders, like asset managers, should not outperform the broad market. Here we report the findings of a study conducted in the City of London which shows that a population of experienced traders attain Sharpe Ratios significantly higher than the broad market. To explain this anomaly we examine a surrogate marker of prenatal androgen exposure, the second-to-fourth finger length ratio (2D:4D, which has previously been identified as predicting a trader's long term profitability. We find that it predicts the amount of risk taken by traders but not their Sharpe Ratios. We do, however, find that the traders' Sharpe Ratios increase markedly with the number of years they have traded, a result suggesting that learning plays a role in increasing the returns of traders. Our findings present anomalous data for the Efficient Markets Hypothesis.

  20. Hippocampal network oscillations in APP/APLP2-deficient mice.

    Directory of Open Access Journals (Sweden)

    Xiaomin Zhang

    Full Text Available The physiological function of amyloid precursor protein (APP and its two homologues APP-like protein 1 (APLP1 and 2 (APLP2 is largely unknown. Previous work suggests that lack of APP or APLP2 impairs synaptic plasticity and spatial learning. There is, however, almost no data on the role of APP or APLP at the network level which forms a critical interface between cellular functions and behavior. We have therefore investigated memory-related synaptic and network functions in hippocampal slices from three lines of transgenic mice: APPsα-KI (mice expressing extracellular fragment of APP, corresponding to the secreted APPsα ectodomain, APLP2-KO, and combined APPsα-KI/APLP2-KO (APPsα-DM for "double mutants". We analyzed two prominent patterns of network activity, gamma oscillations and sharp-wave ripple complexes (SPW-R. Both patterns were generally preserved in all strains. We find, however, a significantly reduced frequency of gamma oscillations in CA3 of APLP2-KO mice in comparison to APPsα-KI and WT mice. Network activity, basic synaptic transmission and short-term plasticity were unaltered in the combined mutants (APPsα-DM which showed, however, reduced long-term potentiation (LTP. Together, our data indicate that APLP2 and the intracellular domain of APP are not essential for coherent activity patterns in the hippocampus, but have subtle effects on synaptic plasticity and fine-tuning of network oscillations.

  1. Vagus Nerve Stimulation Applied with a Rapid Cycle Has More Profound Influence on Hippocampal Electrophysiology Than a Standard Cycle.

    NARCIS (Netherlands)

    Larsen, L.E.; Wadman, W.J.; Marinazzo, D.; van Mierlo, P.; Delbeke, J.; Daelemans, S.; Sprengers, M.; Thyrion, L.; Van Lysebettens, W.; Carrette, E.; Boon, P; Vonck, K.; Raedt, R.

    2016-01-01

    Although vagus nerve stimulation (VNS) is widely used, therapeutic mechanisms and optimal stimulation parameters remain elusive. In the present study, we investigated the effect of VNS on hippocampal field activity and compared the efficiency of different VNS paradigms. Hippocampal

  2. The Sharp Lepton Quandary: Reasonable cautions

    International Nuclear Information System (INIS)

    Griffin, J.J.

    1996-02-01

    Surprisingly, the new APEX experiment designed to measure a definitive invariant mass distribution of the sharp pairs previously reported in similar heavy ion studies reports null results. Although it asserts no direct conflict with any data reported by EPOS/I, the APEX report nevertheless seems to have encouraged the view that the earlier (EPOS/I) observations were erroneous, and by extrapolation, that the whole (e + e - ) Puzzle data set can be dismissed as an unfortunate set of physically meaningless statistical fluctuations. We wish here to argue that such sweeping judgments should be postponed, on the grounds that (1) the published APEX analysis of their data is self-inconsistent, and can therefore sustain no valid inference about the EPOS/I data; (2) the data which supports the occurrence of sharp (e + e - ) pairs is much more extensive than the EPOS/I data, so that the APEX surprise must be considered as one episode in a much longer struggle finally to settle the question of whether these weak signals are significant or not; (3) a qualitative phenomenology exists which can organize the whole range of data of the Sharp Lepton Problem, and which suggests that (4) certain low energy (and low cost) experiments ought to be explored for their creation of sharp pairs; as follows: the study of pairs emitted following scattering of few MeV electron and positron beams from neutral U and Th atoms, and the study of pairs emitted following the resonant absorption of photons of 1.5 to 2.0 MeV on U and Th atoms. We first present a brief data-oriented history of the Sharp Lepton Problem, to show that no single unexpected null result can provide an adequate basis for rejecting the great range and quantity of data which evidences the occurrence of sharp pairs. We then consider the Quadronium Composite Particle Scenario for these processes, and its Quantum Electrodynamical implications, in support of the above recommendations

  3. PRACTICES FOR PREVENTION NEEDLESTICK AND SHARPS INJURIES AMONG NURSING STUDENTS

    Directory of Open Access Journals (Sweden)

    Anh Tran Thi Quynh

    2017-07-01

    Full Text Available Background: Needlestick and sharp injuries are a serious hazard in any health care setting for health care workers and students during clinical practice. Thus, the efforts to prevent the needlestick and sharps injuries are needed and considered a part of the routine practice. Objective: This study aimed to investigate the frequency of nursing students in doing the correct practice in prevention needlestick and sharps injuries. Methods: This cross- sectional study was conducted between 2013 and 2014 in nursing students of Tien Giang Medical College who participated in clinical practice. There were 360 students participated in the study using simple random sampling. Data were collected using the practical assessment checklist and demographic characteristics questionnaire. Data were processed using STATA 12.0, and analyzed using Chi-square and Fisher test. Results: The students who did general practice correctly accounted for 52.50%, and those who did practice incorrectly was 47.5%. The students who used gauze or wool wrap in inhaler were 59.7%, wearing gloves in practice (39.2%, do not disassemble needles from syringes after injection 50%, and removing needles into barrel after injection (65.6%. There was statistically significant relationship between time of participation in clinical practice and correct practice with p-value 0.04 (<0.05 Conclusion: The correct practice of nursing students related to the prevention of needlestick and sharps injuries remains low. There was a significant relationship between time of participation in clinical practice and correct nursing practice. It is suggested that students must be taught about the risk of infection at the beginning of clinical practice, and constantly reminded throughout the learning process, especially for injection safety awareness, knowledge and techniques about the risk of transmission of HBV, HCV and HIV by sharp objects in the healthcare facility.

  4. Hippocampal Abnormalities after Prolonged Febrile Convulsions

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2003-11-01

    Full Text Available Hippocampal volume and T2 relaxation times were determined in an MRI study of 14 children with prolonged febrile convulsions (PFC who were investigated, 1 within 5 days of a PFC, and 2 at follow-up 4-8 months after the acute study, at the Institute of Child Health, University College, and Great Ormond Street Hospital, London, UK.

  5. Acoustic streaming of a sharp edge.

    Science.gov (United States)

    Ovchinnikov, Mikhail; Zhou, Jianbo; Yalamanchili, Satish

    2014-07-01

    Anomalous acoustic streaming is observed emanating from sharp edges of solid bodies that are vibrating in fluids. The streaming velocities can be orders of magnitude higher than expected from the Rayleigh streaming at similar amplitudes of vibration. Acoustic velocity of fluid relative to a solid body diverges at a sharp edge, giving rise to a localized time-independent body force acting on the fluid. This force results in a formation of a localized jet. Two-dimensional numerical simulations are performed to predict acoustic streaming for low amplitude vibration using two methods: (1) Steady-state solution utilizing perturbation theory and (2) direct transient solution of the Navier-Stokes equations. Both analyses agree with each other and correctly predict the streaming of a sharp-edged vibrating blade measured experimentally. The origin of the streaming can be attributed to the centrifugal force of the acoustic fluid flow around a sharp edge. The dependence of this acoustic streaming on frequency and velocity is examined using dimensional analysis. The dependence law is devised and confirmed by numerical simulations.

  6. Sharp and the Jules Verne Launcher

    Science.gov (United States)

    Hunter, John; Cartland, Harry

    1996-03-01

    Lawrence Livermore National Laboratory (LLNL) has built the worlds largest hydrogen gas gun called SHARP, (Super High Altitude Research Project). Originally designed to launch 5 kg to a 450 km altitude, SHARP is configured horizontally at Site 300 in Tracy, California. SHARP is successfully delivering 5 kg scramjets at Mach 9 in aerophysics tests. Some of the results of the scramjet tests are enlightening and are presented insofar as they are relevant to future launches into space. Using a light gas gun to launch payloads into orbit has been analyzed. We look at LEO (Low Earth Orbit), GEO (Geosynchronous Earth Orbit), and LO (Lunar Orbit). We present a conceptual design for a large light gas gun called the Jules Verne Launcher (JVL). The JVL can deliver 3.3 metric tons to a 500 km low earth orbit. We anticipate one launch per day. We present the history of light gas guns, the SHARP design and performance, and the JVL design. Another section is devoted to the vehicle environment and resultant design. Lastly, we present a cost analysis. Our results indicated that the JVL will be able to deliver 1000 metric tons of payload to LEO yearly. The cost will be 5% of the best US rocket delivery cost. This technology will enable the next phase of man's exploration of space.

  7. SHARP {Summer High School Apprenticeship Research Program}

    Science.gov (United States)

    Glasco, Deborah (Technical Monitor)

    2002-01-01

    The Year 2002 was another successful year for SHARP. Even after 22 years of SHARP, the Program continues to grow. There were 12 NASA Field Installations with a total of 210 apprentices who participated in the summer 2002 Program supported by 215 mentors in the fields of science and engineering. The apprentices were chosen from a pool of 1,379 applicants. This was a record year for applications exceeding the previous year by over 60%. For the second consecutive year, the number of female participants exceeded the number of males with 53% female and 47% male participants in the program. The main thrust of our recruiting efforts is still focused on underrepresented populations; especially African American, Hispanic, and Native American. At the conclusion of the summer program, most SHARP Apprentices indicated on the EDCATS that they would be interested in pursuing careers in Aerospace (56.2%) while the second largest career choice was a job at NASA (45.7%). The smallest number (11.9%) were interested in careers in the government. The table of responses is listed in the Appendix. Once again this year we were fortunate in that the SHARP COTR, Ms. Deborah Glasco, gained the support of MURED funding sources at NASA to fully fund additional apprentices and boost the number of apprentices to 210.

  8. Optogenetic activation of septal cholinergic neurons suppresses sharp wave ripples and enhances theta oscillations in the hippocampus.

    Science.gov (United States)

    Vandecasteele, Marie; Varga, Viktor; Berényi, Antal; Papp, Edit; Barthó, Péter; Venance, Laurent; Freund, Tamás F; Buzsáki, György

    2014-09-16

    Theta oscillations in the limbic system depend on the integrity of the medial septum. The different populations of medial septal neurons (cholinergic and GABAergic) are assumed to affect different aspects of theta oscillations. Using optogenetic stimulation of cholinergic neurons in ChAT-Cre mice, we investigated their effects on hippocampal local field potentials in both anesthetized and behaving mice. Cholinergic stimulation completely blocked sharp wave ripples and strongly suppressed the power of both slow oscillations (0.5-2 Hz in anesthetized, 0.5-4 Hz in behaving animals) and supratheta (6-10 Hz in anesthetized, 10-25 Hz in behaving animals) bands. The same stimulation robustly increased both the power and coherence of theta oscillations (2-6 Hz) in urethane-anesthetized mice. In behaving mice, cholinergic stimulation was less effective in the theta (4-10 Hz) band yet it also increased the ratio of theta/slow oscillation and theta coherence. The effects on gamma oscillations largely mirrored those of theta. These findings show that medial septal cholinergic activation can both enhance theta rhythm and suppress peri-theta frequency bands, allowing theta oscillations to dominate.

  9. End-point sharpness in thermometric titrimetry.

    Science.gov (United States)

    Tyrrell, H J

    1967-07-01

    It is shown that the sharpness of an end-point in a thermometric titration where the simple reaction A + B right harpoon over left harpoon AB takes place, depends on Kc(A') where K is the equilibrium constant for the reaction, and c(A') is the total concentration of the titrand (A) in the reaction mixture. The end-point is sharp if, (i) the enthalpy change in the reaction is not negligible, and (ii) Kc(A') > 10(3). This shows that it should, for example, be possible to titrate 0.1 M acid, pK(A) = 10, using a thennometric end-point. Some aspects of thermometric titrimetry when Kc(A') < 10(3) are also considered.

  10. Interface sharpness in the Potts model

    International Nuclear Information System (INIS)

    Ruiz, J.

    1989-01-01

    A simple proof is given for the existence of a sharp interface between two ordered phases for the three-dimensional 2 double-prime-state Potts model (n integer). The results show that the roughening temperature of the three-dimensional Potts model is greater than the transition temperature of the two-dimensional Potts model. For a large arbitrary spin integer, it is expected that this roughening temperature is equal to the transition temperature (of the 3D model), i.e., that the interface between two ordered phases is harp up to the transition temperature, at which it is wetted by a film of the disordered phase. It is also expected that for a large arbitrary spin integer, the a-f interface (between an ordered and the disordered phase) is sharp at the transition temperature

  11. Sharp inequalities for tangent function with applications

    Directory of Open Access Journals (Sweden)

    Hui-Lin Lv

    2017-05-01

    Full Text Available Abstract In the article, we present new bounds for the function e t cot ( t − 1 $e^{t\\cot(t-1}$ on the interval ( 0 , π / 2 $(0, \\pi/2$ and find sharp estimations for the Sine integral and the Catalan constant based on a new monotonicity criterion for the quotient of power series, which refine the Redheffer and Becker-Stark type inequalities for tangent function.

  12. Hippocampal multimodal structural changes and subclinical depression in healthy individuals.

    Science.gov (United States)

    Spalletta, Gianfranco; Piras, Fabrizio; Caltagirone, Carlo; Fagioli, Sabrina

    2014-01-01

    Several neuroimaging studies report reduced hippocampal volume in depressed patients. However, it is still unclear if hippocampal changes in healthy individuals can be considered a risk factor for progression to clinical depression. Here, we investigated subclinical depression and its hippocampal correlates in a non-clinical sample of healthy individuals, with particular regard to gender differences. One-hundred-two participants underwent a comprehensive clinical assessment, a high-resolution T1-weighted magnetic resonance imaging and diffusion tensor imaging protocol using a 3T MRI scanner. Data of macro-(volume) and micro-(mean diffusivity, MD) structural changes of the hippocampus were analyzed with reference to the Beck Depression Inventory score. Results of multivariate regression analyses revealed reduced bilateral volume, along with increased bilateral MD in hippocampal formation predicting subclinical depressive phenomenology only in healthy males. Conversely, subclinical depressive phenomenology in healthy female was accounted for by only lower educational level, in the absence of any hippocampal structure variations. To date, this is the only evidence reporting a relationship between subclinical depressive phenomenology and changes in hippocampal formation in healthy individuals. Our findings demonstrated that reduced volume, along with increased MD in hippocampal formation, is significantly associated with subclinical depressive phenomenology in healthy males. This encourages to study the hypothesis that early macro- and microstructural changes in hippocampi associated with subclinical depression may constitute a risk factor of developing depressive disorders in males. © 2013 Elsevier B.V. All rights reserved.

  13. Hippocampal MR volumetry

    Science.gov (United States)

    Haller, John W.; Botteron, K.; Brunsden, Barry S.; Sheline, Yvette I.; Walkup, Ronald K.; Black, Kevin J.; Gado, Mokhtar; Vannier, Michael W.

    1994-09-01

    Goal: To estimate hippocampal volumes from in vivo 3D magnetic resonance (MR) brain images and determine inter-rater and intra- rater repeatability. Objective: The precision and repeatability of hippocampal volume estimates using stereologic measurement methods is sought. Design: Five normal control and five schizophrenic subjects were MR scanned using a MPRAGE protocol. Fixed grid stereologic methods were used to estimate hippocampal volumes on a graphics workstation. The images were preprocessed using histogram analysis to standardize 3D MR image scaling from 16 to 8 bits and image volumes were interpolated to 0.5 mm3 isotropic voxels. The following variables were constant for the repeated stereologic measures: grid size, inter-slice distance (1.5 mm), voxel dimensions (0.5 mm3), number of hippocampi measured (10), total number of measurements per rater (40), and number of raters (5). Two grid sizes were tested to determine the coefficient of error associated with the number of sampled 'hits' (approximately 140 and 280) on the hippocampus. Starting slice and grid position were randomly varied to assure unbiased volume estimates. Raters were blind to subject identity, diagnosis, and side of the brain from which the image volumes were extracted and the order of subject presentation was randomized for each of the raters. Inter- and intra-rater intraclass correlation coefficients (ICC) were determined. Results: The data indicate excellent repeatability of fixed grid stereologic hippocampal volume measures when using an inter-slice distance of 1.5 mm and a 6.25 mm2 grid (inter-rater ICCs equals 0.86 - 0.97, intra- rater ICCs equals 0.85 - 0.97). One major advantage of the current study was the use of 3D MR data which significantly improved visualization of hippocampal boundaries by providing the ability to access simultaneous orthogonal views while counting stereological marks within the hippocampus. Conclusion: Stereological estimates of 3D volumes from 2D MR

  14. Network state-dependent inhibition of identified hippocampal CA3 axo-axonic cells in vivo

    Science.gov (United States)

    Tukker, John J; Klausberger, Thomas; Somogyi, Peter

    2015-01-01

    Hippocampal sharp waves are population discharges initiated by an unknown mechanism in pyramidal cell networks of CA3. Axo-axonic cells (AACs) regulate action potential generation through GABAergic synapses on the axon initial segment. We found that CA3 AACs in anesthetized rats and AACs in freely moving rats stopped firing during sharp waves, when pyramidal cells fire most. AACs fired strongly and rhythmically around the peak of theta oscillations, when pyramidal cells fire at low probability. Distinguishing AACs from other parvalbumin-expressing interneurons by their lack of detectable SATB1 transcription factor immunoreactivity, we discovered a somatic GABAergic input originating from the medial septum that preferentially targets AACs. We recorded septo-hippocampal GABAergic cells that were activated during hippocampal sharp waves and projected to CA3. We hypothesize that inhibition of AACs, and the resulting subcellular redistribution of inhibition from the axon initial segment to other pyramidal cell domains, is a necessary condition for the emergence of sharp waves promoting memory consolidation. PMID:24141313

  15. Flow Control Over Sharp-Edged Wings

    Science.gov (United States)

    2007-07-01

    Gad-el-Hak (2001) as the ability to actively or passively manipulate a flow field to effect a desired change. The challenge is to achieve that change...combinations. Been able to independently control both is a great challenge . These requirements may appear too stringent for the sharp- edged airfoils...06 0𔄁 08 09 lic Vlc Figure 22: Pressure distributions for Model B at a=13 °. Stations I (left); 2 (right) 1 , -2 1 F - [12 1 -6a -16 08 -08 06 -06

  16. DSMC simulations of shock interactions about sharp double cones

    Science.gov (United States)

    Moss, James N.

    2001-08-01

    This paper presents the results of a numerical study of shock interactions resulting from Mach 10 flow about sharp double cones. Computations are made by using the direct simulation Monte Carlo (DSMC) method of Bird. The sensitivity and characteristics of the interactions are examined by varying flow conditions, model size, and configuration. The range of conditions investigated includes those for which experiments have been or will be performed in the ONERA R5Ch low-density wind tunnel and the Calspan-University of Buffalo Research Center (CUBRC) Large Energy National Shock (LENS) tunnel.

  17. Focal CA3 hippocampal subfield atrophy following LGI1 VGKC-complex antibody limbic encephalitis

    OpenAIRE

    Miller, T; Chong, T; Aimola Davies, A; Ng, T; Johnson, M; Irani, S; Vincent, A; Husain, M; Jacob, S; Maddison, P; Kennard, C; Gowland, P; Rosenthal, C

    2017-01-01

    Magnetic resonance imaging has linked chronic voltage-gated potassium channel (VGKC) complex antibody-mediated limbic encephalitis with generalized hippocampal atrophy. However, autoantibodies bind to specific rodent hippocampal subfields. Here, human hippocampal subfield (subiculum, cornu ammonis 1-3, and dentate gyrus) targets of immunomodulation-treated LGI1 VGKC-complex antibody-mediated limbic encephalitis were investigated using in vivo ultra-high resolution (0.39 × 0....

  18. Comparison with hippocampal atrophy and hypoperfusion in Alzheimer's disease

    International Nuclear Information System (INIS)

    Chung, YA; Kim, SH; Chung, SK; Juh, RH; Sohn, HS; Suh, TS; Choe, BY

    2004-01-01

    Objective: Hypoperfusion and hippocampal atropy of the medial temporal lobe are peculiarity of Alzheimer's disease (AD). The manual ROI (region of interest) technique for hippocampal volume estimation is specific and sensitive for the detection of hippocampal atrophy. In patients with AD reported a significant correlation between hippocampal volume and hypoperfusion. This study investigated correlations between atrophy distinct medial temporal lobe structure and hypoperfusion in hippocampal volumetry. Methods: The hippocampi were individually outlined on Tl-weighted volumetry MRI and calculated with MATLAB in 12 patients with AD. All volume measurements were performed by a segmentation technique with a combination of tracing and thresholding. The volume of a given structure in each slice was obtained by automatically counting the number of pixels within the segmented regions and multiplying the number by a voxel size. In order to permit direct regional comparisons, both of each patient's Tc- 99m ECD SPECT was then registered to the patient's MRI. Delineation continued anteriorly in each contiguous slice reaching the head of the hippocampus, which was distinguished from the overlying amygdala by the presence of the alveus or uncal recess. The right hippocampus (RH) was measured first, followed by the left hippocampus (LH). The accuracy of registration was investigated in a validation study with developed brain phantom. Results:The mean total intracranial volume of the AD was significantly smaller volume (1492.9 cm 3 ) and hypo perfused than those in normal subjects. The mean hippocampal volumes were 2.01 cm 3 and l.99 cm 3 for the RH and LH. The correlations between volume and hypoperfusion in the affected hippocampi were found to be significant; especially the medial temporal lobe is markedly hypo perfused. Conclusion: Volumetry is the most sensitive tool for the detection of hippocampal abnormality in AD, and significant correlation between asymmetry in

  19. Sharp fronts within geochemical transport problems

    International Nuclear Information System (INIS)

    Grindrod, P.

    1995-01-01

    The authors consider some reactive geochemical transport problems in groundwater systems. When incoming fluid is in disequilibrium with the mineralogy sharp transition fronts may develop. They show that this is a generic property for a class of systems where the timescales associated with reaction and diffusion phenomena are much shorter than those associated with advective transport. Such multiple timescale problems are relevant to a variety of processes in natural systems: mathematically methods of singular perturbation theory reduce the dimension of the problems to be solved locally. Furthermore, they consider how spatial heterogeneous mineralogy can impact upon the propagation of sharp geochemical fronts. The authors developed an asymptotic approach in which they solve equations for the evolving geometry of the front and indicate how the non-smooth perturbations due to natural heterogeneity of the mineralogy on underlying ground water flow field are balanced against the smoothing effect of diffusion/dispersive processes. Fronts are curvature damped, and the results here indicate the generic nature of separate front propagation within both model (idealized) and natural (heterogeneous) geochemical systems

  20. Status report on SHARP coupling framework.

    Energy Technology Data Exchange (ETDEWEB)

    Caceres, A.; Tautges, T. J.; Lottes, J.; Fischer, P.; Rabiti, C.; Smith, M. A.; Siegel, A.; Yang, W. S.; Palmiotti, G.

    2008-05-30

    This report presents the software engineering effort under way at ANL towards a comprehensive integrated computational framework (SHARP) for high fidelity simulations of sodium cooled fast reactors. The primary objective of this framework is to provide accurate and flexible analysis tools to nuclear reactor designers by simulating multiphysics phenomena happening in complex reactor geometries. Ideally, the coupling among different physics modules (such as neutronics, thermal-hydraulics, and structural mechanics) needs to be tight to preserve the accuracy achieved in each module. However, fast reactor cores in steady state mode represent a special case where weak coupling between neutronics and thermal-hydraulics is usually adequate. Our framework design allows for both options. Another requirement for SHARP framework has been to implement various coupling algorithms that are parallel and scalable to large scale since nuclear reactor core simulations are among the most memory and computationally intensive, requiring the use of leadership-class petascale platforms. This report details our progress toward achieving these goals. Specifically, we demonstrate coupling independently developed parallel codes in a manner that does not compromise performance or portability, while minimizing the impact on individual developers. This year, our focus has been on developing a lightweight and loosely coupled framework targeted at UNIC (our neutronics code) and Nek (our thermal hydraulics code). However, the framework design is not limited to just using these two codes.

  1. 77 FR 56647 - Lisa Jean Sharp: Debarment Order

    Science.gov (United States)

    2012-09-13

    ... Act (the FD&C Act) permanently debarring Lisa Jean Sharp from providing services in any capacity to a...&C Act. Ms. Sharp was given notice of the proposed permanent debarment and an opportunity to request... drug product under the FD&C Act. The factual basis for this conviction is as follows: Ms. Sharp was the...

  2. Prediction of dementia by hippocampal shape analysis

    DEFF Research Database (Denmark)

    Achterberg, Hakim C.; van der Lijn, Fedde; den Heijer, Tom

    2010-01-01

    This work investigates the possibility of predicting future onset of dementia in subjects who are cognitively normal, using hippocampal shape and volume information extracted from MRI scans. A group of 47 subjects who were non-demented normal at the time of the MRI acquisition, but were diagnosed...... with dementia during a 9 year follow-up period, was selected from a large population based cohort study. 47 Age and gender matched subjects who stayed cognitively intact were selected from the same cohort study as a control group. The hippocampi were automatically segmented and all segmentations were inspected...... and, if necessary, manually corrected by a trained observer. From this data a statistical model of hippocampal shape was constructed, using an entropy-based particle system. This shape model provided the input for a Support Vector Machine classifier to predict dementia. Cross validation experiments...

  3. Preliminary evidence of hippocampal damage in chronic users of ecstasy.

    Science.gov (United States)

    den Hollander, Bjørnar; Schouw, Marieke; Groot, Paul; Huisman, Henk; Caan, Matthan; Barkhof, Frederik; Reneman, Liesbeth

    2012-01-01

    Various studies have shown that ecstasy (3,4-methylenedioxymethamphetamine) users display significant memory impairments, whereas their performance on other cognitive tests is generally normal. The hippocampus plays an essential role in short-term memory. There are, however, no structural human data on the effects of ecstasy on the hippocampus. The objective of this study was to investigate whether the hippocampal volume of chronic ecstasy users is reduced when compared with healthy polydrug-using controls, as an indicator of hippocampal damage. The hippocampus was manually outlined in volumetric MRI scans in 10 male ecstasy users (mean age 25.4 years) and seven healthy age- and gender-matched control subjects (21.3 years). Other than the use of ecstasy, there were no statistically significant differences between both groups in exposure to other drugs of abuse and alcohol. The ecstasy users were on average drug-free for more than 2 months and had used on average 281 tablets over the past six and a half years. The hippocampal volume in the ecstasy using group was on average 10.5% smaller than the hippocampal volume in the control group (p=0.032). These data provide preliminary evidence that ecstasy users may be prone to incurring hippocampal damage, in line with previous reports of acute hippocampal sclerosis and subsequent atrophy in chronic users of this drug.

  4. Sharp corners as sources of spiral pairs

    International Nuclear Information System (INIS)

    Biton, Y.; Rabinovitch, A.; Braunstein, D.; Friedman, M.; Aviram, I.

    2010-01-01

    It is demonstrated that using the FitzHugh-Nagumo model, stimulation of excitable media inside a region possessing sharp corners, can lead to the appearance of sources of spiral-pairs of sustained activity. The two conditions for such source creation are: The corners should be less than 120 deg. and the range of stimulating amplitudes should be small, occurring just above the threshold value and decreasing with the corner angle. The basic mechanisms driving the phenomenon are discussed. These include: A. If the corner angle is below 120 deg., the wave generated inside cannot emerge at the corner tip, resulting in the creation of two free edges which start spiraling towards each other. B. Spiraling must be strong enough; otherwise annihilation of the rotating arms would occur too soon to create a viable source. C. The intricacies of the different radii involved are elucidated. Possible applications in heart stimulation and in chemical reactions are considered.

  5. Sharp estimates for damped oscillatory integrals

    International Nuclear Information System (INIS)

    Ikromov, I.A.; Shaimardanov, S.S.

    2004-05-01

    We consider a real-analytic hypersurface S in R 3 with surface measure dS, ψ is a smooth function with compact support, and we let dμ α be the surface measure with dμ α = ψ vertical bar K(x) vertical bar α dS, where K(x) is the Gaussian curvature of the surface. We show that if S is a real analytic hypersurface with one non-vanishing principal curvature and α > 1, then μ-circumflex α (ξ) decays as O (vertical bar ξ vertical bar -1 ). The well-known examples show that the estimate for the exponent α is sharp. (author)

  6. SHARP ENTRYWISE PERTURBATION BOUNDS FOR MARKOV CHAINS.

    Science.gov (United States)

    Thiede, Erik; VAN Koten, Brian; Weare, Jonathan

    For many Markov chains of practical interest, the invariant distribution is extremely sensitive to perturbations of some entries of the transition matrix, but insensitive to others; we give an example of such a chain, motivated by a problem in computational statistical physics. We have derived perturbation bounds on the relative error of the invariant distribution that reveal these variations in sensitivity. Our bounds are sharp, we do not impose any structural assumptions on the transition matrix or on the perturbation, and computing the bounds has the same complexity as computing the invariant distribution or computing other bounds in the literature. Moreover, our bounds have a simple interpretation in terms of hitting times, which can be used to draw intuitive but rigorous conclusions about the sensitivity of a chain to various types of perturbations.

  7. Associative reinstatement memory measures hippocampal function in Parkinson's Disease.

    Science.gov (United States)

    Cohn, Melanie; Giannoylis, Irene; De Belder, Maya; Saint-Cyr, Jean A; McAndrews, Mary Pat

    2016-09-01

    In Parkinson's Disease (PD), hippocampal atrophy is associated with rapid cognitive decline. Hippocampal function is typically assessed using memory tests but current clinical tools (e.g., free recall) also rely on executive functions or use material that is not optimally engaging hippocampal memory networks. Because of the ubiquity of executive dysfunction in PD, our ability to detect true memory deficits is suboptimal. Our previous behavioural and neuroimaging work in other populations suggests that an experimental memory task - Associative Reinstatement Memory (ARM) - may prove useful in investigating hippocampal function in PD. In this study, we investigated whether ARM is compromised in PD and we assessed its convergent and divergent validity by comparing it to standardized measures of memory and of attention and executive functioning in PD, respectively. Using fMRI, we also investigated whether performance in PD relates to degree of hippocampal engagement. Fifteen participants with PD and 13 age-matched healthy controls completed neuropsychological testing as well as an ARM fMRI recognition paradigm in which they were instructed to identify word pairs comprised of two studied words (intact or rearranged pairs) and those containing at least one new word (new or half new pairs). ARM is measured by the differences in hit rates between intact and rearranged pairs. Behaviourally, ARM was poorer in PD relative to controls and was correlated with verbal memory measures, but not with attention or executive functioning in the PD group. Hippocampal activation associated with ARM was reduced in PD relative to controls and covaried with ARM scores in both groups. To conclude, ARM is a sensitive measure of hippocampal memory function that is unaffected by attention or executive dysfunction in PD. Our study highlights the benefit of integrating cognitive neuroscience frameworks and novel experimental tasks to improve the practice of clinical neuropsychology in PD

  8. Active sulforhodamine 101 uptake into hippocampal astrocytes.

    Directory of Open Access Journals (Sweden)

    Christian Schnell

    Full Text Available Sulforhodamine 101 (SR101 is widely used as a marker of astrocytes. In this study we investigated labeling of astrocytes by SR101 in acute slices from the ventrolateral medulla and the hippocampus of transgenic mice expressing EGFP under the control of the astrocyte-specific human GFAP promoter. While SR101 efficiently and specifically labeled EGFP-expressing astrocytes in hippocampus, we found that the same staining procedure failed to label astrocytes efficiently in the ventrolateral medulla. Although carbenoxolone is able to decrease the SR101-labeling of astrocytes in the hippocampus, it is unlikely that SR101 is taken up via gap-junction hemichannels because mefloquine, a blocker for pannexin and connexin hemichannels, was unable to prevent SR101-labeling of hippocampal astrocytes. However, SR101-labeling of the hippocampal astrocytes was significantly reduced by substrates of organic anion transport polypeptides, including estron-3-sulfate and dehydroepiandrosterone sulfate, suggesting that SR101 is actively transported into hippocampal astrocytes.

  9. Structural hippocampal network alterations during healthy aging: A multi-modal MRI study

    Directory of Open Access Journals (Sweden)

    Amandine ePelletier

    2013-12-01

    Full Text Available While hippocampal atrophy has been described during healthy aging, few studies have examined its relationship with the integrity of White Matter (WM connecting tracts of the limbic system. This investigation examined WM structural damage specifically related to hippocampal atrophy in healthy aging subjects (n=129, using morphological MRI to assess hippocampal volume and Diffusion Tensor Imaging (DTI to assess WM integrity. Subjects with Mild Cognitive Impairment (MCI or dementia were excluded from the analysis. In our sample, increasing age was significantly associated with reduced hippocampal volume and reduced Fractional Anisotropy (FA at the level of the fornix and the cingulum bundle. The findings also demonstrate that hippocampal atrophy was specifically associated with reduced FA of the fornix bundle, but it was not related to alteration of the cingulum bundle. Our results indicate that the relationship between hippocampal atrophy and fornix FA values is not due to an independent effect of age on both structures. A recursive regression procedure was applied to evaluate sequential relationships between the alterations of these two brain structures. When both hippocampal atrophy and fornix FA values were included in the same model to predict age, fornix FA values remained significant whereas hippocampal atrophy was no longer significantly associated with age. According to this latter finding, hippocampal atrophy in healthy aging could be mediated by a loss of fornix connections. Structural alterations of this part of the limbic system, which have been associated with neurodegeneration in Alzheimer’s disease, result at least in part from the aging process.

  10. Hippocampal EEG and motor activity in the cat: The role of eye movements and body acceleration

    NARCIS (Netherlands)

    Kamp, A.; Arnolds, D.E.A.T.; Lopes da Silva, F.H.; Boeijinga, P.; Aitink, W.

    1984-01-01

    In cat the relation between various behaviours and the spectral properties of the hippocampal EEG was investigated. Both EEG and behaviour were quantified and results were evaluated statistically. Significant relationships were found between the properties of the hippocampal EEG and motor acts

  11. Anticonvulsant Effects of Memantine and MK-801 in Guinea Pig Hippocampal Neurons.

    Science.gov (United States)

    investigation we compared the anticonvulsant properties of Mem to those of MK-801 in guinea pig hippocampal slices. Extracellular recordings were...obtained from area CA1 of guinea pig hippocampal slices in a total submersion chamber at 32 deg C in normal oxygenated artificial cerebrospinal fluid (ACSF

  12. A computational method for sharp interface advection

    Science.gov (United States)

    Bredmose, Henrik; Jasak, Hrvoje

    2016-01-01

    We devise a numerical method for passive advection of a surface, such as the interface between two incompressible fluids, across a computational mesh. The method is called isoAdvector, and is developed for general meshes consisting of arbitrary polyhedral cells. The algorithm is based on the volume of fluid (VOF) idea of calculating the volume of one of the fluids transported across the mesh faces during a time step. The novelty of the isoAdvector concept consists of two parts. First, we exploit an isosurface concept for modelling the interface inside cells in a geometric surface reconstruction step. Second, from the reconstructed surface, we model the motion of the face–interface intersection line for a general polygonal face to obtain the time evolution within a time step of the submerged face area. Integrating this submerged area over the time step leads to an accurate estimate for the total volume of fluid transported across the face. The method was tested on simple two-dimensional and three-dimensional interface advection problems on both structured and unstructured meshes. The results are very satisfactory in terms of volume conservation, boundedness, surface sharpness and efficiency. The isoAdvector method was implemented as an OpenFOAM® extension and is published as open source. PMID:28018619

  13. A computational method for sharp interface advection.

    Science.gov (United States)

    Roenby, Johan; Bredmose, Henrik; Jasak, Hrvoje

    2016-11-01

    We devise a numerical method for passive advection of a surface, such as the interface between two incompressible fluids, across a computational mesh. The method is called isoAdvector, and is developed for general meshes consisting of arbitrary polyhedral cells. The algorithm is based on the volume of fluid (VOF) idea of calculating the volume of one of the fluids transported across the mesh faces during a time step. The novelty of the isoAdvector concept consists of two parts. First, we exploit an isosurface concept for modelling the interface inside cells in a geometric surface reconstruction step. Second, from the reconstructed surface, we model the motion of the face-interface intersection line for a general polygonal face to obtain the time evolution within a time step of the submerged face area. Integrating this submerged area over the time step leads to an accurate estimate for the total volume of fluid transported across the face. The method was tested on simple two-dimensional and three-dimensional interface advection problems on both structured and unstructured meshes. The results are very satisfactory in terms of volume conservation, boundedness, surface sharpness and efficiency. The isoAdvector method was implemented as an OpenFOAM ® extension and is published as open source.

  14. Deciphering the role of CA1 inhibitory circuits in sharp wave-ripple complexes.

    Science.gov (United States)

    Cutsuridis, Vassilis; Taxidis, Jiannis

    2013-01-01

    Sharp wave-ripples (SWRs) are population oscillatory patterns in hippocampal LFPs during deep sleep and immobility, involved in the replay of memories acquired during wakefulness. SWRs have been extensively studied, but their exact generation mechanism is still unknown. A computational model has suggested that fast perisomatic inhibition may generate the high frequency ripples (~200 Hz). Another model showed how replay of memories can be controlled by various classes of inhibitory interneurons targeting specific parts of pyramidal cells (PC) and firing at particular SWR phases. Optogenetic studies revealed new roles for interneuronal classes and rich dynamic interplays between them, shedding new light in their potential role in SWRs. Here, we integrate these findings in a conceptual model of how dendritic and somatic inhibition may collectively contribute to the SWR generation. We suggest that sharp wave excitation and basket cell (BC) recurrent inhibition synchronises BC spiking in ripple frequencies. This rhythm is imposed on bistratified cells which prevent pyramidal bursting. Axo-axonic and stratum lacunosum/moleculare interneurons are silenced by inhibitory inputs originating in the medial septum. PCs receiving rippling inhibition in both dendritic and perisomatic areas and excitation in their apical dendrites, exhibit sparse ripple phase-locked spiking.

  15. Variational reconstruction using subdivision surfaces with continuous sharpness control

    Institute of Scientific and Technical Information of China (English)

    Xiaoqun Wu; Jianmin Zheng; Yiyu Cai; Haisheng Li

    2017-01-01

    We present a variational method for subdivision surface reconstruction from a noisy dense mesh.A new set of subdivision rules with continuous sharpness control is introduced into Loop subdivision for better modeling subdivision surface features such as semi-sharp creases,creases,and corners.The key idea is to assign a sharpness value to each edge of the control mesh to continuously control the surface features.Based on the new subdivision rules,a variational model with L1 norm is formulated to find the control mesh and the corresponding sharpness values of the subdivision surface that best fits the input mesh.An iterative solver based on the augmented Lagrangian method and particle swarm optimization is used to solve the resulting non-linear,non-differentiable optimization problem.Our experimental results show that our method can handle meshes well with sharp/semi-sharp features and noise.

  16. Neuropsychology, autobiographical memory and hippocampal volume in younger and older patients with chronic schizophrenia

    Directory of Open Access Journals (Sweden)

    Christina Josefa Herold

    2015-04-01

    Full Text Available Despite a wide range of studies on neuropsychology in schizophrenia, autobiographical memory (AM has been scarcely investigated in these patients. Hence less is known about AM in older patients and hippocampal contribution to autobiographical memories of varying remoteness. Therefore we investigated hippocampal volume and AM along with important neuropsychological domains in patients with chronic schizophrenia and the respective relationships between these parameters. We compared 25 older patients with chronic schizophrenia to 23 younger patients and an older healthy control group (N = 21 with respect to AM, additional neuropsychological parameters and hippocampal volume. Personal episodic and semantic memory was investigated using a semi-structured interview. Additional neuropsychological parameters were assessed by using a battery of standard neuropsychological tests. Structural magnetic resonance imaging data were analysed with an automated region-of-interest procedure. While hippocampal volume reduction and neuropsychological impairment were more pronounced in the older than in the younger patients, both groups showed equivalent reduced AM performance for recent personal episodes. In the patient group significant correlations between left hippocampal volume and recent autobiographical episodes as well as personal semantic memories arose. Verbal memory and working memory were significantly correlated with right hippocampal volume, executive functions, however, were associated with bilateral hippocampal volumes. These findings underline the complexity of AM and its impairments in the course of schizophrenia in comparison to rather progressive neuropsychological deficits and address the importance of hippocampal contribution.

  17. Neuropsychology, autobiographical memory, and hippocampal volume in "younger" and "older" patients with chronic schizophrenia.

    Science.gov (United States)

    Herold, Christina Josefa; Lässer, Marc Montgomery; Schmid, Lena Anna; Seidl, Ulrich; Kong, Li; Fellhauer, Iven; Thomann, Philipp Arthur; Essig, Marco; Schröder, Johannes

    2015-01-01

    Despite a wide range of studies on neuropsychology in schizophrenia, autobiographical memory (AM) has been scarcely investigated in these patients. Hence, less is known about AM in older patients and hippocampal contribution to autobiographical memories of varying remoteness. Therefore, we investigated hippocampal volume and AM along with important neuropsychological domains in patients with chronic schizophrenia and the respective relationships between these parameters. We compared 25 older patients with chronic schizophrenia to 23 younger patients and an older healthy control group (N = 21) with respect to AM, additional neuropsychological parameters, and hippocampal volume. Personal episodic and semantic memory was investigated using a semi-structured interview. Additional neuropsychological parameters were assessed by using a battery of standard neuropsychological tests. Structural magnetic resonance imaging data were analyzed with an automated region-of-interest procedure. While hippocampal volume reduction and neuropsychological impairment were more pronounced in the older than in the younger patients, both groups showed equivalent reduced AM performance for recent personal episodes. In the patient group, significant correlations between left hippocampal volume and recent autobiographical episodes as well as personal semantic memories arose. Verbal memory and working memory were significantly correlated with right hippocampal volume; executive functions, however, were associated with bilateral hippocampal volumes. These findings underline the complexity of AM and its impairments in the course of schizophrenia in comparison to rather progressive neuropsychological deficits and address the importance of hippocampal contribution.

  18. Hippocampal dosimetry correlates with the change in neurocognitive function after hippocampal sparing during whole brain radiotherapy: a prospective study

    International Nuclear Information System (INIS)

    Tsai, Ping-Fang; Yang, Chi-Cheng; Chuang, Chi-Cheng; Huang, Ting-Yi; Wu, Yi-Ming; Pai, Ping-Ching; Tseng, Chen-Kan; Wu, Tung-Ho; Shen, Yi-Liang; Lin, Shinn-Yn

    2015-01-01

    Whole brain radiotherapy (WBRT) has been the treatment of choice for patients with brain metastases. However, change/decline of neurocognitive functions (NCFs) resulting from impaired hippocampal neurogenesis might occur after WBRT. It is reported that conformal hippocampal sparing would provide the preservation of NCFs. Our study aims to investigate the hippocampal dosimetry and to demonstrate the correlation between hippocampal dosimetry and neurocognitive outcomes in patients receiving hippocampal sparing during WBRT (HS-WBRT). Forty prospectively recruited cancer patients underwent HS-WBRT for therapeutic or prophylactic purposes. Before receiving HS-WBRT, all participants received a battery of baseline neurocognitive assessment, including memory, executive functions and psychomotor speed. The follow-up neurocognitive assessment at 4 months after HS-WBRT was also performed. For the delivery of HS-WBRT, Volumetric Modulated Arc Therapy (VMAT) with two full arcs and two non-coplanar partial arcs was employed. For each treatment planning, dose volume histograms were generated for left hippocampus, right hippocampus, and the composite hippocampal structure respectively. Biologically equivalent doses in 2-Gy fractions (EQD 2 ) assuming an alpha/beta ratio of 2 Gy were computed. To perform analyses addressing the correlation between hippocampal dosimetry and the change in scores of NCFs, pre- and post-HS-WBRT neurocognitive assessments were available in 24 patients in this study. Scores of NCFs were quite stable before and after HS-WBRT in terms of hippocampus-dependent memory. Regarding verbal memory, the corresponding EQD 2 values of 0, 10, 50, 80 % irradiating the composite hippocampal structure with <12.60 Gy, <8.81, <7.45 Gy and <5.83 Gy respectively were significantly associated with neurocognitive preservation indicated by the immediate recall of Word List Test of Wechsler Memory Scale-III. According to logistic regression analyses, it was noted that

  19. Sharp Gronwall-Bellman type integral inequalities with delay

    Directory of Open Access Journals (Sweden)

    István Győri

    2016-11-01

    Full Text Available Various attempts have been made to give an upper bound for the solutions of the delayed version of the Gronwall-Bellman integral inequality, but the obtained estimations are not sharp. In this paper a new approach is presented to get sharp estimations for the nonnegative solutions of the considered delayed inequalities. The results are based on the idea of the generalized characteristic inequality. Our method gives sharp estimation, and therefore the results are more exact than the earlier ones.

  20. Sharp Efficiency for Vector Equilibrium Problems on Banach Spaces

    Directory of Open Access Journals (Sweden)

    Si-Huan Li

    2013-01-01

    Full Text Available The concept of sharp efficient solution for vector equilibrium problems on Banach spaces is proposed. Moreover, the Fermat rules for local efficient solutions of vector equilibrium problems are extended to the sharp efficient solutions by means of the Clarke generalized differentiation and the normal cone. As applications, some necessary optimality conditions and sufficient optimality conditions for local sharp efficient solutions of a vector optimization problem with an abstract constraint and a vector variational inequality are obtained, respectively.

  1. Role of adult hippocampal neurogenesis in stress resilience

    Directory of Open Access Journals (Sweden)

    Brunno R. Levone

    2015-01-01

    Full Text Available There is a growing appreciation that adult hippocampal neurogenesis plays a role in emotional and cognitive processes related to psychiatric disorders. Although many studies have investigated the effects of stress on adult hippocampal neurogenesis, most have not focused on whether stress-induced changes in neurogenesis occur specifically in animals that are more resilient or more susceptible to the behavioural and neuroendocrine effects of stress. Thus, in the present review we explore whether there is a clear relationship between stress-induced changes in adult hippocampal neurogenesis, stress resilience and antidepressant-induced recovery from stress-induced changes in behaviour. Exposure to different stressors is known to reduce adult hippocampal neurogenesis, but some stressors have also been shown to exert opposite effects. Ablation of neurogenesis does not lead to a depressive phenotype, but it can enhance responsiveness to stress and affect stress susceptibility. Monoaminergic-targeted antidepressants, environmental enrichment and adrenalectomy are beneficial for reversing stress-induced changes in behaviour and have been shown to do so in a neurogenesis-dependant manner. In addition, stress and antidepressants can affect hippocampal neurogenesis, preferentially in the ventral hippocampus. Together, these data show that adult hippocampal neurogenesis may play a role in the neuroendocrine and behavioural responses to stress, although it is not yet fully clear under which circumstances neurogenesis promotes resilience or susceptibility to stress. It will be important that future studies carefully examine how adult hippocampal neurogenesis can contribute to stress resilience/susceptibility so that it may be appropriately exploited for the development of new and more effective treatments for stress-related psychiatric disorders.

  2. The sharp edge: a frequent radiographic sign in neonatal pneumothorax

    International Nuclear Information System (INIS)

    Oestreich, A.E.

    1987-01-01

    The sharp edge sign, an unusually sharply defined silhouette of the heart and/or hemidiaphragm on frontal radiographs of the supine neonate, has been valuable in the initial recognition of pneumothorax. In a prospective study of 50 neonatal pneumothoraces, a sharp edge sign was present on the initial pneumothorax film 49 times. In seven of these, only the hemidiaphragm showed a sharp edge, while the heart margin was superimposed on the vertebral column. Greater awareness of the sharp edge sign would promote earlier recognition of neonatal pneumothorax. 6 refs.; 3 figs

  3. Real time algorithms for sharp wave ripple detection.

    Science.gov (United States)

    Sethi, Ankit; Kemere, Caleb

    2014-01-01

    Neural activity during sharp wave ripples (SWR), short bursts of co-ordinated oscillatory activity in the CA1 region of the rodent hippocampus, is implicated in a variety of memory functions from consolidation to recall. Detection of these events in an algorithmic framework, has thus far relied on simple thresholding techniques with heuristically derived parameters. This study is an investigation into testing and improving the current methods for detection of SWR events in neural recordings. We propose and profile methods to reduce latency in ripple detection. Proposed algorithms are tested on simulated ripple data. The findings show that simple realtime algorithms can improve upon existing power thresholding methods and can detect ripple activity with latencies in the range of 10-20 ms.

  4. Initiation of sleep-dependent cortical-hippocampal correlations at wakefulness-sleep transition.

    Science.gov (United States)

    Haggerty, Daniel C; Ji, Daoyun

    2014-10-01

    Sleep is involved in memory consolidation. Current theories propose that sleep-dependent memory consolidation requires active communication between the hippocampus and neocortex. Indeed, it is known that neuronal activities in the hippocampus and various neocortical areas are correlated during slow-wave sleep. However, transitioning from wakefulness to slow-wave sleep is a gradual process. How the hippocampal-cortical correlation is established during the wakefulness-sleep transition is unknown. By examining local field potentials and multiunit activities in the rat hippocampus and visual cortex, we show that the wakefulness-sleep transition is characterized by sharp-wave ripple events in the hippocampus and high-voltage spike-wave events in the cortex, both of which are accompanied by highly synchronized multiunit activities in the corresponding area. Hippocampal ripple events occur earlier than the cortical high-voltage spike-wave events, and hippocampal ripple incidence is attenuated by the onset of cortical high-voltage spike waves. This attenuation leads to a temporary weak correlation in the hippocampal-cortical multiunit activities, which eventually evolves to a strong correlation as the brain enters slow-wave sleep. The results suggest that the hippocampal-cortical correlation is established through a concerted, two-step state change that first synchronizes the neuronal firing within each brain area and then couples the synchronized activities between the two regions. Copyright © 2014 the American Physiological Society.

  5. Novel genetic loci associated with hippocampal volume

    NARCIS (Netherlands)

    D.P. Hibar (Derrek); H.H.H. Adams (Hieab); N. Jahanshad (Neda); G. Chauhan (Ganesh); J.L. Stein; E. Hofer (Edith); M.E. Rentería (Miguel); J.C. Bis (Joshua); A. Arias-Vásquez (Alejandro); Ikram, M.K. (M. Kamran); S. Desrivières (Sylvane); M.W. Vernooij (Meike); L. Abramovic (Lucija); S. Alhusaini (Saud); N. Amin (Najaf); M. Andersson (Micael); K. Arfanakis (Konstantinos); B. Aribisala (Benjamin); N.J. Armstrong (Nicola J.); L. Athanasiu (Lavinia); T. Axelsson (Tomas); A.H. Beecham (Ashley); A. Beiser (Alexa); M. Bernard (Manon); S.H. Blanton (Susan H.); M.M. Bohlken (Marc M.); M.P.M. Boks (Marco); L.B.C. Bralten (Linda); A.M. Brickman (Adam M.); Carmichael, O. (Owen); M.M. Chakravarty (M. Mallar); Q. Chen (Qiang); C.R.K. Ching (Christopher); V. Chouraki (Vincent); G. Cuellar-Partida (Gabriel); F. Crivello (Fabrice); A. den Braber (Anouk); Doan, N.T. (Nhat Trung); S.M. Ehrlich (Stefan); S. Giddaluru (Sudheer); A.L. Goldman (Aaron L.); R.F. Gottesman (Rebecca); O. Grimm (Oliver); M.D. Griswold (Michael); T. Guadalupe (Tulio); Gutman, B.A. (Boris A.); J. Hass (Johanna); U.K. Haukvik (Unn); D. Hoehn (David); A.J. Holmes (Avram); M. Hoogman (Martine); D. Janowitz (Deborah); T. Jia (Tianye); Jørgensen, K.N. (Kjetil N.); N. Karbalai (Nazanin); D. Kasperaviciute (Dalia); S. Kim (Shinseog); M. Klein (Marieke); B. Kraemer (Bernd); P.H. Lee (Phil); D.C. Liewald (David C.); L.M. Lopez (Lorna); M. Luciano (Michelle); C. MacAre (Christine); Marquand, A.F. (Andre F.); M. Matarin (Mar); R. Mather; M. Mattheisen (Manuel); McKay, D.R. (David R.); Milaneschi, Y. (Yuri); S. Muñoz Maniega (Susana); K. Nho (Kwangsik); A.C. Nugent (Allison); P. Nyquist (Paul); Loohuis, L.M.O. (Loes M. Olde); J. Oosterlaan (Jaap); M. Papmeyer (Martina); Pirpamer, L. (Lukas); B. Pütz (Benno); A. Ramasamy (Adaikalavan); Richards, J.S. (Jennifer S.); S.L. Risacher (Shannon); R. Roiz-Santiañez (Roberto); N. Rommelse (Nanda); S. Ropele (Stefan); E.J. Rose (Emma); N.A. Royle (Natalie); T. Rundek (Tatjana); P.G. Sämann (Philipp); Saremi, A. (Arvin); C.L. Satizabal (Claudia L.); L. Schmaal (Lianne); N.J. Schork (Nicholas); Shen, L. (Li); J. Shin (Jean); Shumskaya, E. (Elena); A.V. Smith (Albert Vernon); R. Sprooten (Roy); L.T. Strike (Lachlan); A. Teumer (Alexander); D. Tordesillas-Gutierrez (Diana); R. Toro (Roberto); D. Trabzuni (Danyah); S. Trompet (Stella); D. Vaidya (Dhananjay); J. van der Grond (Jeroen); S.J. van der Lee (Sven); Van Der Meer, D. (Dennis); M.M.J. Van Donkelaar (Marjolein M. J.); K.R. van Eijk (Kristel); T.G.M. van Erp (Theo G.); Van Rooij, D. (Daan); E. Walton (Esther); L.T. Westlye (Lars); C.D. Whelan (Christopher); B.G. Windham (B Gwen); A.M. Winkler (Anderson); K. Wittfeld (Katharina); G. Woldehawariat (Girma); A. Björnsson (Asgeir); Wolfers, T. (Thomas); L.R. Yanek (Lisa); Yang, J. (Jingyun); A.P. Zijdenbos; M.P. Zwiers (Marcel); I. Agartz (Ingrid); L. Almasy (Laura); D.J. Ames (David); Amouyel, P. (Philippe); O.A. Andreassen (Ole); S. Arepalli (Sampath); A.A. Assareh; S. Barral (Sandra); M.E. Bastin (Mark); Becker, D.M. (Diane M.); J.T. Becker (James); D.A. Bennett (David A.); J. Blangero (John); H. van Bokhoven (Hans); D.I. Boomsma (Dorret); H. Brodaty (Henry); R.M. Brouwer (Rachel); H.G. Brunner; M. Buckner; J.K. Buitelaar (Jan); K. Bulayeva (Kazima); W. Cahn (Wiepke); V.D. Calhoun Vince D. (V.); D.M. Cannon (Dara); G. Cavalleri (Gianpiero); Cheng, C.-Y. (Ching-Yu); S. Cichon (Sven); M.R. Cookson (Mark); A. Corvin (Aiden); B. Crespo-Facorro (Benedicto); J.E. Curran (Joanne); M. Czisch (Michael); A.M. Dale (Anders); G.E. Davies (Gareth); A.J. de Craen (Anton); E.J.C. de Geus (Eco); P.L. de Jager (Philip); G.I. de Zubicaray (Greig); I.J. Deary (Ian J.); S. Debette (Stéphanie); C. DeCarli (Charles); N. Delanty; C. Depondt (Chantal); A.L. DeStefano (Anita); A. Dillman (Allissa); S. Djurovic (Srdjan); D.J. Donohoe (Dennis); D.A. Drevets (Douglas); Duggirala, R. (Ravi); M.D. Dyer (Matthew); C. Enzinger (Christian); S. Erk; T. Espeseth (Thomas); Fedko, I.O. (Iryna O.); Fernández, G. (Guillén); L. Ferrucci (Luigi); S.E. Fisher (Simon); D. Fleischman (Debra); I. Ford (Ian); M. Fornage (Myriam); T. Foroud (Tatiana); P.T. Fox (Peter); C. Francks (Clyde); Fukunaga, M. (Masaki); Gibbs, J.R. (J. Raphael); D.C. Glahn (David); R.L. Gollub (Randy); H.H.H. Göring (Harald H.); R.C. Green (Robert C.); O. Gruber (Oliver); V. Gudnason (Vilmundur); S. Guelfi (Sebastian); Håberg, A.K. (Asta K.); N.K. Hansell (Narelle); J. Hardy (John); C.A. Hartman (C.); Hashimoto, R. (Ryota); K. Hegenscheid (Katrin); J. Heinz (Judith); S. Le Hellard (Stephanie); D.G. Hernandez (Dena); D.J. Heslenfeld (Dirk); Ho, B.-C. (Beng-Choon); P.J. Hoekstra (Pieter); W. Hoffmann (Wolfgang); A. Hofman (Albert); F. Holsboer (Florian); G. Homuth (Georg); N. Hosten (Norbert); J.J. Hottenga (Jouke Jan); M.J. Huentelman (Matthew); H.H. Pol; Ikeda, M. (Masashi); Jack, C.R. (Clifford R.); S. Jenkinson (Sarah); R. Johnson (Robert); Jönsson, E.G. (Erik G.); J.W. Jukema; R. Kahn (René); Kanai, R. (Ryota); I. Kloszewska (Iwona); Knopman, D.S. (David S.); P. Kochunov (Peter); Kwok, J.B. (John B.); S. Lawrie (Stephen); H. Lemaître (Herve); X. Liu (Xinmin); D.L. Longo (Dan L.); O.L. Lopez (Oscar L.); S. Lovestone (Simon); Martinez, O. (Oliver); J.-L. Martinot (Jean-Luc); V.S. Mattay (Venkata S.); McDonald, C. (Colm); A.M. McIntosh (Andrew); McMahon, F.J. (Francis J.); McMahon, K.L. (Katie L.); P. Mecocci (Patrizia); I. Melle (Ingrid); Meyer-Lindenberg, A. (Andreas); S. Mohnke (Sebastian); Montgomery, G.W. (Grant W.); D.W. Morris (Derek W); T.H. Mosley (Thomas H.); T.W. Mühleisen (Thomas); B. Müller-Myhsok (B.); M.A. Nalls (Michael); M. Nauck (Matthias); T.E. Nichols (Thomas); W.J. Niessen (Wiro); M.M. Nöthen (Markus); L. Nyberg (Lars); Ohi, K. (Kazutaka); R.L. Olvera (Rene); R.A. Ophoff (Roel); M. Pandolfo (Massimo); T. Paus (Tomas); Z. Pausova (Zdenka); B.W.J.H. Penninx (Brenda); Pike, G.B. (G. Bruce); S.G. Potkin (Steven); B.M. Psaty (Bruce); S. Reppermund; M. Rietschel (Marcella); J.L. Roffman (Joshua); N. Seiferth (Nina); J.I. Rotter (Jerome I.); M. Ryten (Mina); Sacco, R.L. (Ralph L.); P.S. Sachdev (Perminder); A.J. Saykin (Andrew); R. Schmidt (Reinhold); Schmidt, H. (Helena); C.J. Schofield (Christopher); Sigursson, S. (Sigurdur); Simmons, A. (Andrew); A. Singleton (Andrew); S.M. Sisodiya (Sanjay); Smith, C. (Colin); J.W. Smoller; H. Soininen (H.); V.M. Steen (Vidar); D.J. Stott (David J.); J. Sussmann (Jessika); A. Thalamuthu (Anbupalam); A.W. Toga (Arthur W.); B. Traynor (Bryan); J.C. Troncoso (Juan); M. Tsolaki (Magda); C. Tzourio (Christophe); A.G. Uitterlinden (André); Hernández, M.C.V. (Maria C. Valdés); M.P. van der Brug (Marcel); A. van der Lugt (Aad); N.J. van der Wee (Nic); N.E.M. van Haren (Neeltje E.); D. van 't Ent (Dennis); M.J.D. van Tol (Marie-José); B.N. Vardarajan (Badri); B. Vellas (Bruno); D.J. Veltman (Dick); H. Völzke (Henry); H.J. Walter (Henrik); J. Wardlaw (Joanna); A.M.J. Wassink (Annemarie); M.E. Weale (Michael); Weinberger, D.R. (Daniel R.); Weiner, M.W. (Michael W.); Wen, W. (Wei); E. Westman (Eric); T.J.H. White (Tonya); Wong, T.Y. (Tien Y.); Wright, C.B. (Clinton B.); R.H. Zielke (Ronald H.); A.B. Zonderman; N.G. Martin (Nicholas); C.M. van Duijn (Cornelia); M.J. Wright (Margaret); W.T. Longstreth Jr; G. Schumann (Gunter); H.J. Grabe (Hans Jörgen); B. Franke (Barbara); L.J. Launer (Lenore); S.E. Medland (Sarah Elizabeth); S. Seshadri (Sudha); P.M. Thompson (Paul); M.K. Ikram (Kamran)

    2017-01-01

    textabstractThe hippocampal formation is a brain structure integrally involved in episodic memory, spatial navigation, cognition and stress responsiveness. Structural abnormalities in hippocampal volume and shape are found in several common neuropsychiatric disorders. To identify the genetic

  6. Novel genetic loci associated with hippocampal volume

    NARCIS (Netherlands)

    Hibar, Derrek P.; Adams, Hieab H. H.; Jahanshad, Neda; Chauhan, Ganesh; Stein, Jason L.; Hofer, Edith; Renteria, Miguel E.; Bis, Joshua C.; Arias-Vasquez, Alejandro; Ikram, M. Kamran; Desrivières, Sylvane; Vernooij, Meike W.; Abramovic, Lucija; Alhusaini, Saud; Amin, Najaf; Andersson, Micael; Arfanakis, Konstantinos; Aribisala, Benjamin S.; Armstrong, Nicola J.; Athanasiu, Lavinia; Axelsson, Tomas; Beecham, Ashley H.; Beiser, Alexa; Bernard, Manon; Blanton, Susan H.; Bohlken, Marc M.; Boks, Marco P.; Bralten, Janita; Brickman, Adam M.; Carmichael, Owen; Chakravarty, M. Mallar; Chen, Qiang; Ching, Christopher R. K.; Chouraki, Vincent; Cuellar-Partida, Gabriel; Crivello, Fabrice; den Braber, Anouk; Doan, Nhat Trung; Ehrlich, Stefan; Giddaluru, Sudheer; Goldman, Aaron L.; Gottesman, Rebecca F.; Grimm, Oliver; Griswold, Michael E.; Guadalupe, Tulio; Gutman, Boris A.; Hass, Johanna; Haukvik, Unn K.; Hoehn, David; Holmes, Avram J.; Hoogman, Martine; Janowitz, Deborah; Jia, Tianye; Jørgensen, Kjetil N.; Karbalai, Nazanin; Kasperaviciute, Dalia; Kim, Sungeun; Klein, Marieke; Kraemer, Bernd; Lee, Phil H.; Liewald, David C. M.; Lopez, Lorna M.; Luciano, Michelle; Macare, Christine; Marquand, Andre F.; Matarin, Mar; Mather, Karen A.; Mattheisen, Manuel; McKay, David R.; Milaneschi, Yuri; Muñoz Maniega, Susana; Nho, Kwangsik; Nugent, Allison C.; Nyquist, Paul; Loohuis, Loes M. Olde; Oosterlaan, Jaap; Papmeyer, Martina; Pirpamer, Lukas; Pütz, Benno; Ramasamy, Adaikalavan; Richards, Jennifer S.; Risacher, Shannon L.; Roiz-Santiañez, Roberto; Rommelse, Nanda; Ropele, Stefan; Rose, Emma J.; Royle, Natalie A.; Rundek, Tatjana; Sämann, Philipp G.; Saremi, Arvin; Satizabal, Claudia L.; Schmaal, Lianne; Schork, Andrew J.; Shen, Li; Shin, Jean; Shumskaya, Elena; Smith, Albert V.; Sprooten, Emma; Strike, Lachlan T.; Teumer, Alexander; Tordesillas-Gutierrez, Diana; Toro, Roberto; Trabzuni, Daniah; Trompet, Stella; Vaidya, Dhananjay; van der Grond, Jeroen; van der Lee, Sven J.; van der Meer, Dennis; van Donkelaar, Marjolein M. J.; van Eijk, Kristel R.; van Erp, Theo G. M.; van Rooij, Daan; Walton, Esther; Westlye, Lars T.; Whelan, Christopher D.; Windham, Beverly G.; Winkler, Anderson M.; Wittfeld, Katharina; Woldehawariat, Girma; Wolf, Christiane; Wolfers, Thomas; Yanek, Lisa R.; Yang, Jingyun; Zijdenbos, Alex; Zwiers, Marcel P.; Agartz, Ingrid; Almasy, Laura; Ames, David; Amouyel, Philippe; Andreassen, Ole A.; Arepalli, Sampath; Assareh, Amelia A.; Barral, Sandra; Bastin, Mark E.; Becker, Diane M.; Becker, James T.; Bennett, David A.; Blangero, John; van Bokhoven, Hans; Boomsma, Dorret I.; Brodaty, Henry; Brouwer, Rachel M.; Brunner, Han G.; Buckner, Randy L.; Buitelaar, Jan K.; Bulayeva, Kazima B.; Cahn, Wiepke; Calhoun, Vince D.; Cannon, Dara M.; Cavalleri, Gianpiero L.; Cheng, Ching-Yu; Cichon, Sven; Cookson, Mark R.; Corvin, Aiden; Crespo-Facorro, Benedicto; Curran, Joanne E.; Czisch, Michael; Dale, Anders M.; Davies, Gareth E.; de Craen, Anton J. M.; de Geus, Eco J. C.; de Jager, Philip L.; de Zubicaray, Greig I.; Deary, Ian J.; Debette, Stéphanie; Decarli, Charles; Delanty, Norman; Depondt, Chantal; DeStefano, Anita; Dillman, Allissa; Djurovic, Srdjan; Donohoe, Gary; Drevets, Wayne C.; Duggirala, Ravi; Dyer, Thomas D.; Enzinger, Christian; Erk, Susanne; Espeseth, Thomas; Fedko, Iryna O.; Fernández, Guillén; Ferrucci, Luigi; Fisher, Simon E.; Fleischman, Debra A.; Ford, Ian; Fornage, Myriam; Foroud, Tatiana M.; Fox, Peter T.; Francks, Clyde; Fukunaga, Masaki; Gibbs, J. Raphael; Glahn, David C.; Gollub, Randy L.; Göring, Harald H. H.; Green, Robert C.; Gruber, Oliver; Gudnason, Vilmundur; Guelfi, Sebastian; Håberg, Asta K.; Hansell, Narelle K.; Hardy, John; Hartman, Catharina A.; Hashimoto, Ryota; Hegenscheid, Katrin; Heinz, Andreas; Le Hellard, Stephanie; Hernandez, Dena G.; Heslenfeld, Dirk J.; Ho, Beng-Choon; Hoekstra, Pieter J.; Hoffmann, Wolfgang; Hofman, Albert; Holsboer, Florian; Homuth, Georg; Hosten, Norbert; Hottenga, Jouke-Jan; Huentelman, Matthew; Pol, Hilleke E. Hulshoff; Ikeda, Masashi; Jack, Clifford R.; Jenkinson, Mark; Johnson, Robert; Jönsson, Erik G.; Jukema, J. Wouter; Kahn, René S.; Kanai, Ryota; Kloszewska, Iwona; Knopman, David S.; Kochunov, Peter; Kwok, John B.; Lawrie, Stephen M.; Lemaître, Hervé; Liu, Xinmin; Longo, Dan L.; Lopez, Oscar L.; Lovestone, Simon; Martinez, Oliver; Martinot, Jean-Luc; Mattay, Venkata S.; McDonald, Colm; McIntosh, Andrew M.; McMahon, Francis J.; McMahon, Katie L.; Mecocci, Patrizia; Melle, Ingrid; Meyer-Lindenberg, Andreas; Mohnke, Sebastian; Montgomery, Grant W.; Morris, Derek W.; Mosley, Thomas H.; Mühleisen, Thomas W.; Müller-Myhsok, Bertram; Nalls, Michael A.; Nauck, Matthias; Nichols, Thomas E.; Niessen, Wiro J.; Nöthen, Markus M.; Nyberg, Lars; Ohi, Kazutaka; Olvera, Rene L.; Ophoff, Roel A.; Pandolfo, Massimo; Paus, Tomas; Pausova, Zdenka; Penninx, Brenda W. J. H.; Pike, G. Bruce; Potkin, Steven G.; Psaty, Bruce M.; Reppermund, Simone; Rietschel, Marcella; Roffman, Joshua L.; Romanczuk-Seiferth, Nina; Rotter, Jerome I.; Ryten, Mina; Sacco, Ralph L.; Sachdev, Perminder S.; Saykin, Andrew J.; Schmidt, Reinhold; Schmidt, Helena; Schofield, Peter R.; Sigursson, Sigurdur; Simmons, Andrew; Singleton, Andrew; Sisodiya, Sanjay M.; Smith, Colin; Smoller, Jordan W.; Soininen, Hilkka; Steen, Vidar M.; Stott, David J.; Sussmann, Jessika E.; Thalamuthu, Anbupalam; Toga, Arthur W.; Traynor, Bryan J.; Troncoso, Juan; Tsolaki, Magda; Tzourio, Christophe; Uitterlinden, Andre G.; Hernández, Maria C. Valdés; van der Brug, Marcel; van der Lugt, Aad; van der Wee, Nic J. A.; van Haren, Neeltje E. M.; van 't Ent, Dennis; van Tol, Marie-Jose; Vardarajan, Badri N.; Vellas, Bruno; Veltman, Dick J.; Völzke, Henry; Walter, Henrik; Wardlaw, Joanna M.; Wassink, Thomas H.; Weale, Michael E.; Weinberger, Daniel R.; Weiner, Michael W.; Wen, Wei; Westman, Eric; White, Tonya; Wong, Tien Y.; Wright, Clinton B.; Zielke, Ronald H.; Zonderman, Alan B.; Martin, Nicholas G.; van Duijn, Cornelia M.; Wright, Margaret J.; Longstreth, W. T.; Schumann, Gunter; Grabe, Hans J.; Franke, Barbara; Launer, Lenore J.; Medland, Sarah E.; Seshadri, Sudha; Thompson, Paul M.; Ikram, M. Arfan

    2017-01-01

    The hippocampal formation is a brain structure integrally involved in episodic memory, spatial navigation, cognition and stress responsiveness. Structural abnormalities in hippocampal volume and shape are found in several common neuropsychiatric disorders. To identify the genetic underpinnings of

  7. Novel genetic loci associated with hippocampal volume

    OpenAIRE

    Hibar, Derrek P.; Adams, Hieab H. H.; Jahanshad, Neda; Chauhan, Ganesh; Stein, Jason L.; Hofer, Edith; Renteria, Miguel E.; Bis, Joshua C.; Arias-Vasquez, Alejandro; Ikram, M. Kamran; Desrivieres, Sylvane; Vernooij, Meike W.; Abramovic, Lucija; Alhusaini, Saud; Amin, Najaf

    2017-01-01

    International audience; The hippocampal formation is a brain structure integrally involved in episodic memory, spatial navigation, cognition and stress responsiveness. Structural abnormalities in hippocampal volume and shape are found in several common neuropsychiatric disorders. To identify the genetic underpinnings of hippocampal structure here we perform a genome-wide association study (GWAS) of 33,536 individuals and discover six independent loci significantly associated with hippocampal ...

  8. Hydrodynamic processes in sharp meander bends and their morphological implications

    NARCIS (Netherlands)

    Blanckaert, K.

    2011-01-01

    The migration rate of sharp meander bends exhibits large variance and indicates that some sharply curved bends tend to stabilize. These observations remain unexplained. This paper examines three hydrodynamic processes in sharp bends with fixed banks and discusses their morphological implications:

  9. Sharp foreign body ingestion by a young girl

    African Journals Online (AJOL)

    Riyadh Mohamad Hasan

    2017-06-09

    Jun 9, 2017 ... Sharp foreign body ingestion by a young girl. Riyadh Mohamad Hasan. University of Baghdad ... ray imaging and retrieved with the aid of C-arm fluoroscope at a laparotomy. Her postoperative period ... In our patient the foreign bodies were long sharp ones (sewing needles). Foreign body ingestion can be ...

  10. Hippocampal Sclerosis in Older Patients

    Science.gov (United States)

    Cykowski, Matthew D.; Powell, Suzanne Z.; Schulz, Paul E.; Takei, Hidehiro; Rivera, Andreana L.; Jackson, Robert E.; Roman, Gustavo; Jicha, Gregory A.; Nelson, Peter T.

    2018-01-01

    Context Autopsy studies of the older population (≥65 years of age), and particularly of the “oldest-old” (≥85 years of age), have identified a significant proportion (~20%) of cognitively impaired patients in which hippocampal sclerosis is the major substrate of an amnestic syndrome. Hippocampal sclerosis may also be comorbid with frontotemporal lobar degeneration, Alzheimer disease, and Lewy body disease. Until recently, the terms hippocampal sclerosis of aging or hippocampal sclerosis dementia were applied in this context. Recent discoveries have prompted a conceptual expansion of hippocampal sclerosis of aging because (1) cellular inclusions of TAR DNA-binding protein 43 kDa (TDP-43) are frequent; (2) TDP-43 pathology may be found outside hippocampus; and (3) brain arteriolosclerosis is a common, possibly pathogenic, component. Objective To aid pathologists with recent recommendations for diagnoses of common neuropathologies in older persons, particularly hippocampal sclerosis, and highlight the recent shift in diagnostic terminology from HS-aging to cerebral age-related TDP-43 with sclerosis (CARTS). Data Sources Peer-reviewed literature and 5 autopsy examples that illustrate common age-related neuropathologies, including CARTS, and emphasize the importance of distinguishing CARTS from late-onset frontotemporal lobar degeneration with TDP-43 pathology and from advanced Alzheimer disease with TDP-43 pathology. Conclusions In advanced old age, the substrates of cognitive impairment are often multifactorial. This article demonstrates common and frequently comorbid neuropathologic substrates of cognitive impairment in the older population, including CARTS, to aid those practicing in this area of pathology. PMID:28467211

  11. Weapon Use in Korean Homicide: Differences Between Homicides Involving Sharp and Blunt Instruments.

    Science.gov (United States)

    Park, Jisun; Son, Hyeonseo

    2017-10-23

    On the basis of information regarding 276 homicides committed in South Korea between 1987 and 2008, we compared offenders' and victims' characteristics, injury locations, weapon-related behavior, and offending behavior between homicides involving sharp and blunt instruments. The victims of sharp-force homicide were much younger relative to those of blunt-force homicide. In addition, homicides involving blunt instruments were more likely to be committed by offenders who lived with the victims. Most sharp-force homicides involved injuries to the torso, while blunt-force homicides involved mainly head injuries. Furthermore, perpetrators of sharp-force homicides tended to preselect their weapons, while those of blunt-force homicides were likely to use weapons of opportunity. Logistic regression analysis identified a number of factors, including injury location and body transportation, which significantly predicted weapon type. As this was the first South Korean study to compare sharp- and blunt-force homicides, the results have practical implications for homicide investigations. © 2017 American Academy of Forensic Sciences.

  12. HIPPOCAMPAL SCLEROSIS IN EPILEPSY AND CHILDHOOD FEBRILE SEIZURES

    NARCIS (Netherlands)

    KUKS, JBM; COOK, MJ; FISH, DR; STEVENS, JM; SHORVON, SD

    1993-01-01

    The connection between hippocampal sclerosis and childhood febrile seizures (CFS) is a contentious issue in the study of epilepsy. We investigated 107 patients with drug-resistant epilepsy by high-resolution volumetric magnetic resonance imaging (MRI). 20 had a history of CFS, 45 had focal (26) or

  13. Endurance Factors Improve Hippocampal Neurogenesis and Spatial Memory in Mice

    Science.gov (United States)

    Kobilo, Tali; Yuan, Chunyan; van Praag, Henriette

    2011-01-01

    Physical activity improves learning and hippocampal neurogenesis. It is unknown whether compounds that increase endurance in muscle also enhance cognition. We investigated the effects of endurance factors, peroxisome proliferator-activated receptor [delta] agonist GW501516 and AICAR, activator of AMP-activated protein kinase on memory and…

  14. Spatio-temporal specialization of GABAergic septo-hippocampal neurons for rhythmic network activity.

    Science.gov (United States)

    Unal, Gunes; Crump, Michael G; Viney, Tim J; Éltes, Tímea; Katona, Linda; Klausberger, Thomas; Somogyi, Peter

    2018-03-03

    Medial septal GABAergic neurons of the basal forebrain innervate the hippocampus and related cortical areas, contributing to the coordination of network activity, such as theta oscillations and sharp wave-ripple events, via a preferential innervation of GABAergic interneurons. Individual medial septal neurons display diverse activity patterns, which may be related to their termination in different cortical areas and/or to the different types of innervated interneurons. To test these hypotheses, we extracellularly recorded and juxtacellularly labeled single medial septal neurons in anesthetized rats in vivo during hippocampal theta and ripple oscillations, traced their axons to distant cortical target areas, and analyzed their postsynaptic interneurons. Medial septal GABAergic neurons exhibiting different hippocampal theta phase preferences and/or sharp wave-ripple related activity terminated in restricted hippocampal regions, and selectively targeted a limited number of interneuron types, as established on the basis of molecular markers. We demonstrate the preferential innervation of bistratified cells in CA1 and of basket cells in CA3 by individual axons. One group of septal neurons was suppressed during sharp wave-ripples, maintained their firing rate across theta and non-theta network states and mainly fired along the descending phase of CA1 theta oscillations. In contrast, neurons that were active during sharp wave-ripples increased their firing significantly during "theta" compared to "non-theta" states, with most firing during the ascending phase of theta oscillations. These results demonstrate that specialized septal GABAergic neurons contribute to the coordination of network activity through parallel, target area- and cell type-selective projections to the hippocampus.

  15. Enhanced Transmissions Through Three-dimensional Cascade Sharp Waveguide Bends Using C-slit Diaphragms.

    Science.gov (United States)

    Yang, Rui; Hu, Bowei; Zhang, Aofang; Gao, Dongxing; Wang, Hui; Shi, Ayuan; Lei, Zhenya; Yang, Pei

    2017-03-21

    Transmission properties through sharp rectangular waveguide bends are investigated to determine the cut-off bending angles of the wave propagation. We show that a simple metallic diaphragm at the bending corner with properly devised sub-wavelength defect apertures of C-slits would be readily to turn on the transmissions with scarce reflections of the propagating modes, while preserving the integrity of the transmitting fields soon after the bends. In particularly, our design also demonstrates the capability of eliminating all the unwanted cavity resonant transmissions that exist in the three-dimensional cascade sharp waveguide bends, and solely let the desired signals travel along the whole passage of the waveguide. The present approach, using C-slit diaphragms to support the sharp bending behaviors of the guided waves with greatly enhanced transmissions, would be especially effective in constructing novel waveguides and pave the way for the development of more compact and miniaturized electromagnetic systems that exploit these waveguide bends.

  16. Mechanisms for Selective Single-Cell Reactivation during Offline Sharp-Wave Ripples and Their Distortion by Fast Ripples.

    Science.gov (United States)

    Valero, Manuel; Averkin, Robert G; Fernandez-Lamo, Ivan; Aguilar, Juan; Lopez-Pigozzi, Diego; Brotons-Mas, Jorge R; Cid, Elena; Tamas, Gabor; Menendez de la Prida, Liset

    2017-06-21

    Memory traces are reactivated selectively during sharp-wave ripples. The mechanisms of selective reactivation, and how degraded reactivation affects memory, are poorly understood. We evaluated hippocampal single-cell activity during physiological and pathological sharp-wave ripples using juxtacellular and intracellular recordings in normal and epileptic rats with different memory abilities. CA1 pyramidal cells participate selectively during physiological events but fired together during epileptic fast ripples. We found that firing selectivity was dominated by an event- and cell-specific synaptic drive, modulated in single cells by changes in the excitatory/inhibitory ratio measured intracellularly. This mechanism collapses during pathological fast ripples to exacerbate and randomize neuronal firing. Acute administration of a use- and cell-type-dependent sodium channel blocker reduced neuronal collapse and randomness and improved recall in epileptic rats. We propose that cell-specific synaptic inputs govern firing selectivity of CA1 pyramidal cells during sharp-wave ripples. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Reversibility and hysteresis of the sharp yielding transition of a colloidal glass under oscillatory shear

    NARCIS (Netherlands)

    Dang, M. T.; Denisov, D.; Struth, B.; Zaccone, A.; Schall, P.

    The mechanical response of glasses remains challenging to understand. Recent results indicate that the oscillatory rheology of soft glasses is accompanied by a sharp non-equilibrium transition in the microscopic dynamics. Here, we use simultaneous x-ray scattering and rheology to investigate the

  18. Short-term responses of Dutch vacationers to a sharp increase in transport costs

    NARCIS (Netherlands)

    van Cranenburgh, S.

    2016-01-01

    This paper investigates vacationers’ short-term responses to a sharp increase in transport costs. It aims to (1) acquire an understanding of the relative popularity of the different types of responses among vacationers and (2) explore whether there are distinct market segments of vacationers that

  19. Comparison of Hippocampal Volume in Dementia Subtypes

    International Nuclear Information System (INIS)

    Vijayakumar, Avinash; Vijayakumar, Abhishek

    2012-01-01

    Aims. To examine the relationship between different types of dementia and hippocampal volume. Methods. Hippocampal volume was measured using FL3D sequence magnetic resonance imaging in 26 Alzheimer's, vascular dementia, mixed dementia, and normal pressure hydrocephalus patients and 15 healthy controls and also hippocampal ratio, analyzed. Minimental scale was used to stratify patients on cognitive function impairments. Results. Hippocampal volume and ratio was reduced by 25% in Alzheimer's disease, 21% in mixed dementia, 11% in vascular dementia and 5% in normal pressure hydrocephalus in comparison to control. Also an asymmetrical decrease in volume of left hippocampus was noted. The severity of dementia increased in accordance to decreasing hippocampal volume. Conclusion. Measurement in hippocampal volume may facilitate in differentiating different types of dementia and in disease progression. There was a correlation between hippocampal volume and severity of cognitive impairment

  20. An alternative window upon the GSI sharp lepton problem

    International Nuclear Information System (INIS)

    Griffin, J.J.

    1997-10-01

    Two major heavy ion studies of the GSI ''(e + e - )-Puzzle'' have ended in stalemate: APEX reports no evidence, but its data show a peak near 800 keV. EPOS/II cannot reproduce its own results,and leans towards random fluctuations as the explanation of sharp pair lines. (But one EPOS/II report shows evidence for a peak at an EPOS/I line energy, 610 keV, and under selection conditions the same as EPOSII's.) It is clear that these latest heavy ion studies, designed to settle once and for all the question of sharp pairs, have failed to fulfill that goal. Attention must now turn towards the sharp electron lines reported by Sakai et al. and others in collisions of few MeV beta decay positrons on U and Th atoms. In the Q 0 Scenario of the Sharp Lepton Problem these arise from the same source as the GSI pairs. Verification of Sakai's 100 mb cross section for such sharp electrons in collisions of few MeV electrons (or positrons) upon U or Th atoms would confirm this new experimental window upon the Sharp Lepton Problem. These relatively simple experiments, which are both inexpensive and reproducible (as their heavy ion counterparts are not), promise a less ponderous pace for the study of these questions. On the other hand, they require a challenging combination of proficiencies to measure a nuclear sized cross section in an atomic physics environment. The authors review briefly the diverse history (and especially the most recent developments) of the Sharp Lepton Problem, and outline how the Quadronium Scenario provides it with a unifying conceptual framework. That discussion points clearly towards the experimental study of sharp leptons and sharp pairs from few MeV (lepton+ATOM) and (photon+ATOM) processes as the appropriate next step towards either verifying the earlier results or precluding them

  1. Radiation Dose–Dependent Hippocampal Atrophy Detected With Longitudinal Volumetric Magnetic Resonance Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Seibert, Tyler M.; Karunamuni, Roshan [Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, California (United States); Bartsch, Hauke [Department of Radiology, University of California, San Diego, La Jolla, California (United States); Kaifi, Samar [Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, California (United States); Krishnan, Anitha Priya [Department of Radiology, University of California, San Diego, La Jolla, California (United States); Dalia, Yoseph; Burkeen, Jeffrey; Murzin, Vyacheslav; Moiseenko, Vitali [Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, California (United States); Kuperman, Joshua; White, Nathan S. [Department of Radiology, University of California, San Diego, La Jolla, California (United States); Brewer, James B. [Department of Radiology, University of California, San Diego, La Jolla, California (United States); Department of Neurosciences, University of California, San Diego, La Jolla, California (United States); Farid, Nikdokht [Department of Radiology, University of California, San Diego, La Jolla, California (United States); McDonald, Carrie R. [Department of Psychiatry, University of California, San Diego, La Jolla, California (United States); Hattangadi-Gluth, Jona A., E-mail: jhattangadi@ucsd.edu [Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, California (United States)

    2017-02-01

    Purpose: After radiation therapy (RT) to the brain, patients often experience memory impairment, which may be partially mediated by damage to the hippocampus. Hippocampal sparing in RT planning is the subject of recent and ongoing clinical trials. Calculating appropriate hippocampal dose constraints would be improved by efficient in vivo measurements of hippocampal damage. In this study we sought to determine whether brain RT was associated with dose-dependent hippocampal atrophy. Methods and Materials: Hippocampal volume was measured with magnetic resonance imaging (MRI) in 52 patients who underwent fractionated, partial brain RT for primary brain tumors. Study patients had high-resolution, 3-dimensional volumetric MRI before and 1 year after RT. Images were processed using software with clearance from the US Food and Drug Administration and Conformité Européene marking for automated measurement of hippocampal volume. Automated results were inspected visually for accuracy. Tumor and surgical changes were censored. Mean hippocampal dose was tested for correlation with hippocampal atrophy 1 year after RT. Average hippocampal volume change was also calculated for hippocampi receiving high (>40 Gy) or low (<10 Gy) mean RT dose. A multivariate analysis was conducted with linear mixed-effects modeling to evaluate other potential predictors of hippocampal volume change, including patient (random effect), age, hemisphere, sex, seizure history, and baseline volume. Statistical significance was evaluated at α = 0.05. Results: Mean hippocampal dose was significantly correlated with hippocampal volume loss (r=−0.24, P=.03). Mean hippocampal volume was significantly reduced 1 year after high-dose RT (mean −6%, P=.009) but not after low-dose RT. In multivariate analysis, both RT dose and patient age were significant predictors of hippocampal atrophy (P<.01). Conclusions: The hippocampus demonstrates radiation dose–dependent atrophy after treatment for brain

  2. Food restriction reduces neurogenesis in the avian hippocampal formation.

    Directory of Open Access Journals (Sweden)

    Barbara-Anne Robertson

    Full Text Available The mammalian hippocampus is particularly vulnerable to chronic stress. Adult neurogenesis in the dentate gyrus is suppressed by chronic stress and by administration of glucocorticoid hormones. Post-natal and adult neurogenesis are present in the avian hippocampal formation as well, but much less is known about its sensitivity to chronic stressors. In this study, we investigate this question in a commercial bird model: the broiler breeder chicken. Commercial broiler breeders are food restricted during development to manipulate their growth curve and to avoid negative health outcomes, including obesity and poor reproductive performance. Beyond knowing that these chickens are healthier than fully-fed birds and that they have a high motivation to eat, little is known about how food restriction impacts the animals' physiology. Chickens were kept on a commercial food-restricted diet during the first 12 weeks of life, or released from this restriction by feeding them ad libitum from weeks 7-12 of life. To test the hypothesis that chronic food restriction decreases the production of new neurons (neurogenesis in the hippocampal formation, the cell proliferation marker bromodeoxyuridine was injected one week prior to tissue collection. Corticosterone levels in blood plasma were elevated during food restriction, even though molecular markers of hypothalamic-pituitary-adrenal axis activation did not differ between the treatments. The density of new hippocampal neurons was significantly reduced in the food-restricted condition, as compared to chickens fed ad libitum, similar to findings in rats at a similar developmental stage. Food restriction did not affect hippocampal volume or the total number of neurons. These findings indicate that in birds, like in mammals, reduction in hippocampal neurogenesis is associated with chronically elevated corticosterone levels, and therefore potentially with chronic stress in general. This finding is consistent with the

  3. Bilateral reorganization of the dentate gyrus in hippocampal sclerosis

    Science.gov (United States)

    Thom, M; Martinian, L; Catarino, C; Yogarajah, M; Koepp, M J.; Caboclo, L; Sisodiya, S M.

    2009-01-01

    Background: Hippocampal sclerosis (HS) is the most common surgical pathology associated with mesial temporal lobe epilepsy (MTLE). HS is typically characterized by mossy fiber sprouting (MFS) and reorganization of neuropeptide Y (NPY) fiber networks in the dentate gyrus. One potential cause of postoperative seizure recurrence following temporal lobe surgery may be the presence of seizure-associated bilateral hippocampal damage. We aimed to investigate patterns of hippocampal abnormalities in a postmortem series as identified by NPY and dynorphin immunohistochemistry. Methods: Analysis of dentate gyrus fiber reorganization, using dynorphin (to demonstrate MFS) and NPY immunohistochemistry, was carried out in a postmortem epilepsy series of 25 cases (age range 21–96 years). In 9 patients, previously refractory seizures had become well controlled for up to 34 years prior to death. Results: Bilateral MFS or abnormal NPY patterns were seen in 15 patients including those with bilateral symmetric, asymmetric, and unilateral HS by conventional histologic criteria. MFS and NPY reorganization was present in all classical HS cases, more variably in atypical HS, present in both MTLE and non-MTLE syndromes and with seizure histories of up to 92 years, despite seizure remission in some patients. Conclusion: Synaptic reorganization in the dentate gyrus may be a bilateral, persistent process in epilepsy. It is unlikely to be sufficient to generate seizures and more likely to represent a seizure-induced phenomenon. GLOSSARY AED = antiepileptic drug; CA1p = CA1-predominant hippocampal sclerosis; CHS = classical hippocampal sclerosis; EFG = end folium gliosis; EFS = end folium sclerosis; GCD = granule cell dispersion; GCL = granule cell layer; HS = hippocampal sclerosis; MFS = mossy fiber sprouting; MTLE = mesial temporal lobe epilepsy; NPY = neuropeptide Y; ROI = region of interest; SE = status epilepticus; TLE = temporal lobe epilepsy. PMID:19710404

  4. Roles of hippocampal subfields in verbal and visual episodic memory.

    Science.gov (United States)

    Zammit, Andrea R; Ezzati, Ali; Zimmerman, Molly E; Lipton, Richard B; Lipton, Michael L; Katz, Mindy J

    2017-01-15

    Selective hippocampal (HC) subfield atrophy has been reported in older adults with mild cognitive impairment and Alzheimer's disease. The goal of this study was to investigate the associations between the volume of hippocampal subfields and visual and verbal episodic memory in cognitively normal older adults. This study was conducted on a subset of 133 participants from the Einstein Aging Study (EAS), a community-based study of non-demented older adults systematically recruited from the Bronx, N.Y. All participants completed comprehensive EAS neuropsychological assessment. Visual episodic memory was assessed using the Complex Figure Delayed Recall subtest from the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Verbal episodic memory was assessed using Delayed Recall from the Free and Cued Selective Reminding Test (FCSRT). All participants underwent 3T MRI brain scanning with subsequent automatic measurement of the hemispheric hippocampal subfield volumes (CA1, CA2-CA3, CA4-dente gyrus, presubiculum, and subiculum). We used linear regressions to model the association between hippocampal subfield volumes and visual and verbal episodic memory tests while adjusting for age, sex, education, and total intracranial volume. Participants had a mean age of 78.9 (SD=5.1) and 60.2% were female. Total hippocampal volume was associated with Complex Figure Delayed Recall (β=0.31, p=0.001) and FCSRT Delayed Recall (β=0.27, p=0.007); subiculum volume was associated with Complex Figure Delayed Recall (β=0.27, p=0.002) and FCSRT Delayed Recall (β=0.24, p=0.010); CA1 was associated with Complex Figure Delayed Recall (β=0.26, pepisodic memory. Our results suggest that hippocampal subfields have sensitive roles in the process of visual and verbal episodic memory. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Mesopontine median raphe regulates hippocampal ripple oscillation and memory consolidation.

    Science.gov (United States)

    Wang, Dong V; Yau, Hau-Jie; Broker, Carl J; Tsou, Jen-Hui; Bonci, Antonello; Ikemoto, Satoshi

    2015-05-01

    Sharp wave-associated field oscillations (∼200 Hz) of the hippocampus, referred to as ripples, are believed to be important for consolidation of explicit memory. Little is known about how ripples are regulated by other brain regions. We found that the median raphe region (MnR) is important for regulating hippocampal ripple activity and memory consolidation. We performed in vivo simultaneous recording in the MnR and hippocampus of mice and found that, when a group of MnR neurons was active, ripples were absent. Consistently, optogenetic stimulation of MnR neurons suppressed ripple activity and inhibition of these neurons increased ripple activity. Notably, using a fear conditioning procedure, we found that photostimulation of MnR neurons interfered with memory consolidation. Our results demonstrate a critical role of the MnR in regulating ripples and memory consolidation.

  6. Disruption of perineuronal nets increases the frequency of sharp wave ripple events.

    Science.gov (United States)

    Sun, Zhi Yong; Bozzelli, P Lorenzo; Caccavano, Adam; Allen, Megan; Balmuth, Jason; Vicini, Stefano; Wu, Jian-Young; Conant, Katherine

    2018-01-01

    Hippocampal sharp wave ripples (SWRs) represent irregularly occurring synchronous neuronal population events that are observed during phases of rest and slow wave sleep. SWR activity that follows learning involves sequential replay of training-associated neuronal assemblies and is critical for systems level memory consolidation. SWRs are initiated by CA2 or CA3 pyramidal cells (PCs) and require initial excitation of CA1 PCs as well as participation of parvalbumin (PV) expressing fast spiking (FS) inhibitory interneurons. These interneurons are relatively unique in that they represent the major neuronal cell type known to be surrounded by perineuronal nets (PNNs), lattice like structures composed of a hyaluronin backbone that surround the cell soma and proximal dendrites. Though the function of the PNN is not completely understood, previous studies suggest it may serve to localize glutamatergic input to synaptic contacts and thus influence the activity of ensheathed cells. Noting that FS PV interneurons impact the activity of PCs thought to initiate SWRs, and that their activity is critical to ripple expression, we examine the effects of PNN integrity on SWR activity in the hippocampus. Extracellular recordings from the stratum radiatum of horizontal murine hippocampal hemisections demonstrate SWRs that occur spontaneously in CA1. As compared with vehicle, pre-treatment (120 min) of paired hemislices with hyaluronidase, which cleaves the hyaluronin backbone of the PNN, decreases PNN integrity and increases SWR frequency. Pre-treatment with chondroitinase, which cleaves PNN side chains, also increases SWR frequency. Together, these data contribute to an emerging appreciation of extracellular matrix as a regulator of neuronal plasticity and suggest that one function of mature perineuronal nets could be to modulate the frequency of SWR events. © 2017 Wiley Periodicals, Inc.

  7. Hippocampal Abnormalities and Seizure Recurrence

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2006-08-01

    Full Text Available Hippocampal volumetry and T2 relaxometry were performed on 84 consecutive patients (adolescents and adults with partial epilepsy submitted to antiepileptic drug (AED withdrawal after at least 2 years of seizure control, in a study at State University of Campinas-UNICAMP, Brazil.

  8. Relationship between sharps disposal containers and Clostridium difficile infections in acute care hospitals.

    Science.gov (United States)

    Pogorzelska-Maziarz, Monika

    2015-10-01

    Sharps disposal containers are ubiquitous in health care facilities; however, there is paucity of data on their potential role in pathogen transmission. This study assessed the relationship between use of single-use versus reusable sharps containers and rates of Clostridium difficile infections in a national sample of hospitals. A 2013 survey of 1,990 hospitals collected data on the use of sharps containers. Responses were linked to the 2012 Medicare Provider Analysis and Review dataset. Bivariate and multivariable negative binomial regression were conducted to examine differences in C difficile rates between hospitals using single-use versus reusable containers. There were 604 hospitals who completed the survey; of these, 539 provided data on use of sharps containers in 2012 (27% response rate). Hospitals had, on average, 289 beds (SD ± 203) and were predominantly non-for-profit (67%) and nonteaching (63%). Most used reusable sharps containers (72%). In bivariate regression, hospitals using single-use containers had significantly lower rates of C difficile versus hospitals using reusable containers (incidence rate ratio [IRR] = 0.846, P = .001). This relationship persisted in multivariable regression (IRR = 0.870, P = .003) after controlling for other hospital characteristics. This is the first study to show a link between use of single-use sharps containers and lower C difficile rates. Future research should investigate the potential for environmental contamination of reusable containers and the role they may play in pathogen transmission. Copyright © 2015 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

  9. Neuropsychology, Autobiographical Memory, and Hippocampal Volume in ?Younger? and ?Older? Patients with Chronic Schizophrenia

    OpenAIRE

    Herold, Christina Josefa; L?sser, Marc Montgomery; Schmid, Lena Anna; Seidl, Ulrich; Kong, Li; Fellhauer, Iven; Thomann, Philipp Arthur; Essig, Marco; Schr?der, Johannes

    2015-01-01

    Despite a wide range of studies on neuropsychology in schizophrenia, autobiographical memory (AM) has been scarcely investigated in these patients. Hence, less is known about AM in older patients and hippocampal contribution to autobiographical memories of varying remoteness. Therefore, we investigated hippocampal volume and AM along with important neuropsychological domains in patients with chronic schizophrenia and the respective relationships between these parameters. We compared 25 older ...

  10. Altered hippocampal replay is associated with memory impairment in mice heterozygous for the Scn2a gene.

    Science.gov (United States)

    Middleton, Steven J; Kneller, Emily M; Chen, Shuo; Ogiwara, Ikuo; Montal, Mauricio; Yamakawa, Kazuhiro; McHugh, Thomas J

    2018-06-04

    An accumulating body of experimental evidence has implicated hippocampal replay occurring within sharp wave ripples (SPW-Rs) as crucial for learning and memory in healthy subjects. This raises speculation that neurological disorders impairing memory disrupt either SPW-Rs or their underlying neuronal activity. We report that mice heterozygous for the gene Scn2a, a site of frequent de novo mutations in humans with intellectual disability, displayed impaired spatial memory. While we observed no changes during encoding, to either single place cells or cell assemblies, we identified abnormalities restricted to SPW-R episodes that manifest as decreased cell assembly reactivation strengths and truncated hippocampal replay sequences. Our results suggest that alterations to hippocampal replay content may underlie disease-associated memory deficits.

  11. Sharp tipped plastic hollow microneedle array by microinjection moulding

    Science.gov (United States)

    Yung, K. L.; Xu, Yan; Kang, Chunlei; Liu, H.; Tam, K. F.; Ko, S. M.; Kwan, F. Y.; Lee, Thomas M. H.

    2012-01-01

    A method of producing sharp tipped plastic hollow microneedle arrays using microinjection moulding is presented in this paper. Unlike traditional approaches, three mould inserts were used to create the sharp tips of the microneedles. Mould inserts with low surface roughness were fabricated using a picosecond laser machine. Sharp tipped plastic hollow microneedles 500 µm in height were fabricated using a microinjection moulding machine developed by the authors’ group. In addition, the strength of the microneedle was studied by simulation and penetration experiments. Results show that the microneedles can penetrate into skin, delivering liquid successfully without any breakage or severe deformation. Techniques presented in this paper can be used to fabricate sharp tipped plastic hollow microneedle arrays massively with low cost.

  12. Sharp tipped plastic hollow microneedle array by microinjection moulding

    International Nuclear Information System (INIS)

    Yung, K L; Xu, Yan; Kang, Chunlei; Liu, H; Tam, K F; Ko, S M; Kwan, F Y; Lee, Thomas M H

    2012-01-01

    A method of producing sharp tipped plastic hollow microneedle arrays using microinjection moulding is presented in this paper. Unlike traditional approaches, three mould inserts were used to create the sharp tips of the microneedles. Mould inserts with low surface roughness were fabricated using a picosecond laser machine. Sharp tipped plastic hollow microneedles 500 µm in height were fabricated using a microinjection moulding machine developed by the authors’ group. In addition, the strength of the microneedle was studied by simulation and penetration experiments. Results show that the microneedles can penetrate into skin, delivering liquid successfully without any breakage or severe deformation. Techniques presented in this paper can be used to fabricate sharp tipped plastic hollow microneedle arrays massively with low cost. (paper)

  13. The effectiveness of sharp end and rounded end bristle toothbrush

    OpenAIRE

    Paulus Januar; Anastasia Susetyo; Ratih Widyastuti

    2010-01-01

    Background: Numerous designs of manual toothbrush are available in the market with the claims of superiority in plaque removal. It often makes the public confuse which is the best design. The sharp end bristle toothbrush is a modification that commercially available in the market. Purpose: The objective of the study was to compare the effectiveness in plaque removal of the sharp end bristle toothbrush and the rounded end bristle toothbrush. Methods: This clinical trial was a double blind cros...

  14. The sharp peak-flat trough pattern and critical speculation

    OpenAIRE

    Roehner, B. M.; Sornette, D.

    1998-01-01

    We find empirically a characteristic sharp peak-flat trough pattern in a large set of commodity prices. We argue that the sharp peak structure reflects an endogenous inter-market organization, and that peaks may be seen as local ``singularities'' resulting from imitation and herding. These findings impose a novel stringent constraint on the construction of models. Intermittent amplification is not sufficient and nonlinear effects seem necessary to account for the observations.

  15. Hippocampal and diencephalic pathology in developmental amnesia.

    Science.gov (United States)

    Dzieciol, Anna M; Bachevalier, Jocelyne; Saleem, Kadharbatcha S; Gadian, David G; Saunders, Richard; Chong, W K Kling; Banks, Tina; Mishkin, Mortimer; Vargha-Khadem, Faraneh

    2017-01-01

    Developmental amnesia (DA) is a selective episodic memory disorder associated with hypoxia-induced bilateral hippocampal atrophy of early onset. Despite the systemic impact of hypoxia-ischaemia, the resulting brain damage was previously reported to be largely limited to the hippocampus. However, the thalamus and the mammillary bodies are parts of the hippocampal-diencephalic network and are therefore also at risk of injury following hypoxic-ischaemic events. Here, we report a neuroimaging investigation of diencephalic damage in a group of 18 patients with DA (age range 11-35 years), and an equal number of controls. Importantly, we uncovered a marked degree of atrophy in the mammillary bodies in two thirds of our patients. In addition, as a group, patients had mildly reduced thalamic volumes. The size of the anterior-mid thalamic (AMT) segment was correlated with patients' visual memory performance. Thus, in addition to the hippocampus, the diencephalic structures also appear to play a role in the patients' memory deficit. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  16. Physical Exercise Leads to Rapid Adaptations in Hippocampal Vasculature : Temporal Dynamics and Relationship to Cell Proliferation and Neurogenesis

    NARCIS (Netherlands)

    Van der Borght, Karin; Kobor-Nyakas, Dora E.; Klauke, Karin; Eggen, Bart J. L.; Nyakas, Csaba; Van der Zee, Eddy A.; Meerlo, Peter

    2009-01-01

    Increased levels of angiogenesis and neurogenesis possibly mediate the beneficial effects of physical activity on hippocampal plasticity. This study was designed to investigate the temporal dynamics of exercise-induced changes in hippocampal angiogenesis and cell proliferation. Mice were housed with

  17. Restoration of hippocampal growth hormone reverses stress-induced hippocampal impairment

    Directory of Open Access Journals (Sweden)

    Caitlin M. Vander Weele

    2013-06-01

    Full Text Available Though growth hormone (GH is synthesized by hippocampal neurons, where its expression is influenced by stress exposure, its function is poorly characterized. Here, we show that a regimen of chronic stress that impairs hippocampal function in rats also leads to a profound decrease in hippocampal GH levels. Restoration of hippocampal GH in the dorsal hippocampus via viral-mediated gene transfer completely reversed stress-related impairment of two hippocampus-dependent behavioral tasks, auditory trace fear conditioning and contextual fear conditioning, without affecting hippocampal function in unstressed control rats. GH overexpression reversed stress-induced decrements in both fear acquisition and long-term fear memory. These results suggest that loss of hippocampal GH contributes to hippocampal dysfunction following prolonged stress and demonstrate that restoring hippocampal GH levels following stress can promote stress resilience.

  18. Episodic autobiographical memory is associated with variation in the size of hippocampal subregions.

    Science.gov (United States)

    Palombo, Daniela J; Bacopulos, Agnes; Amaral, Robert S C; Olsen, Rosanna K; Todd, Rebecca M; Anderson, Adam K; Levine, Brian

    2018-02-01

    Striking individual differences exist in the human capacity to recollect past events, yet, little is known about the neural correlates of such individual differences. Studies investigating hippocampal volume in relation to individual differences in laboratory measures of episodic memory in young adults suggest that whole hippocampal volume is unrelated (or even negatively associated) with episodic memory. However, anatomical and functional specialization across hippocampal subregions suggests that individual differences in episodic memory may be linked to particular hippocampal subregions, as opposed to whole hippocampal volume. Given that the DG/CA 2/3 circuitry is thought to be especially critical for supporting episodic memory in humans, we predicted that the volume of this region would be associated with individual variability in episodic memory. This prediction was supported using high-resolution MRI of the hippocampal subfields and measures of real-world (autobiographical) episodic memory. In addition to the association with DG/CA 2/3 , we further observed a relationship between episodic autobiographical memory and subiculum volume, whereas no association was observed with CA 1 or with whole hippocampal volume. These findings provide insight into the possible neural substrates that mediate individual differences in real-world episodic remembering in humans. © 2017 Wiley Periodicals, Inc.

  19. Hippocampal atrophy in people with memory deficits: results from the population-based IPREA study.

    Science.gov (United States)

    Ferrarini, Luca; van Lew, Baldur; Reiber, Johan H C; Gandin, Claudia; Galluzzo, Lucia; Scafato, Emanuele; Frisoni, Giovanni B; Milles, Julien; Pievani, Michela

    2014-07-01

    Clinical studies have shown that hippocampal atrophy is present before dementia in people with memory deficits and can predict dementia development. The question remains whether this association holds in the general population. This is of interest for the possible use of hippocampal atrophy to screen population for preventive interventions. The aim of this study was to assess hippocampal volume and shape abnormalities in elderly adults with memory deficits in a cross-sectional population-based study. We included individuals participating in the Italian Project on the Epidemiology of Alzheimer Disease (IPREA) study: 75 cognitively normal individuals (HC), 31 individuals with memory deficits (MEM), and 31 individuals with memory deficits not otherwise specified (MEMnos). Hippocampal volumes and shape were extracted through manual tracing and the growing and adaptive meshes (GAMEs) shape-modeling algorithm. We investigated between-group differences in hippocampal volume and shape, and correlations with memory deficits. In MEM participants, hippocampal volumes were significantly smaller than in HC and were mildly associated with worse memory scores. Memory-associated shape changes mapped to the anterior hippocampus. Shape-based analysis detected no significant difference between MEM and HC, while MEMnos showed shape changes in the posterior hippocampus compared with HC and MEM groups. These findings support the discriminant validity of hippocampal volumetry as a biomarker of memory impairment in the general population. The detection of shape changes in MEMnos but not in MEM participants suggests that shape-based biomarkers might lack sensitivity to detect Alzheimer's-like pathology in the general population.

  20. Relation between hippocampal damage and cerebral cortical function in Alzheimer's disease

    International Nuclear Information System (INIS)

    Hanyu, Haruo; Asano, Tetsuichi; Kogure, Daiji; Sakurai, Hirofumi; Iwamoto, Toshihiko; Takasaki, Masaru

    2000-01-01

    We investigated the relation between hippocampal damage and cerebral cortical dysfunction in Alzheimer's disease (AD) using MRI and SPECT. Nineteen patients with AD and 10 control subjects were studied. Hippocampal damage (including hippocampal formation, entorhinal cortex, and parahippocampal white matter) was assessed to evaluate the severity of atrophy and the magnetization transfer ratio (MTR) and cerebral cortical dysfunction was evaluated by quantitative cerebral blood flow (CBF) measurements using SPECT with 99mTc-ECD. Compared with controls, patients with AD had significantly more atrophy of the medial temporal lobe and a decrease in MTRs of the hippocampus and parahippocampus. There were significant correlations between the severity of hippocampal damage and regional CBF in temporoparietal lobes. Mini-Mental State Examination scores significantly correlated with the severity of hippocampal damage and regional CBFs in temporoparietal lobes. These results suggest that the functional effect of hippocampal damage occurs in temporoparietal lobes in AD, probably due to neuronal disconnections between hippocampal areas (including the entorhinal cortex) and temporoparietal lobes. (author)

  1. High dose tetrabromobisphenol A impairs hippocampal neurogenesis and memory retention.

    Science.gov (United States)

    Kim, Ah Hyun; Chun, Hye Jeong; Lee, Seulah; Kim, Hyung Sik; Lee, Jaewon

    2017-08-01

    Tetrabromobisphenol A (TBBPA) is a brominated flame retardant that is commonly used in commercial and household products, such as, computers, televisions, mobile phones, and electronic boards. TBBPA can accumulate in human body fluids, and it has been reported that TBBPA possesses endocrine disruptive activity. However, the neurotoxic effect of TBBPA on hippocampal neurogenesis has not yet been investigated. Accordingly, the present study was undertaken to evaluate the effect of TBBPA on adult hippocampal neurogenesis and cognitive function. Male C57BL/6 mice were orally administrated vehicle or TBBPA (20 mg/kg, 100 mg/kg, or 500 mg/kg daily) for two weeks. TBBPA was observed to significantly and dose-dependently reduce the survival of newly generated cells in the hippocampus but not to affect the proliferation of newly generated cells. Numbers of hippocampal BrdU and NeuN positive cells were dose-dependently reduced by TBBPA, indicating impaired neurogenesis in the hippocampus. Interestingly, glial activation without neuronal death was observed in hippocampi exposed to TBBPA. Furthermore, memory retention was found to be adversely affected by TBBPA exposure by a mechanism involving suppression of the BDNF-CREB signaling pathway. The study suggests high dose TBBPA disrupts hippocampal neurogenesis and induces associated memory deficits. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Adult hippocampal neurogenesis in natural populations of mammals.

    Science.gov (United States)

    Amrein, Irmgard

    2015-05-01

    This review will discuss adult hippocampal neurogenesis in wild mammals of different taxa and outline similarities with and differences from laboratory animals. It begins with a review of evidence for hippocampal neurogenesis in various mammals, and shows the similar patterns of age-dependent decline in cell proliferation in wild and domesticated mammals. In contrast, the pool of immature neurons that originate from proliferative activity varies between species, implying a selective advantage for mammals that can make use of a large number of these functionally special neurons. Furthermore, rapid adaptation of hippocampal neurogenesis to experimental challenges appears to be a characteristic of laboratory rodents. Wild mammals show species-specific, rather stable hippocampal neurogenesis, which appears related to demands that characterize the niche exploited by a species rather than to acute events in the life of its members. Studies that investigate adult neurogenesis in wild mammals are not numerous, but the findings of neurogenesis under natural conditions can provide new insights, and thereby also address the question to which cognitive demands neurogenesis may respond during selection. Copyright © 2015 Cold Spring Harbor Laboratory Press; all rights reserved.

  3. Hippocampal development in youth with a history of childhood maltreatment.

    Science.gov (United States)

    Paquola, Casey; Bennett, Maxwell R; Hatton, Sean N; Hermens, Daniel F; Groote, Inge; Lagopoulos, Jim

    2017-08-01

    Childhood maltreatment (CM) is associated with enhanced risk of psychiatric illness and reduced subcortical grey matter in adulthood. The hippocampus and amygdala, due to their involvement in stress and emotion circuitries, have been subject to extensive investigations regarding the effect of CM. However, the complex relationship between CM, subcortical grey matter and mental illness remains poorly understood partially due to a lack of longitudinal studies. Here we used segmentation and linear mixed effect modelling to examine the impact of CM on hippocampal and amygdala development in young people with emerging mental illness. A total of 215 structural magnetic resonance imaging (MRI) scans were acquired from 123 individuals (age: 14-28 years, 79 female), 52 of whom were scanned twice or more. Hippocampal and amygdala volumes increased linearly with age, and their developmental trajectories were not moderated by symptom severity. However, exposure to CM was associated with significantly stunted right hippocampal growth. This finding bridges the gap between child and adult research in the field and provides novel evidence that CM is associated with disrupted hippocampal development in youth. Although CM was associated with worse symptom severity, we did not find evidence that CM-induced structural abnormalities directly underpin psychopathology. This study has important implications for the psychiatric treatment of individuals with CM since they are clinically and neurobiologically distinct from their peers who were not maltreated. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Neuropsychology, Autobiographical Memory, and Hippocampal Volume in “Younger” and “Older” Patients with Chronic Schizophrenia

    Science.gov (United States)

    Herold, Christina Josefa; Lässer, Marc Montgomery; Schmid, Lena Anna; Seidl, Ulrich; Kong, Li; Fellhauer, Iven; Thomann, Philipp Arthur; Essig, Marco; Schröder, Johannes

    2015-01-01

    Despite a wide range of studies on neuropsychology in schizophrenia, autobiographical memory (AM) has been scarcely investigated in these patients. Hence, less is known about AM in older patients and hippocampal contribution to autobiographical memories of varying remoteness. Therefore, we investigated hippocampal volume and AM along with important neuropsychological domains in patients with chronic schizophrenia and the respective relationships between these parameters. We compared 25 older patients with chronic schizophrenia to 23 younger patients and an older healthy control group (N = 21) with respect to AM, additional neuropsychological parameters, and hippocampal volume. Personal episodic and semantic memory was investigated using a semi-structured interview. Additional neuropsychological parameters were assessed by using a battery of standard neuropsychological tests. Structural magnetic resonance imaging data were analyzed with an automated region-of-interest procedure. While hippocampal volume reduction and neuropsychological impairment were more pronounced in the older than in the younger patients, both groups showed equivalent reduced AM performance for recent personal episodes. In the patient group, significant correlations between left hippocampal volume and recent autobiographical episodes as well as personal semantic memories arose. Verbal memory and working memory were significantly correlated with right hippocampal volume; executive functions, however, were associated with bilateral hippocampal volumes. These findings underline the complexity of AM and its impairments in the course of schizophrenia in comparison to rather progressive neuropsychological deficits and address the importance of hippocampal contribution. PMID:25954208

  5. A grading system for hippocampal sclerosis based on the degree of hippocampal mossy fiber sprouting

    NARCIS (Netherlands)

    Gispen, W.H.; Proper, E.A.; Jansen, G.H.; Veelen, C.W. van; Rijen, P.C. van; Graan, P.N.E. de

    2001-01-01

    Abstract. In patients suffering from temporal lobe epilepsy (TLE) a highly variable degree of hippocampal sclerosis (HS) can be observed. For standard neuropathological evaluation after hippocampal resection, neuronal cell loss in the hippocampal subareas is assessed (Wyler score 0-4) [Wyler et al.

  6. Diversity of sharp-wave–ripple LFP signatures reveals differentiated brain-wide dynamical events

    Science.gov (United States)

    Ramirez-Villegas, Juan F.; Logothetis, Nikos K.; Besserve, Michel

    2015-01-01

    Sharp-wave–ripple (SPW-R) complexes are believed to mediate memory reactivation, transfer, and consolidation. However, their underlying neuronal dynamics at multiple scales remains poorly understood. Using concurrent hippocampal local field potential (LFP) recordings and functional MRI (fMRI), we study local changes in neuronal activity during SPW-R episodes and their brain-wide correlates. Analysis of the temporal alignment between SPW and ripple components reveals well-differentiated SPW-R subtypes in the CA1 LFP. SPW-R–triggered fMRI maps show that ripples aligned to the positive peak of their SPWs have enhanced neocortical metabolic up-regulation. In contrast, ripples occurring at the trough of their SPWs relate to weaker neocortical up-regulation and absent subcortical down-regulation, indicating differentiated involvement of neuromodulatory pathways in the ripple phenomenon mediated by long-range interactions. To our knowledge, this study provides the first evidence for the existence of SPW-R subtypes with differentiated CA1 activity and metabolic correlates in related brain areas, possibly serving different memory functions. PMID:26540729

  7. Diversity of sharp-wave-ripple LFP signatures reveals differentiated brain-wide dynamical events.

    Science.gov (United States)

    Ramirez-Villegas, Juan F; Logothetis, Nikos K; Besserve, Michel

    2015-11-17

    Sharp-wave-ripple (SPW-R) complexes are believed to mediate memory reactivation, transfer, and consolidation. However, their underlying neuronal dynamics at multiple scales remains poorly understood. Using concurrent hippocampal local field potential (LFP) recordings and functional MRI (fMRI), we study local changes in neuronal activity during SPW-R episodes and their brain-wide correlates. Analysis of the temporal alignment between SPW and ripple components reveals well-differentiated SPW-R subtypes in the CA1 LFP. SPW-R-triggered fMRI maps show that ripples aligned to the positive peak of their SPWs have enhanced neocortical metabolic up-regulation. In contrast, ripples occurring at the trough of their SPWs relate to weaker neocortical up-regulation and absent subcortical down-regulation, indicating differentiated involvement of neuromodulatory pathways in the ripple phenomenon mediated by long-range interactions. To our knowledge, this study provides the first evidence for the existence of SPW-R subtypes with differentiated CA1 activity and metabolic correlates in related brain areas, possibly serving different memory functions.

  8. Reading, writing, and reserve: Literacy activities are linked to hippocampal volume and memory in multiple sclerosis.

    Science.gov (United States)

    Sumowski, James F; Rocca, Maria A; Leavitt, Victoria M; Riccitelli, Gianna; Meani, Alessandro; Comi, Giancarlo; Filippi, Massimo

    2016-10-01

    Engagement in cognitive leisure activities during early adulthood has been linked to preserved memory and larger hippocampal volume in persons with multiple sclerosis (MS). To investigate which specific types of cognitive leisure activities contribute to hippocampal volume and memory. We investigated links between three types of cognitive activities (Reading-Writing, Art-Music, Games-Hobbies) and (a) hippocampal volume within independent samples of Italian (n=187) and American (n=55) MS patients and (b) memory in subsamples of Italian (n=97) and American (n=53) patients. Reading-Writing was the only predictor of hippocampal volume (rp=.204, p=.002), and the best predictor of memory (rp=.288, p=.001). Findings inform the development of targeted evidence-based enrichment programs aiming to bolster reserve against memory decline. © The Author(s), 2016.

  9. Numerical deconvolution to enhance sharpness and contrast of portal images for radiotherapy patient positioning verification

    International Nuclear Information System (INIS)

    Looe, H.K.; Uphoff, Y.; Poppe, B.; Carl von Ossietzky Univ., Oldenburg; Harder, D.; Willborn, K.C.

    2012-01-01

    The quality of megavoltage clinical portal images is impaired by physical and geometrical effects. This image blurring can be corrected by a fast numerical two-dimensional (2D) deconvolution algorithm implemented in the electronic portal image device. We present some clinical examples of deconvolved portal images and evaluate the clinical advantages achieved by the improved sharpness and contrast. The principle of numerical 2D image deconvolution and the enhancement of sharpness and contrast thereby achieved are shortly explained. The key concept is the convolution kernel K(x,y), the mathematical equivalent of the smearing or blurring of a picture, and the computer-based elimination of this influence. Enhancements of sharpness and contrast were observed in all clinical portal images investigated. The images of fine bone structures were restored. The identification of organ boundaries and anatomical landmarks was improved, thereby permitting a more accurate comparison with the x-ray simulator radiographs. The visibility of prostate gold markers is also shown to be enhanced by deconvolution. The blurring effects of clinical portal images were eliminated by a numerical deconvolution algorithm that leads to better image sharpness and contrast. The fast algorithm permits the image blurring correction to be performed in real time, so that patient positioning verification with increased accuracy can be achieved in clinical practice. (orig.)

  10. Numerical deconvolution to enhance sharpness and contrast of portal images for radiotherapy patient positioning verification

    Energy Technology Data Exchange (ETDEWEB)

    Looe, H.K.; Uphoff, Y.; Poppe, B. [Pius Hospital, Oldenburg (Germany). Clinic for Radiation Therapy; Carl von Ossietzky Univ., Oldenburg (Germany). WG Medical Radiation Physics; Harder, D. [Georg August Univ., Goettingen (Germany). Medical Physics and Biophysics; Willborn, K.C. [Pius Hospital, Oldenburg (Germany). Clinic for Radiation Therapy

    2012-02-15

    The quality of megavoltage clinical portal images is impaired by physical and geometrical effects. This image blurring can be corrected by a fast numerical two-dimensional (2D) deconvolution algorithm implemented in the electronic portal image device. We present some clinical examples of deconvolved portal images and evaluate the clinical advantages achieved by the improved sharpness and contrast. The principle of numerical 2D image deconvolution and the enhancement of sharpness and contrast thereby achieved are shortly explained. The key concept is the convolution kernel K(x,y), the mathematical equivalent of the smearing or blurring of a picture, and the computer-based elimination of this influence. Enhancements of sharpness and contrast were observed in all clinical portal images investigated. The images of fine bone structures were restored. The identification of organ boundaries and anatomical landmarks was improved, thereby permitting a more accurate comparison with the x-ray simulator radiographs. The visibility of prostate gold markers is also shown to be enhanced by deconvolution. The blurring effects of clinical portal images were eliminated by a numerical deconvolution algorithm that leads to better image sharpness and contrast. The fast algorithm permits the image blurring correction to be performed in real time, so that patient positioning verification with increased accuracy can be achieved in clinical practice. (orig.)

  11. Moderate exercise ameliorates dysregulated hippocampal glycometabolism and memory function in a rat model of type 2 diabetes.

    Science.gov (United States)

    Shima, Takeru; Matsui, Takashi; Jesmin, Subrina; Okamoto, Masahiro; Soya, Mariko; Inoue, Koshiro; Liu, Yu-Fan; Torres-Aleman, Ignacio; McEwen, Bruce S; Soya, Hideaki

    2017-03-01

    Type 2 diabetes is likely to be an independent risk factor for hippocampal-based memory dysfunction, although this complication has yet to be investigated in detail. As dysregulated glycometabolism in peripheral tissues is a key symptom of type 2 diabetes, it is hypothesised that diabetes-mediated memory dysfunction is also caused by hippocampal glycometabolic dysfunction. If so, such dysfunction should also be ameliorated with moderate exercise by normalising hippocampal glycometabolism, since 4 weeks of moderate exercise enhances memory function and local hippocampal glycogen levels in normal animals. The hippocampal glycometabolism in OLETF rats (model of human type 2 diabetes) was assessed and, subsequently, the effects of exercise on memory function and hippocampal glycometabolism were investigated. OLETF rats, which have memory dysfunction, exhibited higher levels of glycogen in the hippocampus than did control rats, and breakdown of hippocampal glycogen with a single bout of exercise remained unimpaired. However, OLETF rats expressed lower levels of hippocampal monocarboxylate transporter 2 (MCT2, a transporter for lactate to neurons). Four weeks of moderate exercise improved spatial memory accompanied by further increase in hippocampal glycogen levels and restoration of MCT2 expression independent of neurotrophic factor and clinical symptoms in OLETF rats. Our findings are the first to describe detailed profiles of glycometabolism in the type 2 diabetic hippocampus and to show that 4 weeks of moderate exercise improves memory dysfunction in type 2 diabetes via amelioration of dysregulated hippocampal glycometabolism. Dysregulated hippocampal lactate-transport-related glycometabolism is a possible aetiology of type-2-diabetes-mediated memory dysfunction.

  12. NASA-Ames Summer High School Apprenticeship Research Program (SHARP)

    Science.gov (United States)

    Powell, P.

    1983-01-01

    The function of SHARP is to recognize high school juniors who have demonstrated unusually high promise for sucess in mathemtics and science. Twenty academically talented students who will be seniors in high school in September were chosen to participate in SHARP 83. Mentors were selected to provide students with first-hand experiences in a research and development environment in order that each student might try out his or her tentative professional career choice. Some special features of SHARP included field trips to private industries doing similar and related research, special lectures on topics of research here at ARC, individual and group counseling sessions, written research papers and oral reports, and primarily the opportunity to be exposed to the present frontiers in space exploration and research. The long-range goal of SHARP is to contribute to the future recruitment of needed scientists and engineers. This final report is summary of all the phases of the planning and implemenation of the 1983 Summer High School Apprenticeship Research Program (SHARP).

  13. Effects of low-level sarin and cyclosarin exposure on hippocampal microstructure in Gulf War Veterans.

    Science.gov (United States)

    Chao, Linda L; Zhang, Yu

    2018-05-04

    In early March 1991, shortly after the end of the Gulf War (GW), a munitions dump was destroyed at Khamisiyah, Iraq. Later, in 1996, the dump was found to have contained the organophosphorus (OP) nerve agents sarin and cyclosarin. We previously reported evidence of smaller hippocampal volumes in GW veterans with predicted exposure to the Khamisiyah plume compared to unexposed GW veterans. To investigate whether these macroscopic hippocampal volume changes are accompanied by microstructural alterations in the hippocampus, the current study acquired diffusion-tensor imaging (DTI), T1-, and T2-weighted images from 170 GW veterans (mean age: 53 ± 7 years), 81 of whom had predicted exposure to the Khamisiyah plume according to Department of Defense (DOD) plume modeling. We examined fractional anisotropy (FA), mean diffusivity (MD), and grey matter (GM) density from a hippocampal region of interest (ROI). Results indicate that, even after accounting for total hippocampal GM density (or hippocampal volume), age, sex, apolipoprotein ε4 genotype, and potential confounding OP pesticide exposures, hippocampal MD significantly predicted Khamisiyah exposure status (model p = 0.005, R 2  = 0.215, standardized coefficient β = 0.26, t = 2.85). Hippocampal MD was also inversely correlated with verbal memory learning performance in the entire study sample (p = 0.001). There were no differences in hippocampal FA or GM density; however, veterans with predicted Khamisiyah exposure had smaller hippocampal volumes compared to unexposed veterans. Because MD is sensitive to general microstructural disruptions that lead to increased extracellular spaces due to neuronal death, inflammation and gliosis, and/or to axonal loss or demyelination, these findings suggest that low-level exposure to the Khamisiyah plume has a detrimental, lasting effects on both macro- and micro-structure of the hippocampus. Copyright © 2018. Published by Elsevier Inc.

  14. Spatial representation in the hippocampal formation: a history.

    Science.gov (United States)

    Moser, Edvard I; Moser, May-Britt; McNaughton, Bruce L

    2017-10-26

    Since the first place cell was recorded and the cognitive-map theory was subsequently formulated, investigation of spatial representation in the hippocampal formation has evolved in stages. Early studies sought to verify the spatial nature of place cell activity and determine its sensory origin. A new epoch started with the discovery of head direction cells and the realization of the importance of angular and linear movement-integration in generating spatial maps. A third epoch began when investigators turned their attention to the entorhinal cortex, which led to the discovery of grid cells and border cells. This review will show how ideas about integration of self-motion cues have shaped our understanding of spatial representation in hippocampal-entorhinal systems from the 1970s until today. It is now possible to investigate how specialized cell types of these systems work together, and spatial mapping may become one of the first cognitive functions to be understood in mechanistic detail.

  15. Anti-Hebbian long-term potentiation in the hippocampal feedback inhibitory circuit.

    Science.gov (United States)

    Lamsa, Karri P; Heeroma, Joost H; Somogyi, Peter; Rusakov, Dmitri A; Kullmann, Dimitri M

    2007-03-02

    Long-term potentiation (LTP), which approximates Hebb's postulate of associative learning, typically requires depolarization-dependent glutamate receptors of the NMDA (N-methyl-D-aspartate) subtype. However, in some neurons, LTP depends instead on calcium-permeable AMPA-type receptors. This is paradoxical because intracellular polyamines block such receptors during depolarization. We report that LTP at synapses on hippocampal interneurons mediating feedback inhibition is "anti-Hebbian":Itis induced by presynaptic activity but prevented by postsynaptic depolarization. Anti-Hebbian LTP may occur in interneurons that are silent during periods of intense pyramidal cell firing, such as sharp waves, and lead to their altered activation during theta activity.

  16. Hippocampal sleep features: relations to human memory function

    Directory of Open Access Journals (Sweden)

    Michele eFerrara

    2012-04-01

    Full Text Available The recent spread of intracranial EEG recordings techniques for presurgical evaluation of drug-resistant epileptic patients is providing new information on the activity of different brain structures during both wakefulness and sleep. The interest has been mainly focused on the medial temporal lobe, and in particular the hippocampal formation, whose peculiar local sleep features have been recently described, providing support to the idea that sleep is not a spatially global phenomenon. The study of the hippocampal sleep electrophysiology is particularly interesting because of its central role in the declarative memory formation. Recent data indicate that sleep contributes to memory formation. Therefore, it is relevant to understand whether specific pattern of activity taking place during sleep are related to memory consolidation processes. Fascinating similarities between different states of consciousness (wakefulness, REM sleep, NREM sleep in some electrophysiological mechanisms underlying cognitive processes have been reported. For instance, large-scale synchrony in gamma activity is important for waking memory and perception processes, and its changes during sleep may be the neurophysiological substrate of sleep-related deficits of declarative memory. Hippocampal activity seems to specifically support memory consolidation during sleep, through specific coordinated neurophysiological events (slow waves, spindles, ripples that would facilitate the integration of new information into the pre-existing cortical networks. A few studies indeed provided direct evidence that rhinal ripples as well as slow hippocampal oscillations are correlated with memory consolidation in humans. More detailed electrophysiological investigations assessing the specific relations between different types of memory consolidation and hippocampal EEG features are in order. These studies will add an important piece of knowledge to the elucidation of the ultimate sleep

  17. Hippocampal Sleep Features: Relations to Human Memory Function

    Science.gov (United States)

    Ferrara, Michele; Moroni, Fabio; De Gennaro, Luigi; Nobili, Lino

    2012-01-01

    The recent spread of intracranial electroencephalographic (EEG) recording techniques for presurgical evaluation of drug-resistant epileptic patients is providing new information on the activity of different brain structures during both wakefulness and sleep. The interest has been mainly focused on the medial temporal lobe, and in particular the hippocampal formation, whose peculiar local sleep features have been recently described, providing support to the idea that sleep is not a spatially global phenomenon. The study of the hippocampal sleep electrophysiology is particularly interesting because of its central role in the declarative memory formation. Recent data indicate that sleep contributes to memory formation. Therefore, it is relevant to understand whether specific patterns of activity taking place during sleep are related to memory consolidation processes. Fascinating similarities between different states of consciousness (wakefulness, REM sleep, non-REM sleep) in some electrophysiological mechanisms underlying cognitive processes have been reported. For instance, large-scale synchrony in gamma activity is important for waking memory and perception processes, and its changes during sleep may be the neurophysiological substrate of sleep-related deficits of declarative memory. Hippocampal activity seems to specifically support memory consolidation during sleep, through specific coordinated neurophysiological events (slow waves, spindles, ripples) that would facilitate the integration of new information into the pre-existing cortical networks. A few studies indeed provided direct evidence that rhinal ripples as well as slow hippocampal oscillations are correlated with memory consolidation in humans. More detailed electrophysiological investigations assessing the specific relations between different types of memory consolidation and hippocampal EEG features are in order. These studies will add an important piece of knowledge to the elucidation of the ultimate

  18. Heterogeneous sharpness for cross-spectral face recognition

    Science.gov (United States)

    Cao, Zhicheng; Schmid, Natalia A.

    2017-05-01

    Matching images acquired in different electromagnetic bands remains a challenging problem. An example of this type of comparison is matching active or passive infrared (IR) against a gallery of visible face images, known as cross-spectral face recognition. Among many unsolved issues is the one of quality disparity of the heterogeneous images. Images acquired in different spectral bands are of unequal image quality due to distinct imaging mechanism, standoff distances, or imaging environment, etc. To reduce the effect of quality disparity on the recognition performance, one can manipulate images to either improve the quality of poor-quality images or to degrade the high-quality images to the level of the quality of their heterogeneous counterparts. To estimate the level of discrepancy in quality of two heterogeneous images a quality metric such as image sharpness is needed. It provides a guidance in how much quality improvement or degradation is appropriate. In this work we consider sharpness as a relative measure of heterogeneous image quality. We propose a generalized definition of sharpness by first achieving image quality parity and then finding and building a relationship between the image quality of two heterogeneous images. Therefore, the new sharpness metric is named heterogeneous sharpness. Image quality parity is achieved by experimentally finding the optimal cross-spectral face recognition performance where quality of the heterogeneous images is varied using a Gaussian smoothing function with different standard deviation. This relationship is established using two models; one of them involves a regression model and the other involves a neural network. To train, test and validate the model, we use composite operators developed in our lab to extract features from heterogeneous face images and use the sharpness metric to evaluate the face image quality within each band. Images from three different spectral bands visible light, near infrared, and short

  19. Four year-old girl with having bled intestinal sharp

    International Nuclear Information System (INIS)

    Rodriguez Toro, Gerzain

    2001-01-01

    Indigenous girl, natural of Vaupes, Colombia conduction to the Mitu Hospital to present depositions with bleed. Their father says that the girl is sick for two days; she presents anorexia, moderate abdominal pain and vomit scarce postprandial, followed by discreet diarrhea and of two depositions with blood and abundant clots, with posterior syncope. It confirms a bled digestive with sharp anemic syndrome. The possibilities of gastritis sharp erosive, gastric ulcer or duodenal and intestinal poliparasitism are suggested. It is diagnosed abdominal angioestrongilosis, illness produce by helminths that lives inside the blind and the distal ileum

  20. Feeding ecology of sharp-shinned hawks in deciduous and coniferous forests in Colorado

    Science.gov (United States)

    Suzanne M. Joy; Richard T. Reynolds; Richard L. Knight; Richard W. Hoffman

    1994-01-01

    Feeding ecology of 11 Sharp-skinned Hawk (Accipiter striates) pairs nesting in aspen (Populus tremuloides), conifer (Abies, Picea spp.), and mixed aspen-conifer habitats in southwest Colorado was investigated during 1988-1989. Small birds (x-bar = 20.9 g, SE = 0.8 g) and mammals (x-bar = 41.1 g, SE = 3.3 g) comprised 91 and 9% of...

  1. Hippocampal volume in relation to clinical and cognitive outcome after electroconvulsive therapy in depression.

    Science.gov (United States)

    Nordanskog, P; Larsson, M R; Larsson, E-M; Johanson, A

    2014-04-01

    In a previous magnetic resonance imaging (MRI) study, we found a significant increase in hippocampal volume immediately after electroconvulsive therapy (ECT) in patients with depression. The aim of this study was to evaluate hippocampal volume up to 1 year after ECT and investigate its possible relation to clinical and cognitive outcome. Clinical and cognitive outcome in 12 in-patients with depression receiving antidepressive pharmacological treatment referred for ECT were investigated with the Montgomery-Asberg Depression Rating Scale (MADRS) and a broad neuropsychological test battery within 1 week before and after ECT. The assessments were repeated 6 and 12 months after baseline in 10 and seven of these patients, respectively. Hippocampal volumes were measured on all four occasions with 3 Tesla MRI. Hippocampal volume returned to baseline during the follow-up period of 6 months. Neither the significant antidepressant effect nor the significant transient decrease in executive and verbal episodic memory tests after ECT could be related to changes in hippocampal volume. No persistent cognitive side effects were observed 1 year after ECT. The immediate increase in hippocampal volume after ECT is reversible and is not related to clinical or cognitive outcome. © 2013 The Authors. Acta Psychiatrica Scandinavica published by John Wiley & Sons Ltd.

  2. Decreased rhythmic GABAergic septal activity and memory-associated theta oscillations after hippocampal amyloid-beta pathology in the rat.

    Science.gov (United States)

    Villette, Vincent; Poindessous-Jazat, Frédérique; Simon, Axelle; Léna, Clément; Roullot, Elodie; Bellessort, Brice; Epelbaum, Jacques; Dutar, Patrick; Stéphan, Aline

    2010-08-18

    The memory deficits associated with Alzheimer's disease result to a great extent from hippocampal network dysfunction. The coordination of this network relies on theta (symbol) oscillations generated in the medial septum. Here, we investigated in rats the impact of hippocampal amyloid beta (Abeta) injections on the physiological and cognitive functions that depend on the septohippocampal system. Hippocampal Abeta injections progressively impaired behavioral performances, the associated hippocampal theta power, and theta frequency response in a visuospatial recognition test. These alterations were associated with a specific reduction in the firing of the identified rhythmic bursting GABAergic neurons responsible for the propagation of the theta rhythm to the hippocampus, but without loss of medial septal neurons. Such results indicate that hippocampal Abeta treatment leads to a specific functional depression of inhibitory projection neurons of the medial septum, resulting in the functional impairment of the temporal network.

  3. Changes in rat hippocampal CA1 synapses following imipramine treatment

    DEFF Research Database (Denmark)

    Chen, Fenghua; Madsen, Torsten M; Wegener, Gregers

    2008-01-01

    Neuronal plasticity in hippocampus is hypothesized to play an important role in both the pathophysiology of depressive disorders and the treatment. In this study, we investigated the consequences of imipramine treatment on neuroplasticity (including neurogenesis, synaptogenesis, and remodelling...... and number of neurons of hippocampal subregions following imipramine treatment were found. However, the number and percentage of CA1 asymmetric spine synapses increased significantly and, conversely, the percentage of asymmetric shaft synapses significantly decreased in the imipramine treated group. Our...

  4. Linking adult hippocampal neurogenesis with human physiology and disease.

    Science.gov (United States)

    Bowers, Megan; Jessberger, Sebastian

    2016-07-01

    We here review the existing evidence linking adult hippocampal neurogenesis and human brain function in physiology and disease. Furthermore, we aim to point out where evidence is missing, highlight current promising avenues of investigation, and suggest future tools and approaches to foster the link between life-long neurogenesis and human brain function. Developmental Dynamics 245:702-709, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  5. Two New Sharp Ostrowski-Grüss Type Inequalities

    Directory of Open Access Journals (Sweden)

    Zheng Liu

    2013-11-01

    Full Text Available The purpose of this paper is to use a variant of the Grüss inequality to derive two new sharp Ostrowski-Grüss type inequalities related to a perturbed trapezoidal type rule and a perturbed generalized interior point rule, respectively, which provide improvements of some previous results in the literatures.

  6. Conservative sharp debridement: the professional and legal issues.

    Science.gov (United States)

    Ashworth, Jenny; Chivers, Marc

    2002-06-01

    In recent years there has been much debate over the use of conservative sharp debridement in the treatment of certain wound types. Here it is discussed in relation to increasing the speed of wound healing in slow-to-heal wounds. The authors examine education and skill competence in relation to the professional's duty of care to patients with wounds.

  7. Sharp Injuries Among Hospital Waste Handlers | Olaitan | Nigerian ...

    African Journals Online (AJOL)

    , C as well as other before commencing on their jobs. Workers should be screened for infective diseases that can be of legal problem while at the job and the workers should be effectively immunized. Key words: sharp injuries, waste, handlers, ...

  8. Herbivores Enforce Sharp Boundaries Between Terrestrial and Aquatic Ecosystems

    NARCIS (Netherlands)

    Sarneel, Judith M.; Huig, N.; Veen, G. F.; Rip, W.; Bakker, E. S.

    2014-01-01

    The transitions between ecosystems (ecotones) are often biodiversity hotspots, but we know little about the forces that shape them. Today, often sharp boundaries with low diversity are found between terrestrial and aquatic ecosystems. This has been attributed to environmental factors that hamper

  9. Sharp Bounds for Symmetric and Asymmetric Diophantine Approximation

    Institute of Scientific and Technical Information of China (English)

    Cornelis KRAAIKAMP; Ionica SMEETS

    2011-01-01

    In 2004,Tong found bounds for the approximation quality of a regular continued fraction convergent to a rational number,expressed in bounds for both the previous and next approximation.The authors sharpen his results with a geometric method and give both sharp upper and lower bounds.The asymptotic frequencies that these bounds occur are also calculated.

  10. Sharp Embeddings of Besov Spaces with Logarithmic Smoothness

    Czech Academy of Sciences Publication Activity Database

    Gurka, P.; Opic, Bohumír

    2005-01-01

    Roč. 18, č. 1 (2005), s. 81-110 ISSN 1139-1138 R&D Projects: GA ČR(CZ) GA201/01/0333 Institutional research plan: CEZ:AV0Z10190503 Keywords : Besov spaces wirh logarithmic smoothness * Lorentz-Zygmund spaces * sharp embeddings Subject RIV: BA - General Mathematics

  11. Surface-Wave Pulse Routing around Sharp Right Angles

    Science.gov (United States)

    Gao, Z.; Xu, H.; Gao, F.; Zhang, Y.; Luo, Y.; Zhang, B.

    2018-04-01

    Surface-plasmon polaritons (SPPs), or localized electromagnetic surface waves propagating on a metal-dielectric interface, are deemed promising information carriers for future subwavelength terahertz and optical photonic circuitry. However, surface waves fundamentally suffer from scattering loss when encountering sharp corners in routing and interconnection of photonic signals. Previous approaches enabling scattering-free surface-wave guidance around sharp corners are limited to either volumetric waveguide environments or extremely narrow bandwidth, being unable to guide a surface-wave pulse (SPP wave packet) on an on-chip platform. Here, in a surface-wave band-gap crystal implemented on a single metal surface, we demonstrate in time-domain routing a surface-wave pulse around multiple sharp right angles without perceptible scattering. Our work not only offers a solution to on-chip surface-wave pulse routing along an arbitrary path, but it also provides spatiotemporal information on the interplay between surface-wave pulses and sharp corners, both of which are desirable in developing high-performance large-scale integrated photonic circuits.

  12. [Overview of sharps injuries among health-care workers].

    Science.gov (United States)

    Gopar-Nieto, Rodrigo; Juárez-Pérez, Cuauhtémoc Arturo; Cabello-López, Alejandro; Haro-García, Luis Cuauhtémoc; Aguilar-Madrid, Guadalupe

    2015-01-01

    Sharps injuries are one of the most frequent health-care related accidents. It is estimated globally that 35 million workers are at risk; in Mexico there is no data available for this type of injuries. They are associated with lack of training, instrument and procedure risk, fatigue and stress. The occupational distribution is nurses 45 %, technicians 20 %, doctors 20 % and maintenance workers 5 %. The most commonly associated procedures are injection, venipuncture, suture, and insertion and manipulation of IV catheters. Hepatitis B is the most commonly transmitted agent. Emotional distress is huge as well as the cost of prophylaxis and follow-up. More than half of the injuries are not notified. The most common reasons for not reporting are: the belief that the exposure has low risk of infection, the lack of knowledge of reporting systems and the assumption that it is difficult to notify. Many strategies have been created to reduce the incidence of sharps injuries, such as: identifying the risk of blood exposure, the creation of politics to minimize the risk, the education and training to create a safe workplace, the enhancing of the reporting system, the use of double-gloving and using safety-engineered sharps devices. In many countries these politics have reduced the incidence of sharps injuries as well as the economic burden.

  13. Aerobic exercise increases hippocampal volume and improves memory in multiple sclerosis: preliminary findings.

    Science.gov (United States)

    Leavitt, V M; Cirnigliaro, C; Cohen, A; Farag, A; Brooks, M; Wecht, J M; Wylie, G R; Chiaravalloti, N D; DeLuca, J; Sumowski, J F

    2014-01-01

    Multiple sclerosis leads to prominent hippocampal atrophy, which is linked to memory deficits. Indeed, 50% of multiple sclerosis patients suffer memory impairment, with negative consequences for quality of life. There are currently no effective memory treatments for multiple sclerosis either pharmacological or behavioral. Aerobic exercise improves memory and promotes hippocampal neurogenesis in nonhuman animals. Here, we investigate the benefits of aerobic exercise in memory-impaired multiple sclerosis patients. Pilot data were collected from two ambulatory, memory-impaired multiple sclerosis participants randomized to non-aerobic (stretching) and aerobic (stationary cycling) conditions. The following baseline/follow-up measurements were taken: high-resolution MRI (neuroanatomical volumes), fMRI (functional connectivity), and memory assessment. Intervention was 30-minute sessions 3 times per week for 3 months. Aerobic exercise resulted in 16.5% increase in hippocampal volume and 53.7% increase in memory, as well as increased hippocampal resting-state functional connectivity. Improvements were specific, with no comparable changes in overall cerebral gray matter (+2.4%), non-hippocampal deep gray matter structures (thalamus, caudate: -4.0%), or in non-memory cognitive functioning (executive functions, processing speed, working memory: changes ranged from -11% to +4%). Non-aerobic exercise resulted in relatively no change in hippocampal volume (2.8%) or memory (0.0%), and no changes in hippocampal functional connectivity. This is the first evidence for aerobic exercise to increase hippocampal volume and connectivity and improve memory in multiple sclerosis. Aerobic exercise represents a cost-effective, widely available, natural, and self-administered treatment with no adverse side effects that may be the first effective memory treatment for multiple sclerosis patients.

  14. 17β Estradiol increases resilience and improves hippocampal synaptic function in helpless ovariectomized rats

    Science.gov (United States)

    Bredemann, Teruko M.; McMahon, Lori L.

    2014-01-01

    Summary Memory impairment is the most commonly reported cognitive symptom associated with major depressive disorder. Decreased hippocampal volume and neurogenesis in depression link hippocampal dysfunction with deficits in memory. Stress decreases hippocampal dendritic spine density and long-term potentiation (LTP) at glutamate synapses, a cellular correlate of learning and memory. However, elevated plasma levels of 17β estradiol (E2) during proestrus increase hippocampal structure and function, directly opposing the negative consequences of stress. In women, significant fluctuations in ovarian hormones likely increase vulnerability of hippocampal circuits to stress, potentially contributing to the greater incidence of depression compared to men. Using the learned helplessness model of depression and ovariectomized female rats, we investigated whether acquisition of helplessness and hippocampal synaptic dysfunction is differentially impacted by the presence or absence of plasma E2. We find that inescapable shock induces a greater incidence of helplessness in vehicle- versus E2-treated OVX rats. In the vehicle-treated group, LTP was absent at CA3-CA1 synapses in slices only from helpless rats, and CA1 spine density was decreased compared to resilient rats. In contrast, significant LTP was observed in slices from E2-treated helpless rats; importantly, spine density was not different between E2-treated helpless and resilient rats, dissociating spine density from the LTP magnitude. We also find that E2 replacement can reverse previously established helpless behavior. Thus, our results show that E2 replacement in OVX rats increases resilience and improves hippocampal plasticity, suggesting that E2 therapy may increase resilience to stress and preserve hippocampal function in women experiencing large fluctuations in plasma estrogen levels. PMID:24636504

  15. Effects of Early-Life Adversity on Hippocampal Structures and Associated HPA Axis Functions.

    Science.gov (United States)

    Dahmen, Brigitte; Puetz, Vanessa B; Scharke, Wolfgang; von Polier, Georg G; Herpertz-Dahlmann, Beate; Konrad, Kerstin

    2018-01-01

    Early-life adversity (ELA) is one of the major risk factors for serious mental and physical health risks later in life. ELA has been associated with dysfunctional neurodevelopment, especially in brain structures such as the hippocampus, and with dysfunction of the stress system, including the hypothalamic-pituitary-adrenal (HPA) axis. Children who have experienced ELA are also more likely to suffer from mental health disorders such as depression later in life. The exact interplay of aberrant neurodevelopment and HPA axis dysfunction as risks for psychopathology is not yet clear. We investigated volume differences in the bilateral hippocampus and in stress-sensitive hippocampal subfields, behavior problems, and diurnal cortisol activity in 24 children who had experienced documented ELA (including out-of-home placement) in a circumscribed duration of adversity only in their first 3 years of life in comparison to data on 25 control children raised by their biological parents. Hippocampal volumes and stress-sensitive hippocampal subfields (Cornu ammonis [CA]1, CA3, and the granule-cell layer of the dentate gyrus [GCL-DG]) were significantly smaller in children who had experienced ELA, taking psychiatric diagnoses and dimensional psychopathological symptoms into account. ELA moderated the relationship between left hippocampal volume and cortisol: in the control group, hippocampal volumes were not related to diurnal cortisol, while in ELA children, a positive linear relationship between left hippocampal volume and diurnal cortisol was present. Our findings show that ELA is associated with altered development of the hippocampus, and an altered relationship between hippocampal volume and HPA axis activity in youth in care, even after they have lived in stable and caring foster family environments for years. Altered hippocampal development after ELA could thus be associated with a risk phenotype for the development of psychiatric disorders later in life. © 2017 S. Karger

  16. Correlation between volume and morphological changes in the hippocampal formation in Alzheimer's disease: rounding of the outline of the hippocampal body on coronal MR images

    International Nuclear Information System (INIS)

    Adachi, Michito; Sato, Takamichi; Kawakatsu, Shinobu; Ohshima, Fumi

    2012-01-01

    The aim of this study was to investigate whether the outline of the hippocampal body becomes rounded on coronal magnetic resonance imaging (MRI) as the volume of the hippocampal formation decreases in Alzheimer's disease (AD). Institutional review board approval of the study protocol was obtained, and all subjects provided informed consent for the mini-mental state examination (MMSE) and MRI. The MRI and MMSE were prospectively performed in all 103 subjects (27 men and 76 women; mean age ± standard deviation, 77.7 ± 7.8 years) who had AD or were concerned about having of dementia and who consulted our institute over 1 year. The subjects included 14 non-dementia cases (MMSE score ≥ 28) and 89 AD cases (MMSE score ≤ 27). The total volume of the bilateral hippocampal formation (VHF) was assessed with a tracing method, and the ratio of the VHF to the intracranial volume (RVHF) and the rounding ratio (RR) of the hippocampal body (mean ratio of its short dimension to the long dimension in the bilateral hippocampal body) were calculated. Using Spearman's correlation coefficient, the correlations between RR and VHF and between RR and RVHF were assessed. Correlation coefficients between RR and VHF and between RR and RVHF were -0.419 (p < 0.01) and -0.418 (p < 0.01), respectively. There was a significant negative correlation between RR and the volume of the hippocampal formation. The outline of the body of the hippocampal formation becomes rounded on coronal images as its volume decreases in AD. (orig.)

  17. Potential hippocampal region atrophy in diabetes mellitus type 2. A voxel-based morphometry VSRAD study

    International Nuclear Information System (INIS)

    Kamiyama, Kazutoshi; Sugihara, Masaki; Wada, Akihiko

    2010-01-01

    Among diabetes mellitus type 2 (DM2) patients, the frequency of cognitive dysfunction is higher and the relative risk of Alzheimer's disease (AD) is approximately twice that of nondiabetics. Cognitive impairment symptoms of AD are induced by limbic system dysfunction, and an early-stage AD brain without dementia has the potential for atrophy in the hippocampal region. In this study, we estimated potential hippocampal region atrophy in DM2 and pursued the association between DM2 and cognitive impairment/AD. Voxel-based morphometry analysis was performed in 28 diabetics (14 men, 14 women; ages 59-79 years, mean 70.7 years) and 28 sex- and age- matched (±1 year) nondiabetics. Severity of gray matter loss in the hippocampal region and whole brain were investigated. Group analysis was performed using two-tailed unpaired t-test; significance was assumed with less than 1% (P<0.01) of the critical rate. There was a significant difference between diabetics and nondiabetics regarding the severity of hippocampal region atrophy and whole-brain atrophy. Only diabetics showed a positive correlation for severity of hippocampal region atrophy and whole-brain atrophy (rs=0.69, P<0.0001). Aged DM2 patients have the potential for hippocampal region atrophy, and its dysfunction can be related to the expression of a cognitive impairment that resembles AD. (author)

  18. Differential Atrophy of Hippocampal Subfields: A Comparative Study of Dementia with Lewy Bodies and Alzheimer Disease.

    Science.gov (United States)

    Mak, Elijah; Su, Li; Williams, Guy B; Watson, Rosie; Firbank, Michael; Blamire, Andrew; O'Brien, John

    2016-02-01

    Dementia with Lewy bodies (DLB) is characterized by relative preservation of the medial temporal lobe compared with Alzheimer disease (AD). The differential involvement of the hippocampal subfields in both diseases has not been clearly established, however. We aim to investigate hippocampal subfield differences in vivo in a clinical cohort of DLB and AD subjects. 104 participants (35 DLBs, 36 ADs, and 35 healthy comparison [HC] subjects) underwent clinical assessment and 3T T1-weighted imaging. A Bayesian model implemented in Freesurfer was used to automatically segment the hippocampus and its subfields. We also examined associations between hippocampal subfields and tests of memory function. Both the AD and DLB groups demonstrated significant atrophy of the total hippocampus relative to HC but the DLB group was characterized by preservation of the cornu ammonis 1 (CA1), fimbria, and fissure. In contrast, all the hippocampal subfields except the fissure were significantly atrophied in AD compared with both DLB and HC groups. Among DLB subjects, CA1 was correlated with the Recent Memory score of the CAMCOG and Delayed Recall subscores of the HVLT. DLB is characterized by milder hippocampal atrophy that was accompanied by preservation of the CA1. The CA1 was also associated with memory function in DLB. Our findings highlight the promising role of hippocampal subfield volumetry, particularly that of the CA1, as a biomarker for the distinction between AD and DLB. Copyright © 2016 American Association for Geriatric Psychiatry. Published by Elsevier Inc. All rights reserved.

  19. A prospective evaluation of hippocampal radiation dose volume effects and memory deficits following cranial irradiation.

    Science.gov (United States)

    Ma, Ting Martin; Grimm, Jimm; McIntyre, Riley; Anderson-Keightly, Heather; Kleinberg, Lawrence R; Hales, Russell K; Moore, Joseph; Vannorsdall, Tracy; Redmond, Kristin J

    2017-11-01

    To prospectively evaluate hippocampal radiation dose volume effects and memory decline following cranial irradiation. Effects of hippocampal radiation over a wide range of doses were investigated by combining data from three prospective studies. In one, adults with small cell lung cancer received hippocampal-avoidance prophylactic cranial irradiation. In the other two, adults with glioblastoma multiforme received neural progenitor cell sparing radiation or no sparing with extra dose delivered to subventricular zone. Memory was measured by the Hopkins Verbal Learning Test-Revised Delayed Recall (HVLT-R DR) at 6 months after radiation. Dose-volume histograms were generated and dose-response data were fitted to a nonlinear model. Of 60 patients enrolled, 30 were analyzable based on HVLT-R DR testing completion status, baseline HVLT-R DR and intracranial metastasis/recurrence or prior hippocampal resection status. We observed a dose-response of radiation to the hippocampus with regard to decline in HVLT-R DR. D50% of the bilateral hippocampi of 22.1 Gy is associated with 20% risk of decline. This prospective study demonstrates an association between hippocampal dose volume effects and memory decline measured by HVLT-R DR over a wide dose range. These data support a potential benefit of hippocampal sparing and encourage continued trial enrollment. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. The relationship between hippocampal asymmetry and temperament in adolescent borderline and antisocial personality pathology.

    Science.gov (United States)

    Jovev, Martina; Whittle, Sarah; Yücel, Murat; Simmons, Julian Guy; Allen, Nicholas B; Chanen, Andrew M

    2014-02-01

    Investigating etiological processes early in the life span represents an important step toward a better understanding of the development of personality pathology. The current study evaluated the interaction between an individual difference risk factor (i.e., temperament) and a biological risk factor for aggressive behavior (i.e., atypical [larger] rightward hippocampal asymmetry) in predicting the emergence of borderline personality disorder (BPD) and antisocial personality disorder symptoms during early adolescence. The sample consisted of 153 healthy adolescents (M = 12.6 years, SD = 0.4, range = 11.4-13.7) who were selected from a larger sample to maximize variation in temperament. Interactions between four temperament factors (effortful control, negative affectivity, surgency, and affiliativeness), based on the Early Adolescent Temperament Questionnaire-Revised, and volumetric measures of hippocampal asymmetry were examined as cross-sectional predictors of BPD and antisocial personality disorder symptoms. Boys were more likely to have elevated BPD symptoms if they were high on affiliation and had larger rightward hippocampal asymmetry. In boys, low affiliation was a significant predictor of BPD symptoms in the presence of low rightward hippocampal asymmetry. For girls, low effortful control was associated with elevated BPD symptoms in the presence of atypical rightward hippocampal asymmetry. This study builds on previous work reporting significant associations between atypical hippocampal asymmetry and poor behavioral regulation.

  1. Dosimetric Properties of Plasma Density Effects on Laser-Accelerated VHEE Beams Using a Sharp Density-Transition Scheme

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Seung Hoon; Cho, Sungho; Kim, Eun Ho; Park, Jeong Hoon; Jung, Won-Gyun; Kim, Geun Beom; Kim, Kum Bae [Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Min, Byung Jun [Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Kim, Jaehoon [Korea Electrotechnology Research Institute, Ansan (Korea, Republic of); Jeong, Hojin [Gyeongsang National University Hospital, Jinju (Korea, Republic of); Lee, Kitae [Korea Atomic Energy Research Institute, Deajeon (Korea, Republic of); Park, Sung Yong [Karmanos Cancer Institute, Michigan (United States)

    2017-01-15

    In this paper, the effects of the plasma density on laser-accelerated electron beams for radiation therapy with a sharp density transition are investigated. In the sharp density-transition scheme for electron injection, the crucial issue is finding the optimum density conditions under which electrons injected only during the first period of the laser wake wave are accelerated further. In this paper, we report particle-in-cell simulation results for the effects of both the scale length and the density transition ratio on the generation of a quasi-mono-energetic electron bunch. The effects of both the transverse parabolic channel and the plasma length on the electron-beam's quality are investigated. Also, we show the experimental results for the feasibility of a sharp density-transition structure. The dosimetric properties of these very high-energy electron beams are calculated using Monte Carlo simulations.

  2. Application of the SHARP Toolkit to Sodium-Cooled Fast Reactor Challenge Problems

    Energy Technology Data Exchange (ETDEWEB)

    Shemon, E. R. [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Yu, Y. [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Kim, T. K. [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division

    2017-09-30

    STAR-CCM+ calculations. The HCFs of the peak temperatures at cladding outer surface, cladding inner wall surface, and fuel centerline induced by cladding manufacturing tolerance and uncertainties on the cladding, coolant, and fuel properties were evaluated for the AFR-100. Some assessment on the effect of wire wrap configuration and size of the bundle shows that it is practical to use the 7-pin bare rod bundle to calculate the HCFs. The resulting HCFs obtained from the high-fidelity SHARP calculations are generally smaller than those developed for the earlier SFRs because the most uncertainties involved in the modeling and simulations were disappeared. For completeness, additional investigations are planned in FY 2018, which will use random sampling techniques.

  3. Novel genetic loci associated with hippocampal volume.

    Science.gov (United States)

    Hibar, Derrek P; Adams, Hieab H H; Jahanshad, Neda; Chauhan, Ganesh; Stein, Jason L; Hofer, Edith; Renteria, Miguel E; Bis, Joshua C; Arias-Vasquez, Alejandro; Ikram, M Kamran; Desrivières, Sylvane; Vernooij, Meike W; Abramovic, Lucija; Alhusaini, Saud; Amin, Najaf; Andersson, Micael; Arfanakis, Konstantinos; Aribisala, Benjamin S; Armstrong, Nicola J; Athanasiu, Lavinia; Axelsson, Tomas; Beecham, Ashley H; Beiser, Alexa; Bernard, Manon; Blanton, Susan H; Bohlken, Marc M; Boks, Marco P; Bralten, Janita; Brickman, Adam M; Carmichael, Owen; Chakravarty, M Mallar; Chen, Qiang; Ching, Christopher R K; Chouraki, Vincent; Cuellar-Partida, Gabriel; Crivello, Fabrice; Den Braber, Anouk; Doan, Nhat Trung; Ehrlich, Stefan; Giddaluru, Sudheer; Goldman, Aaron L; Gottesman, Rebecca F; Grimm, Oliver; Griswold, Michael E; Guadalupe, Tulio; Gutman, Boris A; Hass, Johanna; Haukvik, Unn K; Hoehn, David; Holmes, Avram J; Hoogman, Martine; Janowitz, Deborah; Jia, Tianye; Jørgensen, Kjetil N; Karbalai, Nazanin; Kasperaviciute, Dalia; Kim, Sungeun; Klein, Marieke; Kraemer, Bernd; Lee, Phil H; Liewald, David C M; Lopez, Lorna M; Luciano, Michelle; Macare, Christine; Marquand, Andre F; Matarin, Mar; Mather, Karen A; Mattheisen, Manuel; McKay, David R; Milaneschi, Yuri; Muñoz Maniega, Susana; Nho, Kwangsik; Nugent, Allison C; Nyquist, Paul; Loohuis, Loes M Olde; Oosterlaan, Jaap; Papmeyer, Martina; Pirpamer, Lukas; Pütz, Benno; Ramasamy, Adaikalavan; Richards, Jennifer S; Risacher, Shannon L; Roiz-Santiañez, Roberto; Rommelse, Nanda; Ropele, Stefan; Rose, Emma J; Royle, Natalie A; Rundek, Tatjana; Sämann, Philipp G; Saremi, Arvin; Satizabal, Claudia L; Schmaal, Lianne; Schork, Andrew J; Shen, Li; Shin, Jean; Shumskaya, Elena; Smith, Albert V; Sprooten, Emma; Strike, Lachlan T; Teumer, Alexander; Tordesillas-Gutierrez, Diana; Toro, Roberto; Trabzuni, Daniah; Trompet, Stella; Vaidya, Dhananjay; Van der Grond, Jeroen; Van der Lee, Sven J; Van der Meer, Dennis; Van Donkelaar, Marjolein M J; Van Eijk, Kristel R; Van Erp, Theo G M; Van Rooij, Daan; Walton, Esther; Westlye, Lars T; Whelan, Christopher D; Windham, Beverly G; Winkler, Anderson M; Wittfeld, Katharina; Woldehawariat, Girma; Wolf, Christiane; Wolfers, Thomas; Yanek, Lisa R; Yang, Jingyun; Zijdenbos, Alex; Zwiers, Marcel P; Agartz, Ingrid; Almasy, Laura; Ames, David; Amouyel, Philippe; Andreassen, Ole A; Arepalli, Sampath; Assareh, Amelia A; Barral, Sandra; Bastin, Mark E; Becker, Diane M; Becker, James T; Bennett, David A; Blangero, John; van Bokhoven, Hans; Boomsma, Dorret I; Brodaty, Henry; Brouwer, Rachel M; Brunner, Han G; Buckner, Randy L; Buitelaar, Jan K; Bulayeva, Kazima B; Cahn, Wiepke; Calhoun, Vince D; Cannon, Dara M; Cavalleri, Gianpiero L; Cheng, Ching-Yu; Cichon, Sven; Cookson, Mark R; Corvin, Aiden; Crespo-Facorro, Benedicto; Curran, Joanne E; Czisch, Michael; Dale, Anders M; Davies, Gareth E; De Craen, Anton J M; De Geus, Eco J C; De Jager, Philip L; De Zubicaray, Greig I; Deary, Ian J; Debette, Stéphanie; DeCarli, Charles; Delanty, Norman; Depondt, Chantal; DeStefano, Anita; Dillman, Allissa; Djurovic, Srdjan; Donohoe, Gary; Drevets, Wayne C; Duggirala, Ravi; Dyer, Thomas D; Enzinger, Christian; Erk, Susanne; Espeseth, Thomas; Fedko, Iryna O; Fernández, Guillén; Ferrucci, Luigi; Fisher, Simon E; Fleischman, Debra A; Ford, Ian; Fornage, Myriam; Foroud, Tatiana M; Fox, Peter T; Francks, Clyde; Fukunaga, Masaki; Gibbs, J Raphael; Glahn, David C; Gollub, Randy L; Göring, Harald H H; Green, Robert C; Gruber, Oliver; Gudnason, Vilmundur; Guelfi, Sebastian; Håberg, Asta K; Hansell, Narelle K; Hardy, John; Hartman, Catharina A; Hashimoto, Ryota; Hegenscheid, Katrin; Heinz, Andreas; Le Hellard, Stephanie; Hernandez, Dena G; Heslenfeld, Dirk J; Ho, Beng-Choon; Hoekstra, Pieter J; Hoffmann, Wolfgang; Hofman, Albert; Holsboer, Florian; Homuth, Georg; Hosten, Norbert; Hottenga, Jouke-Jan; Huentelman, Matthew; Hulshoff Pol, Hilleke E; Ikeda, Masashi; Jack, Clifford R; Jenkinson, Mark; Johnson, Robert; Jönsson, Erik G; Jukema, J Wouter; Kahn, René S; Kanai, Ryota; Kloszewska, Iwona; Knopman, David S; Kochunov, Peter; Kwok, John B; Lawrie, Stephen M; Lemaître, Hervé; Liu, Xinmin; Longo, Dan L; Lopez, Oscar L; Lovestone, Simon; Martinez, Oliver; Martinot, Jean-Luc; Mattay, Venkata S; McDonald, Colm; McIntosh, Andrew M; McMahon, Francis J; McMahon, Katie L; Mecocci, Patrizia; Melle, Ingrid; Meyer-Lindenberg, Andreas; Mohnke, Sebastian; Montgomery, Grant W; Morris, Derek W; Mosley, Thomas H; Mühleisen, Thomas W; Müller-Myhsok, Bertram; Nalls, Michael A; Nauck, Matthias; Nichols, Thomas E; Niessen, Wiro J; Nöthen, Markus M; Nyberg, Lars; Ohi, Kazutaka; Olvera, Rene L; Ophoff, Roel A; Pandolfo, Massimo; Paus, Tomas; Pausova, Zdenka; Penninx, Brenda W J H; Pike, G Bruce; Potkin, Steven G; Psaty, Bruce M; Reppermund, Simone; Rietschel, Marcella; Roffman, Joshua L; Romanczuk-Seiferth, Nina; Rotter, Jerome I; Ryten, Mina; Sacco, Ralph L; Sachdev, Perminder S; Saykin, Andrew J; Schmidt, Reinhold; Schmidt, Helena; Schofield, Peter R; Sigursson, Sigurdur; Simmons, Andrew; Singleton, Andrew; Sisodiya, Sanjay M; Smith, Colin; Smoller, Jordan W; Soininen, Hilkka; Steen, Vidar M; Stott, David J; Sussmann, Jessika E; Thalamuthu, Anbupalam; Toga, Arthur W; Traynor, Bryan J; Troncoso, Juan; Tsolaki, Magda; Tzourio, Christophe; Uitterlinden, Andre G; Hernández, Maria C Valdés; Van der Brug, Marcel; van der Lugt, Aad; van der Wee, Nic J A; Van Haren, Neeltje E M; van 't Ent, Dennis; Van Tol, Marie-Jose; Vardarajan, Badri N; Vellas, Bruno; Veltman, Dick J; Völzke, Henry; Walter, Henrik; Wardlaw, Joanna M; Wassink, Thomas H; Weale, Michael E; Weinberger, Daniel R; Weiner, Michael W; Wen, Wei; Westman, Eric; White, Tonya; Wong, Tien Y; Wright, Clinton B; Zielke, Ronald H; Zonderman, Alan B; Martin, Nicholas G; Van Duijn, Cornelia M; Wright, Margaret J; Longstreth, W T; Schumann, Gunter; Grabe, Hans J; Franke, Barbara; Launer, Lenore J; Medland, Sarah E; Seshadri, Sudha; Thompson, Paul M; Ikram, M Arfan

    2017-01-18

    The hippocampal formation is a brain structure integrally involved in episodic memory, spatial navigation, cognition and stress responsiveness. Structural abnormalities in hippocampal volume and shape are found in several common neuropsychiatric disorders. To identify the genetic underpinnings of hippocampal structure here we perform a genome-wide association study (GWAS) of 33,536 individuals and discover six independent loci significantly associated with hippocampal volume, four of them novel. Of the novel loci, three lie within genes (ASTN2, DPP4 and MAST4) and one is found 200 kb upstream of SHH. A hippocampal subfield analysis shows that a locus within the MSRB3 gene shows evidence of a localized effect along the dentate gyrus, subiculum, CA1 and fissure. Further, we show that genetic variants associated with decreased hippocampal volume are also associated with increased risk for Alzheimer's disease (r g =-0.155). Our findings suggest novel biological pathways through which human genetic variation influences hippocampal volume and risk for neuropsychiatric illness.

  4. Visual performance of pigeons following hippocampal lesions.

    Science.gov (United States)

    Bingman, V P; Hodos, W

    1992-11-15

    The effect of hippocampal lesions on performance in two psychophysical measures of spatial vision (acuity and size-difference threshold) was examined in 7 pigeons. No difference between the preoperative and postoperative thresholds of the experimental birds was found. The visual performance of pigeons in the psychophysical tasks failed to reveal a role of the hippocampal formation in vision. The results argue strongly that the behavioral deficits found in pigeons with hippocampal lesions when tested in a variety of memory-related spatial tasks is not based on a defect in spatial vision but impaired spatial cognition.

  5. Energy dissipation characteristics of sharp-edged orifice plate

    Directory of Open Access Journals (Sweden)

    Ai Wanzheng

    2015-08-01

    Full Text Available The energy loss coefficient, relating directly to the energy dissipation ratio, is an important index of this energy dissipater. In this article, this coefficient and its affecting parameters were analyzed by theoretical considerations, and their relationships were obtained by numerical simulations. It could be concluded that the energy loss coefficient of sharp-edged orifice plate and its backflow region length were mainly dominated by the contraction ratio of the orifice plate. Sharp-edged orifice plate’s energy loss coefficient and its backflow region length all increase slightly with the increase in its thickness. When Reynolds number is in the range of 9.00×104–10.3×106, Reynolds number has little impacts on energy loss coefficient and backflow region length. Two empirical expressions, relating to backflow region length and energy loss coefficient, respectively, were presented.

  6. Sharp bounds for periodic solutions of Lipschitzian differential equations

    International Nuclear Information System (INIS)

    Zevin, A A

    2009-01-01

    A general system of Lipschitzian differential equations, containing simultaneously terms without delay and with arbitrary constant and time-varying delays, is considered. For the autonomous case, a lower bound for the period of nonconstant periodic solutions, expressed in the respective supremum Lipschitz constants, is found. For nonautonomous periodic equations, explicit upper bounds for the amplitudes and maximum derivatives of periodic solutions are obtained. For all n ≥ 2, the bounds do not depend on n and, in general, are different from that for n = 1. All the bounds are sharp; they are attained in linear differential equations with piece-wise constant deviating arguments. A relation between the obtained bounds and the sharp bounds in other metrics is established

  7. Cryogenic receiver front-end with sharp skirt characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Narahashi, S [RF Technology Laboratory, Wireless Laboratories, NTT DoCoMo, Inc, Yokosuka, Kanagawa 239-8536 (Japan); Satoh, K [RF Technology Laboratory, Wireless Laboratories, NTT DoCoMo, Inc, Yokosuka, Kanagawa 239-8536 (Japan); Kawai, K [RF Technology Laboratory, Wireless Laboratories, NTT DoCoMo, Inc, Yokosuka, Kanagawa 239-8536 (Japan); Koizumi, D [RF Technology Laboratory, Wireless Laboratories, NTT DoCoMo, Inc, Yokosuka, Kanagawa 239-8536 (Japan); Nojima, T [Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Hokkaido 060-0808 (Japan)

    2006-05-15

    This paper presents an experimental cryogenic receiver front-end (CRFE) with sharp skirt characteristics for mobile base stations. The CRFE comprises a high-temperature superconducting filter, a cryogenic low-noise amplifier, and a highly reliable cryostat that is very compact. The major characteristics of the proposed CRFE measured at 70 K are a centre frequency of 1.95 GHz, passband width of 20 MHz, sharp selectivity of 20 dB/100 kHz, 1.4 dB ripple, 31.3 dB average passband gain, and average passband equivalent noise temperature of 47.9 K. The CRFE weighs 19 kg and occupies 35 l. Random failure of the cryostat is also evaluated by a continuous operation test using four identical ones simultaneously. The cryostat used in the CRFE has a high reliability level of over five years of continuous maintenance-free operation.

  8. A Constructive Sharp Approach to Functional Quantization of Stochastic Processes

    OpenAIRE

    Junglen, Stefan; Luschgy, Harald

    2010-01-01

    We present a constructive approach to the functional quantization problem of stochastic processes, with an emphasis on Gaussian processes. The approach is constructive, since we reduce the infinite-dimensional functional quantization problem to a finite-dimensional quantization problem that can be solved numerically. Our approach achieves the sharp rate of the minimal quantization error and can be used to quantize the path space for Gaussian processes and also, for example, Lévy processes.

  9. Treatment of sharp mandibular alveolar process with hybrid prosthesis

    OpenAIRE

    Sukaedi, Sukaedi; Djulaeha, Eha

    2010-01-01

    Background: Losing posterior teeth for a long time would occasionally lead to the sharpening of alveolar process. The removable partial denture usually have problems when used during mastication, because of the pressure on the mucosa under the alveolar ridge. Purpose: The purpose of this case report was to manage patients with sharp mandibular alveolar process by wearing hybrid prosthesis with extra coronal precision attachment retention and soft liner on the surface base beneath the removabl...

  10. Sharp Dissection versus Electrocautery for Radial Artery Harvesting

    Science.gov (United States)

    Marzban, Mehrab; Arya, Reza; Mandegar, Mohammad Hossein; Karimi, Abbas Ali; Abbasi, Kiomars; Movahed, Namvar; Abbasi, Seyed Hesameddin

    2006-01-01

    Radial arteries have been increasingly used during the last decade as conduits for coronary artery revascularization. Although various harvesting techniques have been described, there has been little comparative study of arterial damage and patency. A radial artery graft was used in 44 consecutive patients, who were randomly divided into 2 groups. In the 1st group, the radial artery was harvested by sharp dissection and in the 2nd, by electrocautery. These groups were compared with regard to radial artery free flow, harvest time, number of clips used, complications, and endothelial damage. Radial artery free flow before and after intraluminal administration of papaverine was significantly greater in the electrocautery group (84.3 ± 50.7 mL/min and 109.7 ± 68.5 mL/min) than in the sharp-dissection group (52.9 ± 18.3 mL/min and 69.6 ± 28.2 mL/ min) (P =0.003). Harvesting time by electrocautery was significantly shorter (25.4 ± 4.3 min vs 34.4 ± 5.9 min) (P =0.0001). Electrocautery consumed an average of 9.76 clips, versus 22.45 clips consumed by sharp dissection. The 2 groups were not different regarding postoperative complications, except for 3 cases of temporary paresthesia of the thumb in the electrocautery group; histopathologic examination found no endothelial damage. We conclude that radial artery harvesting by electrocautery is faster and more economical than harvesting by sharp dissection and is associated with better intraoperative flow and good preservation of endothelial integrity. PMID:16572861

  11. Adaptive moving mesh methods for simulating one-dimensional groundwater problems with sharp moving fronts

    Science.gov (United States)

    Huang, W.; Zheng, Lingyun; Zhan, X.

    2002-01-01

    Accurate modelling of groundwater flow and transport with sharp moving fronts often involves high computational cost, when a fixed/uniform mesh is used. In this paper, we investigate the modelling of groundwater problems using a particular adaptive mesh method called the moving mesh partial differential equation approach. With this approach, the mesh is dynamically relocated through a partial differential equation to capture the evolving sharp fronts with a relatively small number of grid points. The mesh movement and physical system modelling are realized by solving the mesh movement and physical partial differential equations alternately. The method is applied to the modelling of a range of groundwater problems, including advection dominated chemical transport and reaction, non-linear infiltration in soil, and the coupling of density dependent flow and transport. Numerical results demonstrate that sharp moving fronts can be accurately and efficiently captured by the moving mesh approach. Also addressed are important implementation strategies, e.g. the construction of the monitor function based on the interpolation error, control of mesh concentration, and two-layer mesh movement. Copyright ?? 2002 John Wiley and Sons, Ltd.

  12. Lithium implantation at low temperature in silicon for sharp buried amorphous layer formation and defect engineering

    International Nuclear Information System (INIS)

    Oliviero, E.; David, M. L.; Beaufort, M. F.; Barbot, J. F.; Fichtner, P. F. P.

    2013-01-01

    The crystalline-to-amorphous transformation induced by lithium ion implantation at low temperature has been investigated. The resulting damage structure and its thermal evolution have been studied by a combination of Rutherford backscattering spectroscopy channelling (RBS/C) and cross sectional transmission electron microscopy (XTEM). Lithium low-fluence implantation at liquid nitrogen temperature is shown to produce a three layers structure: an amorphous layer surrounded by two highly damaged layers. A thermal treatment at 400 °C leads to the formation of a sharp amorphous/crystalline interfacial transition and defect annihilation of the front heavily damaged layer. After 600 °C annealing, complete recrystallization takes place and no extended defects are left. Anomalous recrystallization rate is observed with different motion velocities of the a/c interfaces and is ascribed to lithium acting as a surfactant. Moreover, the sharp buried amorphous layer is shown to be an efficient sink for interstitials impeding interstitial supersaturation and {311} defect formation in case of subsequent neon implantation. This study shows that lithium implantation at liquid nitrogen temperature can be suitable to form a sharp buried amorphous layer with a well-defined crystalline front layer, thus having potential applications for defects engineering in the improvement of post-implantation layers quality and for shallow junction formation.

  13. Needlestick and Sharp Instruments Injuries among Brazilian Dentistry Students

    Science.gov (United States)

    Fernandes, Liege Helena Freitas; Nunes, Wanúbia Barbosa; Silva, Larissa Costa; Wanderley, Rayssa Lucena; Barros, Criseuda Maria Benício; Cavalcanti, Alessandro Leite

    2017-01-01

    Background: The occurrence of occupational accidents is common among students and dentists. The present study is aimed to evaluate the prevalence and characteristics of needlestick and sharp instrument injuries among dentistry students. Materials and Methods: A documentary research was carried out with data being obtained from the analysis of 137 medical records of injuries caused by needlestick and sharp instruments occurring in the period from 2012 to 2016 and were analyzed regarding the characteristics of the victim (gender and age) and the accident (year, time, environment, and time interval between exposure and search for care). Data were organized in the Statistical Package for Social Sciences software version 18 and were presented through descriptive statistics. Results: The occurrence of accidents was high (43.1%), with the predominance of female victims (66.1%) and aged up to 23 years (55.9%). The majority of events occurred in the afternoon (54.4%), in the clinical setting (70.7%), and in 75% of the cases, the search for care occurred within 2 h after exposure. Conclusion: Accidents with needlestick and sharp instruments have high frequency and involve mainly female students. They are more common in the afternoon and in the clinical setting and the time interval was between exposure and the search for care complied with recommendations of the Brazilian legislation. PMID:28566861

  14. SHARP - a framework for incorporating human interactions into PRA studies

    International Nuclear Information System (INIS)

    Hannaman, G.W.; Joksimovich, V.; Spurgin, A.J.; Worledge, D.H.

    1985-01-01

    Recently, increased attention has been given to understanding the role of humans in the safe operation of nuclear power plants. By virtue of the ability to combine equipment reliability with human reliability probabilistic risk assessment (PRA) technology was deemed capable of providing significant insights about the contributions of human interations in accident scenarios. EPRI recognized the need to strengthen the methodology for incorporating human interactions into PRAs as one element of their broad research program to improve the credibility of PRAs. This research project lead to the development and detailed description of SHARP (Systematic Human Application Reliability Procedure) in EPRI NP-3583. The objective of this paper is to illustrate the SHARP framework. This should help PRA analysts state more clearly their assumptions and approach no matter which human reliability assessment technique is used. SHARP includes a structure of seven analysis steps which can be formally or informally performed during PRAs. The seven steps are termed definition, screening, breakdown, representation, impact assessment, quantification, and documentation

  15. Weighting of field heights for sharpness and noisiness

    Science.gov (United States)

    Keelan, Brian W.; Jin, Elaine W.

    2009-01-01

    Weighting of field heights is important in cases when a single numerical value needs to be calculated that characterizes an attribute's overall impact on perceived image quality. In this paper we report an observer study to derive the weighting of field heights for sharpness and noisiness. One-hundred-forty images were selected to represent a typical consumer photo space distribution. Fifty-three sample points were sampled per image, representing field heights of 0, 14, 32, 42, 51, 58, 71, 76, 86% and 100%. Six observers participated in this study. The field weights derived in this report include both: the effect of area versus field height (which is a purely objective, geometric factor); and the effect of the spatial distribution of image content that draws attention to or masks each of these image structure attributes. The results show that relative to the geometrical area weights, sharpness weights were skewed to lower field heights, because sharpness-critical subject matter was often positioned relatively near the center of an image. Conversely, because noise can be masked by signal, noisiness-critical content (such as blue skies, skin tones, walls, etc.) tended to occur farther from the center of an image, causing the weights to be skewed to higher field heights.

  16. Is there a sharp phase transition for deterministic cellular automata?

    International Nuclear Information System (INIS)

    Wootters, W.K.

    1990-01-01

    Previous work has suggested that there is a kind of phase transition between deterministic automata exhibiting periodic behavior and those exhibiting chaotic behavior. However, unlike the usual phase transitions of physics, this transition takes place over a range of values of the parameter rather than at a specific value. The present paper asks whether the transition can be made sharp, either by taking the limit of an infinitely large rule table, or by changing the parameter in terms of which the space of automata is explored. We find strong evidence that, for the class of automata we consider, the transition does become sharp in the limit of an infinite number of symbols, the size of the neighborhood being held fixed. Our work also suggests an alternative parameter in terms of which it is likely that the transition will become fairly sharp even if one does not increase the number of symbols. In the course of our analysis, we find that mean field theory, which is our main tool, gives surprisingly good predictions of the statistical properties of the class of automata we consider. 18 refs., 6 figs

  17. SHARP1: A revised systematic human action reliability procedure

    International Nuclear Information System (INIS)

    Wakefield, D.J.; Parry, G.W.; Hannaman, G.W.; Spurgin, A.J.

    1990-12-01

    Individual plant examinations (IPE) are being performed by utilities to evaluate plant-specific vulnerabilities to severe accidents. A major tool in performing an IPE is a probabilistic risk assessment (PRA). The importance of human interactions in determining the plant response in past PRAs is well documented. The modeling and quantification of the probabilities of human interactions have been the subjects of considerable research by the Electric Power Research Institute (EPRI). A revised framework, SHARP1, for incorporating human interactions into PRA is summarized in this report. SHARP1 emphasizes that the process stages are iterative and directed at specific goals rather than being performed sequentially in a stepwise procedure. This expanded summary provides the reader with a flavor of the full report content. Excerpts from the full report are presented, following the same outline as the full report. In the full report, the interface of the human reliability analysis with the plant logic model development in a PRA is given special attention. In addition to describing a methodology framework, the report also discusses the types of human interactions to be evaluated, and how to formulate a project team to perform the human reliability analysis. A concise description and comparative evaluation of the selected existing methods of quantification of human error are also presented. Four case studies are also provided to illustrate the SHARP1 process

  18. Hippocampal Volume Reduction in Humans Predicts Impaired Allocentric Spatial Memory in Virtual-Reality Navigation.

    Science.gov (United States)

    Guderian, Sebastian; Dzieciol, Anna M; Gadian, David G; Jentschke, Sebastian; Doeller, Christian F; Burgess, Neil; Mishkin, Mortimer; Vargha-Khadem, Faraneh

    2015-10-21

    The extent to which navigational spatial memory depends on hippocampal integrity in humans is not well documented. We investigated allocentric spatial recall using a virtual environment in a group of patients with severe hippocampal damage (SHD), a group of patients with "moderate" hippocampal damage (MHD), and a normal control group. Through four learning blocks with feedback, participants learned the target locations of four different objects in a circular arena. Distal cues were present throughout the experiment to provide orientation. A circular boundary as well as an intra-arena landmark provided spatial reference frames. During a subsequent test phase, recall of all four objects was tested with only the boundary or the landmark being present. Patients with SHD were impaired in both phases of this task. Across groups, performance on both types of spatial recall was highly correlated with memory quotient (MQ), but not with intelligence quotient (IQ), age, or sex. However, both measures of spatial recall separated experimental groups beyond what would be expected based on MQ, a widely used measure of general memory function. Boundary-based and landmark-based spatial recall were both strongly related to bilateral hippocampal volumes, but not to volumes of the thalamus, putamen, pallidum, nucleus accumbens, or caudate nucleus. The results show that boundary-based and landmark-based allocentric spatial recall are similarly impaired in patients with SHD, that both types of recall are impaired beyond that predicted by MQ, and that recall deficits are best explained by a reduction in bilateral hippocampal volumes. In humans, bilateral hippocampal atrophy can lead to profound impairments in episodic memory. Across species, perhaps the most well-established contribution of the hippocampus to memory is not to episodic memory generally but to allocentric spatial memory. However, the extent to which navigational spatial memory depends on hippocampal integrity in humans is

  19. Improvement in perception of image sharpness through the addition of noise and its relationship with memory texture

    Science.gov (United States)

    Wan, Xiazi; Kobayashi, Hiroyuki; Aoki, Naokazu

    2015-03-01

    In a preceding study, we investigated the effects of image noise on the perception of image sharpness using white noise, and one- and two-dimensional single-frequency sinusoidal patterns as stimuli. This study extends our preceding study by evaluating natural color images, rather than black-and-white patterns. The results showed that the effect of noise in improving image sharpness perception is more evident in blurred images than in sharp images. This is consistent with the results of the preceding study. In another preceding study, we proposed "memory texture" to explain the preferred granularity of images, as a concept similar to "memory color" for preferred color reproduction. We observed individual differences in type of memory texture for each object, that is, white or 1/f noise. This study discusses the relationship between improvement of sharpness perception by adding noise, and the memory texture, following its individual differences. We found that memory texture is one of the elements that affect sharpness perception.

  20. Recruitment of Perisomatic Inhibition during Spontaneous Hippocampal Activity In Vitro.

    Directory of Open Access Journals (Sweden)

    Anna Beyeler

    Full Text Available It was recently shown that perisomatic GABAergic inhibitory postsynaptic potentials (IPSPs originating from basket and chandelier cells can be recorded as population IPSPs from the hippocampal pyramidal layer using extracellular electrodes (eIPSPs. Taking advantage of this approach, we have investigated the recruitment of perisomatic inhibition during spontaneous hippocampal activity in vitro. Combining intracellular and extracellular recordings from pyramidal cells and interneurons, we confirm that inhibitory signals generated by basket cells can be recorded extracellularly, but our results suggest that, during spontaneous activity, eIPSPs are mostly confined to the CA3 rather than CA1 region. CA3 eIPSPs produced the powerful time-locked inhibition of multi-unit activity expected from perisomatic inhibition. Analysis of the temporal dynamics of spike discharges relative to eIPSPs suggests significant but moderate recruitment of excitatory and inhibitory neurons within the CA3 network on a 10 ms time scale, within which neurons recruit each other through recurrent collaterals and trigger powerful feedback inhibition. Such quantified parameters of neuronal interactions in the hippocampal network may serve as a basis for future characterisation of pathological conditions potentially affecting the interactions between excitation and inhibition in this circuit.

  1. A weak magnetic field inhibits hippocampal neurogenesis in SD rats

    Science.gov (United States)

    Zhang, B.; Tian, L.; Cai, Y.; Pan, Y.

    2017-12-01

    Geomagnetic field is an important barrier that protects life forms on Earth from solar wind and radiation. Paleomagnetic data have well demonstrated that the strength of ancient geomagnetic field was dramatically weakened during a polarity transition. Accumulating evidence has shown that weak magnetic field exposures has serious adverse effects on the metabolism and behaviors in organisms. Hippocampal neurogenesis occurs throughout life in mammals' brains which plays a key role in brain function, and can be influenced by animals' age as well as environmental factors, but few studies have examined the response of hippocampal neurogenesis to it. In the present study, we have investigated the weak magnetic field effects on hippocampal neurogenesis of adult Sprague Dawley (SD) rats. Two types of magnetic fields were used, a weak magnetic field (≤1.3 μT) and the geomagnetic fields (51 μT).The latter is treated as a control condition. SD rats were exposure to the weak magnetic field up to 6 weeks. We measured the changes of newborn nerve cells' proliferation and survival, immature neurons, neurons and apoptosis in the dentate gyrus (DG) of hippocampus in SD rats. Results showed that, the weak magnetic field (≤1.3 μT) inhibited their neural stem cells proliferation and significantly reduced the survival of newborn nerve cells, immature neurons and neurons after 2 or 4 weeks continuous treatment (i.e. exposure to weak magnetic field). Moreover, apoptosis tests indicated the weak magnetic field can promote apoptosis of nerve cells in the hippocampus after 4 weeks treatment. Together, our new data indicate that weak magnetic field decrease adult hippocampal neurogenesis through inhibiting neural stem cells proliferation and promoting apoptosis, which provides useful experimental constraints on better understanding the mechanism of linkage between life and geomagnetic field.

  2. Oral administration of fisetin promotes the induction of hippocampal long-term potentiation in vivo

    Directory of Open Access Journals (Sweden)

    Wen-bin He

    2018-01-01

    Full Text Available To explore memory enhancing effect of the flavonoid fisetin, we investigated the effect of oral administration of flavonoids on the induction of long-term potentiation (LTP at hippocampal CA1 synapses of anesthetized rats. Among four flavonoids (fisetin, quercetin, luteolin and myricetin tested, only fisetin significantly facilitated the induction of hippocampal LTP. The effect of oral fisetin was abolished by intracerebroventricular injection of U0126, an agent that was previously found to inhibit its effect in hippocampal slices in vitro. These results suggest that orally administered fisetin crosses the blood–brain barrier and promotes synaptic functions in the hippocampus.

  3. Cavernous angioma associated with ipsilateral hippocampal sclerosis

    International Nuclear Information System (INIS)

    Okujava, M.; Ebner, A.; Schmitt, J.; Woermann, F.G.

    2002-01-01

    We report two cases with extratemporal cavernous angioma (CA) and coexisting ipsilateral hippocampal sclerosis. Classically dual pathology is defined as the association of hippocampal sclerosis with an extrahippocampal lesion. Subtle changes in hippocampus might be overlooked in the presence of an unequivocal extrahippocampal abnormality. Seizure outcome after epilepsy surgery in cases with dual pathology is less favourable if only one of the lesions is removed. Dual pathology must always be considered in diagnostic imaging of patients with intractable epilepsy and CA. (orig.)

  4. Cavernous angioma associated with ipsilateral hippocampal sclerosis

    Energy Technology Data Exchange (ETDEWEB)

    Okujava, M [Institute of Radiology and Interventional Diagnostics, Tbilisi (Georgia); Ebner, A; Schmitt, J; Woermann, F G [Bethel Epilepsy Centre, Mara Hospital, Bielefeld (Germany)

    2002-07-01

    We report two cases with extratemporal cavernous angioma (CA) and coexisting ipsilateral hippocampal sclerosis. Classically dual pathology is defined as the association of hippocampal sclerosis with an extrahippocampal lesion. Subtle changes in hippocampus might be overlooked in the presence of an unequivocal extrahippocampal abnormality. Seizure outcome after epilepsy surgery in cases with dual pathology is less favourable if only one of the lesions is removed. Dual pathology must always be considered in diagnostic imaging of patients with intractable epilepsy and CA. (orig.)

  5. Morphological Variations of Hippocampal Formation in Epilepsy

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2013-02-01

    Full Text Available Researchers at Hospital Sao Paulo and other centers in Brazil compared the hippocampal formation (HF morphology of healthy asymptomatic individuals (n=30 with that of patients with mesial temporal lobe epilepsy and hippocampal sclerosis (MTLE-HS(n=68, of patients with malformations of cortical development (MCD(n=34, and of patients with morphological HF variations without other structural signs (pure MVHF(n=12.

  6. The impact of cocaine on adult hippocampal neurogenesis: Potential neurobiological mechanisms and contributions to maladaptive cognition in cocaine addiction disorder.

    Science.gov (United States)

    Castilla-Ortega, Estela; Ladrón de Guevara-Miranda, David; Serrano, Antonia; Pavón, Francisco J; Suárez, Juan; Rodríguez de Fonseca, Fernando; Santín, Luis J

    2017-10-01

    After discovering that addictive drugs alter adult neurogenesis, the potential role of adult-born hippocampal neurons in drug addiction has become a promising research field, in which cocaine is the most frequently investigated drug. Although a substantial amount of pre-clinical evidence has accumulated, additional studies are required to reveal the mechanisms by which cocaine modulates adult hippocampal neurogenesis (AHN) and determine whether these adult-born neurons have a role in cocaine-related behaviors, such as cocaine-mediated cognitive symptoms. First, this review will summarize the cocaine-induced alterations in a number of neurobiological factors (neurotransmitters, neurotrophins, glucocorticoids, inflammatory mediators) that likely regulate both hippocampal-dependent learning and adult hippocampal neurogenesis after cocaine exposure. A separate section will provide a detailed review of the available literature that challenges the common view that cocaine reduces adult hippocampal neurogenesis. In fact, cocaine has a short-term anti-proliferative role, but the young adult-born neurons are apparently spared, or even enhanced, following certain cocaine protocols. Thus, we will try to reconcile this evidence with the hippocampal-dependent cognitive symptoms that are typically observed in cocaine addicts, and we will propose new directions for future studies to test the relevant hypothesis. Based on the evidence presented here, the regulation of adult hippocampal neurogenesis might be one of the many mechanisms by which cocaine sculpts hippocampus-dependent learning. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Analysis and protective measures of sharp instrument injury causes of sterilization and supply center

    Directory of Open Access Journals (Sweden)

    Hua YANG

    2014-11-01

    Full Text Available Objective: To analyze the causes of sharp injury in the sterilization and supply center, take protective measures, effectively avoid sharp instrument injury, and guarantee staff safety. Methods: Adopt a retrospective survey method, summarize sharp instrument injury data of sterilization and supply center in 2013, analyze the reasons of the occurrence of sharp instrument injury, and make protective countermeasures. Results: Sharp instrument injuries occurred mainly in the device classification, manual cleaning and device packaging process. Conclusion: Poor consciousness of occupational protection of the staff in the sterilization and supply center, nonstandard operation, and lack of training and supervision in place are the main reasons of occurrence of sharp instrument injury.

  8. Temporal Modulation Detection Depends on Sharpness of Spatial Tuning.

    Science.gov (United States)

    Zhou, Ning; Cadmus, Matthew; Dong, Lixue; Mathews, Juliana

    2018-04-25

    Prior research has shown that in electrical hearing, cochlear implant (CI) users' speech recognition performance is related in part to their ability to detect temporal modulation (i.e., modulation sensitivity). Previous studies have also shown better speech recognition when selectively stimulating sites with good modulation sensitivity rather than all stimulation sites. Site selection based on channel interaction measures, such as those using imaging or psychophysical estimates of spread of neural excitation, has also been shown to improve speech recognition. This led to the question of whether temporal modulation sensitivity and spatial selectivity of neural excitation are two related variables. In the present study, CI users' modulation sensitivity was compared for sites with relatively broad or narrow neural excitation patterns. This was achieved by measuring temporal modulation detection thresholds (MDTs) at stimulation sites that were significantly different in their sharpness of the psychophysical spatial tuning curves (PTCs) and measuring MDTs at the same sites in monopolar (MP) and bipolar (BP) stimulation modes. Nine postlingually deafened subjects implanted with Cochlear Nucleus® device took part in the study. Results showed a significant correlation between the sharpness of PTCs and MDTs, indicating that modulation detection benefits from a more spatially restricted neural activation pattern. There was a significant interaction between stimulation site and mode. That is, using BP stimulation only improved MDTs at stimulation sites with broad PTCs but had no effect or sometimes a detrimental effect on MDTs at stimulation sites with sharp PTCs. This interaction could suggest that a criterion number of nerve fibers is needed to achieve optimal temporal resolution, and, to achieve optimized speech recognition outcomes, individualized selection of site-specific current focusing strategies may be necessary. These results also suggest that the removal of

  9. Nitrous Oxide Induces Prominent Cell Proliferation in Adult Rat Hippocampal Dentate Gyrus

    Directory of Open Access Journals (Sweden)

    Farah Chamaa

    2018-05-01

    Full Text Available The identification of distinct and more efficacious antidepressant treatments is highly needed. Nitrous oxide (N2O is an N-methyl-D-aspartic acid (NMDA antagonist that has been reported to exhibit antidepressant effects in treatment-resistant depression (TRD patients. Yet, no studies have investigated the effects of sub-anesthetic dosages of N2O on hippocampal cell proliferation and neurogenesis in adult brain rats. In our study, adult male Sprague-Dawley rats were exposed to single or multiple exposures to mixtures of 70% N2O and 30% oxygen (O2. Sham groups were exposed to 30% O2 and the control groups to atmospheric air. Hippocampal cell proliferation was assessed by bromodeoxyuridine (BrdU incorporation, and BrdU-positive cells were counted in the dentate gyrus (DG using confocal microscopy. Results showed that while the rates of hippocampal cell proliferation were comparable between the N2O and sham groups at day 1, levels increased by 1.4 folds at day 7 after one session exposure to N2O. Multiple N2O exposures significantly increased the rate of hippocampal cell proliferation to two folds. Therefore, sub-anesthetic doses of N2O, similar to ketamine, increase hippocampal cell proliferation, suggesting that there will ultimately be an increase in neurogenesis. Future studies should investigate added N2O exposures and their antidepressant behavioral correlates.

  10. Cannabis-related hippocampal volumetric abnormalities specific to subregions in dependent users.

    Science.gov (United States)

    Chye, Yann; Suo, Chao; Yücel, Murat; den Ouden, Lauren; Solowij, Nadia; Lorenzetti, Valentina

    2017-07-01

    Cannabis use is associated with neuroanatomical alterations in the hippocampus. While the hippocampus is composed of multiple subregions, their differential vulnerability to cannabis dependence remains unknown. The objective of the study is to investigate gray matter alteration in each of the hippocampal subregions (presubiculum, subiculum, cornu ammonis (CA) subfields CA1-4, and dentate gyrus (DG)) as associated with cannabis use and dependence. A total of 35 healthy controls (HC), 22 non-dependent (CB-nondep), and 39 dependent (CB-dep) cannabis users were recruited. We investigated group differences in hippocampal subregion volumes between HC, CB-nondep, and CB-dep users. We further explored the association between CB use variables (age of onset of regular use, monthly use, lifetime use) and hippocampal subregions in CB-nondep and CB-dep users separately. The CA1, CA2/3, CA4/DG, as well as total hippocampal gray matter were reduced in volume in CB-dep but not in CB-nondep users, relative to HC. The right CA2/3 and CA4/DG volumes were also negatively associated with lifetime cannabis use in CB-dep users. Our results suggest a regionally and dependence-specific influence of cannabis use on the hippocampus. Hippocampal alteration in cannabis users was specific to the CA and DG regions and confined to dependent users.

  11. Slow waves, sharp waves, ripples, and REM in sleeping dragons.

    Science.gov (United States)

    Shein-Idelson, Mark; Ondracek, Janie M; Liaw, Hua-Peng; Reiter, Sam; Laurent, Gilles

    2016-04-29

    Sleep has been described in animals ranging from worms to humans. Yet the electrophysiological characteristics of brain sleep, such as slow-wave (SW) and rapid eye movement (REM) activities, are thought to be restricted to mammals and birds. Recording from the brain of a lizard, the Australian dragon Pogona vitticeps, we identified SW and REM sleep patterns, thus pushing back the probable evolution of these dynamics at least to the emergence of amniotes. The SW and REM sleep patterns that we observed in lizards oscillated continuously for 6 to 10 hours with a period of ~80 seconds. The networks controlling SW-REM antagonism in amniotes may thus originate from a common, ancient oscillator circuit. Lizard SW dynamics closely resemble those observed in rodent hippocampal CA1, yet they originate from a brain area, the dorsal ventricular ridge, that has no obvious hodological similarity with the mammalian hippocampus. Copyright © 2016, American Association for the Advancement of Science.

  12. Effects of Post-Training Hippocampal Injections of Midazolam on Fear Conditioning

    Science.gov (United States)

    Gafford, Georgette M.; Parsons, Ryan G.; Helmstetter, Fred J.

    2005-01-01

    Benzodiazepines have been useful tools for investigating mechanisms underlying learning and memory. The present set of experiments investigates the role of hippocampal GABA[subscript A]/benzodiazepine receptors in memory consolidation using Pavlovian fear conditioning. Rats were prepared with cannulae aimed at the dorsal hippocampus and trained…

  13. An Intersection–Union Test for the Sharpe Ratio

    Directory of Open Access Journals (Sweden)

    Gabriel Frahm

    2018-04-01

    Full Text Available An intersection–union test for supporting the hypothesis that a given investment strategy is optimal among a set of alternatives is presented. It compares the Sharpe ratio of the benchmark with that of each other strategy. The intersection–union test takes serial dependence into account and does not presume that asset returns are multivariate normally distributed. An empirical study based on the G–7 countries demonstrates that it is hard to find significant results due to the lack of data, which confirms a general observation in empirical finance.

  14. On the sharpness of the Rüssmann estimates

    Science.gov (United States)

    Figueras, Jordi-Lluís; Haro, Alex; Luque, Alejandro

    2018-02-01

    Estimating the norm of the solution of the linear difference equation u(θ) - u(θ + ω) = v(θ) plays a fundamental role in KAM theory. Optimal (in certain sense) estimates for the solution of this equation were provided by Rüssmann in the mid 70's. The aim of this paper is to compare the sharpness of these classical estimates with more specific estimates obtained with the help of the computer. We perform several experiments to quantify the improvement obtained when using computer assisted estimates. By comparing these estimates with the actual norm of the solution, we can analyze the different sources of overestimation, thus encouraging future improvements.

  15. Sharp metric obstructions for quasi-Einstein metrics

    Science.gov (United States)

    Case, Jeffrey S.

    2013-02-01

    Using the tractor calculus to study smooth metric measure spaces, we adapt results of Gover and Nurowski to give sharp metric obstructions to the existence of quasi-Einstein metrics on suitably generic manifolds. We do this by introducing an analogue of the Weyl tractor W to the setting of smooth metric measure spaces. The obstructions we obtain can be realized as tensorial invariants which are polynomial in the Riemann curvature tensor and its divergence. By taking suitable limits of their tensorial forms, we then find obstructions to the existence of static potentials, generalizing to higher dimensions a result of Bartnik and Tod, and to the existence of potentials for gradient Ricci solitons.

  16. Optimizing 3D Triangulations to Recapture Sharp Edges

    DEFF Research Database (Denmark)

    Bærentzen, Jakob Andreas

    2006-01-01

    In this report, a technique for optimizing 3D triangulations is proposed. The method seeks to minimize an energy defined as a sum of energy terms for each edge in a triangle mesh. The main contribution is a novel per edge energy which strikes a balance between penalizing dihedral angle yet allowing...... sharp edges. The energy is minimized using edge swapping, and this can be done either in a greedy fashion or using simulated annealing. The latter is more costly, but effectively avoids local minima. The method has been used on a number of models. Particularly good results have been obtained on digital...

  17. Sharp Bounds by Probability-Generating Functions and Variable Drift

    DEFF Research Database (Denmark)

    Doerr, Benjamin; Fouz, Mahmoud; Witt, Carsten

    2011-01-01

    We introduce to the runtime analysis of evolutionary algorithms two powerful techniques: probability-generating functions and variable drift analysis. They are shown to provide a clean framework for proving sharp upper and lower bounds. As an application, we improve the results by Doerr et al....... (GECCO 2010) in several respects. First, the upper bound on the expected running time of the most successful quasirandom evolutionary algorithm for the OneMax function is improved from 1.28nln n to 0.982nlnn, which breaks the barrier of nln n posed by coupon-collector processes. Compared to the classical...

  18. Axisymmetric MHD stability of sharp-boundary Tokamaks

    International Nuclear Information System (INIS)

    Rebhan, E.; Salat, A.

    1976-09-01

    For a sharp-boundary, constant pressure plasma model of axisymmetric equilibria the MHD stability problem of axisymmetric perturbations is solved by analytic reduction to a one-dimensional problem on the boundary and subsequent numerical treatment, using the energy principle. The stability boundaries are determined for arbitrary aspect ratio, arbitrary βsub(p) and elliptical, triangular and rectangular plasma cross-sections, wall stabilization not being taken into account. It is found that the axisymmetric stability strongly depends on the plasma shape and is almost independent of the safety factor q. (orig.) [de

  19. Magnetic field penetration into superconductors with sharp edges

    International Nuclear Information System (INIS)

    Zhilichev, Yuriy N.

    2003-01-01

    The magnetic field and surface currents induced within a superconductor are calculated assuming the field penetrates in it near sharp corners. Rounding the corners is used to keep the field less than a critical value. Analytical formulas for a corner radius are given for a wire of the rectangular cross-section and a cylinder in the external magnetic field. A boundary integral method is used to calculate the boundary of the Meissner domain when the external field penetrates deep into the superconductor. The effect of degree of penetration on the magnetic moment of superconducting cylinders and wires is discussed

  20. Endovascular Sharp Recanalization for Calcified Femoropopliteal Artery Occlusion

    Directory of Open Access Journals (Sweden)

    Hsuan-Li Huang

    2012-01-01

    Full Text Available Endovascular intervention of peripheral chronic total occlusion (CTO is technically challenging and time consuming. Various techniques and devices are used to facilitate lesion crossing and improve the success rate of the procedure. However, these new devices are quite expensive and not readily available. We report 2 cases of peripheral CTO wherein the occlusions were successfully crossed by using stiff end of Terumo glidewire. This sharp recanalization may be a useful technique for the recanalization of calcified peripheral CTOs when conventional techniques fail and new devices are not readily available, but it is accompanied by the risk of distal atheroembolism.

  1. Maturation- and sex-sensitive depression of hippocampal excitatory transmission in a rat schizophrenia model.

    Science.gov (United States)

    Patrich, Eti; Piontkewitz, Yael; Peretz, Asher; Weiner, Ina; Attali, Bernard

    2016-01-01

    Schizophrenia is associated with behavioral and brain structural abnormalities, of which the hippocampus appears to be one of the most consistent region affected. Previous studies performed on the poly I:C model of schizophrenia suggest that alterations in hippocampal synaptic transmission and plasticity take place in the offspring. However, these investigations yielded conflicting results and the neurophysiological alterations responsible for these deficits are still unclear. Here we performed for the first time a longitudinal study examining the impact of prenatal poly I:C treatment and of gender on hippocampal excitatory neurotransmission. In addition, we examined the potential preventive/curative effects of risperidone (RIS) treatment during the peri-adolescence period. Excitatory synaptic transmission was determined by stimulating Schaffer collaterals and monitoring fiber volley amplitude and slope of field-EPSP (fEPSP) in CA1 pyramidal neurons in male and female offspring hippocampal slices from postnatal days (PNDs) 18-20, 34, 70 and 90. Depression of hippocampal excitatory transmission appeared at juvenile age in male offspring of the poly I:C group, while it expressed with a delay in female, manifesting at adulthood. In addition, a reduced hippocampal size was found in both adult male and female offspring of poly I:C treated dams. Treatment with RIS at the peri-adolescence period fully restored in males but partly repaired in females these deficiencies. A maturation- and sex-dependent decrease in hippocampal excitatory transmission occurs in the offspring of poly I:C treated pregnant mothers. Pharmacological intervention with RIS during peri-adolescence can cure in a gender-sensitive fashion early occurring hippocampal synaptic deficits. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Hippocampal volumes are important predictors for memory function in elderly women

    Directory of Open Access Journals (Sweden)

    Adolfsdottir Steinunn

    2009-08-01

    Full Text Available Abstract Background Normal aging involves a decline in cognitive function that has been shown to correlate with volumetric change in the hippocampus, and with genetic variability in the APOE-gene. In the present study we utilize 3D MR imaging, genetic analysis and assessment of verbal memory function to investigate relationships between these factors in a sample of 170 healthy volunteers (age range 46–77 years. Methods Brain morphometric analysis was performed with the automated segmentation work-flow implemented in FreeSurfer. Genetic analysis of the APOE genotype was determined with polymerase chain reaction (PCR on DNA from whole-blood. All individuals were subjected to extensive neuropsychological testing, including the California Verbal Learning Test-II (CVLT. To obtain robust and easily interpretable relationships between explanatory variables and verbal memory function we applied the recent method of conditional inference trees in addition to scatterplot matrices and simple pairwise linear least-squares regression analysis. Results APOE genotype had no significant impact on the CVLT results (scores on long delay free recall, CVLT-LD or the ICV-normalized hippocampal volumes. Hippocampal volumes were found to decrease with age and a right-larger-than-left hippocampal asymmetry was also found. These findings are in accordance with previous studies. CVLT-LD score was shown to correlate with hippocampal volume. Multivariate conditional inference analysis showed that gender and left hippocampal volume largely dominated predictive values for CVLT-LD scores in our sample. Left hippocampal volume dominated predictive values for females but not for males. APOE genotype did not alter the model significantly, and age was only partly influencing the results. Conclusion Gender and left hippocampal volumes are main predictors for verbal memory function in normal aging. APOE genotype did not affect the results in any part of our analysis.

  3. Hippocampal sparing radiotherapy for pediatric medulloblastoma: impact of treatment margins and treatment technique.

    Science.gov (United States)

    Brodin, N Patrik; Munck af Rosenschöld, Per; Blomstrand, Malin; Kiil-Berthlesen, Anne; Hollensen, Christian; Vogelius, Ivan R; Lannering, Birgitta; Bentzen, Søren M; Björk-Eriksson, Thomas

    2014-04-01

    We investigated how varying the treatment margin and applying hippocampal sparing and proton therapy impact the risk of neurocognitive impairment in pediatric medulloblastoma patients compared with current standard 3D conformal radiotherapy. We included 17 pediatric medulloblastoma patients to represent the variability in tumor location relative to the hippocampal region. Treatment plans were generated using 3D conformal radiotherapy, hippocampal sparing intensity-modulated radiotherapy, and spot-scanned proton therapy, using 3 different treatment margins for the conformal tumor boost. Neurocognitive impairment risk was estimated based on dose-response models from pediatric CNS malignancy survivors and compared among different margins and treatment techniques. Mean hippocampal dose and corresponding risk of cognitive impairment were decreased with decreasing treatment margins (P < .05). The largest risk reduction, however, was seen when applying hippocampal sparing proton therapy-the estimated risk of impaired task efficiency (95% confidence interval) was 92% (66%-98%), 81% (51%-95%), and 50% (30%-70%) for 3D conformal radiotherapy, intensity-modulated radiotherapy, and proton therapy, respectively, for the smallest boost margin and 98% (78%-100%), 90% (60%-98%), and 70% (39%-90%) if boosting the whole posterior fossa. Also, the distance between the closest point of the planning target volume and the center of the hippocampus can be used to predict mean hippocampal dose for a given treatment technique. We estimate a considerable clinical benefit of hippocampal sparing radiotherapy. In choosing treatment margins, the tradeoff between margin size and risk of neurocognitive impairment quantified here should be considered.

  4. Membrane metamaterial resonators with a sharp resonance: A comprehensive study towards practical terahertz filters and sensors

    Directory of Open Access Journals (Sweden)

    Yongyao Chen

    2012-06-01

    Full Text Available We investigate the resonant properties of high quality-factor membrane-based metamaterial resonators functioning in the terahertz regime. A number of factors, including the resonator geometry, dielectric loss, and most importantly the membrane thickness are found to extensively influence the resonance strength and quality factor of the sharp resonance. Further studies on the membrane thickness-dependent-sensitivity for sensing applications reveal that high quality-factor membrane metamaterials with a moderate thickness ranging from 10 to 50 μm are the most promising option towards developing realistic integrated terahertz filters and sensors.

  5. Overexpression of TiERF1 enhances resistance to sharp eyespot in transgenic wheat

    OpenAIRE

    Chen, Liang; Zhang, ZengYan; Liang, HongXia; Liu, HongXia; Du, LiPu; Xu, Huijun; Xin, Zhiyong

    2008-01-01

    Wheat sharp eyespot, primarily caused by a soil-borne fungus Rhizoctonia cerealis, has become one of the most serious diseases of wheat in China. In this study, an ethylene response factor (ERF) gene from a wheat relative Thinopyrum intermedium, TiERF1, was characterized further, transgenic wheat lines expressing TiERF1 were developed, and the resistance of the transgenic wheat lines against R. cerealis was investigated. Southern blotting analysis indicated that at least two copies of the TiE...

  6. Thermally induced high frequency random amplitude fatigue damage at sharp notches

    International Nuclear Information System (INIS)

    Lewis, M.W.J.

    1992-01-01

    Experiments have been performed using the SUPERSOMITE facility to investigate the initiation and growth of fatigue cracks at the tips of sharp surface notches subjected to random thermally-induced stress. The experimental situation is complex involving plasticity, random amplitude loading and heat transfer medium/surface coupling. Crack initiation and growth prediction have been considered using the Creager and Neuber methods to compute the strain ranges in the vicinity of the notch root. Good agreement has been obtained between the experimental results and theoretical predictions. The paper reports the results of the analysis of the notch behavior

  7. Prefrontal-hippocampal interactions for spatial navigation.

    Science.gov (United States)

    Ito, Hiroshi T

    2018-04-01

    Animals have the ability to navigate to a desired location by making use of information about environmental landmarks and their own movements. While decades of neuroscience research have identified neurons in the hippocampus and parahippocampal structures that represent an animal's position in space, it is still largely unclear how an animal can choose the next movement direction to reach a desired goal. As the goal destination is typically located somewhere outside of the range of sensory perception, the animal is required to rely on the internal metric of space to estimate the direction and distance of the destination to plan a next action. Therefore, the hippocampal spatial map should interact with action-planning systems in other cortical regions. In accordance with this idea, several recent studies have indicated the importance of functional interactions between the hippocampus and the prefrontal cortex for goal-directed navigation. In this paper, I will review these studies and discuss how an animal can estimate its future positions correspond to a next movement. Investigation of the navigation problem may further provide general insights into internal models of the brain for action planning. Copyright © 2017 Elsevier Ireland Ltd and Japan Neuroscience Society. All rights reserved.

  8. Juvenile Hippocampal CA2 Region Expresses Aggrecan

    Directory of Open Access Journals (Sweden)

    Asako Noguchi

    2017-05-01

    Full Text Available Perineuronal nets (PNNs are distributed primarily around inhibitory interneurons in the hippocampus, such as parvalbumin-positive interneurons. PNNs are also present around excitatory neurons in some brain regions and prevent plasticity in these neurons. A recent study demonstrated that PNNs also exist around mouse hippocampal pyramidal cells, which are the principle type of excitatory neurons, in the CA2 subregion and modulate the excitability and plasticity of these neurons. However, the development of PNNs in the CA2 region during postnatal maturation was not fully investigated. This study found that a main component of PNNs, aggrecan, existed in the pyramidal cell layer of the putative CA2 subarea prior to the appearance of the CA2 region, which was defined by the CA2 marker protein regulator of G protein signaling 14 (RGS14. We also found that aggrecan immunoreactivity was more evident in the anterior sections of the CA2 area than the posterior sections, which suggests that the function of CA2 PNNs varies along the anterior-posterior axis.

  9. Oral administration of fisetin promotes the induction of hippocampal long-term potentiation in vivo

    OpenAIRE

    Wen-bin He; Kazuho Abe; Tatsuhiro Akaishi

    2018-01-01

    To explore memory enhancing effect of the flavonoid fisetin, we investigated the effect of oral administration of flavonoids on the induction of long-term potentiation (LTP) at hippocampal CA1 synapses of anesthetized rats. Among four flavonoids (fisetin, quercetin, luteolin and myricetin) tested, only fisetin significantly facilitated the induction of hippocampal LTP. The effect of oral fisetin was abolished by intracerebroventricular injection of U0126, an agent that was previously found to...

  10. Hippocampal phosphoproteomics of F344 rats exposed to 1-bromopropane

    International Nuclear Information System (INIS)

    Huang, Zhenlie; Ichihara, Sahoko; Oikawa, Shinji; Chang, Jie; Zhang, Lingyi; Hu, Shijie; Huang, Hanlin; Ichihara, Gaku

    2015-01-01

    1-Bromopropane (1-BP) is neurotoxic in both experimental animals and human. To identify phosphorylated modification on the unrecognized post-translational modifications of proteins and investigate their role in 1-BP-induced neurotoxicity, changes in hippocampal phosphoprotein expression levels were analyzed quantitatively in male F344 rats exposed to 1-BP inhalation at 0, 400, or 1000 ppm for 8 h/day for 1 or 4 weeks. Hippocampal protein extracts were analyzed qualitatively and quantitatively by Pro-Q Diamond gel staining and SYPRO Ruby staining coupled with two-dimensional difference in gel electrophoresis (2D-DIGE), respectively, as well as by matrix-assisted laser-desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) to identify phosphoproteins. Changes in selected proteins were further confirmed by Manganese II (Mn 2+ )-Phos-tag SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Bax and cytochrome c protein levels were determined by western blotting. Pro-Q Diamond gel staining combined with 2D-DIGE identified 26 phosphoprotein spots (p < 0.05), and MALDI-TOF/MS identified 18 up-regulated proteins and 8 down-regulated proteins. These proteins are involved in the biological process of response to stimuli, metabolic processes, and apoptosis signaling. Changes in the expression of phosphorylated 14-3-3 θ were further confirmed by Mn 2+ -Phos-tag SDS-PAGE. Western blotting showed overexpression of Bax protein in the mitochondria with down-regulation in the cytoplasm, whereas cytochrome c expression was high in the cytoplasm but low in the mitochondria after 1-BP exposure. Our results suggest that the pathogenesis of 1-BP-induced hippocampal damage involves inhibition of antiapoptosis process. Phosphoproteins identified in this study can potentially serve as biomarkers for 1-BP-induced neurotoxicity. - Highlights: • 1-BP modified hippocampal phosphoproteome in rat and 23 altered proteins were identified. • 1-BP changed phosphorylation of GRP78

  11. Hippocampal phosphoproteomics of F344 rats exposed to 1-bromopropane

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Zhenlie [Guangdong Provincial Key Laboratory of Occupational Disease Prevention and Treatment, Guangdong Province Hospital for Occupational Disease Prevention and Treatment, Guangzhou 510-300 (China); Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Ichihara, Sahoko [Graduate School of Regional Innovation Studies, Mie University, Tsu 514-8507 (Japan); Oikawa, Shinji [Department of Environmental and Molecular Medicine, Mie University Graduate School of Medicine, Mie 514-8507 (Japan); Chang, Jie [Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Graduate School of Regional Innovation Studies, Mie University, Tsu 514-8507 (Japan); Zhang, Lingyi [Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Department of Occupational and Environmental Health, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Noda 278-8510 (Japan); Hu, Shijie [Guangdong Provincial Key Laboratory of Occupational Disease Prevention and Treatment, Guangdong Province Hospital for Occupational Disease Prevention and Treatment, Guangzhou 510-300 (China); Huang, Hanlin, E-mail: huanghl@gdoh.org [Guangdong Provincial Key Laboratory of Occupational Disease Prevention and Treatment, Guangdong Province Hospital for Occupational Disease Prevention and Treatment, Guangzhou 510-300 (China); Ichihara, Gaku, E-mail: gak@rs.tus.ac.jp [Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Department of Occupational and Environmental Health, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Noda 278-8510 (Japan)

    2015-01-15

    1-Bromopropane (1-BP) is neurotoxic in both experimental animals and human. To identify phosphorylated modification on the unrecognized post-translational modifications of proteins and investigate their role in 1-BP-induced neurotoxicity, changes in hippocampal phosphoprotein expression levels were analyzed quantitatively in male F344 rats exposed to 1-BP inhalation at 0, 400, or 1000 ppm for 8 h/day for 1 or 4 weeks. Hippocampal protein extracts were analyzed qualitatively and quantitatively by Pro-Q Diamond gel staining and SYPRO Ruby staining coupled with two-dimensional difference in gel electrophoresis (2D-DIGE), respectively, as well as by matrix-assisted laser-desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) to identify phosphoproteins. Changes in selected proteins were further confirmed by Manganese II (Mn{sup 2+})-Phos-tag SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Bax and cytochrome c protein levels were determined by western blotting. Pro-Q Diamond gel staining combined with 2D-DIGE identified 26 phosphoprotein spots (p < 0.05), and MALDI-TOF/MS identified 18 up-regulated proteins and 8 down-regulated proteins. These proteins are involved in the biological process of response to stimuli, metabolic processes, and apoptosis signaling. Changes in the expression of phosphorylated 14-3-3 θ were further confirmed by Mn{sup 2+}-Phos-tag SDS-PAGE. Western blotting showed overexpression of Bax protein in the mitochondria with down-regulation in the cytoplasm, whereas cytochrome c expression was high in the cytoplasm but low in the mitochondria after 1-BP exposure. Our results suggest that the pathogenesis of 1-BP-induced hippocampal damage involves inhibition of antiapoptosis process. Phosphoproteins identified in this study can potentially serve as biomarkers for 1-BP-induced neurotoxicity. - Highlights: • 1-BP modified hippocampal phosphoproteome in rat and 23 altered proteins were identified. • 1-BP changed phosphorylation

  12. The Spectral Sharpness Angle of Gamma-ray Bursts

    Directory of Open Access Journals (Sweden)

    Hendrik J. van Eerten

    2016-06-01

    Full Text Available We extend the results of Yu et al. (2015b of the novel sharpness angle measurement to a large number of spectra obtained from the Fermi gamma-ray burst monitor. The sharpness angle is compared to the values obtained from various representative emission models: blackbody, single-electron synchrotron, synchrotron emission from a Maxwellian or power-law electron distribution. It is found that more than 91% of the high temporally and spectrally resolved spectra are inconsistent with any kind of optically thin synchrotron emission model alone. It is also found that the limiting case, a single temperature Maxwellian synchrotron function, can only contribute up to 58+23 -18% of the peak flux. These results show that even the sharpest but non-realistic case, the single-electron synchrotron function, cannot explain a large fraction of the observed spectra. Since any combination of physically possible synchrotron spectra added together will always further broaden the spectrum, emission mechanisms other than optically thin synchrotron radiation are likely required in a full explanation of the spectral peaks or breaks of the GRB prompt emission phase.

  13. Hybridization between Dusky Grouse and Sharp-tailed Grouse

    Science.gov (United States)

    O'Donnell, Ryan P.

    2015-01-01

    Cache County, Utah, 7 April 2013: rare hybrid combination of grouse noted. Hybridization between Dusky Grouse (Dendragapus obscurus) and Sharp-tailed Grouse (Tympanuchus phasianellus) has been rarely documented in the wild. The only published record was of one collected from Osoyoos, British Columbia, in 1906 (Brooks 1907, Lincoln 1950). There is also one record of this hybrid in captivity (McCarthy 2006)...Although hybridization within genera is more common than between genera, it is perhaps not all too remarkable that these species would hybridize, given that Dendragapus and Tympanuchus are each other’s closest relatives (Drovetski 2002). The ranges of these two species overlap over a broad area ranging roughly from parts of northern Utah and Colorado to Yukon and the Northwest Territories. Given the close relatedness and extent of overlap of their ranges, it is perhaps surprising that there have not been more reports of this hybrid combination in the over-100 years since Brooks (1907) first described one. The species may be segregated by habitat use, as Sharp-tailed prefer open grassland sites for lekking and shrub areas for nesting, and Dusky are often found in more densely forested conifer stands—although Dusky often use more open habitats in the spring.

  14. Sharp-tailed Grouse and Pygmy Rabbit Wildlife Mitigation Project

    International Nuclear Information System (INIS)

    1992-10-01

    The Proposed Action is needed to protect and enhance shrub-steppe and riparian habitat for sharp-tailed grouse (Tympanuchus phasianellus columbianus), Pygmy rabbits (Brachylagus idahoensis), and other indigenous wildlife species. The purpose of the Proposed Action is to compensate, in part, for wildlife habitat lost from the construction of Grand Coulee Dam and the inundation of Lake Roosevelt. Bonneville Power Administration proposes to fund management agreements, conservation easements, acquisition of fee title, or a combination of these on as many as 29,000 acres in Lincoln and Douglas Counties to improve shrub-steppe and riparian habitat for sharp-tailed grouse and pygmy rabbits. The BPA also proposes to fund habitat improvements (enhancements) on project lands including existing public lands. Proposed habitat treatments would include control of grazing; planting of native trees, shrubs, forbs and grasses; protection of wetlands and streambanks; herbicide use; fire prescriptions; and wildfire suppression. Proposed management activities may include predator control, population introductions, and control of crop depredation

  15. Sharp superconductor-insulator transition in short wires

    International Nuclear Information System (INIS)

    Meidan, Dganit; Oreg, Yuval; Refael, Gil; Smith, Robert A.

    2008-01-01

    Recent experiments on short MoGe nanowires show a sharp superconductor-insulator transition tuned by the normal state resistance of the wire, with a critical resistance of R c ∼ R Q = h/(4e 2 ). These results are at odds with a broad range of theoretical work on Josephson-like systems that predicts a smooth transition, tuned by the value of the resistance that shunts the junction. We develop a self-consistent renormalization group treatment of interacting phase-slips and their dual counterparts, correlated cooper pair tunneling, beyond the dilute approximation. This analysis leads to a very sharp transition with a critical resistance of R Q . The addition of the quasi-particles' resistance at finite temperature leads to a quantitative agreement with the experimental results. This self-consistent renormalization group method should also be applicable to other physical systems that can be mapped onto similar sine-Gordon models, in the previously inaccessible intermediate-coupling regime

  16. Consistency relations for sharp inflationary non-Gaussian features

    Energy Technology Data Exchange (ETDEWEB)

    Mooij, Sander; Palma, Gonzalo A.; Panotopoulos, Grigoris [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Blanco Encalada 2008, Santiago (Chile); Soto, Alex, E-mail: sander.mooij@ing.uchile.cl, E-mail: gpalmaquilod@ing.uchile.cl, E-mail: gpanotop@ing.uchile.cl, E-mail: gatogeno@gmail.com [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Ñuñoa, Santiago (Chile)

    2016-09-01

    If cosmic inflation suffered tiny time-dependent deviations from the slow-roll regime, these would induce the existence of small scale-dependent features imprinted in the primordial spectra, with their shapes and sizes revealing information about the physics that produced them. Small sharp features could be suppressed at the level of the two-point correlation function, making them undetectable in the power spectrum, but could be amplified at the level of the three-point correlation function, offering us a window of opportunity to uncover them in the non-Gaussian bispectrum. In this article, we show that sharp features may be analyzed using only data coming from the three point correlation function parametrizing primordial non-Gaussianity. More precisely, we show that if features appear in a particular non-Gaussian triangle configuration (e.g. equilateral, folded, squeezed), these must reappear in every other configuration according to a specific relation allowing us to correlate features across the non-Gaussian bispectrum. As a result, we offer a method to study scale-dependent features generated during inflation that depends only on data coming from measurements of non-Gaussianity, allowing us to omit data from the power spectrum.

  17. Consistency relations for sharp inflationary non-Gaussian features

    International Nuclear Information System (INIS)

    Mooij, Sander; Palma, Gonzalo A.; Panotopoulos, Grigoris; Soto, Alex

    2016-01-01

    If cosmic inflation suffered tiny time-dependent deviations from the slow-roll regime, these would induce the existence of small scale-dependent features imprinted in the primordial spectra, with their shapes and sizes revealing information about the physics that produced them. Small sharp features could be suppressed at the level of the two-point correlation function, making them undetectable in the power spectrum, but could be amplified at the level of the three-point correlation function, offering us a window of opportunity to uncover them in the non-Gaussian bispectrum. In this article, we show that sharp features may be analyzed using only data coming from the three point correlation function parametrizing primordial non-Gaussianity. More precisely, we show that if features appear in a particular non-Gaussian triangle configuration (e.g. equilateral, folded, squeezed), these must reappear in every other configuration according to a specific relation allowing us to correlate features across the non-Gaussian bispectrum. As a result, we offer a method to study scale-dependent features generated during inflation that depends only on data coming from measurements of non-Gaussianity, allowing us to omit data from the power spectrum.

  18. The visibility of IQHE at sharp edges: experimental proposals based on interactions and edge electrostatics

    International Nuclear Information System (INIS)

    Erkarslan, U; Oylumluoglu, G; Grayson, M; Siddiki, A

    2012-01-01

    The influence of the incompressible strips on the integer quantized Hall effect (IQHE) is investigated, considering a cleaved-edge overgrown (CEO) sample as an experimentally realizable sharp edge system. We propose a set of experiments to clarify the distinction between the large-sample limit when bulk disorder defines the IQHE plateau width and the small-sample limit smaller than the disorder correlation length, when self-consistent edge electrostatics define the IQHE plateau width. The large-sample or bulk quantized Hall (QH) regime is described by the usual localization picture, whereas the small-sample or edge regime is discussed within the compressible/incompressible strips picture, known as the screening theory of QH edges. Utilizing the unusually sharp edge profiles of the CEO samples, a Hall bar design is proposed to manipulate the edge potential profile from smooth to extremely sharp. By making use of a side-gate perpendicular to the two-dimensional electron system, it is shown that the plateau widths can be changed or even eliminated altogether. Hence, the visibility of IQHE is strongly influenced when adjusting the edge potential profile and/or changing the dc current direction under high currents in the nonlinear transport regime. As a second investigation, we consider two different types of ohmic contacts, namely highly transmitting (ideal) and highly reflecting (non-ideal) contacts. We show that if the injection contacts are non-ideal, but still ohmic, it is possible to measure directly the non-quantized transport taking place at the bulk of the CEO samples. The results of the experiments we propose will clarify the influence of the edge potential profile and the quality of the contacts, under QH conditions. (paper)

  19. Moxibustion upregulates hippocampal progranulin expression

    Directory of Open Access Journals (Sweden)

    Tao Yi

    2016-01-01

    Full Text Available In China, moxibustion is reported to be useful and has few side effects for chronic fatigue syndrome, but its mechanisms are largely unknown. More recently, the focus has been on the wealth of information supporting stress as a factor in chronic fatigue syndrome, and largely concerns dysregulation in the stress-related hypothalamic-pituitary-adrenal axis. In the present study, we aimed to determine the effect of moxibustion on behavioral symptoms in chronic fatigue syndrome rats and examine possible mechanisms. Rats were subjected to a combination of chronic restraint stress and forced swimming to induce chronic fatigue syndrome. The acupoints Guanyuan (CV4 and Zusanli (ST36, bilateral were simultaneously administered moxibustion. Untreated chronic fatigue syndrome rats and normal rats were used as controls. Results from the forced swimming test, open field test, tail suspension test, real-time PCR, enzyme-linked immunosorbent assay, and western blot assay showed that moxibustion treatment decreased mRNA expression of corticotropin-releasing hormone in the hypothalamus, and adrenocorticotropic hormone and corticosterone levels in plasma, and markedly increased progranulin mRNA and protein expression in the hippocampus. These findings suggest that moxibustion may relieve the behavioral symptoms of chronic fatigue syndrome, at least in part, by modulating the hypothalamic-pituitary-adrenal axis and upregulating hippocampal progranulin.

  20. Spacecraft Health Automated Reasoning Prototype (SHARP): The fiscal year 1989 SHARP portability evaluations task for NASA Solar System Exploration Division's Voyager project

    Science.gov (United States)

    Atkinson, David J.; Doyle, Richard J.; James, Mark L.; Kaufman, Tim; Martin, R. Gaius

    1990-01-01

    A Spacecraft Health Automated Reasoning Prototype (SHARP) portability study is presented. Some specific progress is described on the portability studies, plans for technology transfer, and potential applications of SHARP and related artificial intelligence technology to telescience operations. The application of SHARP to Voyager telecommunications was a proof-of-capability demonstration of artificial intelligence as applied to the problem of real time monitoring functions in planetary mission operations. An overview of the design and functional description of the SHARP system is also presented as it was applied to Voyager.

  1. Influence and evolution mechanism of different sharpness contact forms to mechanical property of cortical bone by nanoindentation

    Science.gov (United States)

    Sun, Xingdong; Guo, Yue; Li, Lijia; Liu, Zeyang; Wu, Di; Shi, Dong; Zhao, Hongwei; Zhang, Shizhong

    2018-03-01

    Based on different damage forms of various contact forms to bone, the mechanical response and mechanism were investigated by nanoindentation under different sharpness contact forms. For the purpose of simulating the different sharpness contact forms, two kinds of indenters were used in experiments and finite elements simulations. Through nanoindentation experiments, it was concluded that the residual depth of sharp indenter was bigger than that of blunt indenter with small penetration depth. However, the contrary law was obtained with bigger penetration depth. There was a turning point of transition from blunt tendency to sharp tendency. By calculation, it was concluded that the sharper the indenter was, the bigger the proportion of plastic energy in total energy was. Basically, results of finite elements simulation could correspond with the experimental conclusions. By the observation of FE-SEM, the surface of cortical bone compressed was more seriously directly below the blunt indenter than the lateral face. For the berkovich indenter, the surface of indentation compressed was less directly below the indenter, but seriously on three lateral faces. This research may provide some new references to the studies of bone fracture mechanism in different load patterns in the initial press-in stage and offer new explanation for bone trauma diagnosis in clinical treatment and criminal investigation.

  2. Influence and evolution mechanism of different sharpness contact forms to mechanical property of cortical bone by nanoindentation

    Directory of Open Access Journals (Sweden)

    Xingdong Sun

    2018-03-01

    Full Text Available Based on different damage forms of various contact forms to bone, the mechanical response and mechanism were investigated by nanoindentation under different sharpness contact forms. For the purpose of simulating the different sharpness contact forms, two kinds of indenters were used in experiments and finite elements simulations. Through nanoindentation experiments, it was concluded that the residual depth of sharp indenter was bigger than that of blunt indenter with small penetration depth. However, the contrary law was obtained with bigger penetration depth. There was a turning point of transition from blunt tendency to sharp tendency. By calculation, it was concluded that the sharper the indenter was, the bigger the proportion of plastic energy in total energy was. Basically, results of finite elements simulation could correspond with the experimental conclusions. By the observation of FE-SEM, the surface of cortical bone compressed was more seriously directly below the blunt indenter than the lateral face. For the berkovich indenter, the surface of indentation compressed was less directly below the indenter, but seriously on three lateral faces. This research may provide some new references to the studies of bone fracture mechanism in different load patterns in the initial press-in stage and offer new explanation for bone trauma diagnosis in clinical treatment and criminal investigation.

  3. Synaptic plasticity in the hippocampal area CA1-subiculum projection: implications for theories of memory.

    Science.gov (United States)

    O'Mara, S M; Commins, S; Anderson, M

    2000-01-01

    This paper reviews investigations of synaptic plasticity in the major, and underexplored, pathway from hippocampal area CA1 to the subiculum. This brain area is the major synaptic relay for the majority of hippocampal area CA1 neurons, making the subiculum the last relay of the hippocampal formation prior to the cortex. The subiculum thus has a very major role in mediating hippocampal-cortical interactions. We demonstrate that the projection from hippocampal area CA1 to the subiculum sustains plasticity on a number of levels. We show that this pathway is capable of undergoing both long-term potentiation (LTP) and paired-pulse facilitation (PPF, a short-term plastic effect). Although we failed to induce long-term depression (LTD) of this pathway with low-frequency stimulation (LFS) and two-pulse stimulation (TPS), both protocols can induce a "late-developing" potentiation of synaptic transmission. We further demonstrate that baseline synaptic transmission can be dissociated from paired-pulse stimulation of the same pathway; we also show that it is possible, using appropriate protocols, to change PPF to paired-pulse depression, thus revealing subtle and previously undescribed mechanisms which regulate short-term synaptic plasticity. Finally, we successfully recorded from individual subicular units in the freely-moving animal, and provide a description of the characteristics of such neurons in a pellet-chasing task. We discuss the implications of these findings in relation to theories of the biological consolidation of memory.

  4. An association between human hippocampal volume and topographical memory in healthy young adults.

    Directory of Open Access Journals (Sweden)

    Tom eHartley

    2012-12-01

    Full Text Available The association between human hippocampal structure and topographical memory was investigated in healthy adults (N=30. Structural MR images were acquired, and voxel-based morphometry (VBM was used to estimate local gray matter volume throughout the brain. A complementary automated mesh-based segmentation approach was used to independently isolate and measure specified structures including the hippocampus. Topographical memory was assessed using a version of the Four Mountains Task, a short test designed to target hippocampal spatial function. Each item requires subjects to briefly study a landscape scene before recognizing the depicted place from a novel viewpoint and under altered non-spatial conditions when presented amongst similar alternative scenes. Positive correlations between topographical memory performance and hippocampal volume were observed in both VBM and segmentation-based analyses. Score on the topographical memory task was also correlated with the volume of some subcortical structures, extra-hippocampal gray matter and total brain volume, with the most robust and extensive covariation seen in circumscribed neocortical regions in the insula and anterior temporal lobes. Taken together with earlier findings, the results suggest that global variations in brain morphology affect the volume of the hippocampus and its specific contribution to topographical memory. We speculate that behavioral variation might arise directly through the impact of resource constraints on spatial representations in the hippocampal formation and its inputs, and perhaps indirectly through an increased reliance on non-allocentric strategies.

  5. Relationship between hippocampal subfield volumes and memory deficits in patients with thalamus infarction.

    Science.gov (United States)

    Chen, Li; Luo, Tianyou; Lv, Fajin; Shi, Dandan; Qiu, Jiang; Li, Qi; Fang, Weidong; Peng, Juan; Li, Yongmei; Zhang, Zhiwei; Li, Yang

    2016-09-01

    Clinical studies have shown that thalamus infarction (TI) affects memory function. The thalamic nucleus is directly or indirectly connected to the hippocampal system in animal models. However, this connection has not been investigated using structural magnetic resonance imaging (MRI) in humans. From the pathological perspective, TI patients may serve as valid models for revealing the interaction between the thalamus and hippocampus in memory function. In this study, we aim to assess different hippocampal subfield volumes in TI patients and control subjects using MRI and test their associations with memory function. A total of 37 TI patients (TI group), 38 matched healthy control subjects (HC group), and 22 control patients with other stroke location (SC group) underwent 3.0-T MRI scans and clinical memory examinations. Hippocampal subfield volumes were measured and compared by using FreeSurfer software. We examined the correlation between hippocampal subfield volumes and memory scores. Smaller ipsilesional presubiculum and subiculum volumes were observed, and former was related to graphics recall in both left and right TI patients. The left subiculum volume was correlated with short-delayed recall in left TI patients. The right presubiculum volume was correlated with short- and long-delayed recall in right TI patients. TI was found to result in hippocampal abnormality and memory deficits, and its neural mechanisms might be related with and interaction between the thalamus and hippocampus.

  6. Inhibition of NKCC1 attenuated hippocampal LTP formation and inhibitory avoidance in rat.

    Directory of Open Access Journals (Sweden)

    Meng Chang Ko

    Full Text Available The loop diuretic bumetanide (Bumex is thought to have antiepileptic properties via modulate GABAA mediated signaling through their antagonism of cation-chloride cotransporters. Given that loop diuretics may act as antiepileptic drugs that modulate GABAergic signaling, we sought to investigate whether they also affect hippocampal function. The current study was performed to evaluate the possible role of NKCC1 on the hippocampal function. Brain slice extracellular recording, inhibitory avoidance, and western blot were applied in this study. Results showed that hippocampal Long-term potentiation was attenuated by suprafusion of NKCC1 inhibitor bumetanide, in a dose dependent manner. Sequent experiment result showed that Intravenous injection of bumetanide (15.2 mg/kg 30 min prior to the training session blocked inhibitory avoidance learning significantly. Subsequent control experiment's results excluded the possible non-specific effect of bumetanide on avoidance learning. We also found the phosphorylation of hippocampal MAPK was attenuated after bumetanide administration. These results suggested that hippocampal NKCC1 may via MAPK signaling cascade to possess its function.

  7. Hippocampal activation during face-name associative memory encoding: blocked versus permuted design

    International Nuclear Information System (INIS)

    De Vogelaere, Frederick; Vingerhoets, Guy; Santens, Patrick; Boon, Paul; Achten, Erik

    2010-01-01

    The contribution of the hippocampal subregions to episodic memory through the formation of new associations between previously unrelated items such as faces and names is established but remains under discussion. Block design studies in this area of research generally tend to show posterior hippocampal activation during encoding of novel associational material while event-related studies emphasize anterior hippocampal involvement. We used functional magnetic resonance imaging to assess the involvement of anterior and posterior hippocampus in the encoding of novel associational material compared to the viewing of previously seen associational material. We used two different experimental designs, a block design and a permuted block design, and applied it to the same associative memory task to perform valid statistical comparisons. Our results indicate that the permuted design was able to capture more anterior hippocampal activation compared to the block design, which emphasized more posterior hippocampal involvement. These differences were further investigated and attributed to a combination of the polymodal stimuli we used and the experimental design. Activation patterns during encoding in both designs occurred along the entire longitudinal axis of the hippocampus, but with different centers of gravity. The maximal activated voxel in the block design was situated in the posterior half of the hippocampus while in the permuted design this was located in the anterior half. (orig.)

  8. Hippocampal activation during face-name associative memory encoding: blocked versus permuted design

    Energy Technology Data Exchange (ETDEWEB)

    De Vogelaere, Frederick; Vingerhoets, Guy [Ghent University, Laboratory for Neuropsychology, Department of Neurology, Ghent (Belgium); Santens, Patrick; Boon, Paul [Ghent University Hospital, Department of Neurology, Ghent (Belgium); Achten, Erik [Ghent University Hospital, Department of Radiology, Ghent (Belgium)

    2010-01-15

    The contribution of the hippocampal subregions to episodic memory through the formation of new associations between previously unrelated items such as faces and names is established but remains under discussion. Block design studies in this area of research generally tend to show posterior hippocampal activation during encoding of novel associational material while event-related studies emphasize anterior hippocampal involvement. We used functional magnetic resonance imaging to assess the involvement of anterior and posterior hippocampus in the encoding of novel associational material compared to the viewing of previously seen associational material. We used two different experimental designs, a block design and a permuted block design, and applied it to the same associative memory task to perform valid statistical comparisons. Our results indicate that the permuted design was able to capture more anterior hippocampal activation compared to the block design, which emphasized more posterior hippocampal involvement. These differences were further investigated and attributed to a combination of the polymodal stimuli we used and the experimental design. Activation patterns during encoding in both designs occurred along the entire longitudinal axis of the hippocampus, but with different centers of gravity. The maximal activated voxel in the block design was situated in the posterior half of the hippocampus while in the permuted design this was located in the anterior half. (orig.)

  9. Distinguishing Depressive Pseudodementia from Alzheimer Disease: A Comparative Study of Hippocampal Volumetry and Cognitive Tests

    Directory of Open Access Journals (Sweden)

    Sevki Sahin

    2017-07-01

    Full Text Available Background and Aim: Depressive pseudodementia (DPD is a condition which may develop secondary to depression. The aim of this study was to contribute to the differential diagnosis between Alzheimer disease (AD and DPD by comparing the neurocognitive tests and hippocampal volume. Materials and Methods: Patients who met criteria of AD/DPD were enrolled in the study. All patients were assessed using the Wechsler Memory Scale (WMS, clock-drawing test, Stroop test, Benton Facial Recognition Test (BFRT, Boston Naming Test, Mini-Mental State Examination (MMSE, and Geriatric Depression Scale (GDS. Hippocampal volume was measured by importing the coronal T1-weighted magnetic resonance images to the Vitrea 2 workstation. Results: A significant difference was found between the AD and DPD groups on the WMS test, clock-drawing test, Stroop test, Boston Naming Test, MMSE, GDS, and left hippocampal volume. A significant correlation between BFRT and bilateral hippocampal volumes was found in the AD group. No correlation was found among parameters in DPD patients. Conclusions: Our results suggest that evaluation of facial recognition and left hippocampal volume may provide more reliable evidence for distinguishing DPD from AD. Further investigations combined with functional imaging techniques including more patients are needed.

  10. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT, HVLP COATING EQUIPMENT, SHARPE MANUFACTURING COMPANY PLATINUM 2012 HVLP SPRAY GUN

    Science.gov (United States)

    This report presents the results of the verification test of the Sharpe Platinum 2013 high-volume, low-pressure gravity-feed spray gun, hereafter referred to as the Sharpe Platinum, which is designed for use in automotive refinishing. The test coating chosen by Sharpe Manufacturi...

  11. Occupational exposure to sharps injury among healthcare providers in Ethiopia regional hospitals

    NARCIS (Netherlands)

    Sharew, Nigussie Tadesse; Mulu, Getaneh Baye; Habtewold, Tesfa Dejenie; Gizachew, Kefyalew Dagne

    2017-01-01

    BACKGROUND: Sharps injury is a penetrating stab wound from a needle, scalpel, or another sharp object that may result in exposure to blood or other body fluids. According to World Health Organization pooled estimate, the annual incidence of sharps injury in Africa was ranged from 2.10 to 4.68 per

  12. Three-dimensional vibrations of cylindrical elastic solids with V-notches and sharp radial cracks

    Science.gov (United States)

    McGee, O. G.; Kim, J. W.

    2010-02-01

    This paper provides free vibration data for cylindrical elastic solids, specifically thick circular plates and cylinders with V-notches and sharp radial cracks, for which no extensive previously published database is known to exist. Bending moment and shear force singularities are known to exist at the sharp reentrant corner of a thick V-notched plate under transverse vibratory motion, and three-dimensional (3-D) normal and transverse shear stresses are known to exist at the sharp reentrant terminus edge of a V-notched cylindrical elastic solid under 3-D free vibration. A theoretical analysis is done in this work utilizing a variational Ritz procedure including these essential singularity effects. The procedure incorporates a complete set of admissible algebraic-trigonometric polynomials in conjunction with an admissible set of " edge functions" that explicitly model the 3-D stress singularities which exist along a reentrant terminus edge (i.e., α>180°) of the V-notch. The first set of polynomials guarantees convergence to exact frequencies, as sufficient terms are retained. The second set of edge functions—in addition to representing the corner stress singularities—substantially accelerates the convergence of frequency solutions. This is demonstrated through extensive convergence studies that have been carried out by the investigators. Numerical analysis has been carried out and the results have been given for cylindrical elastic solids with various V-notch angles and depths. The relative depth of the V-notch is defined as (1- c/ a), and the notch angle is defined as (360°- α). For a very small notch angle (1° or less), the notch may be regarded as a "sharp radial crack." Accurate (four significant figure) frequencies are presented for a wide spectrum of notch angles (360°- α), depths (1- c/ a), and thickness ratios ( a/ h for plates and h/ a for cylinders). An extended database of frequencies for completely free thick sectorial, semi-circular, and

  13. Maternal vitamin C deficiency during pregnancy persistently impairs hippocampal neurogenesis in offspring of guinea pigs

    DEFF Research Database (Denmark)

    Tveden-Nyborg, Pernille; Vogt, Lucile; Schjoldager, Janne G

    2012-01-01

    While having the highest vitamin C (VitC) concentrations in the body, specific functions of VitC in the brain have only recently been acknowledged. We have shown that postnatal VitC deficiency in guinea pigs causes impairment of hippocampal memory function and leads to 30% less neurons. This study...... investigates how prenatal VitC deficiency affects postnatal hippocampal development and if any such effect can be reversed by postnatal VitC repletion. Eighty pregnant Dunkin Hartley guinea pig dams were randomized into weight stratified groups receiving High (900 mg) or Low (100 mg) VitC per kg diet. Newborn...... by stereology. Prenatal VitC deficiency resulted in a significant reduction in postnatal hippocampal volume (P...

  14. Long-term potentiation expands information content of hippocampal dentate gyrus synapses.

    Science.gov (United States)

    Bromer, Cailey; Bartol, Thomas M; Bowden, Jared B; Hubbard, Dusten D; Hanka, Dakota C; Gonzalez, Paola V; Kuwajima, Masaaki; Mendenhall, John M; Parker, Patrick H; Abraham, Wickliffe C; Sejnowski, Terrence J; Harris, Kristen M

    2018-03-06

    An approach combining signal detection theory and precise 3D reconstructions from serial section electron microscopy (3DEM) was used to investigate synaptic plasticity and information storage capacity at medial perforant path synapses in adult hippocampal dentate gyrus in vivo. Induction of long-term potentiation (LTP) markedly increased the frequencies of both small and large spines measured 30 minutes later. This bidirectional expansion resulted in heterosynaptic counterbalancing of total synaptic area per unit length of granule cell dendrite. Control hemispheres exhibited 6.5 distinct spine sizes for 2.7 bits of storage capacity while LTP resulted in 12.9 distinct spine sizes (3.7 bits). In contrast, control hippocampal CA1 synapses exhibited 4.7 bits with much greater synaptic precision than either control or potentiated dentate gyrus synapses. Thus, synaptic plasticity altered total capacity, yet hippocampal subregions differed dramatically in their synaptic information storage capacity, reflecting their diverse functions and activation histories.

  15. Bigger is better! Hippocampal volume and declarative memory performance in healthy young men.

    Science.gov (United States)

    Pohlack, Sebastian T; Meyer, Patric; Cacciaglia, Raffaele; Liebscher, Claudia; Ridder, Stephanie; Flor, Herta

    2014-01-01

    The importance of the hippocampus for declarative memory processes is firmly established. Nevertheless, the issue of a correlation between declarative memory performance and hippocampal volume in healthy subjects still remains controversial. The aim of the present study was to investigate this relationship in more detail. For this purpose, 50 healthy young male participants performed the California Verbal Learning Test. Hippocampal volume was assessed by manual segmentation of high-resolution 3D magnetic resonance images. We found a significant positive correlation between putatively hippocampus-dependent memory measures like short-delay retention, long-delay retention and discriminability and percent hippocampal volume. No significant correlation with measures related to executive processes was found. In addition, percent amygdala volume was not related to any of these measures. Our data advance previous findings reported in studies of brain-damaged individuals in a large and homogeneous young healthy sample and are important for theories on the neural basis of episodic memory.

  16. Signal pathway of hippocampal apoptosis and cognitive impairment of mice caused by cerium chloride.

    Science.gov (United States)

    Cheng, Zhe; Li, Na; Cheng, Jie; Hu, Renping; Gao, Guodong; Cui, Yaling; Gong, Xiaolan; Wang, Ling; Hong, Fashui

    2012-12-01

    Experimental studies have demonstrated that lanthanides could impair cognitive functions of children and animals, but very little is known about the hippocampal apoptosis and its molecular mechanism. The study investigated the signal pathway of hippocampal apoptosis induced by intragastric administration of CeCl(3) for 60 consecutive days. It showed that cerium had been significantly accumulated in the mouse hippocampus, and CeCl(3) caused hippocampal apoptosis and impairment of spatial recognition memory of mice. CeCl(3) effectively activated caspase-3 and -9, inhibited Bcl-2, and increased the levels of Bax and cytochrome c, promoted accumulation of reactive oxygen species in the mouse hippocampus. It implied that CeCl(3)-induced apoptosis in the mouse hippocampus could be triggered via mitochondrion-mediated pathway. Our findings suggest the need for great caution to handle the lanthanides for workers and consumers. 2011 Wiley Periodicals, Inc

  17. Taurine increases hippocampal neurogenesis in aging mice

    Directory of Open Access Journals (Sweden)

    Elias Gebara

    2015-05-01

    Full Text Available Aging is associated with increased inflammation and reduced hippocampal neurogenesis, which may in turn contribute to cognitive impairment. Taurine is a free amino acid found in numerous diets, with anti-inflammatory properties. Although abundant in the young brain, the decrease in taurine concentration with age may underlie reduced neurogenesis. Here, we assessed the effect of taurine on hippocampal neurogenesis in middle-aged mice. We found that taurine increased cell proliferation in the dentate gyrus through the activation of quiescent stem cells, resulting in increased number of stem cells and intermediate neural progenitors. Taurine had a direct effect on stem/progenitor cells proliferation, as observed in vitro, and also reduced activated microglia. Furthermore, taurine increased the survival of newborn neurons, resulting in a net increase in adult neurogenesis. Together, these results show that taurine increases several steps of adult neurogenesis and support a beneficial role of taurine on hippocampal neurogenesis in the context of brain aging.

  18. A very sharp drop in the photovoltaic market

    International Nuclear Information System (INIS)

    Boulanger, V.

    2013-01-01

    For the second year in a row the photovoltaic market is in sharp decline in France, it dropped by 37% between 2011 and 2012 and the situation for 2013 is expected to be even worse. The last emergency measures taken by the government have been useless. The syndicate of renewable energies (SER) and the 'Europe Ecologie les Verts' party urge the government to take efficient emergency measures like for instance the implementation of local purchase tariffs instead of the present bidding process or to keep the obligation of the integration to the building only for new constructions. The only good piece of news is that photovoltaic power is getting more and more competitive. France has to reconsider its energy policy and its regulatory framework in order to benefit from it. (A.C.)

  19. SHARP - Automated monitoring of spacecraft health and status

    Science.gov (United States)

    Atkinson, David J.; James, Mark L.; Martin, R. G.

    1990-01-01

    Briefly discussed here are the spacecraft and ground systems monitoring process at the Jet Propulsion Laboratory (JPL). Some of the difficulties associated with the existing technology used in mission operations are highlighted. A new automated system based on artificial intelligence technology is described which seeks to overcome many of these limitations. The system, called the Spacecraft Health Automated Reasoning Prototype (SHARP), is designed to automate health and status analysis for multi-mission spacecraft and ground data systems operations. The system has proved to be effective for detecting and analyzing potential spacecraft and ground systems problems by performing real-time analysis of spacecraft and ground data systems engineering telemetry. Telecommunications link analysis of the Voyager 2 spacecraft was the initial focus for evaluation of the system in real-time operations during the Voyager spacecraft encounter with Neptune in August 1989.

  20. SHARP: Automated monitoring of spacecraft health and status

    Science.gov (United States)

    Atkinson, David J.; James, Mark L.; Martin, R. Gaius

    1991-01-01

    Briefly discussed here are the spacecraft and ground systems monitoring process at the Jet Propulsion Laboratory (JPL). Some of the difficulties associated with the existing technology used in mission operations are highlighted. A new automated system based on artificial intelligence technology is described which seeks to overcome many of these limitations. The system, called the Spacecraft Health Automated Reasoning Prototype (SHARP), is designed to automate health and status analysis for multi-mission spacecraft and ground data systems operations. The system has proved to be effective for detecting and analyzing potential spacecraft and ground systems problems by performing real-time analysis of spacecraft and ground data systems engineering telemetry. Telecommunications link analysis of the Voyager 2 spacecraft was the initial focus for evaluation of the system in real-time operations during the Voyager spacecraft encounter with Neptune in August 1989.

  1. Triomicrus Sharp of Eastern China (Coleoptera: Staphylinidae: Pselaphinae).

    Science.gov (United States)

    Shen, Jia-Wei; Yin, Zi-Wei; Li, Li-Zhen

    2015-08-31

    Twelve species of the genus Triomicrus Sharp are here recognized in eastern China, with eleven of them described as new: T. Inaequalis Shen & Yin, sp. n. and T. mirus Shen & Yin, sp. n. from Anhui, T. abhorridus Shen & Yin, sp. n., T. aculeus Shen & Yin, sp. n., T. damingensis Shen & Yin, sp. n., T. frondosus Shen & Yin, sp. n., T. gutianensis Shen & Yin, sp. n. and T. tibialis Shen & Yin, sp. n. from Zhejiang, T. anfractus Shen & Yin, sp. n. from Anhui and Zhejiang, T. Hamus Shen & Yin, sp. n. from Jiangxi, and T. contus Shen & Yin, sp. n. from Jiangxi and Zhejiang. New distributional data for T. rougemonti Löbl, Kurbatov &Nomura is given. A key for the identification of the Triomicrus species in eastern China is presented.

  2. Hippocampal Astrocytes in Migrating and Wintering Semipalmated Sandpiper Calidris pusilla.

    Science.gov (United States)

    Carvalho-Paulo, Dario; de Morais Magalhães, Nara G; de Almeida Miranda, Diego; Diniz, Daniel G; Henrique, Ediely P; Moraes, Isis A M; Pereira, Patrick D C; de Melo, Mauro A D; de Lima, Camila M; de Oliveira, Marcus A; Guerreiro-Diniz, Cristovam; Sherry, David F; Diniz, Cristovam W P

    2017-01-01

    Seasonal migratory birds return to the same breeding and wintering grounds year after year, and migratory long-distance shorebirds are good examples of this. These tasks require learning and long-term spatial memory abilities that are integrated into a navigational system for repeatedly locating breeding, wintering, and stopover sites. Previous investigations focused on the neurobiological basis of hippocampal plasticity and numerical estimates of hippocampal neurogenesis in birds but only a few studies investigated potential contributions of glial cells to hippocampal-dependent tasks related to migration. Here we hypothesized that the astrocytes of migrating and wintering birds may exhibit significant morphological and numerical differences connected to the long-distance flight. We used as a model the semipalmated sandpiper Calidris pusilla , that migrates from northern Canada and Alaska to South America. Before the transatlantic non-stop long-distance component of their flight, the birds make a stopover at the Bay of Fundy in Canada. To test our hypothesis, we estimated total numbers and compared the three-dimensional (3-D) morphological features of adult C. pusilla astrocytes captured in the Bay of Fundy ( n = 249 cells) with those from birds captured in the coastal region of Bragança, Brazil, during the wintering period ( n = 250 cells). Optical fractionator was used to estimate the number of astrocytes and for 3-D reconstructions we used hierarchical cluster analysis. Both morphological phenotypes showed reduced morphological complexity after the long-distance non-stop flight, but the reduction in complexity was much greater in Type I than in Type II astrocytes. Coherently, we also found a significant reduction in the total number of astrocytes after the transatlantic flight. Taken together these findings suggest that the long-distance non-stop flight altered significantly the astrocytes population and that morphologically distinct astrocytes may play

  3. Hippocampal Astrocytes in Migrating and Wintering Semipalmated Sandpiper Calidris pusilla

    Directory of Open Access Journals (Sweden)

    Dario Carvalho-Paulo

    2018-01-01

    Full Text Available Seasonal migratory birds return to the same breeding and wintering grounds year after year, and migratory long-distance shorebirds are good examples of this. These tasks require learning and long-term spatial memory abilities that are integrated into a navigational system for repeatedly locating breeding, wintering, and stopover sites. Previous investigations focused on the neurobiological basis of hippocampal plasticity and numerical estimates of hippocampal neurogenesis in birds but only a few studies investigated potential contributions of glial cells to hippocampal-dependent tasks related to migration. Here we hypothesized that the astrocytes of migrating and wintering birds may exhibit significant morphological and numerical differences connected to the long-distance flight. We used as a model the semipalmated sandpiper Calidris pusilla, that migrates from northern Canada and Alaska to South America. Before the transatlantic non-stop long-distance component of their flight, the birds make a stopover at the Bay of Fundy in Canada. To test our hypothesis, we estimated total numbers and compared the three-dimensional (3-D morphological features of adult C. pusilla astrocytes captured in the Bay of Fundy (n = 249 cells with those from birds captured in the coastal region of Bragança, Brazil, during the wintering period (n = 250 cells. Optical fractionator was used to estimate the number of astrocytes and for 3-D reconstructions we used hierarchical cluster analysis. Both morphological phenotypes showed reduced morphological complexity after the long-distance non-stop flight, but the reduction in complexity was much greater in Type I than in Type II astrocytes. Coherently, we also found a significant reduction in the total number of astrocytes after the transatlantic flight. Taken together these findings suggest that the long-distance non-stop flight altered significantly the astrocytes population and that morphologically distinct astrocytes

  4. Intervention effects of ganoderma lucidum spores on epileptiform discharge hippocampal neurons and expression of neurotrophin-4 and N-cadherin.

    Directory of Open Access Journals (Sweden)

    Shu-Qiu Wang

    Full Text Available Epilepsy can cause cerebral transient dysfunctions. Ganoderma lucidum spores (GLS, a traditional Chinese medicinal herb, has shown some antiepileptic effects in our previous studies. This was the first study of the effects of GLS on cultured primary hippocampal neurons, treated with Mg(2+ free medium. This in vitro model of epileptiform discharge hippocampal neurons allowed us to investigate the anti-epileptic effects and mechanism of GLS activity. Primary hippocampal neurons from <1 day old rats were cultured and their morphologies observed under fluorescence microscope. Neurons were confirmed by immunofluorescent staining of neuron specific enolase (NSE. Sterile method for GLS generation was investigated and serial dilutions of GLS were used to test the maximum non-toxic concentration of GLS on hippocampal neurons. The optimized concentration of GLS of 0.122 mg/ml was identified and used for subsequent analysis. Using the in vitro model, hippocampal neurons were divided into 4 groups for subsequent treatment i control, ii model (incubated with Mg(2+ free medium for 3 hours, iii GLS group I (incubated with Mg(2+ free medium containing GLS for 3 hours and replaced with normal medium and incubated for 6 hours and iv GLS group II (neurons incubated with Mg(2+ free medium for 3 hours then replaced with a normal medium containing GLS for 6 hours. Neurotrophin-4 and N-Cadherin protein expression were detected using Western blot. The results showed that the number of normal hippocampal neurons increased and the morphologies of hippocampal neurons were well preserved after GLS treatment. Furthermore, the expression of neurotrophin-4 was significantly increased while the expression of N-Cadherin was decreased in the GLS treated group compared with the model group. This data indicates that GLS may protect hippocampal neurons by promoting neurotrophin-4 expression and inhibiting N-Cadherin expression.

  5. Sharp Interface Tracking in Rotating Microflows of Solvent Extraction

    International Nuclear Information System (INIS)

    Glimm, James; Almeida, Valmor de; Jiao, Xiangmin; Sims, Brett

    2013-01-01

    The objective of this project is to develop a specialized sharp interface tracking simulation capability for predicting interaction of micron-sized drops and bubbles in rotating flows relevant to optimized design of contactor devices used in solvent extraction processes of spent nuclear fuel reprocessing. The primary outcomes of this project include the capability to resolve drops and bubbles micro-hydrodynamics in solvent extraction contactors, determining from first principles continuum fluid mechanics how micro-drops and bubbles interact with each other and the surrounding shearing fluid for realistic flows. In the near term, this effort will play a central role in providing parameters and insight into the flow dynamics of models that average over coarser scales, say at the millimeter unit length. In the longer term, it will prove to be the platform to conduct full-device, detailed simulations as parallel computing power reaches the exaflop level. The team will develop an accurate simulation tool for flows containing interacting droplets and bubbles with sharp interfaces under conditions that mimic those found in realistic contactor operations. The main objective is to create an off-line simulation capability to model drop and bubble interactions in a domain representative of the averaged length scale. The technical approach is to combine robust interface tracking software, subgrid modeling, validation quality experiments, powerful computational hardware, and a team with simulation modeling, physical modeling and technology integration experience. Simulations will then fully resolve the microflow of drops and bubbles at the microsecond time scale. This approach is computationally intensive but very accurate in treating important coupled physical phenomena in the vicinity of interfaces. The method makes it possible to resolve spatial scales smaller than the typical distance between bubbles and to model some non-equilibrium thermodynamic features such as finite

  6. The effective field theory of inflation models with sharp features

    International Nuclear Information System (INIS)

    Bartolo, Nicola; Cannone, Dario; Matarrese, Sabino

    2013-01-01

    We describe models of single-field inflation with small and sharp step features in the potential (and sound speed) of the inflaton field, in the context of the Effective Field Theory of Inflation. This approach allows us to study the effects of features in the power-spectrum and in the bispectrum of curvature perturbations, from a model-independent point of view, by parametrizing the features directly with modified ''slow-roll'' parameters. We can obtain a self-consistent power-spectrum, together with enhanced non-Gaussianity, which grows with a quantity β that parametrizes the sharpness of the step. With this treatment it is straightforward to generalize and include features in other coefficients of the effective action of the inflaton field fluctuations. Our conclusion in this case is that, excluding extrinsic curvature terms, the only interesting effects at the level of the bispectrum could arise from features in the first slow-roll parameter ε or in the speed of sound c s . Finally, we derive an upper bound on the parameter β from the consistency of the perturbative expansion of the action for inflaton perturbations. This constraint can be used for an estimation of the signal-to-noise ratio, to show that the observable which is most sensitive to features is the power-spectrum. This conclusion would change if we consider the contemporary presence of a feature and a speed of sound c s < 1, as, in such a case, contributions from an oscillating folded configuration can potentially make the bispectrum the leading observable for feature models

  7. Sharp Interface Tracking in Rotating Microflows of Solvent Extraction

    Energy Technology Data Exchange (ETDEWEB)

    Glimm, James [Stony Brook Univ., NY (United States); Almeida, Valmor de [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jiao, Xiangmin [Stony Brook Univ., NY (United States); Sims, Brett [City Univ. (CUNY), NY (United States). Borough of Manhattan Community College; Li, Xaiolin [Stony Brook Univ., NY (United States)

    2013-01-08

    The objective of this project is to develop a specialized sharp interface tracking simulation capability for predicting interaction of micron-sized drops and bubbles in rotating flows relevant to optimized design of contactor devices used in solvent extraction processes of spent nuclear fuel reprocessing. The primary outcomes of this project include the capability to resolve drops and bubbles micro-hydrodynamics in solvent extraction contactors, determining from first principles continuum fluid mechanics how micro-drops and bubbles interact with each other and the surrounding shearing fluid for realistic flows. In the near term, this effort will play a central role in providing parameters and insight into the flow dynamics of models that average over coarser scales, say at the millimeter unit length. In the longer term, it will prove to be the platform to conduct full-device, detailed simulations as parallel computing power reaches the exaflop level. The team will develop an accurate simulation tool for flows containing interacting droplets and bubbles with sharp interfaces under conditions that mimic those found in realistic contactor operations. The main objective is to create an off-line simulation capability to model drop and bubble interactions in a domain representative of the averaged length scale. The technical approach is to combine robust interface tracking software, subgrid modeling, validation quality experiments, powerful computational hardware, and a team with simulation modeling, physical modeling and technology integration experience. Simulations will then fully resolve the microflow of drops and bubbles at the microsecond time scale. This approach is computationally intensive but very accurate in treating important coupled physical phenomena in the vicinity of interfaces. The method makes it possible to resolve spatial scales smaller than the typical distance between bubbles and to model some non-equilibrium thermodynamic features such as finite

  8. Sharp-Wave Ripples Orchestrate the Induction of Synaptic Plasticity during Reactivation of Place Cell Firing Patterns in the Hippocampus

    Directory of Open Access Journals (Sweden)

    Josef H.L.P. Sadowski

    2016-03-01

    Full Text Available Place cell firing patterns reactivated during hippocampal sharp-wave ripples (SWRs in rest or sleep are thought to induce synaptic plasticity and thereby promote the consolidation of recently encoded information. However, the capacity of reactivated spike trains to induce plasticity has not been directly tested. Here, we show that reactivated place cell firing patterns simultaneously recorded from CA3 and CA1 of rat dorsal hippocampus are able to induce long-term potentiation (LTP at synapses between CA3 and CA1 cells but only if accompanied by SWR-associated synaptic activity and resulting dendritic depolarization. In addition, we show that the precise timing of coincident CA3 and CA1 place cell spikes in relation to SWR onset is critical for the induction of LTP and predictive of plasticity generated by reactivation. Our findings confirm an important role for SWRs in triggering and tuning plasticity processes that underlie memory consolidation in the hippocampus during rest or sleep.

  9. Adult hippocampal neurogenesis and cognitive aging

    Directory of Open Access Journals (Sweden)

    Román Darío Moreno Fernández

    2013-12-01

    Full Text Available Aging is a normal developmental process associated with neurobiological changes leading to cognitive alterations with preserved, impaired, and enhanced functions. Evidence from animal and human studies is reviewed to explore the potential role of hippocampal plasticity on age-related cognitive changes with special attention to adult hippocampal neurogenesis. Results from lesion and stimulation strategies, as well as correlation data, support either a direct or modulatory role for adult newborn neurons in cognition at advanced ages. Further research on this topic may help to develop new treatments and to improve the quality of life of older people.

  10. Detecting global and local hippocampal shape changes in Alzheimer's disease using statistical shape models

    NARCIS (Netherlands)

    Shen, Kai-kai; Fripp, Jurgen; Mériaudeau, Fabrice; Chételat, Gaël; Salvado, Olivier; Bourgeat, Pierrick; Saradha, A.; Abdi, Hervé; Abdulkadir, Ahmed; Acharya, Deepa; Achuthan, Anusha; Adluru, Nagesh; Aghajanian, Jania; Agrusti, Antonella; Agyemang, Alex; Ahdidan, Jamila; Ahmad, Duaa; Ahmed, Shiek; Aisen, Paul; Akhondi-Asl, Alireza; Aksu, Yaman; Alberca, Roman; Alcauter, Sarael; Alexander, Daniel; Alin, Aylin; Almeida, Fabio; Alvarez-Lineara, Juan; Amlien, Inge; Anand, Shyam; Anderson, Dallas; Ang, Amma; Angersbach, Steve; Ansarian, Reza; Aoyama, Eiji; Appannah, Arti; Arfanakis, Konstantinos; Armor, Tom; Arrighi, Michael; Arumughababu, S. Vethanayaki; Arunagiri, Vidhya; Ashe-McNalley, Cody; Ashford, Wes; Le Page, Aurelie; Avants, Brian; Aviv, Richard; Awasthi, Sukrati; Ayache, Nicholas; Chen, Wei; Richard, Edo; Schmand, Ben

    2012-01-01

    The hippocampus is affected at an early stage in the development of Alzheimer's disease (AD). With the use of structural magnetic resonance (MR) imaging, we can investigate the effect of AD on the morphology of the hippocampus. The hippocampal shape variations among a population can be usually

  11. Hippocampal sparing radiotherapy for pediatric medulloblastoma: impact of treatment margins and treatment technique

    DEFF Research Database (Denmark)

    Brodin, N. Patrik; af Rosenschold, Per Munck; Blomstrand, Malin

    2014-01-01

    BackgroundWe investigated how varying the treatment margin and applying hippocampal sparing and proton therapy impact the risk of neurocognitive impairment in pediatric medulloblastoma patients compared with current standard 3D conformal radiotherapy.MethodsWe included 17 pediatric medulloblastoma...

  12. Optogenetically Blocking Sharp Wave Ripple Events in Sleep Does Not Interfere with the Formation of Stable Spatial Representation in the CA1 Area of the Hippocampus.

    Directory of Open Access Journals (Sweden)

    Krisztián A Kovács

    Full Text Available During hippocampal sharp wave/ripple (SWR events, previously occurring, sensory input-driven neuronal firing patterns are replayed. Such replay is thought to be important for plasticity-related processes and consolidation of memory traces. It has previously been shown that the electrical stimulation-induced disruption of SWR events interferes with learning in rodents in different experimental paradigms. On the other hand, the cognitive map theory posits that the plastic changes of the firing of hippocampal place cells constitute the electrophysiological counterpart of the spatial learning, observable at the behavioral level. Therefore, we tested whether intact SWR events occurring during the sleep/rest session after the first exploration of a novel environment are needed for the stabilization of the CA1 code, which process requires plasticity. We found that the newly-formed representation in the CA1 has the same level of stability with optogenetic SWR blockade as with a control manipulation that delivered the same amount of light into the brain. Therefore our results suggest that at least in the case of passive exploratory behavior, SWR-related plasticity is dispensable for the stability of CA1 ensembles.

  13. Cannabinoids modulate hippocampal memory and plasticity.

    Science.gov (United States)

    Abush, Hila; Akirav, Irit

    2010-10-01

    Considerable evidence demonstrates that cannabinoid agonists impair whereas cannabinoid antagonists improve memory and plasticity. However, recent studies suggest that the effects of cannabinoids on learning do not necessarily follow these simple patterns, particularly when emotional memory processes are involved. We investigated the involvement of the cannabinoid system in hippocampal learning and plasticity using the fear-related inhibitory avoidance (IA) and the non-fear-related spatial learning paradigms, and cellular models of learning and memory, i.e., long-term potentiation (LTP) and long-term depression (LTD). We found that microinjection into the CA1 of the CB1/CB2 receptor agonist WIN55,212-2 (5 μg/side) and an inhibitor of endocannabinoid reuptake and breakdown AM404 (200 ng/side) facilitated the extinction of IA, while the CB1 receptor antagonist AM251 (6 ng/side) impaired it. WIN55,212-2 and AM251 did not affect IA conditioning, while AM404 enhanced it, probably due to a drug-induced increase in pain sensitivity. However, in the water maze, systemic or local CA1 injections of AM251, WIN55,212-2, and AM404 all impaired spatial learning. We also found that i.p. administration of WIN55,212-2 (0.5 mg/kg), AM404 (10 mg/kg), and AM251 (2 mg/kg) impaired LTP in the Schaffer collateral-CA1 projection, whereas AM404 facilitated LTD. Our findings suggest diverse effects of the cannabinoid system on CA1 memory and plasticity that cannot be categorized simply into an impairing or an enhancing effect of cannabinoid activation and deactivation, respectively. Moreover, they provide preclinical support for the suggestion that targeting the endocannabinoid system may aid in the treatment of disorders associated with impaired extinction-like processes, such as post-traumatic stress disorder. © 2009 Wiley-Liss, Inc.

  14. Differential response of hippocampal subregions to stress and learning.

    Directory of Open Access Journals (Sweden)

    Darby F Hawley

    Full Text Available The hippocampus has two functionally distinct subregions-the dorsal portion, primarily associated with spatial navigation, and the ventral portion, primarily associated with anxiety. In a prior study of chronic unpredictable stress (CUS in rodents, we found that it selectively enhanced cellular plasticity in the dorsal hippocampal subregion while negatively impacting it in the ventral. In the present study, we determined whether this adaptive plasticity in the dorsal subregion would confer CUS rats an advantage in a spatial task-the radial arm water maze (RAWM. RAWM exposure is both stressful and requires spatial navigation, and therefore places demands simultaneously upon both hippocampal subregions. Therefore, we used Western blotting to investigate differential expression of plasticity-associated proteins (brain derived neurotrophic factor [BDNF], proBDNF and postsynaptic density-95 [PSD-95] in the dorsal and ventral subregions following RAWM exposure. Lastly, we used unbiased stereology to compare the effects of CUS on proliferation, survival and neuronal differentiation of cells in the dorsal and ventral hippocampal subregions. We found that CUS and exposure to the RAWM both increased corticosterone, indicating that both are stressful; nevertheless, CUS animals had significantly better long-term spatial memory. We also observed a subregion-specific pattern of protein expression following RAWM, with proBDNF increased in the dorsal and decreased in the ventral subregion, while PSD-95 was selectively upregulated in the ventral. Finally, consistent with our previous study, we found that CUS most negatively affected neurogenesis in the ventral (compared to the dorsal subregion. Taken together, our data support a dual role for the hippocampus in stressful experiences, with the more resilient dorsal portion undergoing adaptive plasticity (perhaps to facilitate escape from or neutralization of the stressor, and the ventral portion involved in

  15. Regional hippocampal volumes and development predict learning and memory.

    Science.gov (United States)

    Tamnes, Christian K; Walhovd, Kristine B; Engvig, Andreas; Grydeland, Håkon; Krogsrud, Stine K; Østby, Ylva; Holland, Dominic; Dale, Anders M; Fjell, Anders M

    2014-01-01

    The hippocampus is an anatomically and functionally heterogeneous structure, but longitudinal studies of its regional development are scarce and it is not known whether protracted maturation of the hippocampus in adolescence is related to memory development. First, we investigated hippocampal subfield development using 170 longitudinally acquired brain magnetic resonance imaging scans from 85 participants aged 8-21 years. Hippocampal subfield volumes were estimated by the use of automated segmentation of 7 subfields, including the cornu ammonis (CA) sectors and the dentate gyrus (DG), while longitudinal subfield volumetric change was quantified using a nonlinear registration procedure. Second, associations between subfield volumes and change and verbal learning/memory across multiple retention intervals (5 min, 30 min and 1 week) were tested. It was hypothesized that short and intermediate memory would be more closely related to CA2-3/CA4-DG and extended, remote memory to CA1. Change rates were significantly different across hippocampal subfields, but nearly all subfields showed significant volume decreases over time throughout adolescence. Several subfield volumes were larger in the right hemisphere and in males, while for change rates there were no hemisphere or sex differences. Partly in support of the hypotheses, greater volume of CA1 and CA2-3 was related to recall and retention after an extended delay, while longitudinal reduction of CA2-3 and CA4-DG was related to learning. This suggests continued regional development of the hippocampus across adolescence and that volume and volume change in specific subfields differentially predict verbal learning and memory over different retention intervals, but future high-resolution studies are called for. © 2014 S. Karger AG, Basel.

  16. The role of endoplasmic reticulum stress in hippocampal insulin resistance.

    Science.gov (United States)

    Sims-Robinson, Catrina; Bakeman, Anna; Glasser, Rebecca; Boggs, Janet; Pacut, Crystal; Feldman, Eva L

    2016-03-01

    Metabolic syndrome, which includes hypertension, hyperglycemia, obesity, insulin resistance, and dyslipidemia, has a negative impact on cognitive health. Endoplasmic reticulum (ER) stress is activated during metabolic syndrome, however it is not known which factor associated with metabolic syndrome contributes to this stress. ER stress has been reported to play a role in the development of insulin resistance in peripheral tissues. The role of ER stress in the development of insulin resistance in hippocampal neurons is not known. In the current study, we investigated ER stress in the hippocampus of 3 different mouse models of metabolic syndrome: the C57BL6 mouse on a high fat (HF) diet; apolipoprotein E, leptin, and apolipoprotein B-48 deficient (ApoE 3KO) mice; and the low density lipoprotein receptor, leptin, and apolipoprotein B-48 deficient (LDLR 3KO) mice. We demonstrate that ER stress is activated in the hippocampus of HF mice, and for the first time, in ApoE 3KO mice, but not LDLR 3KO mice. The HF and ApoE 3KO mice are hyperglycemic; however, the LDLR 3KO mice have normal glycemia. This suggests that hyperglycemia may play a role in the activation of ER stress in the hippocampus. Similarly, we also demonstrate that impaired insulin signaling is only present in the HF and ApoE 3KO mice, which suggests that ER stress may play a role in insulin resistance in the hippocampus. To confirm this we pharmacologically induced ER stress with thapsigargin in human hippocampal neurons. We demonstrate for the first time that thapsigargin leads to ER stress and impaired insulin signaling in human hippocampal neurons. Our results may provide a potential mechanism that links metabolic syndrome and cognitive health. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Development of a Modelling to Correlate Site and Diameter of Brain Metastases with Hippocampal Sparing Using Volumetric Modulated Arc Therapy

    Directory of Open Access Journals (Sweden)

    Silvia Chiesa

    2013-01-01

    Full Text Available Purpose. To correlate site and diameter of brain metastases with hippocampal sparing in patients treated by RapidArc (RA technique on whole brain with simultaneously integrated boost (SIB. Methods and Materials. An RA plan was calculated for brain metastases of 1-2-3 cm of diameter. The whole brain dose was 32.25 Gy (15 fractions, and SIB doses to brain metastases were 63 Gy (2 and 3 cm or 70.8 Gy (1 cm. Plans were optimized and evaluated for conformity, target coverage, prescription isodose to target volume, homogeneity index, and hippocampal sparing. Results. Fifteen brain lesions and RA plan were generated. Hippocampal volume was 4.09 cm3, and hippocampal avoidance volume was 17.50 cm3. Related to site of metastases, the mean hippocampal dose was 9.68 Gy2 for occipital lobe, 10.56 Gy2 for frontal lobe, 10.56 Gy2 for parietal lobe, 10.94 Gy2 for deep brain structures, and 40.44 Gy2 for temporal lobe. The mean hippocampal dose was 9.45 Gy2, 10.15 Gy2, and 11.70 Gy2 for diameter’s metastases of 1.2 and 3 cm, respectively, excluding results relative to temporal brain lesions. Conclusions. Location more than size of metastases can adversely influence the hippocampus sparing. Further investigation is necessary to meet definitive considerations.

  18. Hippocampal atrophy and memory dysfunction associated with physical inactivity in community-dwelling elderly subjects: The Sefuri study.

    Science.gov (United States)

    Hashimoto, Manabu; Araki, Yuko; Takashima, Yuki; Nogami, Kohjiro; Uchino, Akira; Yuzuriha, Takefumi; Yao, Hiroshi

    2017-02-01

    Physical inactivity is one of the modifiable risk factors for hippocampal atrophy and Alzheimer's disease. We investigated the relationship between physical activity, hippocampal atrophy, and memory using structural equation modeling (SEM). We examined 213 community-dwelling elderly subjects (99 men and 114 women with a mean age of 68.9 years) without dementia or clinically apparent depression. All participants underwent Mini-Mental State Examination (MMSE) and Rivermead Behavioral Memory Test (RBMT). Physical activities were assessed with a structured questionnaire. We evaluated the degree of hippocampal atrophy (z-score-referred to as ZAdvance hereafter), using a free software program-the voxel-based specific regional analysis system for Alzheimer's disease (VSRAD) based on statistical parametric mapping 8 plus Diffeomorphic Anatomical Registration Through an Exponentiated Lie algebra. Routine magnetic resonance imaging findings were as follows: silent brain infarction, n  = 24 (11.3%); deep white matter lesions, n  = 72 (33.8%); periventricular hyperintensities, n  = 35 (16.4%); and cerebral microbleeds, n  = 14 (6.6%). Path analysis based on SEM indicated that the direct paths from leisure-time activity to hippocampal atrophy (β = -.18, p  physical inactivity, and hippocampal atrophy appeared to cause memory dysfunction, although we are unable to infer a causal or temporal association between hippocampal atrophy and memory dysfunction from the present observational study.

  19. Behavioral inhibition in childhood predicts smaller hippocampal volume in adolescent offspring of parents with panic disorder

    Science.gov (United States)

    Schwartz, C E; Kunwar, P S; Hirshfeld-Becker, D R; Henin, A; Vangel, M G; Rauch, S L; Biederman, J; Rosenbaum, J F

    2015-01-01

    Behavioral inhibition (BI) is a genetically influenced behavioral profile seen in 15–20% of 2-year-old children. Children with BI are timid with people, objects and situations that are novel or unfamiliar, and are more reactive physiologically to these challenges as evidenced by higher heart rate, pupillary dilation, vocal cord tension and higher levels of cortisol. BI predisposes to the later development of anxiety, depression and substance abuse. Reduced hippocampal volumes have been observed in anxiety disorders, depression and posttraumatic stress disorder. Animal models have demonstrated that chronic stress can damage the hippocampal formation and implicated cortisol in these effects. We, therefore, hypothesized that the hippocampi of late adolescents who had been behaviorally inhibited as children would be smaller compared with those who had not been inhibited. Hippocampal volume was measured with high-resolution structural magnetic resonance imaging in 43 females and 40 males at 17 years of age who were determined to be BI+ or BI− based on behaviors observed in the laboratory as young children. BI in childhood predicted reduced hippocampal volumes in the adolescents who were offspring of parents with panic disorder, or panic disorder with comorbid major depression. We discuss genetic and environmental factors emanating from both child and parent that may explain these findings. To the best of our knowledge, this is the first study to demonstrate a relationship between the most extensively studied form of temperamentally based human trait anxiety, BI, and hippocampal structure. The reduction in hippocampal volume, as reported by us, suggests a role for the hippocampus in human trait anxiety and anxiety disorder that warrants further investigation. PMID:26196438

  20. Effects of low-level sarin and cyclosarin exposure on hippocampal subfields in Gulf War Veterans.

    Science.gov (United States)

    Chao, Linda L; Kriger, Stephen; Buckley, Shannon; Ng, Peter; Mueller, Susanne G

    2014-09-01

    More than 100,000 US troops were potentially exposed to chemical warfare agents sarin (GB) and cyclosarin (GF) when an ammunition dump at Khamisiyah, Iraq was destroyed during the 1991 Gulf War (GW). We previously reported reduced hippocampal volume in GW veterans with suspected GB/GF exposure relative to matched, unexposed GW veterans estimated from 1.5T magnetic resonance images (MRI). Here we investigate, in a different cohort of GW veterans, whether low-level GB/GF exposure is associated with structural alterations in specific hippocampal subfields, estimated from 4T MRI. The Automatic Segmentation of Hippocampal Subfields (ASHS) technique was used to quantify CA1, CA2, CA3 and dentate gyrus (DG), and subiculum (SUB) subfields volumes from high-resolution T2-weighted images acquired on a 4T MR scanner in 56 GW veterans with suspected GB/GF exposure and 56 "matched" unexposed GW veterans (mean age 49±7 years). GB/GF exposed veterans had smaller CA2 (p=0.003) and CA3/DG (p=0.01) subfield volumes compared to matched, unexposed GW veterans. There were no group difference in total hippocampal volume, quantified with FreeSurfer, and no dose-response relationship between estimated levels of GB/GF exposure and total hippocampal or subfield volume. These findings extend our previous report of structural alterations in the hippocampi of GW veterans with suspected GB/GF exposure to volume changes in the CA2, CA3, and DG hippocampal subfields in a different cohort of GW veterans with suspected GB/GF exposure. Published by Elsevier B.V.

  1. A Larger Social Network Enhances Novel Object Location Memory and Reduces Hippocampal Microgliosis in Aged Mice

    Science.gov (United States)

    Smith, Bryon M.; Yao, Xinyue; Chen, Kelly S.; Kirby, Elizabeth D.

    2018-01-01

    The mammalian hippocampus shows marked decline in function with aging across many species, including humans and laboratory rodent models. This decline frequently manifests in memory impairments that occur even in the absence of dementia pathology. In humans, a number of factors correlate with preserved hippocampal memory in aging, such as exercise, cognitive stimulation and number of social ties. While interventional studies and animal models clearly indicate that exercise and cognitive stimulation lead to hippocampal preservation, there is relatively little research on whether a decline in social ties leads to cognitive decline or vice versa. Even in animal studies of environmental enrichment in aging, the focus typically falls on physical enrichment such as a rotating cast of toys, rather than the role of social interactions. The present studies investigated the hypothesis that a greater number of social ties in aging mice would lead to improved hippocampal function. Aged, female C57/Bl6 mice were housed for 3 months in pairs or large groups (7 mice per cage). Group-housed mice showed greater novel object location memory and stronger preference for a spatial navigation strategy in the Barnes maze, though no difference in escape latency, compared to pair-housed mice. Group-housed mice did not differ from pair-housed mice in basal corticosterone levels or adult hippocampal neurogenesis. Group-housed mice did, however, show reduced numbers of Iba1/CD68+ microglia in the hippocampus. These findings suggest that group housing led to better memory function and reduced markers of neuroinflammation in aged mice. More broadly, they support a causative link between social ties and hippocampal function, suggesting that merely having a larger social network can positively influence the aging brain. Future research should address the molecular mechanisms by which a greater number of social ties alters hippocampal function. PMID:29904345

  2. Memory function and hippocampal volumes in preterm born very-low-birth-weight (VLBW) young adults.

    Science.gov (United States)

    Aanes, Synne; Bjuland, Knut Jørgen; Skranes, Jon; Løhaugen, Gro C C

    2015-01-15

    The hippocampi are regarded as core structures for learning and memory functions, which is important for daily functioning and educational achievements. Previous studies have linked reduction in hippocampal volume to working memory problems in very low birth weight (VLBW; ≤ 1500 g) children and reduced general cognitive ability in VLBW adolescents. However, the relationship between memory function and hippocampal volume has not been described in VLBW subjects reaching adulthood. The aim of the study was to investigate memory function and hippocampal volume in VLBW young adults, both in relation to perinatal risk factors and compared to term born controls, and to look for structure-function relationships. Using Wechsler Memory Scale-III and MRI, we included 42 non-disabled VLBW and 61 control individuals at age 19-20 years, and related our findings to perinatal risk factors in the VLBW-group. The VLBW young adults achieved lower scores on several subtests of the Wechsler Memory Scale-III, resulting in lower results in the immediate memory indices (visual and auditory), the working memory index, and in the visual delayed and general memory delayed indices, but not in the auditory delayed and auditory recognition delayed indices. The VLBW group had smaller absolute and relative hippocampal volumes than the controls. In the VLBW group inferior memory function, especially for the working memory index, was related to smaller hippocampal volume, and both correlated with lower birth weight and more days in the neonatal intensive care unit (NICU). Our results may indicate a structural-functional relationship in the VLBW group due to aberrant hippocampal development and functioning after preterm birth. Copyright © 2014 Elsevier Inc. All rights reserved.

  3. Dietary lipids are differentially associated with hippocampal-dependent relational memory in prepubescent children1234

    Science.gov (United States)

    Khan, Naiman A; Monti, Jim M; Raine, Lauren B; Drollette, Eric S; Moore, R Davis; Scudder, Mark R; Kramer, Arthur F; Hillman, Charles H; Cohen, Neal J

    2014-01-01

    Background: Studies in rodents and older humans have shown that the hippocampus—a brain structure critical to relational/associative memory—has remarkable plasticity as a result of lifestyle factors (eg, exercise). However, the effect of dietary intake on hippocampal-dependent memory during childhood has remained unexamined. Objective: We investigated the cross-sectional relation of dietary components characteristic of the Western diet, including saturated fatty acids (SFAs), omega-3 (n−3) fatty acids, and refined sugar, with hippocampal-dependent relational memory in prepubescent children. Design: Participants aged 7–9 y (n = 52) reported their dietary intake by using the Youth-Adolescent Food-Frequency Questionnaire and completed memory tasks designed to assess relational (hippocampal-dependent) and item (hippocampal-independent) memory. Performance on the memory tasks was assessed with both direct (accuracy) and indirect (eye movement) measures. Results: Partial correlations adjusted for body mass index showed a positive relation between relational memory accuracy and intake of omega-3 fatty acids and a negative relation of both relational and item memory accuracy with intake of SFAs. Potential confounding factors of age, sex, intelligence quotient, socioeconomic status, pubertal timing, and aerobic fitness (maximal oxygen volume) were not significantly related to any of the dietary intake measures. Eye movement measures of relational memory (preferential viewing to the target stimulus) showed a negative relation with intake of added sugar. Conclusions: SFA intake was negatively associated with both forms of memory, whereas omega-3 fatty acid intake was selectively positively associated with hippocampal-dependent relational memory. These findings are among the first to show a link between habitual dietary intake and cognitive health as pertaining to hippocampal function in childhood. The Fitness Improves Thinking Kids (FITKids) and FITKids2 trials were

  4. Dietary lipids are differentially associated with hippocampal-dependent relational memory in prepubescent children.

    Science.gov (United States)

    Baym, Carol L; Khan, Naiman A; Monti, Jim M; Raine, Lauren B; Drollette, Eric S; Moore, R Davis; Scudder, Mark R; Kramer, Arthur F; Hillman, Charles H; Cohen, Neal J

    2014-05-01

    Studies in rodents and older humans have shown that the hippocampus-a brain structure critical to relational/associative memory-has remarkable plasticity as a result of lifestyle factors (eg, exercise). However, the effect of dietary intake on hippocampal-dependent memory during childhood has remained unexamined. We investigated the cross-sectional relation of dietary components characteristic of the Western diet, including saturated fatty acids (SFAs), omega-3 (n-3) fatty acids, and refined sugar, with hippocampal-dependent relational memory in prepubescent children. Participants aged 7-9 y (n = 52) reported their dietary intake by using the Youth-Adolescent Food-Frequency Questionnaire and completed memory tasks designed to assess relational (hippocampal-dependent) and item (hippocampal-independent) memory. Performance on the memory tasks was assessed with both direct (accuracy) and indirect (eye movement) measures. Partial correlations adjusted for body mass index showed a positive relation between relational memory accuracy and intake of omega-3 fatty acids and a negative relation of both relational and item memory accuracy with intake of SFAs. Potential confounding factors of age, sex, intelligence quotient, socioeconomic status, pubertal timing, and aerobic fitness (maximal oxygen volume) were not significantly related to any of the dietary intake measures. Eye movement measures of relational memory (preferential viewing to the target stimulus) showed a negative relation with intake of added sugar. SFA intake was negatively associated with both forms of memory, whereas omega-3 fatty acid intake was selectively positively associated with hippocampal-dependent relational memory. These findings are among the first to show a link between habitual dietary intake and cognitive health as pertaining to hippocampal function in childhood. The Fitness Improves Thinking Kids (FITKids) and FITKids2 trials were registered at www.clinicaltrials.gov as NCT01334359 and NCT

  5. Ripples Make Waves: Binding Structured Activity and Plasticity in Hippocampal Networks

    Directory of Open Access Journals (Sweden)

    Josef H. L. P. Sadowski

    2011-01-01

    Full Text Available Establishing novel episodic memories and stable spatial representations depends on an exquisitely choreographed, multistage process involving the online encoding and offline consolidation of sensory information, a process that is largely dependent on the hippocampus. Each step is influenced by distinct neural network states that influence the pattern of activation across cellular assemblies. In recent years, the occurrence of hippocampal sharp wave ripple (SWR oscillations has emerged as a potentially vital network phenomenon mediating the steps between encoding and consolidation, both at a cellular and network level by promoting the rapid replay and reactivation of recent activity patterns. Such events facilitate memory formation by optimising the conditions for synaptic plasticity to occur between contingent neural elements. In this paper, we explore the ways in which SWRs and other network events can bridge the gap between spatiomnemonic processing at cellular/synaptic and network levels in the hippocampus.

  6. Treatment of sharp mandibular alveolar process with hybrid prosthesis

    Directory of Open Access Journals (Sweden)

    Sukaedi Sukaedi

    2010-09-01

    Full Text Available Background: Losing posterior teeth for a long time would occasionally lead to the sharpening of alveolar process. The removable partial denture usually have problems when used during mastication, because of the pressure on the mucosa under the alveolar ridge. Purpose: The purpose of this case report was to manage patients with sharp mandibular alveolar process by wearing hybrid prosthesis with extra coronal precision attachment retention and soft liner on the surface base beneath the removable partial denture. Case: A 76 years old woman visited the Prosthodontic Clinic Faculty of Dentistry Airlangga University. The patient had a long span bridge on the upper jaw and a free end acrylic removable partial denture on the lower jaw. She was having problems with mastication. The patient did not wear her lower denture because of the discomfort with it during mastication. Hence, she would like to replace it with a new removable partial denture. Case management: The patient was treated by wearing a hybrid prosthesis with extra coronal precision attachment on the lower jaw. Soft liner was applied on the surface of the removable partial denture. Hybrid prosthesis is a complex denture consisting of removable partial denture and fixed bridge. Conclusion: It concluded that after restoration, the patient had no problems with sharp alveolar process with her new denture, and she was able to masticate well.Latar belakang: Kehilangan geligi posterior dapat menimbulkan processus alveolaris tajam. Gigi tiruan sebagian lepasan mempunyai masalah selama pengunyahan karena adanya tekanan di mukosa di bawah alveolar ridge. Tujuan: Tujuan laporan kasus ini adalah untuk menjelaskan cara menangani pasien yang mempunyai prosesus alveolaris yang tajam di rahang bawah dengan dibuatkan protesis hybrid dengan daya tahan extra coronal precision attachment dan soft liner di permukaan bawah basis gigi tiruan sebagian lepasan. Kasus: Pasien wanita berumur 76 tahun datang di klinik

  7. Hippocampal insulin resistance and cognitive dysfunction

    NARCIS (Netherlands)

    Biessels, Geert Jan; Reagan, Lawrence P.

    2015-01-01

    Clinical studies suggest a link between type 2 diabetes mellitus (T2DM) and insulin resistance (IR) and cognitive dysfunction, but there are significant gaps in our knowledge of the mechanisms underlying this relationship. Animal models of IR help to bridge these gaps and point to hippocampal IR as

  8. Amnesia due to bilateral hippocampal glioblastoma

    International Nuclear Information System (INIS)

    Shimauchi, M.; Wakisaka, S.; Kinoshita, K.

    1989-01-01

    The authors report a unique case of glioblastoma which caused permanent amnesia. Magnetic resonance imaging showed the lesion to be limited to the hippocampal formation bilaterally. Although glioblastoma extends frequently into fiber pathways and expands into the opposite cerebral hemisphere, making a 'butterfly' lesion, it is unusual for it to invade the limbic system selectively to this extent. (orig.)

  9. Hippocampal theta frequency shifts and operant behaviour

    NARCIS (Netherlands)

    Lopes da Silva, F.H.; Kamp, A.

    1. 1. A shift of hippocampal dominant theta frequency to 6 c/sec has been demonstrated in the post-reward period in two dogs, which occurs consistently related in time to a well defined behavioural pattern in the course of an operant conditioning paradigm. 2. 2. The frequency shift was detected and

  10. Hippocampal gamma oscillations increase with memory load

    NARCIS (Netherlands)

    Van Vugt, Marieke K.; Schulze-Bonhage, Andreas; Litt, Brian; Brandt, Armin; Kahana, Michael J.

    2010-01-01

    Although the hippocampus plays a crucial role in encoding and retrieval of contextually mediated episodic memories, considerable controversy surrounds the role of the hippocampus in short-term or working memory. To examine both hippocampal and neocortical contributions to working memory function, we

  11. Hippocampal sclerosis in advanced age: clinical and pathological features.

    Science.gov (United States)

    Nelson, Peter T; Schmitt, Frederick A; Lin, Yushun; Abner, Erin L; Jicha, Gregory A; Patel, Ela; Thomason, Paula C; Neltner, Janna H; Smith, Charles D; Santacruz, Karen S; Sonnen, Joshua A; Poon, Leonard W; Gearing, Marla; Green, Robert C; Woodard, John L; Van Eldik, Linda J; Kryscio, Richard J

    2011-05-01

    Hippocampal sclerosis is a relatively common neuropathological finding (∼10% of individuals over the age of 85 years) characterized by cell loss and gliosis in the hippocampus that is not explained by Alzheimer's disease. Hippocampal sclerosis pathology can be associated with different underlying causes, and we refer to hippocampal sclerosis in the aged brain as hippocampal sclerosis associated with ageing. Much remains unknown about hippocampal sclerosis associated with ageing. We combined three different large autopsy cohorts: University of Kentucky Alzheimer's Disease Centre, the Nun Study and the Georgia Centenarian Study to obtain a pool of 1110 patients, all of whom were evaluated neuropathologically at the University of Kentucky. We focused on the subset of cases with neuropathology-confirmed hippocampal sclerosis (n=106). For individuals aged≥95 years at death (n=179 in our sample), each year of life beyond the age of 95 years correlated with increased prevalence of hippocampal sclerosis pathology and decreased prevalence of 'definite' Alzheimer's disease pathology. Aberrant TAR DNA protein 43 immunohistochemistry was seen in 89.9% of hippocampal sclerosis positive patients compared with 9.7% of hippocampal sclerosis negative patients. TAR DNA protein 43 immunohistochemistry can be used to demonstrate that the disease is usually bilateral even when hippocampal sclerosis pathology is not obvious by haematoxylin and eosin stains. TAR DNA protein 43 immunohistochemistry was negative on brain sections from younger individuals (n=10) after hippocampectomy due to seizures, who had pathologically confirmed hippocampal sclerosis. There was no association between cases with hippocampal sclerosis associated with ageing and apolipoprotein E genotype. Age of death and clinical features of hippocampal sclerosis associated with ageing (with or without aberrant TAR DNA protein 43) were distinct from previously published cases of frontotemporal lobar degeneration TAR

  12. Updating the lamellar hypothesis of hippocampal organization

    Directory of Open Access Journals (Sweden)

    Robert S Sloviter

    2012-12-01

    Full Text Available In 1971, Andersen and colleagues proposed that excitatory activity in the entorhinal cortex propagates topographically to the dentate gyrus, and on through a trisynaptic circuit lying within transverse hippocampal slices or lamellae [Andersen, Bliss, and Skrede. 1971. Lamellar organization of hippocampal pathways. Exp Brain Res 13, 222-238]. In this way, a relatively simple structure might mediate complex functions in a manner analogous to the way independent piano keys can produce a nearly infinite variety of unique outputs. The lamellar hypothesis derives primary support from the lamellar distribution of dentate granule cell axons (the mossy fibers, which innervate dentate hilar neurons and area CA3 pyramidal cells and interneurons within the confines of a thin transverse hippocampal segment. Following the initial formulation of the lamellar hypothesis, anatomical studies revealed that unlike granule cells, hilar mossy cells, CA3 pyramidal cells, and Layer II entorhinal cells all form axonal projections that are more divergent along the longitudinal axis than the clearly lamellar mossy fiber pathway. The existence of pathways with translamellar distribution patterns has been interpreted, incorrectly in our view, as justifying outright rejection of the lamellar hypothesis [Amaral and Witter. 1989. The three-dimensional organization of the hippocampal formation: a review of anatomical data. Neuroscience 31, 571-591]. We suggest that the functional implications of longitudinally-projecting axons depend not on whether they exist, but on what they do. The observation that focal granule cell layer discharges normally inhibit, rather than excite, distant granule cells suggests that longitudinal axons in the dentate gyrus may mediate "lateral" inhibition and define lamellar function, rather than undermine it. In this review, we attempt a reconsideration of the evidence that most directly impacts the physiological concept of hippocampal lamellar

  13. Short-time quantum dynamics of sharp boundaries potentials

    Energy Technology Data Exchange (ETDEWEB)

    Granot, Er' el, E-mail: erel@ariel.ac.il; Marchewka, Avi

    2015-02-15

    Despite the high prevalence of singular potential in general, and rectangular potentials in particular, in applied scattering models, to date little is known about their short time effects. The reason is that singular potentials cause a mixture of complicated local as well as non-local effects. The object of this work is to derive a generic method to calculate analytically the short-time impact of any singular potential. In this paper it is shown that the scattering of a smooth wavefunction on a singular potential is totally equivalent, in the short-time regime, to the free propagation of a singular wavefunction. However, the latter problem was totally addressed analytically in Ref. [7]. Therefore, this equivalency can be utilized in solving analytically the short time dynamics of any smooth wavefunction at the presence of a singular potentials. In particular, with this method the short-time dynamics of any problem where a sharp boundaries potential (e.g., a rectangular barrier) is turned on instantaneously can easily be solved analytically.

  14. Short-time quantum dynamics of sharp boundaries potentials

    Science.gov (United States)

    Granot, Er'el; Marchewka, Avi

    2015-02-01

    Despite the high prevalence of singular potential in general, and rectangular potentials in particular, in applied scattering models, to date little is known about their short time effects. The reason is that singular potentials cause a mixture of complicated local as well as non-local effects. The object of this work is to derive a generic method to calculate analytically the short-time impact of any singular potential. In this paper it is shown that the scattering of a smooth wavefunction on a singular potential is totally equivalent, in the short-time regime, to the free propagation of a singular wavefunction. However, the latter problem was totally addressed analytically in Ref. [7]. Therefore, this equivalency can be utilized in solving analytically the short time dynamics of any smooth wavefunction at the presence of a singular potentials. In particular, with this method the short-time dynamics of any problem where a sharp boundaries potential (e.g., a rectangular barrier) is turned on instantaneously can easily be solved analytically.

  15. Short-time quantum dynamics of sharp boundaries potentials

    International Nuclear Information System (INIS)

    Granot, Er'el; Marchewka, Avi

    2015-01-01

    Despite the high prevalence of singular potential in general, and rectangular potentials in particular, in applied scattering models, to date little is known about their short time effects. The reason is that singular potentials cause a mixture of complicated local as well as non-local effects. The object of this work is to derive a generic method to calculate analytically the short-time impact of any singular potential. In this paper it is shown that the scattering of a smooth wavefunction on a singular potential is totally equivalent, in the short-time regime, to the free propagation of a singular wavefunction. However, the latter problem was totally addressed analytically in Ref. [7]. Therefore, this equivalency can be utilized in solving analytically the short time dynamics of any smooth wavefunction at the presence of a singular potentials. In particular, with this method the short-time dynamics of any problem where a sharp boundaries potential (e.g., a rectangular barrier) is turned on instantaneously can easily be solved analytically

  16. An evaluation of sharp safety blood evacuation devices.

    Science.gov (United States)

    Ford, Joanna; Phillips, Peter

    This article describes an evaluation of three sharp safety blood evacuation devices in seven Welsh NHS boards and the Welsh Blood Service. Products consisted of two phlebotomy needles possessing safety shields and one phlebotomy device with wings, tubing and a retractable needle. The device companies provided the devices and appropriate training. Participating healthcare workers used the safety device instead of the conventional device to sample blood during the evaluation period and each type of device was evaluated in random order. Participants filled in a questionnaire for each type of device and then a further questionnaire comparing the two shielded evacuation needles with each other Results showed that responses to all three products were fairly positive, although each device was not liked by everyone who used it. When the two shielded evacuation devices were compared with each other, most users preferred the device with the shield positioned directly above the needle to the device with the shield at the side. However, in laboratory tests, the preferred device produced more fluid splatter than the other shielded device on activation.

  17. The alterations in biochemical signaling of hippocampal network activity in the autism brain The alterations in biochemical signaling of hippocampal network activity in the autism brain The alterations in biochemical signaling of hippocampal network activity in the autism brain

    Institute of Scientific and Technical Information of China (English)

    田允; 黄继云; 王锐; 陶蓉蓉; 卢应梅; 廖美华; 陆楠楠; 李静; 芦博; 韩峰

    2012-01-01

    Autism is a highly heritable neurodevelopmental condition characterized by impaired social interaction and communication. However, the role of synaptic dysfunction during development of autism remains unclear. In the present study, we address the alterations of biochemical signaling in hippocampal network following induction of the autism in experimental animals. Here, the an- imal disease model and DNA array being used to investigate the differences in transcriptome or- ganization between autistic and normal brain by gene co--expression network analysis.

  18. [ERK activation effects on GABA secretion inhibition induced by SDF-1 in hippocampal neurons of rats].

    Science.gov (United States)

    Zhang, Zi-juan; Guo, Mei-xia; Xing, Ying

    2015-09-01

    To investigate the effect of extracellular regulating kinase (ERK) signaling pathway on the secretion of gamma-aminobutyric acid (GABA) in cultured rat hippocampal neurons induced by stromal cell derived factor-1 (SDF-1). The hippocampal neurons of newborn SD rats were cultured and identified in vitro; the phosphorylation level of ERK1/2 was examined by Western blot; ELISA was used to detect the effect of PD98059, a ERK1/2 specific blocker on GABA secretion of cultured hippocampal neurons and Western blot were adopted to measure the protein expression levels of glutamate decarboxylase (GAD65/67) and gamma aminobutyric acid transporter (GAT); after blocking ERK1/2 signaling pathway with PD98059; RT-PCR was used to detect the mRNA expression levels of GAT-1 and GAD65 after treated with PD98059. The levels of ERKl/2 phosphorylation were increased significantly by SDF1 acting on hippocampal neurons, and CX-CR4 receptor blocker AMD3100, could inhibit SDF-1 induced ERK1/2 activation; SDF-1 could inhibit the secretion of GABA in cultured hippocampal neurons, and ERK1/2 specific inhibitor PD98059, could partly reverse the inhibition of GABA secretion by SDF-1. The effects of SDF-1 on cultured hippocampal neurons was to decrease the mRNA genesis of glutamic acid decarboxylase GAD65 and GABA transporter GAT-1, besides, ERK inhibitor PD98059 could effectively flip the effect of SDF-1. The results of Western blot showed that SDF-1 could inhibit the protein expression of GAT-1 and GAD65/67 in hippocampal neurons and the inhibition of GAT-1 and GAD65/67 protein expression could be partially restored by ERK1/2 blocker. SDF-1 acts on the CXCR4 of hippocampal neurons in vitro, and inhibits the expression of GAD by activating the ERK1/2 signaling pathway, and this may represent one possible pathway of GABA secretion inhibition.

  19. Hippocampal activation during retrieval of spatial context from episodic and semantic memory.

    Science.gov (United States)

    Hoscheidt, Siobhan M; Nadel, Lynn; Payne, Jessica; Ryan, Lee

    2010-10-15

    The hippocampus, a region implicated in the processing of spatial information and episodic memory, is central to the debate concerning the relationship between episodic and semantic memory. Studies of medial temporal lobe amnesic patients provide evidence that the hippocampus is critical for the retrieval of episodic but not semantic memory. On the other hand, recent neuroimaging studies of intact individuals report hippocampal activation during retrieval of both autobiographical memories and semantic information that includes historical facts, famous faces, and categorical information, suggesting that episodic and semantic memory may engage the hippocampus during memory retrieval in similar ways. Few studies have matched episodic and semantic tasks for the degree to which they include spatial content, even though spatial content may be what drives hippocampal activation during semantic retrieval. To examine this issue, we conducted a functional magnetic resonance imaging (fMRI) study in which retrieval of spatial and nonspatial information was compared during an episodic and semantic recognition task. Results show that the hippocampus (1) participates preferentially in the retrieval of episodic memories; (2) is also engaged by retrieval of semantic memories, particularly those that include spatial information. These data suggest that sharp dissociations between episodic and semantic memory may be overly simplistic and that the hippocampus plays a role in the retrieval of spatial content whether drawn from a memory of one's own life experiences or real-world semantic knowledge. Published by Elsevier B.V.

  20. Influence of gantry angle in helical computed tomography. Usefullness of 1-dimension sharpness filter

    Energy Technology Data Exchange (ETDEWEB)

    Kawano, Hirofumi; Suzuki, Toru; Matsuura, Shigeru; Kai, Tsuyoshi; Shimizu, Toshiyuki [Hyuga Hospital of Saiseikai Foundation, Kadogawa, Miyazaki (Japan)

    2001-05-01

    When we let gantry tilt and do scan in helical CT, vertical sharpness deteriorates. We were able to revise it with 1-dimensional sharpness filter which the square sum of difference of MTF was compared, and was designed this time. And the unsharpness was in proportion to sin of gantry angle. As a result, we led several sets of frequency emphasis degree. There is a model to built 1-dimension sharpness filter in a scan plan. It is useful for clinical diagnoses. (author)

  1. Influence of gantry angle in helical computed tomography. Usefullness of 1-dimension sharpness filter

    International Nuclear Information System (INIS)

    Kawano, Hirofumi; Suzuki, Toru; Matsuura, Shigeru; Kai, Tsuyoshi; Shimizu, Toshiyuki

    2001-01-01

    When we let gantry tilt and do scan in helical CT, vertical sharpness deteriorates. We were able to revise it with 1-dimensional sharpness filter which the square sum of difference of MTF was compared, and was designed this time. And the unsharpness was in proportion to sin of gantry angle. As a result, we led several sets of frequency emphasis degree. There is a model to built 1-dimension sharpness filter in a scan plan. It is useful for clinical diagnoses. (author)

  2. Auditory stimuli elicit hippocampal neuronal responses during sleep

    Directory of Open Access Journals (Sweden)

    Ekaterina eVinnik

    2012-06-01

    Full Text Available To investigate how hippocampal neurons code behaviorally salient stimuli, we recorded from neurons in the CA1 region of hippocampus in rats while they learned to associate the presence of sound with water reward. Rats learned to alternate between two reward ports at which, in 50 percent of the trials, sound stimuli were presented followed by water reward after a 3-second delay. Sound at the water port predicted subsequent reward delivery in 100 percent of the trials and the absence of sound predicted reward omission. During this task, 40% of recorded neurons fired differently according to which of the 2 reward ports the rat was visiting. A smaller fraction of neurons demonstrated onset response to sound/nosepoke (19% and reward delivery (24%. When the sounds were played during passive wakefulness, 8% of neurons responded with short latency onset responses; 25% of neurons responded to sounds when they were played during sleep. Based on the current findings and the results of previous experiments we propose the existence of two types of hippocampal neuronal responses to sounds: sound-onset responses with very short latency and longer-lasting sound-specific responses that are likely to be present when the animal is actively engaged in the task. During sleep the short-latency responses in hippocampus are intermingled with sustained activity which in the current experiment was detected for 1-2 seconds.

  3. Electrical coupling between hippocampal astrocytes in rat brain slices.

    Science.gov (United States)

    Meme, William; Vandecasteele, Marie; Giaume, Christian; Venance, Laurent

    2009-04-01

    Gap junctions in astrocytes play a crucial role in intercellular communication by supporting both biochemical and electrical coupling between adjacent cells. Despite the critical role of electrical coupling in the network organization of these glial cells, the electrophysiological properties of gap junctions have been characterized in cultures while no direct evidence has been sought in situ. In the present study, gap-junctional currents were investigated using simultaneous dual whole-cell patch-clamp recordings between astrocytes from rat hippocampal slices. Bidirectional electrotonic coupling was observed in 82% of the cell pairs with an average coupling coefficient of 5.1%. Double patch-clamp analysis indicated that junctional currents were independent of the transjunctional voltage over a range from -100 to +110 mV. Interestingly, astrocytic electrical coupling displayed weak low-pass filtering properties compared to neuronal electrical synapses. Finally, during uncoupling processes triggered by either the gap-junction inhibitor carbenoxolone or endothelin-1, an increase in the input resistance in the injected cell paralleled the decrease in the coupling coefficient. Altogether, these results demonstrate that hippocampal astrocytes are electrically coupled through gap-junction channels characterized by properties that are distinct from those of electrical synapses between neurons. In addition, gap-junctional communication is efficiently regulated by endogenous compounds. This is taken to represent a mode of communication that may have important implications for the functional role of astrocyte networks in situ.

  4. ASSESSMENT OF THE MANAGEMENT OF SHARPS INJURIES IN GOVERNMENT HOSPITALS: THE MALAYSIAN SITUATION

    Directory of Open Access Journals (Sweden)

    M. Siti Haniza M.D PhD

    2012-11-01

    Full Text Available Introduction: Management of occupational hazards has been a priority and sharps injuries is a known potential risk to health care workers. With the known risks of potential infections, to the workers as well as the patients, our workers need protection from further danger. Objective: This study looked at the measures taken on managing the affected healthcare workers. Methods: A cross-sectional survey using self-administered questionnaire was sent to 55 hospital directors. They were required to inform on their management practices on sharps injuries. Results: The findings showed variations in the management of sharps injuries during and after office hours, variation in the site of keeping the records, person responsible and variation in the frequency of data analysis and presentation to hospital directors. Discussion: According to OSHA Act 1994, it is the responsibility of the employer to ensure safety, health and welfare of the employee. In management of sharps injury data from injury reporting should be compiled and assessed. Reporting feedback need to be encouraged with timely follow-up of all sharps injury cases. Reporting of sharps injuries is essential to ensure that all healthcare workers receive appropriate post-exposure medical treatment. Conclusion & Recommendation: A uniform management of sharps injuries protocol need to be established to improve reporting. An avenue to present sharps injuries data regularly is needed so as appropriate management of workers be ensured. Therefore adherence to the available guidelines need to be ensured. Key words: management, sharps injuries, healthcare workers

  5. Localness of energy cascade in hydrodynamic turbulence, II. Sharp spectral filter

    Energy Technology Data Exchange (ETDEWEB)

    Aluie, Hussein [Los Alamos National Laboratory; Eyink, Gregory L [JOHNS HOPKINS UNIV.

    2009-01-01

    We investigate the scale-locality of subgrid-scale (SGS) energy flux and interband energy transfers defined by the sharp spectral filter. We show by rigorous bounds, physical arguments, and numerical simulations that the spectral SGS flux is dominated by local triadic interactions in an extended turbulent inertial range. Interband energy transfers are also shown to be dominated by local triads if the spectral bands have constant width on a logarithmic scale. We disprove in particular an alternative picture of 'local transfer by nonlocal triads,' with the advecting wavenumber mode at the energy peak. Although such triads have the largest transfer rates of all individual wavenumber triads, we show rigorously that, due to their restricted number, they make an asymptotically negligible contribution to energy flux and log-banded energy transfers at high wavenumbers in the inertial range. We show that it is only the aggregate effect of a geometrically increasing number of local wavenumber triads which can sustain an energy cascade to small scales. Furthermore, nonlocal triads are argued to contribute even less to the space-average energy flux than is implied by our rigorous bounds, because of additional cancellations from scale-decorrelation effects. We can thus recover the -4/3 scaling of nonlocal contributions to spectral energy flux predicted by Kraichnan's abridged Lagrangian-history direct-interaction approximation and test-field model closures. We support our results with numerical data from a 512{sup 3} pseudospectral simulation of isotropic turbulence with phase-shift dealiasing. We also discuss a rigorous counterexample of Eyink [Physica D 78, 222 (1994)], which showed that nonlocal wavenumber triads may dominate in the sharp spectral flux (but not in the SGS energy flux for graded filters). We show that this mathematical counter example fails to satisfy reasonable physical requirements for a turbulent velocity field, which are employed in our

  6. Age Is Associated with Reduced Sharp-Wave Ripple Frequency and Altered Patterns of Neuronal Variability.

    Science.gov (United States)

    Wiegand, Jean-Paul L; Gray, Daniel T; Schimanski, Lesley A; Lipa, Peter; Barnes, C A; Cowen, Stephen L

    2016-05-18

    Spatial and episodic memory performance declines with age, and the neural basis for this decline is not well understood. Sharp-wave ripples are brief (∼70 ms) high-frequency oscillatory events generated in the hippocampus and are associated with the consolidation of spatial memories. Given the connection between ripple oscillations and memory consolidation, we investigated whether the structure of ripple oscillations and ripple-triggered patterns of single-unit activity are altered in aged rats. Local field and single-unit activity surrounding sharp-wave ripple events were examined in the CA1 region of the hippocampus of old (n = 5) and young (n = 6) F344 rats during periods of rest preceding and following performance on a place-dependent eyeblink-conditioning task. Neural responses in aged rats differed from responses in young rats in several ways. First, compared with young rats, the rate of ripple occurrence (ripple density) is reduced in aged rats during postbehavior rest. Second, mean ripple frequency during prebehavior and postbehavior rest is lower in aged animals (aged: 132 Hz; young: 146 Hz). Third, single neurons in aged animals responded more consistently from ripple to ripple. Fourth, variability in interspike intervals was greater in aged rats. Finally, neurons were tuned to a narrower range of phases of the ripple oscillation relative to young animals. Together, these results suggest that the CA1 network in aged animals has a reduced "vocabulary" of available representational states. The hippocampus is a structure that is critical for the formation of episodic memories. Sharp-wave ripple events generated in the hippocampus have been implicated in memory consolidation processes critical to memory stabilization. We examine here whether these ripple oscillations are altered over the course of the life span, which could contribute to hippocampus-dependent memory deficits that occur during aging. This experiment used young and aged memory-impaired rats

  7. Hippocampal testosterone relates to reference memory performance and synaptic plasticity in male rats

    Directory of Open Access Journals (Sweden)

    Kristina eSchulz

    2010-12-01

    Full Text Available Steroids are important neuromodulators influencing cognitive performance and synaptic plasticity. While the majority of literature concerns adrenal- and gonadectomized animals, very little is known about the natural endogenous release of hormones during learning. Therefore, we measured blood and brain (hippocampus, prefrontal cortex testosterone, estradiol, and corticosterone concentrations of intact male rats undergoing a spatial learning paradigm which is known to reinforce hippocampal plasticity. We found significant modulations of all investigated hormones over the training course. Corticosterone and testosterone were correlated manifold with behaviour, while estradiol expressed fewer correlations. In the recall session, testosterone was tightly coupled to reference memory performance, which is crucial for reinforcement of synaptic plasticity in the dentate gyrus. Intriguingly, prefrontal cortex and hippocampal levels related differentially to reference memory performance. Correlations of testosterone and corticosterone switched from unspecific activity to specific cognitive functions over training. Correspondingly, exogenous application of testosterone revealed different effects on synaptic and neuronal plasticity in trained versus untrained animals. While hippocampal long-term potentiation (LTP of the field excitatory postsynaptic potential (fEPSP was prolonged in untrained rats, both the fEPSP- and the population spike amplitude-LTP was impaired in trained rats. Behavioural performance was unaffected, but correlations of hippocampal field potentials with behaviour were decoupled in treated rats. The data provide important evidence that besides adrenal, also gonadal steroids play a mechanistic role in linking synaptic plasticity to cognitive performance.

  8. Intracerebroventricular administration of okadaic acid induces hippocampal glucose uptake dysfunction and tau phosphorylation.

    Science.gov (United States)

    Broetto, Núbia; Hansen, Fernanda; Brolese, Giovana; Batassini, Cristiane; Lirio, Franciane; Galland, Fabiana; Dos Santos, João Paulo Almeida; Dutra, Márcio Ferreira; Gonçalves, Carlos-Alberto

    2016-06-01

    Intraneuronal aggregates of neurofibrillary tangles (NFTs), together with beta-amyloid plaques and astrogliosis, are histological markers of Alzheimer's disease (AD). The underlying mechanism of sporadic AD remains poorly understood, but abnormal hyperphosphorylation of tau protein is suggested to have a role in NFTs genesis, which leads to neuronal dysfunction and death. Okadaic acid (OKA), a strong inhibitor of protein phosphatase 2A, has been used to induce dementia similar to AD in rats. We herein investigated the effect of intracerebroventricular (ICV) infusion of OKA (100 and 200ng) on hippocampal tau phosphorylation at Ser396, which is considered an important fibrillogenic tau protein site, and on glucose uptake, which is reduced early in AD. ICV infusion of OKA (at 200ng) induced a spatial cognitive deficit, hippocampal astrogliosis (based on GFAP increment) and increase in tau phosphorylation at site 396 in this model. Moreover, we observed a decreased glucose uptake in the hippocampal slices of OKA-treated rats. In vitro exposure of hippocampal slices to OKA altered tau phosphorylation at site 396, without any associated change in glucose uptake activity. Taken together, these findings further our understanding of OKA neurotoxicity, in vivo and vitro, particularly with regard to the role of tau phosphorylation, and reinforce the importance of the OKA dementia model for studying the neurochemical alterations that may occur in AD, such as NFTs and glucose hypometabolism. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Hippocampal 3alpha,5alpha-THP may alter depressive behavior of pregnant and lactating rats.

    Science.gov (United States)

    Frye, Cheryl A; Walf, Alicia A

    2004-07-01

    The 5alpha-reduced metabolite of progesterone (P), 5alpha-pregnan-3alpha-ol-20-one (3alpha,5alpha-THP), may mediate progestins' effects to reduce depressive behavior of female rats in part through actions in the hippocampus. To investigate, forced swim test behavior and plasma and hippocampal progestin levels were assessed in groups of rats expected to differ in their 3alpha,5alpha-THP levels due to endogenous differences (pregnant and postpartum), administration of a 5alpha-reductase inhibitor (finasteride; 50 mg/kg sc), and/or gestational stress [prenatal stress (PNS)], an animal model of depression. Pregnant rats had higher plasma and hippocampal 3alpha,5alpha-THP levels and less depressive behavior (decreased immobility, increased struggling and swimming) in the forced swim test than did postpartum rats. Finasteride, compared to vehicle-administration, reduced plasma and hippocampal 3alpha,5alpha-THP levels and increased depressive behavior (increased immobility, decreased struggling and swimming). PNS was associated with lower hippocampal, but not plasma, 3alpha,5alpha-THP levels and increased swimming compared to that observed in control rats. Together, these data suggest that 3alpha,5alpha-THP in the hippocampus may mediate antidepressive behavior of female rats.

  10. Protective Effect of SGK1 in Rat Hippocampal Neurons Subjected to Ischemia Reperfusion

    Directory of Open Access Journals (Sweden)

    Wei Zhang

    2014-07-01

    Full Text Available Background/Aims: To investigate the protective effect of SGK1 (serum- and glucocorticoid-inducible protein kinase 1 in rat hippocampal neurons in vitro and in vivo following ischemia reperfusion (I/R. Methods: Isolated rat hippocampal neurons were subjected to 2 h of oxygen and glucose deprivation (OGD then returned to normoxic conditions for 10, 30 or 60 min. Cell apoptosis and protein expression of SGK1 were analyzed. To examine SGK1 function, we overexpressed SGK1 in rat hippocampal neurons. Finally we examined the involvement of PI3K/Akt/GSK3β signaling by treating the cells (untransfected or transfected with expression vector encoding SGK1 with the PI3K inhibitor LY294002. Findings were confirmed in vivo in a rat model of middle cerebral artery occlusion. Results: I/R caused a time-dependent increase in apoptosis, both in vitro and in vivo. SGK1 protein levels decreased significantly under the same conditions. Overexpression of SGK1 reduced apoptosis following OGD or I/R compared to cells transfected with empty vector and subjected to the same treatment, or sham-operated animals. Addition of LY294002 revealed that the action of SGK1 in suppressing apoptosis was mediated by the PI3K/Akt/GSK3β pathway. Conclusion: SGK1 plays a protective role in ischemia reperfusion in rat hippocampal neurons, exerting its effects via the PI3K/Akt/GSK3β pathway.

  11. PMC-12, a traditional herbal medicine, enhances learning memory and hippocampal neurogenesis in mice.

    Science.gov (United States)

    Park, Hee Ra; Kim, Ju Yeon; Lee, Yujeong; Chun, Hye Jeong; Choi, Young Whan; Shin, Hwa Kyoung; Choi, Byung Tae; Kim, Cheol Min; Lee, Jaewon

    2016-03-23

    The beneficial effects of traditional Korean medicine are recognized during the treatment of neurodegenerative conditions, such as, Alzheimer's disease and neurocognitive dysfunction, and recently, hippocampal neurogenesis has been reported to be associated with memory function. In this study, the authors investigated the beneficial effects of polygonum multiflorum Thunberg complex composition-12 (PMC-12), which is a mixture of four medicinal herbs, that is, Polygonum multiflorum, Polygala tenuifolia, Rehmannia glutinosa, and Acorus gramineus, on hippocampal neurogenesis, learning, and memory in mice. PMC-12 was orally administered to male C57BL/6 mice (5 weeks old) at 100 or 500 mg/kg daily for 2 weeks. PMC-12 administration significantly was found to increase the proliferation of neural progenitor cells and the survival of newly-generated cells in the dentate gyrus. In the Morris water maze test, the latency times of PMC-12 treated mice (100 or 500 mg/kg) were shorter than those of vehicle-control mice. In addition, PMC-12 increased the levels of BDNF, p-CREB, and synaptophysin, which are known to be associated with neural plasticity and hippocampal neurogenesis. These findings suggest PMC-12 enhances hippocampal neurogenesis and neurocognitive function and imply that PMC-12 ameliorates memory impairment and cognitive deficits. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  12. Reorganization of associative memory in humans with long-standing hippocampal damage.

    Science.gov (United States)

    Braun, Mischa; Finke, Carsten; Ostendorf, Florian; Lehmann, Thomas-Nicolas; Hoffmann, Karl-Titus; Ploner, Christoph J

    2008-10-01

    Conflicting theories have been advanced to explain why hippocampal lesions affect distinct memory domains and spare others. Recent findings in monkeys suggest that lesion-induced plasticity may contribute to the seeming preservation of some of these domains. We tested this hypothesis by investigating visuo-spatial associative memory in two patient groups with similar surgical lesions to the right medial temporal lobe, but different preoperative disease courses (benign brain tumours, mean: 1.8 +/- 0.6 years, n = 5, age: 28.2 +/- 4.0 years; hippocampal sclerosis, mean: 16.8 +/- 1.9 years, n = 9, age: 38.9 +/- 4.1 years). Compared to controls (n = 14), tumour patients showed a significant delay-dependent deficit in memory of colour-location associations. No such deficit was observed in hippocampal sclerosis patients, which appeared to benefit from a compensatory mechanism that was inefficient in tumour patients. These results indicate that long-standing hippocampal damage can yield significant functional reorganization of the neural substrate underlying memory in the human brain. We suppose that this process accounts for some of the discrepancies between results from previous lesion studies of the human medial temporal lobe.

  13. Preventive effect of piracetam and vinpocetine on hypoxia-reoxygenation induced injury in primary hippocampal culture.

    Science.gov (United States)

    Solanki, P; Prasad, D; Muthuraju, S; Sharma, A K; Singh, S B; Ilavzhagan, G

    2011-04-01

    The present study investigates the potential of Piracetam and Vinpocetine (nootropic drugs, known to possess neuroprotective properties) in preventing hypoxia-reoxygenation induced oxidative stress in primary hippocampal cell culture. The hippocampal culture was exposed to hypoxia (95% N(2), 5% CO(2)) for 3h and followed by 1h of reoxygenation (21% O(2) and 5% CO(2)) at 37 °C. The primary hippocampal cultures were supplemented with the optimum dose of Piracetam and Vinpocetine, independently, and the cultures were divided into six groups, viz. Control/Normoxia, Hypoxia, Hypoxia+Piracetam, Hypoxia+Vinpocetine, Normoxia + Piracetam and Normoxia+Vinpocetine. The cell-viability assays and biochemical oxidative stress parameters were evaluated for each of the six groups. Administration of 1mM Piracetam or 500 nM Vinpocetine significantly prevents the culture from hypoxia-reoxygenation injury when determined by Neutral Red assay, LDH release and Acetylcholine esterase activity. Results showed that Piracetam and Vinpocetine supplementation significantly prevented the fall of mitochondrial membrane potential, rise in ROS generation and reduction in antioxidant levels associated with the hypoxia-reoxygenation injury. In conclusion, the present study establishes that both Piracetam and Vinpocetine give neuroprotection against hypoxia-reoxygenation injury in primary hippocampal cell culture. Copyright © 2010 Elsevier Ltd. All rights reserved.

  14. Neogenin, a regulator of adult hippocampal neurogenesis, prevents depressive-like behavior.

    Science.gov (United States)

    Sun, Dong; Sun, Xiang-Dong; Zhao, Lu; Lee, Dae-Hoon; Hu, Jin-Xia; Tang, Fu-Lei; Pan, Jin-Xiu; Mei, Lin; Zhu, Xiao-Juan; Xiong, Wen-Cheng

    2018-01-08

    Adult neurogenesis in hippocampal dentate gyrus (DG) is a complex, but precisely controlled process. Dysregulation of this event contributes to multiple neurological disorders, including major depression. Thus, it is of considerable interest to investigate how adult hippocampal neurogenesis is regulated. Here, we present evidence for neogenin, a multifunctional transmembrane receptor, to regulate adult mouse hippocampal neurogenesis. Loss of neogenin in adult neural stem cells (NSCs) or neural progenitor cells (NPCs) impaired NSCs/NPCs proliferation and neurogenesis, whereas increased their astrocytic differentiation. Mechanistic studies revealed a role for neogenin to positively regulate Gli1, a crucial downstream transcriptional factor of sonic hedgehog, and expression of Gli1 into neogenin depleted NSCs/NPCs restores their proliferation. Further morphological and functional studies showed additional abnormities, including reduced dendritic branches and spines, and impaired glutamatergic neuro-transmission, in neogenin-depleted new-born DG neurons; and mice with depletion of neogenin in NSCs/NPCs exhibited depressive-like behavior. These results thus demonstrate unrecognized functions of neogenin in adult hippocampal NSCs/NPCs-promoting NSCs/NPCs proliferation and neurogenesis and preventing astrogliogenesis and depressive-like behavior, and suggest neogenin regulation of Gli1 signaling as a possible underlying mechanism.

  15. Hippocampal spatial mechanisms relate to the development of arithmetic symbol processing in children.

    Science.gov (United States)

    Mathieu, Romain; Epinat-Duclos, Justine; Léone, Jessica; Fayol, Michel; Thevenot, Catherine; Prado, Jérôme

    2017-06-13

    Understanding the meaning of abstract mathematical symbols is a cornerstone of arithmetic learning in children. Studies have long focused on the role of spatial intuitions in the processing of numerals. However, it has been argued that such intuitions may also underlie symbols that convey fundamental arithmetic concepts, such as arithmetic operators. In the present cross-sectional study, we used fMRI to investigate how and when associations between arithmetic operators and brain regions processing spatial information emerge in children from 3 rd to 10 th grade. We found that the mere perception of a '+' sign elicited grade-related increases of spatial activity in the right hippocampus. That is, merely perceiving '+' signs - without any operands - elicited enhanced hippocampal activity after around 7 th grade (12-13 years old). In these children, hippocampal activity in response to a '+' sign was further correlated with the degree to which calculation performance was facilitated by the preview of that sign before an addition problem, an effect termed operator-priming. Grade-related increases of hippocampal spatial activity were operation-specific because they were not observed with '×' signs, which might evoke rote retrieval rather than numerical manipulation. Our study raises the possibility that hippocampal spatial mechanisms help build associations between some arithmetic operators and space throughout age and/or education. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  16. Neuroprotective effect of curcumin on hippocampal injury in 6-OHDA-induced Parkinson's disease rat.

    Science.gov (United States)

    Yang, Jiaqing; Song, Shilei; Li, Jian; Liang, Tao

    2014-06-01

    Clinically, Parkinson's disease (PD)-related neuronal lesions commonly occur. The purpose of this study is to investigate potential therapeutic effect of curcumin against hippocampal damage of 6-hydroxydopamine (6-OHDA)-PD rat model. These results showed that curcumin significantly increased the body weight of 6-OHDA-impaired rats (Pcurcumin-treated PD rats were effectively ameliorated as shown in open field test (Pcurcumin increased the contents of monoaminergic neurotransmitters (PCurcumin effectively alleviated the 6-OHDA-induced hippocampal damage as observed in hematoxylin-eosin (H&E) staining. Furthermore, curcumin obviously up-regulated hippocampal brain derived neurotrophic factor (BDNF), TrkB, phosphatidylinositide 3-kinases (PI3K) protein expressions, respectively as shown in Western blot analysis. These findings demonstrated that curcumin mediated the neuroprotection against 6-OHDA-induced hippocampus neurons in rats, which the underlying mechanism is involved in activating BDNF/TrkB-dependent pathway for promoting neural regeneration of hippocampal tissue. Copyright © 2014 Elsevier GmbH. All rights reserved.

  17. Childhood trauma and hippocampal and amygdalar volumes in first-episode psychosis.

    Science.gov (United States)

    Hoy, Katrina; Barrett, Suzanne; Shannon, Ciaran; Campbell, Clodagh; Watson, David; Rushe, Teresa; Shevlin, Mark; Bai, Feng; Cooper, Stephen; Mulholland, Ciaran

    2012-11-01

    A history of childhood trauma is common in individuals who later develop psychosis. Similar neuroanatomical abnormalities are observed in people who have been exposed to childhood trauma and people with psychosis. However, the relationship between childhood trauma and such abnormalities in psychosis has not been investigated. This study aimed to explore the association between the experience of childhood trauma and hippocampal and amygdalar volumes in a first-episode psychosis (FEP) population. The study employed an observational retrospective design. Twenty-one individuals, who had previously undergone magnetic resonance imaging procedures as part of the longitudinal Northern Ireland First-Episode Psychosis Study, completed measures assessing traumatic experiences and were included in the analysis. Data were subject to correlation analyses (r and r (pb)). Potential confounding variables (age at FEP and delay to scan from recruitment) were selected a priori for inclusion in multiple regression analyses. There was a high prevalence of lifetime (95%) and childhood (76%) trauma in the sample. The experience of childhood trauma was a significant predictor of left hippocampal volume, although age at FEP also significantly contributed to this model. There was no significant association between predictor variables and right hippocampal volume. The experience of childhood trauma was a significant predictor of right and total amygdalar volumes and the hippocampal/amygdalar complex volume as a whole. The findings indicate that childhood trauma is associated with neuroanatomical measures in FEP. Future research controlling for childhood traumatic experiences may contribute to explaining brain morphology in people with psychosis.

  18. Relationships between hippocampal activity and breathing patterns

    DEFF Research Database (Denmark)

    Harper, R M; Poe, G R; Rector, D M

    1998-01-01

    Single cell discharge, EEG activity, and optical changes accompanying alterations in breathing patterns, as well as the knowledge that respiratory musculature is heavily involved in movement and other behavioral acts, implicate hippocampal regions in some aspects of breathing control. The control...... is unlikely to reside in oscillatory breathing movements, because such patterns emerge in preparations retaining only the medulla (and perhaps only the spinal cord). However, momentary changes in breathing patterns induced by affect, startle, whole-body movement changes, or compensatory ventilatory changes...... of hippocampal contributions to breathing control should be viewed in the context that significant interactions exist between blood pressure changes and ventilation, and that modest breathing challenges, such as exposure to hypercapnia or to increased resistive loads, bring into action a vast array of brain...

  19. Hippocampal Processing of Ambiguity Enhances Fear Memory.

    Science.gov (United States)

    Amadi, Ugwechi; Lim, Seh Hong; Liu, Elizabeth; Baratta, Michael V; Goosens, Ki A

    2017-02-01

    Despite the ubiquitous use of Pavlovian fear conditioning as a model for fear learning, the highly predictable conditions used in the laboratory do not resemble real-world conditions, in which dangerous situations can lead to unpleasant outcomes in unpredictable ways. In the current experiments, we varied the timing of aversive events after predictive cues in rodents and discovered that temporal ambiguity of aversive events greatly enhances fear. During fear conditioning with unpredictably timed aversive events, pharmacological inactivation of the dorsal hippocampus or optogenetic silencing of cornu ammonis 1 cells during aversive negative prediction errors prevented this enhancement of fear without affecting fear learning for predictable events. Dorsal hippocampal inactivation also prevented ambiguity-related enhancement of fear during auditory fear conditioning under a partial-reinforcement schedule. These results reveal that information about the timing and occurrence of aversive events is rapidly acquired and that unexpectedly timed or omitted aversive events generate hippocampal signals to enhance fear learning.

  20. Hippocampal Neurogenesis, Depressive Disorders, and Antidepressant Therapy

    Directory of Open Access Journals (Sweden)

    Eleni Paizanis

    2007-01-01

    Full Text Available There is a growing body of evidence that neural stem cells reside in the adult central nervous system where neurogenesis occurs throughout lifespan. Neurogenesis concerns mainly two areas in the brain: the subgranular zone of the dentate gyrus in the hippocampus and the subventricular zone, where it is controlled by several trophic factors and neuroactive molecules. Neurogenesis is involved in processes such as learning and memory and accumulating evidence implicates hippocampal neurogenesis in the physiopathology of depression. We herein review experimental and clinical data demonstrating that stress and antidepressant treatments affect neurogenesis in opposite direction in rodents. In particular, the stimulation of hippocampal neurogenesis by all types of antidepressant drugs supports the view that neuroplastic phenomena are involved in the physiopathology of depression and underlie—at least partly—antidepressant therapy.

  1. A Compressed Sensing Perspective of Hippocampal Function

    Directory of Open Access Journals (Sweden)

    Panagiotis ePetrantonakis

    2014-08-01

    Full Text Available Hippocampus is one of the most important information processing units in the brain. Input from the cortex passes through convergent axon pathways to the downstream hippocampal subregions and, after being appropriately processed, is fanned out back to the cortex. Here, we review evidence of the hypothesis that information flow and processing in the hippocampus complies with the principles of Compressed Sensing (CS. The CS theory comprises a mathematical framework that describes how and under which conditions, restricted sampling of information (data set can lead to condensed, yet concise, forms of the initial, subsampled information entity (i.e. of the original data set. In this work, hippocampus related regions and their respective circuitry are presented as a CS-based system whose different components collaborate to realize efficient memory encoding and decoding processes. This proposition introduces a unifying mathematical framework for hippocampal function and opens new avenues for exploring coding and decoding strategies in the brain.

  2. Iron mediates N-methyl-D-aspartate receptor-dependent stimulation of calcium-induced pathways and hippocampal synaptic plasticity.

    Science.gov (United States)

    Muñoz, Pablo; Humeres, Alexis; Elgueta, Claudio; Kirkwood, Alfredo; Hidalgo, Cecilia; Núñez, Marco T

    2011-04-15

    Iron deficiency hinders hippocampus-dependent learning processes and impairs cognitive performance, but current knowledge on the molecular mechanisms underlying the unique role of iron in neuronal function is sparse. Here, we investigated the participation of iron on calcium signal generation and ERK1/2 stimulation induced by the glutamate agonist N-methyl-D-aspartate (NMDA), and the effects of iron addition/chelation on hippocampal basal synaptic transmission and long-term potentiation (LTP). Addition of NMDA to primary hippocampal cultures elicited persistent calcium signals that required functional NMDA receptors and were independent of calcium influx through L-type calcium channels or α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors; NMDA also promoted ERK1/2 phosphorylation and nuclear translocation. Iron chelation with desferrioxamine or inhibition of ryanodine receptor (RyR)-mediated calcium release with ryanodine-reduced calcium signal duration and prevented NMDA-induced ERK1/2 activation. Iron addition to hippocampal neurons readily increased the intracellular labile iron pool and stimulated reactive oxygen species production; the antioxidant N-acetylcysteine or the hydroxyl radical trapper MCI-186 prevented these responses. Iron addition to primary hippocampal cultures kept in calcium-free medium elicited calcium signals and stimulated ERK1/2 phosphorylation; RyR inhibition abolished these effects. Iron chelation decreased basal synaptic transmission in hippocampal slices, inhibited iron-induced synaptic stimulation, and impaired sustained LTP in hippocampal CA1 neurons induced by strong stimulation. In contrast, iron addition facilitated sustained LTP induction after suboptimal tetanic stimulation. Together, these results suggest that hippocampal neurons require iron to generate RyR-mediated calcium signals after NMDA receptor stimulation, which in turn promotes ERK1/2 activation, an essential step of sustained LTP.

  3. Sustained Na+/H+ exchanger activation promotes gliotransmitter release from reactive hippocampal astrocytes following oxygen-glucose deprivation.

    Directory of Open Access Journals (Sweden)

    Pelin Cengiz

    Full Text Available Hypoxia ischemia (HI-related brain injury is the major cause of long-term morbidity in neonates. One characteristic hallmark of neonatal HI is the development of reactive astrogliosis in the hippocampus. However, the impact of reactive astrogliosis in hippocampal damage after neonatal HI is not fully understood. In the current study, we investigated the role of Na(+/H(+ exchanger isoform 1 (NHE1 protein in mouse reactive hippocampal astrocyte function in an in vitro ischemia model (oxygen/glucose deprivation and reoxygenation, OGD/REOX. 2 h OGD significantly increased NHE1 protein expression and NHE1-mediated H(+ efflux in hippocampal astrocytes. NHE1 activity remained stimulated during 1-5 h REOX and returned to the basal level at 24 h REOX. NHE1 activation in hippocampal astrocytes resulted in intracellular Na(+ and Ca(2+ overload. The latter was mediated by reversal of Na(+/Ca(2+ exchange. Hippocampal astrocytes also exhibited a robust release of gliotransmitters (glutamate and pro-inflammatory cytokines IL-6 and TNFα during 1-24 h REOX. Interestingly, inhibition of NHE1 activity with its potent inhibitor HOE 642 not only reduced Na(+ overload but also gliotransmitter release from hippocampal astrocytes. The noncompetitive excitatory amino acid transporter inhibitor TBOA showed a similar effect on blocking the glutamate release. Taken together, we concluded that NHE1 plays an essential role in maintaining H(+ homeostasis in hippocampal astrocytes. Over-stimulation of NHE1 activity following in vitro ischemia disrupts Na(+ and Ca(2+ homeostasis, which reduces Na(+-dependent glutamate uptake and promotes release of glutamate and cytokines from reactive astrocytes. Therefore, blocking sustained NHE1 activation in reactive astrocytes may provide neuroprotection following HI.

  4. The impact of sharps injuries on student nurses: a systematic review.

    Science.gov (United States)

    Hambridge, Kevin; Nichols, Andrew; Endacott, Ruth

    2016-10-27

    The purpose of this review was to discover the impact of sharps injuries in the student nurse population. Much is known and reported about sharps injuries in registered nurses, but there has been a lack of published evidence regarding sharps injuries within the student nurse population. A systematic review of nursing, health and psychology databases was conducted. The limits set were publications between 1980 and 2014 in the English language. Studies were identified then, following a rigorous critical and quality appraisal with validated tools, were selected for the systematic review. A total of 40 articles met the inclusion criteria, reporting studies conducted in 18 countries. Psychological and physical impacts of sharps injuries in student nurses were reported, such as fear, anxiety and depression, although these impacts were not quantified using a validated instrument. The impact of sharps injuries can be severe, both psychological and physical. This systematic review shows that further research is needed into this, especially in under-researched areas such as the UK, to establish the impact of sharps injuries within this population. Further research would also aid the education and prevention of this harmful problem. The review also emphasises the psychological issues relating to sharps injuries, the impact these can have on individuals and the support and counselling that student nurses require after injury. These findings highlight the potential psychological issues that can result from sharps injuries in this population.

  5. On the sharp front-type solution of the Nagumo equation with ...

    Indian Academy of Sciences (India)

    One of the methods is to solve the travelling wave equations and compute an exact solution which describes the sharp travelling wavefront. The second method is to solve numer- ically an initial-moving boundary-value problem for the partial differential equation and obtain an approximation for this sharp front-type solution.

  6. Stability analysis of sharp-boundary Vlasov-fluid screw-pinch equilibria

    International Nuclear Information System (INIS)

    Lewis, H.R.; Turner, L.

    1975-01-01

    The Vlasov-fluid model is being used to study the linear stability of sharp-boundary screw pinches numerically. The numerical method appears to work well, and some preliminary results are reported. The sharp-boundary calculation is useful for gaining insight and for comparing with known MHD results. (auth)

  7. Investigation of the Electrohydraulic Forming Process with respect to the Design of Sharp Edged Contours

    OpenAIRE

    Beerwald, C.; Homberg, W.; Pröbsting, A.

    2010-01-01

    The overcoming of design constraints with respect to forming of sharply contoured sheet metal workpieces made of high strength steel or other materials which are difficult to form is an important aspect in sheet metal part production. One interesting solution to extend existing forming limits can be the use of electrohydraulic forming as single forming operation or in combination with quasi-static hydroforming. Apart from promising results regarding the feasible part geometries this process a...

  8. NMR assignments of SPOC domain of the human transcriptional corepressor SHARP in complex with a C-terminal SMRT peptide.

    Science.gov (United States)

    Mikami, Suzuka; Kanaba, Teppei; Ito, Yutaka; Mishima, Masaki

    2013-10-01

    The transcriptional corepressor SMRT/HDAC1-associated repressor protein (SHARP) recruits histone deacetylases. Human SHARP protein is thought to function in processes involving steroid hormone responses and the Notch signaling pathway. SHARP consists of RNA recognition motifs (RRMs) in the N-terminal region and the spen paralog and ortholog C-terminal (SPOC) domain in the C-terminal region. It is known that the SPOC domain binds the LSD motif in the C-terminal tail of corepressors silencing mediator for retinoid and thyroid receptor (SMRT)/nuclear receptor corepressor (NcoR). We are interested in delineating the mechanism by which the SPOC domain recognizes the LSD motif of the C-terminal tail of SMRT/NcoR. To this end, we are investigating the tertiary structure of the SPOC/SMRT peptide using NMR. Herein, we report on the (1)H, (13)C and (15)N resonance assignments of the SPOC domain in complex with a SMRT peptide, which contributes towards a structural understanding of the SPOC/SMRT peptide and its molecular recognition.

  9. Maintaining knife sharpness in industrial meat cutting: A matter of knife or meat cutter ability.

    Science.gov (United States)

    Karltun, J; Vogel, K; Bergstrand, M; Eklund, J

    2016-09-01

    Knife sharpness is imperative in meat cutting. The aim of this study was to compare the impact of knife blade steel quality with meat cutters' individual ability to maintain the cutting edge sharp in an industrial production setting. Twelve meat cutters in two different companies using three different knives during normal production were studied in this quasi-experimental study. Methods included were measuring knife cutting force before and after knife use, time knives were used, ratings of sharpness and discomfort and interviews. Results showed that the meat cutters' skill of maintaining sharpness during work had a much larger effect on knife sharpness during work than the knife steel differences. The ability was also related to feelings of discomfort and to physical exertion. It was found that meat cutters using more knives were more likely to suffer from discomfort in the upper limbs, which is a risk for developing MSD. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Plasmonic black metals via radiation absorption by two-dimensional arrays of ultra-sharp convex grooves

    DEFF Research Database (Denmark)

    Beermann, Jonas; Eriksen, René L.; Stær, Tobias Holmgaard

    2014-01-01

    Plasmonic black surfaces formed by two-dimensional arrays of ultra-sharp convex metal grooves, in which the incident radiation is converted into gap surface plasmon polaritons (GSPPs) and subsequently absorbed (via adiabatic nanofocusing), are fabricated and investigated experimentally for gold......%, averaged over the investigated wavelength range of 400-985 nm. The highest averaged absorption level (similar to 97%) is achieved with 250-nm-period arrays in palladium that also has the highest melting temperature(similar to 15526 degrees C), promising thereby potential applications for broadband...

  11. Insulin stimulates the expression of the SHARP-1 gene via multiple signaling pathways.

    Science.gov (United States)

    Takagi, K; Asano, K; Haneishi, A; Ono, M; Komatsu, Y; Yamamoto, T; Tanaka, T; Ueno, H; Ogawa, W; Tomita, K; Noguchi, T; Yamada, K

    2014-06-01

    The rat enhancer of split- and hairy-related protein-1 (SHARP-1) is a basic helix-loop-helix transcription factor. An issue of whether SHARP-1 is an insulin-inducible transcription factor was examined. Insulin rapidly increased the level of SHARP-1 mRNA both in vivo and in vitro. Then, signaling pathways involved with the increase of SHARP-1 mRNA by insulin were determined in H4IIE rat hepatoma cells. Pretreatments with LY294002, wortmannin, and staurosporine completely blocked the induction effect, suggesting the involvement of both phosphoinositide 3-kinase (PI 3-K) and protein kinase C (PKC) pathways. In fact, overexpression of a dominant negative form of atypical protein kinase C lambda (aPKCλ) significantly decreased the induction of the SHARP-1 mRNA. In addition, inhibitors for the small GTPase Rac or Jun N-terminal kinase (JNK) also blocked the induction of SHARP-1 mRNA by insulin. Overexpression of a dominant negative form of Rac1 prevented the activation by insulin. Furthermore, actinomycin D and cycloheximide completely blocked the induction of SHARP-1 mRNA by insulin. Finally, when a SHARP-1 expression plasmid was transiently transfected with various reporter plasmids into H4IIE cells, the promoter activity of PEPCK reporter plasmid was specifically decreased. Thus, we conclude that insulin induces the SHARP-1 gene expression at the transcription level via a both PI 3-K/aPKCλ/JNK- and a PI 3-K/Rac/JNK-signaling pathway; protein synthesis is required for this induction; and that SHARP-1 is a potential repressor of the PEPCK gene expression. © Georg Thieme Verlag KG Stuttgart · New York.

  12. Impaired neuronal maturation of hippocampal neural progenitor cells in mice lacking CRAF.

    Science.gov (United States)

    Pfeiffer, Verena; Götz, Rudolf; Camarero, Guadelupe; Heinsen, Helmut; Blum, Robert; Rapp, Ulf Rüdiger

    2018-01-01

    RAF kinases are major constituents of the mitogen activated signaling pathway, regulating cell proliferation, differentiation and cell survival of many cell types, including neurons. In mammals, the family of RAF proteins consists of three members, ARAF, BRAF, and CRAF. Ablation of CRAF kinase in inbred mouse strains causes major developmental defects during fetal growth and embryonic or perinatal lethality. Heterozygous germline mutations in CRAF result in Noonan syndrome, which is characterized by neurocognitive impairment that may involve hippocampal physiology. The role of CRAF signaling during hippocampal development and generation of new postnatal hippocampal granule neurons has not been examined and may provide novel insight into the cause of hippocampal dysfunction in Noonan syndrome. In this study, by crossing CRAF-deficiency to CD-1 outbred mice, a CRAF mouse model was established which enabled us to investigate the interplay of neural progenitor proliferation and postmitotic differentiation during adult neurogenesis in the hippocampus. Albeit the general morphology of the hippocampus was unchanged, CRAF-deficient mice displayed smaller granule cell layer (GCL) volume at postnatal day 30 (P30). In CRAF-deficient mice a substantial number of abnormal, chromophilic, fast dividing cells were found in the subgranular zone (SGZ) and hilus of the dentate gyrus (DG), indicating that CRAF signaling contributes to hippocampal neural progenitor proliferation. CRAF-deficient neural progenitor cells showed an increased cell death rate and reduced neuronal maturation. These results indicate that CRAF function affects postmitotic neural cell differentiation and points to a critical role of CRAF-dependent growth factor signaling pathway in the postmitotic development of adult-born neurons.

  13. Agmatine abolishes restraint stress-induced depressive-like behavior and hippocampal antioxidant imbalance in mice.

    Science.gov (United States)

    Freitas, Andiara E; Bettio, Luis E B; Neis, Vivian B; Santos, Danúbia B; Ribeiro, Camille M; Rosa, Priscila B; Farina, Marcelo; Rodrigues, Ana Lúcia S

    2014-04-03

    Agmatine has been recently emerged as a novel candidate to assist the conventional pharmacotherapy of depression. The acute restraint stress (ARS) is an unavoidable stress situation that may cause depressive-like behavior in rodents. In this study, we investigated the potential antidepressant-like effect of agmatine (10mg/kg, administered acutely by oral route) in the forced swimming test (FST) in non-stressed mice, as well as its ability to abolish the depressive-like behavior and hippocampal antioxidant imbalance induced by ARS. Agmatine reduced the immobility time in the mouse FST (1-100mg/kg) in non-stressed mice. ARS caused an increase in the immobility time in the FST, indicative of a depressive-like behavior, as well as hippocampal lipid peroxidation, and an increase in the activity of hippocampal superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GR) activities, reduced catalase (CAT) activity and increased SOD/CAT ratio, an index of pro-oxidative conditions. Agmatine was effective to abolish the depressive-like behavior induced by ARS and to prevent the ARS-induced lipid peroxidation and changes in SOD, GR and CAT activities and in SOD/CAT activity ratio. Hippocampal levels of reduced glutathione (GSH) were not altered by any experimental condition. In conclusion, the present study shows that agmatine was able to abrogate the ARS-induced depressive-like behavior and the associated redox hippocampal imbalance observed in stressed restraint mice, suggesting that its antidepressant-like effect may be dependent on its ability to maintain the pro-/anti-oxidative homeostasis in the hippocampus. Copyright © 2013 Elsevier Inc. All rights reserved.

  14. Maternal vitamin C deficiency during pregnancy persistently impairs hippocampal neurogenesis in offspring of guinea pigs.

    Directory of Open Access Journals (Sweden)

    Pernille Tveden-Nyborg

    Full Text Available While having the highest vitamin C (VitC concentrations in the body, specific functions of VitC in the brain have only recently been acknowledged. We have shown that postnatal VitC deficiency in guinea pigs causes impairment of hippocampal memory function and leads to 30% less neurons. This study investigates how prenatal VitC deficiency affects postnatal hippocampal development and if any such effect can be reversed by postnatal VitC repletion. Eighty pregnant Dunkin Hartley guinea pig dams were randomized into weight stratified groups receiving High (900 mg or Low (100 mg VitC per kg diet. Newborn pups (n = 157 were randomized into a total of four postnatal feeding regimens: High/High (Control; High/Low (Depleted, Low/Low (Deficient; and Low/High (Repleted. Proliferation and migration of newborn cells in the dentate gyrus was assessed by BrdU labeling and hippocampal volumes were determined by stereology. Prenatal VitC deficiency resulted in a significant reduction in postnatal hippocampal volume (P<0.001 which was not reversed by postnatal repletion. There was no difference in postnatal cellular proliferation and survival rates in the hippocampus between dietary groups, however, migration of newborn cells into the granular layer of the hippocampus dentate gyrus was significantly reduced in prenatally deficient animals (P<0.01. We conclude that a prenatal VitC deficiency in guinea pigs leads to persistent impairment of postnatal hippocampal development which is not alleviated by postnatal repletion. Our findings place attention on a yet unrecognized consequence of marginal VitC deficiency during pregnancy.

  15. Mitogen-Activated Protein Kinase Phosphatase-2 Deletion Impairs Synaptic Plasticity and Hippocampal-Dependent Memory.

    Science.gov (United States)

    Abdul Rahman, Nor Zaihana; Greenwood, Sam M; Brett, Ros R; Tossell, Kyoko; Ungless, Mark A; Plevin, Robin; Bushell, Trevor J

    2016-02-24

    Mitogen-activated protein kinases (MAPKs) regulate brain function and their dysfunction is implicated in a number of brain disorders, including Alzheimer's disease. Thus, there is great interest in understanding the signaling systems that control MAPK function. One family of proteins that contribute to this process, the mitogen-activated protein kinase phosphatases (MKPs), directly inactivate MAPKs through dephosphorylation. Recent studies have identified novel functions of MKPs in development, the immune system, and cancer. However, a significant gap in our knowledge remains in relation to their role in brain functioning. Here, using transgenic mice where the Dusp4 gene encoding MKP-2 has been knocked out (MKP-2(-/-) mice), we show that long-term potentiation is impaired in MKP-2(-/-) mice compared with MKP-2(+/+) controls whereas neuronal excitability, evoked synaptic transmission, and paired-pulse facilitation remain unaltered. Furthermore, spontaneous EPSC (sEPSC) frequency was increased in acute slices and primary hippocampal cultures prepared from MKP-2(-/-) mice with no effect on EPSC amplitude observed. An increase in synapse number was evident in primary hippocampal cultures, which may account for the increase in sEPSC frequency. In addition, no change in ERK activity was detected in both brain tissue and primary hippocampal cultures, suggesting that the effects of MKP-2 deletion were MAPK independent. Consistent with these alterations in hippocampal function, MKP-2(-/-) mice show deficits in spatial reference and working memory when investigated using the Morris water maze. These data show that MKP-2 plays a role in regulating hippocampal function and that this effect may be independent of MAPK signaling. Copyright © 2016 Abdul Rahman et al.

  16. Beyond dizziness: virtual navigation, spatial anxiety and hippocampal volume in bilateral vestibulopathy

    Directory of Open Access Journals (Sweden)

    Olympia eKremmyda

    2016-03-01

    Full Text Available Bilateral vestibulopathy (BVP is defined as the impairment or loss of function of either the labyrinths or the eighth nerves. Patients with total BVP due to bilateral vestibular nerve section exhibit difficulties in spatial memory and navigation and show a loss of hippocampal volume. In clinical practice, most patients do not have a complete loss of function but rather an asymmetrical residual functioning of the vestibular system. The purpose of the current study was to investigate navigational ability and hippocampal atrophy in BVP patients with residual vestibular function. Fifteen patients with BVP and a group of age- and gender- matched healthy controls were examined. Self-reported questionnaires on spatial anxiety and wayfinding were used to assess the applied strategy of wayfinding and quality of life. Spatial memory and navigation were tested directly using a virtual Morris Water Maze Task. The hippocampal volume of these two groups was evaluated by voxel-based morphometry. In the patients, the questionnaire showed a higher spatial anxiety and the Morris Water Maze Task a delayed spatial learning performance. MRI revealed a significant decrease in the gray matter mid-hippocampal volume (Left: p = 0.006, Z = 4.58, Right: p < 0.001, Z = 3.63 and posterior parahippocampal volume (Right: p = 0.005, Z = 4.65, Left: p < 0.001, Z = 3.87 compared to those of healthy controls. In addition, a decrease in hippocampal formation volume correlated with a more dominant route-finding strategy. Our current findings demonstrate that even partial bilateral vestibular loss leads to anatomical and functional

  17. MicroRNA-132 protects hippocampal neurons against oxygen-glucose deprivation-induced apoptosis.

    Science.gov (United States)

    Sun, Zu-Zhen; Lv, Zhan-Yun; Tian, Wen-Jing; Yang, Yan

    2017-09-01

    Hypoxic-ischemic brain injury (HIBI) results in death or long-term neurologic impairment in both adults and children. In this study, we investigated the effects of microRNA-132 (miR-132) dysregulation on oxygen-glucose deprivation (OGD)-induced apoptosis in fetal rat hippocampal neurons, in order to reveal the therapeutic potential of miR-132 on HIBI. MiR-132 dysregulation was induced prior to OGD exposure by transfection of primary fetal rat hippocampal neurons with miR-132 mimic or miR-132 inhibitor. The effects of miR-132 overexpression and suppression on OGD-stimulated hippocampal neurons were evaluated by detection of cell viability, apoptotic cells rate, and the expression of apoptosis-related proteins. Besides, TargetScan database and dual luciferase activity assay were used to seek a target gene of miR-132. As a result, miR-132 was highly expressed in hippocampal neurons following 2 h of OGD exposure. MiR-132 overexpression significantly increased OGD-diminished cell viability and reduced OGD-induced apoptosis at 12, 24, and 48 h post-OGD. MiR-132 overexpression significantly down-regulated the expressions of Bax, cytochrome c, and caspase-9, but up-regulated BCl-2. Caspase-3 activity was also significantly decreased by miR-132 overexpression. Furthermore, FOXO3 was a direct target of miR-132, and it was negatively regulated by miR-132. To conclude, our results provide evidence that miR-132 protects hippocampal neurons against OGD injury by inhibiting apoptosis.

  18. MDMA enhances hippocampal-dependent learning and memory under restrictive conditions, and modifies hippocampal spine density.

    Science.gov (United States)

    Abad, Sònia; Fole, Alberto; del Olmo, Nuria; Pubill, David; Pallàs, Mercè; Junyent, Fèlix; Camarasa, Jorge; Camins, Antonio; Escubedo, Elena

    2014-03-01

    Addictive drugs produce forms of structural plasticity in the nucleus accumbens and prefrontal cortex. The aim of this study was to investigate the impact of chronic MDMA exposure on pyramidal neurons in the CA1 region of hippocampus and drug-related spatial learning and memory changes. Adolescent rats were exposed to saline or MDMA in a regime that mimicked chronic administration. One week later, when acquisition or reference memory was evaluated in a standard Morris water maze (MWM), no differences were obtained between groups. However, MDMA-exposed animals performed better when the MWM was implemented under more difficult conditions. Animals of MDMA group were less anxious and were more prepared to take risks, as in the open field test they ventured more frequently into the central area. We have demonstrated that MDMA caused an increase in brain-derived neurotrophic factor (BDNF) expression. When spine density was evaluated, MDMA-treated rats presented a reduced density when compared with saline, but overall, training increased the total number of spines, concluding that in MDMA-group, training prevented a reduction in spine density or induced its recovery. This study provides support for the conclusion that binge administration of MDMA, known to be associated to neurotoxic damage of hippocampal serotonergic terminals, increases BDNF expression and stimulates synaptic plasticity when associated with training. In these conditions, adolescent rats perform better in a more difficult water maze task under restricted conditions of learning and memory. The effect on this task could be modulated by other behavioural changes provoked by MDMA.

  19. CX3CR1 deficiency alters hippocampal-dependent plasticity phenomena blunting the effects of enriched environment

    Directory of Open Access Journals (Sweden)

    Laura eMaggi

    2011-10-01

    Full Text Available In recent years several evidence demonstrated that some features of hippocampal biology, like neurogenesis, synaptic transmission, learning and memory performances are deeply modulated by social, motor and sensorial experiences. Fractalkine/CX3CL1 is a transmembrane chemokine abundantly expressed in the brain by neurons, where it modulates glutamatergic transmission and long-term plasticity processes regulating the intercellular communication between glia and neurons, being its specific receptor CX3CR1 expressed by microglia. In this paper we investigated the role of CX3CL1/CX3CR1 signaling on experience-dependent hippocampal plasticity processes. At this aim wt and CX3CR1GFP/GFP mice were exposed to long-lasting-enriched environment (EE and the effects on hippocampal functions were studied by electrophysiological recordings of long-term potentiation (LTP of synaptic activity, behavioral tests of learning and memory in the Morris water maze paradigm and analysis of neurogenesis in the subgranular zone of the dentate gyrus (DG.We found that CX3CR1 deficiency increases hippocampal plasticity and spatial memory blunting the potentiating effects of EE. In contrast, exposure to EE increased the number and migration of neural progenitors in the DG of both wt and CX3CR1GFP/GFP mice. These data indicate that CX3CL1/CX3CR1-mediated signaling is crucial for a normal experience-dependent modulation of hippocampal functions.

  20. Electroacupuncture Improved Hippocampal Neurogenesis following Traumatic Brain Injury in Mice through Inhibition of TLR4 Signaling Pathway

    Directory of Open Access Journals (Sweden)

    Yuqin Ye

    2017-01-01

    Full Text Available The protective role of electroacupuncture (EA treatment in diverse neurological diseases such as ischemic stroke is well acknowledged. However, whether and how EA act on hippocampal neurogenesis following traumatic brain injury (TBI remains poorly understood. This study aims to investigate the effect of EA on hippocampal neurogenesis and neurological functions, as well as its underlying association with toll-like receptor 4 (TLR4 signaling in TBI mice. BrdU/NeuN immunofluorescence was performed to label newborn neurons in the hippocampus after EA treatment. Water maze test and neurological severity score were used to evaluate neurological function posttrauma. The hippocampal level of TLR4 and downstream molecules and inflammatory cytokines were, respectively, detected by Western blot and enzyme-linked immunosorbent assay. EA enhanced hippocampal neurogenesis and inhibited TLR4 expression at 21, 28, and 35 days after TBI, but the beneficial effects of EA on posttraumatic neurogenesis and neurological functions were attenuated by lipopolysaccharide-induced TLR4 activation. In addition, EA exerted an inhibitory effect on both TLR4/Myd88/NF-κB and TLR4/TRIF/NF-κB pathways, as well as the inflammatory cytokine expression in the hippocampus following TBI. In conclusion, EA promoted hippocampal neurogenesis and neurological recovery through inhibition of TLR4 signaling pathway posttrauma, which may be a potential approach to improve the outcome of TBI.

  1. Automatic planning on hippocampal avoidance whole-brain radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shuo, E-mail: shuo0220@gmail.com; Zheng, Dandan; Zhang, Chi; Ma, Rongtao; Bennion, Nathan R.; Lei, Yu; Zhu, Xiaofeng; Enke, Charles A.; Zhou, Sumin

    2017-04-01

    expedited quality planning achieved by Auto-Planning (AP) may facilitate protocol enrollment of patients to further investigate the hippocampal-sparing effect and be used to ensure timely start of palliative treatment in future clinical practice.

  2. Automatic planning on hippocampal avoidance whole-brain radiotherapy

    International Nuclear Information System (INIS)

    Wang, Shuo; Zheng, Dandan; Zhang, Chi; Ma, Rongtao; Bennion, Nathan R.; Lei, Yu; Zhu, Xiaofeng; Enke, Charles A.; Zhou, Sumin

    2017-01-01

    Auto-Planning (AP) may facilitate protocol enrollment of patients to further investigate the hippocampal-sparing effect and be used to ensure timely start of palliative treatment in future clinical practice.

  3. BDNF val(66)met affects hippocampal volume and emotion-related hippocampal memory activity

    NARCIS (Netherlands)

    Molendijk, M. L.; van Tol, M-J; Penninx, B. W. J. H.; van der Wee, N. J. A.; Aleman, A.; Veltman, D. J.; Spinhoven, P.; Elzinga, B. M.

    2012-01-01

    The val(66)met polymorphism on the BDNF gene has been reported to explain individual differences in hippocampal volume and memory-related activity. These findings, however, have not been replicated consistently and no studies to date controlled for the potentially confounding impact of early life

  4. Hippocampal EEG and behaviour in dog. I. Hippocampal EEG correlates of gross motor behaviour

    NARCIS (Netherlands)

    Arnolds, D.E.A.T.; Lopes da Silva, F.H.; Aitink, J.W.; Kamp, A.

    It was shown that rewarding spectral shifts (i.e. increase in amplitude or peak frequency of the hippocampal EEG) causes a solitary dog to show increased motor behaviour. Rewarded spectral shifts concurred with a variety of behavioural transitions. It was found that statistically significant

  5. Preservation of hippocampal neuron numbers and hippocampal subfield volumes in behaviorally characterized aged tree shrews

    NARCIS (Netherlands)

    Keuker, J.I.H.; de Biurrun, G.; Luiten, P.G.M.; Fuchs, E.

    2004-01-01

    Aging is associated with a decreased ability to store and retrieve information. The hippocampal formation plays a critical role in such memory processes, and its integrity is affected during normal aging. We used tree shrews (Tupaia belangeri) as an animal model of aging, because in many

  6. Edge Sharpness Assessment by Parametric Modeling: Application to Magnetic Resonance Imaging.

    Science.gov (United States)

    Ahmad, R; Ding, Y; Simonetti, O P

    2015-05-01

    In biomedical imaging, edge sharpness is an important yet often overlooked image quality metric. In this work, a semi-automatic method to quantify edge sharpness in the presence of significant noise is presented with application to magnetic resonance imaging (MRI). The method is based on parametric modeling of image edges. First, an edge map is automatically generated and one or more edges-of-interest (EOI) are manually selected using graphical user interface. Multiple exclusion criteria are then enforced to eliminate edge pixels that are potentially not suitable for sharpness assessment. Second, at each pixel of the EOI, an image intensity profile is read along a small line segment that runs locally normal to the EOI. Third, the profiles corresponding to all EOI pixels are individually fitted with a sigmoid function characterized by four parameters, including one that represents edge sharpness. Last, the distribution of the sharpness parameter is used to quantify edge sharpness. For validation, the method is applied to simulated data as well as MRI data from both phantom imaging and cine imaging experiments. This method allows for fast, quantitative evaluation of edge sharpness even in images with poor signal-to-noise ratio. Although the utility of this method is demonstrated for MRI, it can be adapted for other medical imaging applications.

  7. Evaluation of Effects of Warning Sign Position on Driving Behavior in Horizontal Sharp Curves

    Directory of Open Access Journals (Sweden)

    Xiao-hua Zhao

    2015-02-01

    Full Text Available In present time, the guidelines on warning sign position in the China National Standard lack detailed and standard regulations of placing warning signs on sharp curves, which may cause road safety problems. Therefore, this paper briefly discussed how to optimize the position of a warning sign on a sharp curve through a driving simulator experiment. This study concluded that a warning sign placed at different positions prior to a sharp curve will have different influence ranges for drivers approaching and negotiating the curve. Meanwhile, different positions of a warning sign imposed different effect obviously on the adjustment of vehicle's lane position on sharp curves with the same radius, especially at the midpoint of a sharp curve. The evaluation results of five positions (0 m, 50 m, 100 m, 200 m, and 400 m in advance showed that only when the warning signs were placed 100 m or 200 m prior to sharp curves, can they achieve positive influence on driving behavior. On this basis, the authors look forward to providing rationalization proposals in selecting the best position of a warning sign on a sharp curve for the engineering implementation and national standard.

  8. Super-Sharp Radio 'Eye' Remeasuring the Universe

    Science.gov (United States)

    2011-02-01

    Using the super-sharp radio "vision" of astronomy's most precise telescope, scientists have extended a directly-measured "yardstick" three times farther into the cosmos than ever before, an achievement with important implications for numerous areas of astrophysics, including determining the nature of Dark Energy, which constitutes 70 percent of the Universe. The continent-wide Very Long Baseline Array (VLBA) also is redrawing the map of our home Galaxy and is poised to yield tantalizing new information about extrasolar planets, among many other cutting-edge research projects. The VLBA provides the greatest ability to see fine detail, called resolving power, of any telescope in the world. It can produce images hundreds of times more detailed than those from the Hubble Space Telescope -- power equivalent to sitting in New York and reading a newspaper in Los Angeles. This power allows astronomers to make precise cosmic measurements with far-ranging implications for research within our own Galaxy and far beyond. New measurements with the VLBA have placed a galaxy called NGC 6264 at a distance of 450 million light-years from Earth, with an uncertainty of no more than 9 percent. This is the farthest distance ever directly measured, surpassing a measurement of 160 million light-years to another galaxy in 2009. Previously, distances beyond our own Galaxy have been estimated through indirect methods. "Our direct, geometric measurements are independent of the assumptions and complications inherent in other techniques," said James Braatz, of the National Radio Astronomy Observatory (NRAO), who worked with Cheng-Yu Kuo, of the University of Virginia and NRAO. Fine-tuning the measurement of ever-greater distances is vital to determining the expansion rate of the Universe, which helps theorists narrow down possible explanations for the nature of Dark Energy. Different models of Dark Energy predict different values for the expansion rate, known as the Hubble Constant. "Solving

  9. Oral administration of fisetin promotes the induction of hippocampal long-term potentiation in vivo.

    Science.gov (United States)

    He, Wen-Bin; Abe, Kazuho; Akaishi, Tatsuhiro

    2018-01-01

    To explore memory enhancing effect of the flavonoid fisetin, we investigated the effect of oral administration of flavonoids on the induction of long-term potentiation (LTP) at hippocampal CA1 synapses of anesthetized rats. Among four flavonoids (fisetin, quercetin, luteolin and myricetin) tested, only fisetin significantly facilitated the induction of hippocampal LTP. The effect of oral fisetin was abolished by intracerebroventricular injection of U0126, an agent that was previously found to inhibit its effect in hippocampal slices in vitro. These results suggest that orally administered fisetin crosses the blood-brain barrier and promotes synaptic functions in the hippocampus. Copyright © 2018 The Authors. Production and hosting by Elsevier B.V. All rights reserved.

  10. Genetic deletion of melanin-concentrating hormone neurons impairs hippocampal short-term synaptic plasticity and hippocampal-dependent forms of short-term memory.

    Science.gov (United States)

    Le Barillier, Léa; Léger, Lucienne; Luppi, Pierre-Hervé; Fort, Patrice; Malleret, Gaël; Salin, Paul-Antoine

    2015-11-01

    The cognitive role of melanin-concentrating hormone (MCH) neurons, a neuronal population located in the mammalian postero-lateral hypothalamus sending projections to all cortical areas, remains poorly understood. Mainly activated during paradoxical sleep (PS), MCH neurons have been implicated in sleep regulation. The genetic deletion of the only known MCH receptor in rodent leads to an impairment of hippocampal dependent forms of memory and to an alteration of hippocampal long-term synaptic plasticity. By using MCH/ataxin3 mice, a genetic model characterized by a selective deletion of MCH neurons in the adult, we investigated the role of MCH neurons in hippocampal synaptic plasticity and hippocampal-dependent forms of memory. MCH/ataxin3 mice exhibited a deficit in the early part of both long-term potentiation and depression in the CA1 area of the hippocampus. Post-tetanic potentiation (PTP) was diminished while synaptic depression induced by repetitive stimulation was enhanced suggesting an alteration of pre-synaptic forms of short-term plasticity in these mice. Behaviorally, MCH/ataxin3 mice spent more time and showed a higher level of hesitation as compared to their controls in performing a short-term memory T-maze task, displayed retardation in acquiring a reference memory task in a Morris water maze, and showed a habituation deficit in an open field task. Deletion of MCH neurons could thus alter spatial short-term memory by impairing short-term plasticity in the hippocampus. Altogether, these findings could provide a cellular mechanism by which PS may facilitate memory encoding. Via MCH neuron activation, PS could prepare the day's learning by increasing and modulating short-term synaptic plasticity in the hippocampus. © 2015 Wiley Periodicals, Inc.

  11. Sharp vorticity gradients in two-dimensional turbulence and the energy spectrum

    DEFF Research Database (Denmark)

    Kuznetsov, E.A.; Naulin, Volker; Nielsen, Anders Henry

    2010-01-01

    Formation of sharp vorticity gradients in two-dimensional (2D) hydrodynamic turbulence and their influence on the turbulent spectra are considered. The analog of the vortex line representation as a transformation to the curvilinear system of coordinates moving together with the di-vorticity lines...... is developed and compressibility of this mapping appears as the main reason for the formation of the sharp vorticity gradients at high Reynolds numbers. In the case of strong anisotropy the sharp vorticity gradients can generate spectra which fall off as k −3 at large k, which appear to take the same form...

  12. Testing the efficiency of the wine market using unit root tests with sharp and smooth breaks

    Directory of Open Access Journals (Sweden)

    Elie Bouri

    2017-12-01

    Full Text Available This paper examines the efficient market hypothesis for the wine market using a novel unit root test while accounting for sharp shifts and smooth breaks in the monthly data. We find evidence of structural shifts and nonlinearity in the wine indices. Contrary to the results from conventional linear unit root tests, when we account for sharp shifts and smooth breaks, the unit root null for each of the wine indices has been rejected. Overall, our results suggest that the wine market is inefficient when we incorporate breaks. We provide some practical and policy implications of our findings. Keywords: Wine market, Efficiency, Sharp and smooth breaks, Unit root tests

  13. Subcellular Localization of Patched and Smoothened, the Receptors for Sonic Hedgehog Signaling, in the Hippocampal Neuron

    OpenAIRE

    Petralia, Ronald S.; Schwartz, Catherine M.; Wang, Ya-Xian; Mattson, Mark P.; Yao, Pamela J.

    2011-01-01

    Cumulative evidence suggests that, aside from patterning the embryonic neural tube, Sonic hedgehog (Shh) signaling plays important roles in the mature nervous system. In this study, we investigate the expression and localization of the Shh signaling receptors, Patched (Ptch) and Smoothened (Smo), in the hippocampal neurons of young and mature rats. Reverse transcriptase-polymerase chain reaction and immunoblotting analyses show that the expression of Ptch and Smo remains at a moderate level i...

  14. Neuroprotective effects of ginsenoside Rg1 against oxygen–glucose deprivation in cultured hippocampal neurons

    OpenAIRE

    He, Qing; Sun, Jianguo; Wang, Qin; Wang, Wei; He, Bin

    2014-01-01

    Background: Ginsenoside Rg1 (Rg1) is believed to be one of the main active principles in ginseng, a traditional Chinese medicine extensively used to enhance stamina and deal with fatigue as well as physical stress. It has been reported that Rg1 performs multiple biological activities, including neuroprotective activity. In this study, we investigated the efficacy of ginsenoside Rg1 on ischemia–reperfusion injury in cultured hippocampal cells and also probed its possible mechanisms. Methods...

  15. Hippocampal “Time Cells”: Time versus Path Integration

    Science.gov (United States)

    Kraus, Benjamin J.; Robinson, Robert J.; White, John A.; Eichenbaum, Howard; Hasselmo, Michael E.

    2014-01-01

    SUMMARY Recent studies have reported the existence of hippocampal “time cells,” neurons that fire at particular moments during periods when behavior and location are relatively constant. However, an alternative explanation of apparent time coding is that hippocampal neurons “path integrate” to encode the distance an animal has traveled. Here, we examined hippocampal neuronal firing patterns as rats ran in place on a treadmill, thus “clamping” behavior and location, while we varied the treadmill speed to distinguish time elapsed from distance traveled. Hippocampal neurons were strongly influenced by time and distance, and less so by minor variations in location. Furthermore, the activity of different neurons reflected integration over time and distance to varying extents, with most neurons strongly influenced by both factors and some significantly influenced by only time or distance. Thus, hippocampal neuronal networks captured both the organization of time and distance in a situation where these dimensions dominated an ongoing experience. PMID:23707613

  16. Hippocampal sclerosis in children younger than 2 years

    Energy Technology Data Exchange (ETDEWEB)

    Kadom, Nadja [Children' s National Medical Center, Department of Diagnostic Imaging and Radiology, Washington, DC (United States); Tsuchida, Tammy; Gaillard, William D. [Children' s National Medical Center, Department of Neurology, Washington, DC (United States)

    2011-10-15

    Hippocampal sclerosis (HS) is rarely considered as a diagnosis in children younger than 2 years. To describe imaging features in conjunction with clinical information in patients with hippocampal sclerosis who are younger than 2 years. We retrospectively reviewed MR brain imaging and clinical information in five children in whom the diagnosis of HS was made both clinically and by MRI prior to 2 years of age. Imaging features establishing the diagnosis of hippocampal sclerosis were bright T2 signal and volume loss, while the internal architecture of the hippocampal formation was preserved in almost all children. Clinically, all children had an infectious trigger. It is necessary for radiologists to consider HS in children with certain clinical features to plan an MRI protocol that is appropriate for detection of hippocampal pathology. (orig.)

  17. Hippocampal sclerosis in children younger than 2 years

    International Nuclear Information System (INIS)

    Kadom, Nadja; Tsuchida, Tammy; Gaillard, William D.

    2011-01-01

    Hippocampal sclerosis (HS) is rarely considered as a diagnosis in children younger than 2 years. To describe imaging features in conjunction with clinical information in patients with hippocampal sclerosis who are younger than 2 years. We retrospectively reviewed MR brain imaging and clinical information in five children in whom the diagnosis of HS was made both clinically and by MRI prior to 2 years of age. Imaging features establishing the diagnosis of hippocampal sclerosis were bright T2 signal and volume loss, while the internal architecture of the hippocampal formation was preserved in almost all children. Clinically, all children had an infectious trigger. It is necessary for radiologists to consider HS in children with certain clinical features to plan an MRI protocol that is appropriate for detection of hippocampal pathology. (orig.)

  18. Plane-stress fields for sharp notches in pressure-sensitive materials

    International Nuclear Information System (INIS)

    Al-Abduljabbar, Abdulhamid

    2003-01-01

    The effect of pressure sensitive yield on materials toughness can be determined by investigating stress fields around cracks and notches. In this work, fully-developed plastic stress fields around sharp wedge-shaped notches of perfectly-plastic pressure-sensitive materials are investigated for plane-stress case and Mode 1 loading condition. The pressure-sensitive yielding behavior is represented using the Drucker-Prager criterion. Using equilibrium equations, boundary conditions, and the yield criterion, closed-form expressions for stress fields are derived. The analysis covers the gradual change in the notch angle and compares it with the limiting case of a pure horizontal crack. Effects of notch geometry and pressure sensitivity on stress fields are examined by considering different specimen geometries, as well as different levels of pressure sensitivity. Results indicate that while the stress values directly ahead of the notch-tip are not affected, the extent of stress sector at notch front is reduced, thereby causing increase in the radial stress value around the notch. As the pressure sensitivity increases the reduction of the stress sector directly ahead of the notch tip is more evident. Also, for high pressure sensitivity values, introduction of the notch angle reduces the variation of the stress levels. Results are useful for design of structural components. (author)

  19. Developmental changes in hippocampal shape among preadolescent children.

    Science.gov (United States)

    Lin, Muqing; Fwu, Peter T; Buss, Claudia; Davis, Elysia P; Head, Kevin; Muftuler, L Tugan; Sandman, Curt A; Su, Min-Ying

    2013-11-01

    It is known that the largest developmental changes in the hippocampus take place during the prenatal period and during the first two years of postnatal life. Few studies have been conducted to address the normal developmental trajectory of the hippocampus during childhood. In this study shape analysis was applied to study the normal developing hippocampus in a group of 103 typically developing 6- to 10-year-old preadolescent children. The individual brain was normalized to a template, and then the hippocampus was manually segmented and further divided into the head, body, and tail sub-regions. Three different methods were applied for hippocampal shape analysis: radial distance mapping, surface-based template registration using the robust point matching (RPM) algorithm, and volume-based template registration using the Demons algorithm. All three methods show that the older children have bilateral expanded head segments compared to the younger children. The results analyzed based on radial distance to the centerline were consistent with those analyzed using template-based registration methods. In analyses stratified by sex, it was found that the age-associated anatomical changes were similar in boys and girls, but the age-association was strongest in girls. Total hippocampal volume and sub-regional volumes analyzed using manual segmentation did not show a significant age-association. Our results suggest that shape analysis is sensitive to detect sub-regional differences that are not revealed in volumetric analysis. The three methods presented in this study may be applied in future studies to investigate the normal developmental trajectory of the hippocampus in children. They may be further applied to detect early deviations from the normal developmental trajectory in young children for evaluating susceptibility for psychopathological disorders involving hippocampus. Copyright © 2013 ISDN. Published by Elsevier Ltd. All rights reserved.

  20. Alzheimer's Disease Diagnostic Performance of a Multi-Atlas Hippocampal Segmentation Method using the Harmonized Hippocampal Protocol

    DEFF Research Database (Denmark)

    Anker, Cecilie Benedicte; Sørensen, Lauge; Pai, Akshay

    PURPOSE Hippocampal volumetry is the most widely used structural MRI biomarker of Alzheimer’s disease (AD), and state-of-the-art, automatic hippocampal segmentation can be obtained using longitudinal FreeSurfer. In this study, we compare the diagnostic AD performance of a single time point, multi...

  1. Commentary: The Development of Hippocampal-Dependent Memory Functions: Theoretical Comments on Jabès and Nelson Review (2015)

    Science.gov (United States)

    Bachevalier, Jocelyne

    2015-01-01

    Studies investigating the development of memory processes and their neural substrates have flourished over the past two decades. The review by Jabès and Nelson (2015) adds an important piece to our understanding of the maturation of different elements and circuits within the hippocampal system and their association with the progressive development…

  2. Sex Steroid Hormones Matter for Learning and Memory: Estrogenic Regulation of Hippocampal Function Inmale and Female Rodents

    Science.gov (United States)

    Frick, Karyn M.; Kim, Jaekyoon; Tuscher, Jennifer J.; Fortress, Ashley M.

    2015-01-01

    Ample evidence has demonstrated that sex steroid hormones, such as the potent estrogen 17ß-estradiol (E[subscript 2]), affect hippocampal morphology, plasticity, and memory in male and female rodents. Yet relatively few investigators who work with male subjects consider the effects of these hormones on learning and memory. This review describes…

  3. Aging is accompanied by a subfield-specific reduction of serotonergic fibers in the tree shrew hippocampal formation

    NARCIS (Netherlands)

    Keuker, Jeanine I H; Keijser, Jan N.; Nyakas, Csaba; Luiten, Paul G.M.; Fuchs, Eberhard

    2005-01-01

    The hippocampal formation is a crucial structure for learning and memory, and serotonin together with other neurotransmitters is essential in these processes. Although the effects of aging on various neurotransmitter systems in the hippocampus have been extensively investigated, it is not entirely

  4. Jasper Sharp - mees, kes jättis varasema töö, et vaadata Jaapani filme / Jasper Sharp ; intervjueerinud Helen Merila

    Index Scriptorium Estoniae

    Sharp, Jasper, 1971-

    2011-01-01

    Euroopa kultuuripealinn Tallinn 2011 programmi osana ning koostöös Zipangu Fest'iga korraldatakse Tallinna Kinomajas 25.-28. aug.-ni Aasia sõltumatute filmide festival EVA - East via Asia. Festivali kuraator, veebisaidi Midnight Eye kaastoimetaja Jasper Sharp endast, festivalist, Jaapani sõltumatust kinost tänapäeval. Festivali kava

  5. Hippocampal sclerosis in advanced age: clinical and pathological features

    Science.gov (United States)

    Schmitt, Frederick A.; Lin, Yushun; Abner, Erin L.; Jicha, Gregory A.; Patel, Ela; Thomason, Paula C.; Neltner, Janna H.; Smith, Charles D.; Santacruz, Karen S.; Sonnen, Joshua A.; Poon, Leonard W.; Gearing, Marla; Green, Robert C.; Woodard, John L.; Van Eldik, Linda J.; Kryscio, Richard J.

    2011-01-01

    Hippocampal sclerosis is a relatively common neuropathological finding (∼10% of individuals over the age of 85 years) characterized by cell loss and gliosis in the hippocampus that is not explained by Alzheimer’s disease. Hippocampal sclerosis pathology can be associated with different underlying causes, and we refer to hippocampal sclerosis in the aged brain as hippocampal sclerosis associated with ageing. Much remains unknown about hippocampal sclerosis associated with ageing. We combined three different large autopsy cohorts: University of Kentucky Alzheimer’s Disease Centre, the Nun Study and the Georgia Centenarian Study to obtain a pool of 1110 patients, all of whom were evaluated neuropathologically at the University of Kentucky. We focused on the subset of cases with neuropathology-confirmed hippocampal sclerosis (n = 106). For individuals aged ≥95 years at death (n = 179 in our sample), each year of life beyond the age of 95 years correlated with increased prevalence of hippocampal sclerosis pathology and decreased prevalence of ‘definite’ Alzheimer’s disease pathology. Aberrant TAR DNA protein 43 immunohistochemistry was seen in 89.9% of hippocampal sclerosis positive patients compared with 9.7% of hippocampal sclerosis negative patients. TAR DNA protein 43 immunohistochemistry can be used to demonstrate that the disease is usually bilateral even when hippocampal sclerosis pathology is not obvious by haematoxylin and eosin stains. TAR DNA protein 43 immunohistochemistry was negative on brain sections from younger individuals (n = 10) after hippocampectomy due to seizures, who had pathologically confirmed hippocampal sclerosis. There was no association between cases with hippocampal sclerosis associated with ageing and apolipoprotein E genotype. Age of death and clinical features of hippocampal sclerosis associated with ageing (with or without aberrant TAR DNA protein 43) were distinct from previously published cases of frontotemporal lobar

  6. Quadrilateral mesh fitting that preserves sharp features based on multi-normals for Laplacian energy

    Directory of Open Access Journals (Sweden)

    Yusuke Imai

    2014-04-01

    Full Text Available Because the cost of performance testing using actual products is expensive, manufacturers use lower-cost computer-aided design simulations for this function. In this paper, we propose using hexahedral meshes, which are more accurate than tetrahedral meshes, for finite element analysis. We propose automatic hexahedral mesh generation with sharp features to precisely represent the corresponding features of a target shape. Our hexahedral mesh is generated using a voxel-based algorithm. In our previous works, we fit the surface of the voxels to the target surface using Laplacian energy minimization. We used normal vectors in the fitting to preserve sharp features. However, this method could not represent concave sharp features precisely. In this proposal, we improve our previous Laplacian energy minimization by adding a term that depends on multi-normal vectors instead of using normal vectors. Furthermore, we accentuate a convex/concave surface subset to represent concave sharp features.

  7. Effects of sharp vorticity gradients in two-dimensional hydrodynamic turbulence

    DEFF Research Database (Denmark)

    Kuznetsov, E.A.; Naulin, Volker; Nielsen, Anders Henry

    2007-01-01

    The appearance of sharp vorticity gradients in two-dimensional hydrodynamic turbulence and their influence on the turbulent spectra are considered. We have developed the analog of the vortex line representation as a transformation to the curvilinear system of coordinates moving together with the ......The appearance of sharp vorticity gradients in two-dimensional hydrodynamic turbulence and their influence on the turbulent spectra are considered. We have developed the analog of the vortex line representation as a transformation to the curvilinear system of coordinates moving together...... with the divorticity lines. Compressibility of this mapping can be considered as the main reason for the formation of the sharp vorticity gradients at high Reynolds numbers. For two-dimensional turbulence in the case of strong anisotropy the sharp vorticity gradients can generate spectra which fall off as k−3 at large...

  8. Best Way to Get Rid of Used Needles and Other Sharps

    Science.gov (United States)

    ... other options are not available. If traveling by plane, check the Transportation Security Administration (TSA) website for ... be thrown away in the common trash. Additional Consumer Information How to Get Rid of a Sharps ...

  9. Surface-enhanced Raman scattering on periodic metal nanotips with tunable sharpness

    International Nuclear Information System (INIS)

    Linn, Nicholas C; Sun, C-H; Arya, Ajay; Jiang Peng; Jiang Bin

    2009-01-01

    This paper reports on a scalable bottom-up technology for producing periodic gold nanotips with tunable sharpness as surface-enhanced Raman scattering (SERS) substrates. Inverted silicon pyramidal pits, which are templated from non-close-packed colloidal crystals prepared by a spin-coating technology, are used as structural templates to replicate arrays of polymer nanopyramids with nanoscale sharp tips. The deposition of a thin layer of gold on the polymer nanopyramids leads to the formation of SERS-active substrates with a high enhancement factor (up to 10 8 ). The thickness of the deposited metal determines the sharpness of the nanotips and the resulting Raman enhancement factor. Finite-element electromagnetic modeling shows that the nanotips can significantly enhance the local electromagnetic field and the sharpness of nanotips greatly affects the SERS enhancement.

  10. 78 FR 43183 - Notice of Availability for Sharpe Permit Relinquishment Project Environmental Assessment Finding...

    Science.gov (United States)

    2013-07-19

    ... for Sharpe Permit Relinquishment Project Environmental Assessment Finding of No Significant Impact... Relinquishment Project Environmental Assessment (EA) Finding of No Significant Impact (FONSI). SUMMARY: On April... environment. Human environment was interpreted comprehensively to include the natural and physical environment...

  11. The pattern of sharps injury to health care workers at Witbank Hospital

    African Journals Online (AJOL)

    800 000 needle stick injuries occur every year.1 According to UK data, there were ... Factors associated with an increased risk of occupational exposure can differ from ... there are many sharps safety devices on the market, but unfortunately.

  12. The close objects buffer : a sharp shadow detection technique for radiosity methods

    NARCIS (Netherlands)

    Telea, A.C.; Overveld, van C.W.A.M.

    1997-01-01

    Detecting sharp illumination variations such as shadow boundaries is an important problem for radiosity methods. Such illumination variations are captured using a nonuniform mesh that refines the areas exhibiting high illumination gradients. Nonuniform meshing techniques like discontinuity meshing

  13. The Close Objects Buffer : A Sharp Shadow Detection Technique for Radiosity Methods

    NARCIS (Netherlands)

    Telea, A.C.; Overveld, C.W.A.M. van

    1998-01-01

    Detecting sharp illumination variations such as shadow boundaries is an important problem for radiosity methods. Such illumination variations are captured using a nonuniform mesh that refines the areas exhibiting high illumination gradients. Nonuniform meshing techniques like discontinuity meshing

  14. LLNL contributions to ANL Report ANL/NE-16/6 'Sharp User Manual'

    International Nuclear Information System (INIS)

    Solberg, J. M.

    2016-01-01

    Diablo is a Multiphysics implicit finite element code with an emphasis on coupled structural/thermal analysis. In the SHARP framework, it is used as the structural solver, and may also be used as the mesh smoother.

  15. Needles and Other Sharps (Safe Disposal Outside of Health Care Settings)

    Science.gov (United States)

    ... disorders, and psoriasis. Examples of sharps include: Needles – hollow needles used to inject drugs (medication) under the ... and Drug Administration 10903 New Hampshire Avenue Silver Spring, MD 20993 1-888-INFO-FDA (1-888- ...

  16. Current status of sharps waste management in the lower-level ...

    African Journals Online (AJOL)

    Key words: Sharps waste management, health facilities, infection, Tanzania ... and hence improve infection prevention and control at work places in Tanzania. .... The UNICEF /WHO safety boxes were observed in 31 (23%) of the LLHFs, while ...

  17. A faunistic study of genus Chasmogenus Sharp, 1882 of China (Coleoptera, Hydrophilidae

    Directory of Open Access Journals (Sweden)

    Fenglong Jia

    2018-02-01

    Full Text Available Chasmogenus Sharp, 1882 is newly reported from the Chinese Mainland. A new species, C. parorbus sp. n., is described from China (Yunnan. Chasmogenus orbus Watanabe, 1987 is reported from Hong Kong, the first record outside Japan. Chasmogenus abnormalis (Sharp, 1890 is reported from the Chinese mainland for the first time. The male genitalia of each species are illustrated. A key to the Chinese species of the genus is provided.

  18. A faunistic study of genus Chasmogenus Sharp, 1882 of China (Coleoptera, Hydrophilidae).

    Science.gov (United States)

    Jia, Fenglong; Tang, Yu-Dan

    2018-01-01

    Chasmogenus Sharp, 1882 is newly reported from the Chinese Mainland. A new species, C. parorbus sp. n. , is described from China (Yunnan). Chasmogenus orbus Watanabe, 1987 is reported from Hong Kong, the first record outside Japan. Chasmogenus abnormalis (Sharp, 1890) is reported from the Chinese mainland for the first time. The male genitalia of each species are illustrated. A key to the Chinese species of the genus is provided.

  19. Single-step electrochemical method for producing very sharp Au scanning tunneling microscopy tips

    International Nuclear Information System (INIS)

    Gingery, David; Buehlmann, Philippe

    2007-01-01

    A single-step electrochemical method for making sharp gold scanning tunneling microscopy tips is described. 3.0M NaCl in 1% perchloric acid is compared to several previously reported etchants. The addition of perchloric acid to sodium chloride solutions drastically shortens etching times and is shown by transmission electron microscopy to produce very sharp tips with a mean radius of curvature of 15 nm

  20. Understanding sharps injuries in home healthcare: The Safe Home Care qualitative methods study to identify pathways for injury prevention.

    Science.gov (United States)

    Markkanen, Pia; Galligan, Catherine; Laramie, Angela; Fisher, June; Sama, Susan; Quinn, Margaret

    2015-04-11

    Home healthcare is one of the fastest growing sectors in the United States. Percutaneous injuries from sharp medical devices (sharps) are a source of bloodborne pathogen infections among home healthcare workers and community members. Sharps use and disposal practices in the home are highly variable and there is no comprehensive analysis of the system of sharps procurement, use and disposal in home healthcare. This gap is a barrier to effective public health interventions. The objectives of this study were to i) identify the full range of pathways by which sharps enter and exit the home, stakeholders involved, and barriers for using sharps with injury prevention features; and ii) assess the leverage points for preventive interventions. This study employed qualitative research methods to develop two systems maps of the use of sharps and prevention of sharps injuries in home healthcare. Twenty-six in-depth interview sessions were conducted including home healthcare agency clinicians, public health practitioners, sharps device manufacturers, injury prevention advocates, pharmacists and others. Interview transcripts were audio-recorded and analyzed thematically using NVIVO qualitative research analysis software. Analysis of supporting archival material also was conducted. All findings guided development of the two maps. Sharps enter the home via multiple complex pathways involving home healthcare providers and home users. The providers reported using sharps with injury prevention features. However, home users' sharps seldom had injury prevention features and sharps were commonly re-used for convenience and cost-savings. Improperly discarded sharps present hazards to caregivers, waste handlers, and community members. The most effective intervention potential exists at the beginning of the sharps systems maps where interventions can eliminate or minimize sharps injuries, in particular with needleless treatment methods and sharps with injury prevention features

  1. A report on SHARP (Spacecraft Health Automated Reasoning Prototype) and the Voyager Neptune encounter

    Science.gov (United States)

    Martin, R. G. (Editor); Atkinson, D. J.; James, M. L.; Lawson, D. L.; Porta, H. J.

    1990-01-01

    The development and application of the Spacecraft Health Automated Reasoning Prototype (SHARP) for the operations of the telecommunications systems and link analysis functions in Voyager mission operations are presented. An overview is provided of the design and functional description of the SHARP system as it was applied to Voyager. Some of the current problems and motivations for automation in real-time mission operations are discussed, as are the specific solutions that SHARP provides. The application of SHARP to Voyager telecommunications had the goal of being a proof-of-capability demonstration of artificial intelligence as applied to the problem of real-time monitoring functions in planetary mission operations. AS part of achieving this central goal, the SHARP application effort was also required to address the issue of the design of an appropriate software system architecture for a ground-based, highly automated spacecraft monitoring system for mission operations, including methods for: (1) embedding a knowledge-based expert system for fault detection, isolation, and recovery within this architecture; (2) acquiring, managing, and fusing the multiple sources of information used by operations personnel; and (3) providing information-rich displays to human operators who need to exercise the capabilities of the automated system. In this regard, SHARP has provided an excellent example of how advanced artificial intelligence techniques can be smoothly integrated with a variety of conventionally programmed software modules, as well as guidance and solutions for many questions about automation in mission operations.

  2. The stratigraphy and evolution of lower Mount Sharp from spectral, morphological, and thermophysical orbital data sets.

    Science.gov (United States)

    Fraeman, A A; Ehlmann, B L; Arvidson, R E; Edwards, C S; Grotzinger, J P; Milliken, R E; Quinn, D P; Rice, M S

    2016-09-01

    We have developed a refined geologic map and stratigraphy for lower Mount Sharp using coordinated analyses of new spectral, thermophysical, and morphologic orbital data products. The Mount Sharp group consists of seven relatively planar units delineated by differences in texture, mineralogy, and thermophysical properties. These units are (1-3) three spatially adjacent units in the Murray formation which contain a variety of secondary phases and are distinguishable by thermal inertia and albedo differences, (4) a phyllosilicate-bearing unit, (5) a hematite-capped ridge unit, (6) a unit associated with material having a strongly sloped spectral signature at visible near-infrared wavelengths, and (7) a layered sulfate unit. The Siccar Point group consists of the Stimson formation and two additional units that unconformably overlie the Mount Sharp group. All Siccar Point group units are distinguished by higher thermal inertia values and record a period of substantial deposition and exhumation that followed the deposition and exhumation of the Mount Sharp group. Several spatially extensive silica deposits associated with veins and fractures show that late-stage silica enrichment within lower Mount Sharp was pervasive. At least two laterally extensive hematitic deposits are present at different stratigraphic intervals, and both are geometrically conformable with lower Mount Sharp strata. The occurrence of hematite at multiple stratigraphic horizons suggests redox interfaces were widespread in space and/or in time, and future measurements by the Mars Science Laboratory Curiosity rover will provide further insights into the depositional settings of these and other mineral phases.

  3. Alterations of White Matter Integrity and Hippocampal Functional Connectivity in Type 2 Diabetes Without Mild Cognitive Impairment

    Directory of Open Access Journals (Sweden)

    Qian Sun

    2018-03-01

    Full Text Available Aims: To investigate the white matter (WM integrity and hippocampal functional connectivity (FC in type 2 diabetes mellitus (T2DM patients without mild cognitive impairment (MCI by using diffusion tensor imaging (DTI and resting-state functional magnetic resonance imaging (rs-fMRI, respectively.Methods: Twelve T2DM patients without MCI and 24 age, sex and education matched healthy controls (HC were recruited. DTI and rs-fMRI data were subsequently acquired on a 3.0T MR scanner. Tract-based spatial statistics (TBSS combining region of interests (ROIs analysis was used to investigate the alterations of DTI metrics (fractional anisotropy (FA, mean diffusivity (MD, λ1 and λ23 and FC measurement was performed to calculate hippocampal FC with other brain regions. Cognitive function was evaluated by using Mini-Mental State Examination (MMSE and Montreal Cognitive Assessment (MoCA. Brain volumes were also evaluated among these participants.Results: There were no difference of MMSE and MoCA scores between two groups. Neither whole brain nor regional brain volume decrease was revealed in T2DM patients without MCI. DTI analysis revealed extensive WM disruptions, especially in the body of corpus callosum (CC. Significant decreases of hippocampal FC with certain brain structures were revealed, especially with the bilateral frontal cortex. Furthermore, the decreased FA in left posterior thalamic radiation (PTR and increased MD in the splenium of CC were closely related with the decreased hippocampal FC to caudate nucleus and frontal cortex.Conclusions: T2DM patients without MCI showed extensive WM disruptions and abnormal hippocampal FC. Moreover, the WM disruptions and abnormal hippocampal FC were closely associated.Highlights-T2DM patients without MCI demonstrated no obvious brain volume decrease.-Extensive white matter disruptions, especially within the body of corpus callosum, were revealed with DTI analysis among the T2DM patients.-Despite no MCI in T2

  4. Increase in hippocampal water diffusion and volume during experimental pneumococcal meningitis is aggravated by bacteremia

    DEFF Research Database (Denmark)

    Holler, Jon G; Brandt, Christian T; Leib, Stephen L

    2014-01-01

    BACKGROUND: The hippocampus undergoes apoptosis in experimental pneumococcal meningitis leading to neurofunctional deficits in learning and memory function. The aim of the present study was 1) to investigate hippocampal apparent diffusion coefficient (ADC) and volume with MRI during the course...... and the volume and size of brain ventricles were positively correlated (Spearman Rank, p volume and the extent of apoptosis (p > 0.05). CONCLUSIONS: In experimental meningitis increase in volume and water diffusion of the hippocampus are significantly...... of experimental pneumococcal meningitis, 2) to explore the influence of accompanying bacteremia on hippocampal water distribution and volume, 3) and to correlate these findings to the extent of apoptosis in the hippocampus. METHODS: Experimental meningitis in rats was induced by intracisternal injection of live...

  5. Hyperexcitability and cell loss in kainate-treated hippocampal slice cultures

    DEFF Research Database (Denmark)

    Benedikz, Eirikur; Casaccia-Bonnefil, P; Stelzer, A

    1993-01-01

    Loss of hippocampal interneurons has been reported in patients with severe temporal lobe epilepsy and in animals treated with kainate. We investigated the relationship between KA induced epileptiform discharge and loss of interneurons in hippocampal slice cultures. Application of KA (1 micro......M) produced reversible epileptiform discharge without neurotoxicity. KA (5 microM), in contrast, produced irreversible epileptiform discharge and neurotoxicity, suggesting that the irreversible epileptiform discharge was required for the neuronal loss. Loss of CA3 pyramidal cells and parvalbumin......-like immunoreactive (PV-I) interneurons preceded loss of somatostatin-like immunoreactive (SS-I) interneurons suggesting a different time course of KA neurotoxicity in these subpopulations of interneurons....

  6. Hippocampal Neurogenesis and the Brain Repair Response to Brief Stereotaxic Insertion of a Microneedle

    Directory of Open Access Journals (Sweden)

    Shijie Song

    2013-01-01

    Full Text Available We tested the hypothesis that transient microinjury to the brain elicits cellular and humoral responses that stimulate hippocampal neurogenesis. Brief stereotaxic insertion and removal of a microneedle into the right hippocampus resulted in (a significantly increased expression of granulocyte-colony stimulating factor (G-CSF, the chemokine MIP-1a, and the proinflammatory cytokine IL12p40; (b pronounced activation of microglia and astrocytes; and (c increase in hippocampal neurogenesis. This study describes immediate and early humoral and cellular mechanisms of the brain’s response to microinjury that will be useful for the investigation of potential neuroprotective and deleterious effects of deep brain stimulation in various neuropsychiatric disorders.

  7. [Protective effect of Uncaria rhynchophylla total alkaloids pretreatment on hippocampal neurons after acute hypoxia].

    Science.gov (United States)

    Liu, Wei; Zhang, Zhao-qin; Zhao, Xiao-min; Gao, Yun-sheng

    2006-05-01

    To investigate the effect of Uncaria rhynchophylla total alkaloids (RTA) pretreatment on the voltage-gated sodium currents of the rat hippocampal neurons after acute hypoxia. Primary cultured hippocampal neurons were divided into RTA pre-treated and non-pretreated groups. Patch clamp whole-cell recording was used to compare the voltage-gated sodium current amplitude and threshold with those before hypoxia. After acute hypoxia, sodium current amplitude was significantly decreased and its threshold was upside. RTA pretreatment could inhibit the reduction of sodium current amplitude. RTA pretreatment alleviates the acute hypoxia-induced change of sodium currents, which may be one of the mechanisms for protective effect of RTA on cells.

  8. Sugar consumption produces effects similar to early life stress exposure on hippocampal markers of neurogenesis and stress response

    Directory of Open Access Journals (Sweden)

    Jayanthi eManiam

    2016-01-01

    Full Text Available Adverse early life experience is a known risk factor for psychiatric disorders. It is also known that stress influences food preference. We were interested in exploring whether the choice of diet following early life stress exerts long-lasting molecular changes in the brain, particularly the hippocampus, a region critically involved in stress regulation and behavioural outcomes. Here, we examined the impact of early life stress induced by limited nesting material (LN and chronic sucrose availability post-weaning on an array of hippocampal genes related to plasticity, neurogenesis, stress and inflammatory responses and mitochondrial biogenesis. To examine mechanisms underlying the impact of LN and sugar intake on hippocampal gene expression, we investigated the role of DNA methylation. As females are more likely to experience adverse life events, we studied female Sprague-Dawley rats. After mating LN was imposed from days 2-9 postpartum. From 3-15 weeks of age, female Control and LN siblings had unlimited to access to either chow and water, or chow, water and 25% sucrose solution. LN markedly reduced glucocorticoid receptor (GR and neurogenic differentiation 1 (Neurod1 mRNA, markers involved in stress and hippocampal plasticity respectively, by more than 40%, with a similar effect of sugar intake in control rats. However, no further impact was observed in LN rats consuming sugar. Hippocampal Akt3 mRNA expression was similarly affected by LN and sucrose consumption. Interestingly, DNA methylation across 4 CpG sites of the GR and Neurod1 promoters was similar in LN and control rats. In summary, early life stress and post-weaning sugar intake produced long-term effects on hippocampal GR and Neurod1 expression. Moreover we found no evidence of altered promoter DNA methylation. We demonstrate for the first time that chronic sucrose consumption alone produces similar detrimental effects on the expression of hippocampal genes as LN exposure.

  9. Specific multi-nutrient enriched diet enhances hippocampal cholinergic transmission in aged rats.

    Science.gov (United States)

    Cansev, Mehmet; van Wijk, Nick; Turkyilmaz, Mesut; Orhan, Fulya; Sijben, John W C; Broersen, Laus M

    2015-01-01

    Fortasyn Connect (FC) is a specific nutrient combination designed to target synaptic dysfunction in Alzheimer's disease by providing neuronal membrane precursors and other supportive nutrients. The aim of the present study was to investigate the effects of FC on hippocampal cholinergic neurotransmission in association with its effects on synaptic membrane formation in aged rats. Eighteen-month-old male Wistar rats were randomized to receive a control diet for 4 weeks or an FC-enriched diet for 4 or 6 weeks. At the end of the dietary treatments, acetylcholine (ACh) release was investigated by in vivo microdialysis in the right hippocampi. On completion of microdialysis studies, the rats were sacrificed, and the left hippocampi were obtained to determine the levels of choline, ACh, membrane phospholipids, synaptic proteins, and choline acetyltransferase. Our results revealed that supplementation with FC diet for 4 or 6 weeks, significantly enhanced basal and stimulated hippocampal ACh release and ACh tissue levels, along with levels of phospholipids. Feeding rats the FC diet for 6 weeks significantly increased the levels of choline acetyltransferase, the presynaptic marker Synapsin-1, and the postsynaptic marker PSD-95, but decreased levels of Nogo-A, a neurite outgrowth inhibitor. These data show that the FC diet enhances hippocampal cholinergic neurotransmission in aged rats and suggest that this effect is mediated by enhanced synaptic membrane formation. These data provide further insight into cellular and molecular mechanisms by which FC may support memory processes in Alzheimer's disease. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  10. Cortisol, Cytokines, and Hippocampal Volume in the Elderly

    Directory of Open Access Journals (Sweden)

    Keith Daniel Sudheimer

    2014-07-01

    Full Text Available Separate bodies of literature report that elevated pro-inflammatory cytokines and cortisol negatively affect hippocampal structure and cognitive functioning, particularly in older adults. Although interactions between cytokines and cortisol occur through a variety of known mechanisms, few studies consider how their interactions affect brain structure. In this preliminary study, we assess the impact of interactions between circulating levels of IL-1Beta, IL-6, IL-8, IL-10, IL-12, TNF-alpha, and waking cortisol on hippocampal volume. Twenty-eight community-dwelling older adults underwent blood draws for quantification of circulating cytokines and saliva collections to quantify the cortisol awakening response. Hippocampal volume measurements were made using structural magnetic resonance imaging. Elevated levels of waking cortisol in conjunction with higher concentrations of IL-6 and TNF-alpha were associated with smaller hippocampal volumes. In addition, independent of cortisol, higher levels of IL-1beta and TNF-alpha were also associated with smaller hippocampal volumes. These data provide preliminary evidence that higher cortisol, in conjunction with higher IL-6 and TNF-alpha, are associated with smaller hippocampal volume in older adults. We suggest that the dynamic balance between the hypothalamic-pituitary adrenal axis and inflammation processes may explain hippocampal volume reductions in older adults better than either set of measures do in isolation.

  11. The hydraulic mechanism in the hind wing veins of Cybister japonicus Sharp (order: Coleoptera

    Directory of Open Access Journals (Sweden)

    Jiyu Sun

    2016-06-01

    Full Text Available The diving beetles (Dytiscidae, Coleoptera are families of water beetles. When they see light, they fly to the light source directly from the water. Their hind wings are thin and fragile under the protection of their elytra (forewings. When the beetle is at rest the hind wings are folded over the abdomen of the beetle and when in flight they unfold to provide the necessary aerodynamic forces. In this paper, the unfolding process of the hind wing of Cybister japonicus Sharp (order: Coleoptera was investigated. The motion characteristics of the blood in the veins of the structure system show that the veins have microfluidic control over the hydraulic mechanism of the unfolding process. A model is established, and the hind wing extending process is simulated. The blood flow and pressure changes are discussed. The driving mechanism for hydraulic control of the folding and unfolding actions of beetle hind wings is put forward. This can assist the design of new deployable micro air vehicles and bioinspired deployable systems.

  12. Childhood maltreatment, psychopathology, and the development of hippocampal subregions during adolescence.

    Science.gov (United States)

    Whittle, Sarah; Simmons, Julian G; Hendriksma, Sylke; Vijayakumar, Nandita; Byrne, Michelle L; Dennison, Meg; Allen, Nicholas B

    2017-02-01

    It is well established that childhood maltreatment has a detrimental impact on the brain, particularly the hippocampus. However, the hippocampus is a functionally and structurally heterogeneous region, and little is known about how maltreatment might affect hippocampal subregion development throughout important periods of plasticity. This study investigated whether childhood maltreatment was associated with the development of hippocampal subregion volumes from early to late adolescence. It also investigated associations between onset of psychiatric disorder and hippocampal subregion volume development. One hundred and sixty-six (85 male) adolescents took part in three magnetic resonance imaging assessments during adolescence (mean age at each assessment: 12.79 [ SD 0.43] years, 16.70 [ SD 0.52] years, and 19.08 [ SD 0.46] years), provided a self-report of childhood maltreatment, and were assessed for Axis I psychopathology. Childhood maltreatment was associated with the development of right total and left cornu ammonis 4 (CA4-DG) volumes from early to late adolescence. Early and late onset psychopathology was associated with the development of right presubiculum and right cornu ammonis 1 (CA1) volumes, respectively. Maltreatment findings appeared to be specific to males, whereas psychopathology findings appeared to be specific to females. These findings provide evidence for possible deleterious effects of childhood maltreatment and early onset psychiatric disorder on the development of different subregions of the hippocampus. Altered development of the right CA1, on the other hand, might precede the development of late-adolescent onset psychopathology. Our results highlight the importance of considering development in research examining associations between stress, mental illness, and hippocampal morphology.

  13. Diazinon and diazoxon impair the ability of astrocytes to foster neurite outgrowth in primary hippocampal neurons

    International Nuclear Information System (INIS)

    Pizzurro, Daniella M.; Dao, Khoi; Costa, Lucio G.

    2014-01-01

    Evidence from in vivo and epidemiological studies suggests that organophosphorus insecticides (OPs) are developmental neurotoxicants, but possible underlying mechanisms are still unclear. Astrocytes are increasingly recognized for their active role in normal neuronal development. This study sought to investigate whether the widely-used OP diazinon (DZ), and its oxygen metabolite diazoxon (DZO), would affect glial–neuronal interactions as a potential mechanism of developmental neurotoxicity. Specifically, we investigated the effects of DZ and DZO on the ability of astrocytes to foster neurite outgrowth in primary hippocampal neurons. The results show that both DZ and DZO adversely affect astrocyte function, resulting in inhibited neurite outgrowth in hippocampal neurons. This effect appears to be mediated by oxidative stress, as indicated by OP-induced increased reactive oxygen species production in astrocytes and prevention of neurite outgrowth inhibition by antioxidants. The concentrations of OPs were devoid of cytotoxicity, and cause limited acetylcholinesterase inhibition in astrocytes (18 and 25% for DZ and DZO, respectively). Among astrocytic neuritogenic factors, the most important one is the extracellular matrix protein fibronectin. DZ and DZO decreased levels of fibronectin in astrocytes, and this effect was also attenuated by antioxidants. Underscoring the importance of fibronectin in this context, adding exogenous fibronectin to the co-culture system successfully prevented inhibition of neurite outgrowth caused by DZ and DZO. These results indicate that DZ and DZO increase oxidative stress in astrocytes, and this in turn modulates astrocytic fibronectin, leading to impaired neurite outgrowth in hippocampal neurons. - Highlights: • DZ and DZO inhibit astrocyte-mediated neurite outgrowth in rat hippocampal neurons. • Oxidative stress is involved in inhibition of neuritogenesis by DZ and DZO. • DZ and DZO decrease expression of the neuritogenic

  14. Diazinon and diazoxon impair the ability of astrocytes to foster neurite outgrowth in primary hippocampal neurons

    Energy Technology Data Exchange (ETDEWEB)

    Pizzurro, Daniella M.; Dao, Khoi [Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA (United States); Costa, Lucio G. [Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA (United States); Department of Neuroscience, University of Parma, Parma (Italy)

    2014-02-01

    Evidence from in vivo and epidemiological studies suggests that organophosphorus insecticides (OPs) are developmental neurotoxicants, but possible underlying mechanisms are still unclear. Astrocytes are increasingly recognized for their active role in normal neuronal development. This study sought to investigate whether the widely-used OP diazinon (DZ), and its oxygen metabolite diazoxon (DZO), would affect glial–neuronal interactions as a potential mechanism of developmental neurotoxicity. Specifically, we investigated the effects of DZ and DZO on the ability of astrocytes to foster neurite outgrowth in primary hippocampal neurons. The results show that both DZ and DZO adversely affect astrocyte function, resulting in inhibited neurite outgrowth in hippocampal neurons. This effect appears to be mediated by oxidative stress, as indicated by OP-induced increased reactive oxygen species production in astrocytes and prevention of neurite outgrowth inhibition by antioxidants. The concentrations of OPs were devoid of cytotoxicity, and cause limited acetylcholinesterase inhibition in astrocytes (18 and 25% for DZ and DZO, respectively). Among astrocytic neuritogenic factors, the most important one is the extracellular matrix protein fibronectin. DZ and DZO decreased levels of fibronectin in astrocytes, and this effect was also attenuated by antioxidants. Underscoring the importance of fibronectin in this context, adding exogenous fibronectin to the co-culture system successfully prevented inhibition of neurite outgrowth caused by DZ and DZO. These results indicate that DZ and DZO increase oxidative stress in astrocytes, and this in turn modulates astrocytic fibronectin, leading to impaired neurite outgrowth in hippocampal neurons. - Highlights: • DZ and DZO inhibit astrocyte-mediated neurite outgrowth in rat hippocampal neurons. • Oxidative stress is involved in inhibition of neuritogenesis by DZ and DZO. • DZ and DZO decrease expression of the neuritogenic

  15. Cognitive deficits caused by prefrontal cortical and hippocampal neural disinhibition.

    Science.gov (United States)

    Bast, Tobias; Pezze, Marie; McGarrity, Stephanie

    2017-10-01

    We review recent evidence concerning the significance of inhibitory GABA transmission and of neural disinhibition, that is, deficient GABA transmission, within the prefrontal cortex and the hippocampus, for clinically relevant cognitive functions. Both regions support important cognitive functions, including attention and memory, and their dysfunction has been implicated in cognitive deficits characterizing neuropsychiatric disorders. GABAergic inhibition shapes cortico-hippocampal neural activity, and, recently, prefrontal and hippocampal neural disinhibition has emerged as a pathophysiological feature of major neuropsychiatric disorders, especially schizophrenia and age-related cognitive decline. Regional neural disinhibition, disrupting spatio-temporal control of neural activity and causing aberrant drive of projections, may disrupt processing within the disinhibited region and efferent regions. Recent studies in rats showed that prefrontal and hippocampal neural disinhibition (by local GABA antagonist microinfusion) dysregulates burst firing, which has been associated with important aspects of neural information processing. Using translational tests of clinically relevant cognitive functions, these studies showed that prefrontal and hippocampal neural disinhibition disrupts regional cognitive functions (including prefrontal attention and hippocampal memory function). Moreover, hippocampal neural disinhibition disrupted attentional performance, which does not require the hippocampus but requires prefrontal-striatal circuits modulated by the hippocampus. However, some prefrontal and hippocampal functions (including inhibitory response control) are spared by regional disinhibition. We consider conceptual implications of these findings, regarding the distinct relationships of distinct cognitive functions to prefrontal and hippocampal GABA tone and neural activity. Moreover, the findings support the proposition that prefrontal and hippocampal neural disinhibition

  16. Hippocampal sclerosis: correlation of MR imaging findings with surgical outcome

    International Nuclear Information System (INIS)

    Kim, Yoon Hee; Chang, Kee Hyun; Kim, Kyung Won; Han, Moon Hee; Park, Sung Ho; Nam, Hyun Woo; Choi, Kyu Ho; Cho, Woo Ho

    2001-01-01

    Atrophy and a high T2 signal of the hippocampus are known to be the principal MR imaging findings of hippocampal sclerosis. The purpose of this study was to determine whether or not individual MRI findings correlate with surgical outcome in patients with this condition. Preoperative MR imaging findings in 57 consecutive patients with pathologically-proven hippocampal sclerosis who underwent anterior temporal lobectomy and were followed-up for 24 months or more were retrospectively reviewed, and the results were compared with the postsurgical outcome (Engel classification). The MR images included routine sagittal T1-weighted and axial T2-weighted spin-echo images, and oblique coronal T1-weighted 3D gradient-echo and T2-weighted 2D fast spin-echo images obtained on either a 1.5 T or 1.0 T unit. The images were visually evaluated by two neuroradiologists blinded to the outcome; their focus was the presence or absence of atrophy and a high T2 hippocampal signal. Hippocampal atrophy was seen in 96% of cases (55/57) [100% (53/53) of the good outcome group (Engel class I and II), and 50% (2/4) of the poor outcome group (class III and IV)]. A high T2 hippocampal signal was seen in 61% of cases (35/57) [62% (33/53) of the good outcome group and 50% (2/4) of the poor outcome group]. All 35 patients with a high T2 signal had hippocampal atrophy. 'Normal' hippocampus, as revealed by MR imaging, occurred in 4% of patients (2/57), both of whom showed a poor outcome (Engel class III). The presence or absence of hippocampal atrophy correlated well with surgical outcome (p 0.05). Compared with a high T2 hippocampal signal, hippocampal atrophy is more common and correlates better with surgical outcome. For the prediction of this, it thus appears to be the more useful indicator

  17. A sharp interface model for void growth in irradiated materials

    Science.gov (United States)

    Hochrainer, Thomas; El-Azab, Anter

    2015-03-01

    A thermodynamic formalism for the interaction of point defects with free surfaces in single-component solids has been developed and applied to the problem of void growth by absorption of point defects in irradiated metals. This formalism consists of two parts, a detailed description of the dynamics of defects within the non-equilibrium thermodynamic frame, and the application of the second law of thermodynamics to provide closure relations for all kinetic equations. Enforcing the principle of non-negative entropy production showed that the description of the problem of void evolution under irradiation must include a relationship between the normal fluxes of defects into the void surface and the driving thermodynamic forces for the void surface motion; these thermodynamic forces are identified for both vacancies and interstitials and the relationships between these forces and the normal point defect fluxes are established using the concepts of transition state theory. The latter theory implies that the defect accommodation into the surface is a thermally activated process. Numerical examples are given to illustrate void growth dynamics in this new formalism and to investigate the effect of the surface energy barriers on void growth. Consequences for phase field models of void growth are discussed.

  18. Posttraumatic Stress Disorder and Depression Symptom Severities Are Differentially Associated With Hippocampal Subfield Volume Loss in Combat Veterans.

    Science.gov (United States)

    Averill, Christopher L; Satodiya, Ritvij M; Scott, J Cobb; Wrocklage, Kristen M; Schweinsburg, Brian; Averill, Lynnette A; Akiki, Teddy J; Amoroso, Timothy; Southwick, Steven M; Krystal, John H; Abdallah, Chadi G

    2017-01-01

    Two decades of human neuroimaging research have associated volume reductions in the hippocampus with posttraumatic stress disorder. However, little is known about the distribution of volume loss across hippocampal subfields. Recent advances in neuroimaging methods have made it possible to accurately delineate 10 gray matter hippocampal subfields. Here, we apply a volumetric analysis of hippocampal subfields to data from a group of combat-exposed Veterans. Veterans (total, n = 68, posttraumatic stress disorder, n = 36; combat control, n = 32) completed high-resolution structural magnetic resonance imaging. Based on previously validated methods, hippocampal subfield volume measurements were conducted using FreeSurfer 6.0. The Clinician-Administered PTSD Scale assessed posttraumatic stress disorder symptom severity; Beck Depression Inventory assessed depressive symptom severity. Controlling for age and intracranial volume, partial correlation analysis examined the relationship between hippocampal subfields and symptom severity. Correction for multiple comparisons was performed using false discovery rate. Gender, intelligence, combat severity, comorbid anxiety, alcohol/substance use disorder, and medication status were investigated as potential confounds. In the whole sample, total hippocampal volume negatively correlated with Clinician-Administered PTSD Scale and Beck Depression Inventory scores. Of the 10 hippocampal subfields, Clinician-Administered PTSD Scale symptom severity negatively correlated with the hippocampus-amygdala transition area (HATA). Beck Depression Inventory scores negatively correlated with dentate gyrus, cornu ammonis 4 (CA4), HATA, CA2/3, molecular layer, and CA1. Follow-up analysis limited to the posttraumatic stress disorder group showed a negative correlation between Clinician-Administered PTSD Scale symptom severity and each of HATA, CA2/3, molecular layer, and CA4. This study provides the first evidence relating posttraumatic stress

  19. Hippocampal atrophy on MRI is predictive of histopathological patterns and surgical prognosis in mesial temporal lobe epilepsy with hippocampal sclerosis.

    Science.gov (United States)

    Jardim, Anaclara Prada; Corso, Jeana Torres; Garcia, Maria Teresa Fernandes Castilho; Gaça, Larissa Botelho; Comper, Sandra Mara; Lancellotti, Carmen Lúcia Penteado; Centeno, Ricardo Silva; Carrete, Henrique; Cavalheiro, Esper Abrão; Scorza, Carla Alessandra; Yacubian, Elza Márcia Targas

    2016-12-01

    To correlate hippocampal volumes obtained from brain structural imaging with histopathological patterns of hippocampal sclerosis (HS), in order to predict surgical outcome. Patients with mesial temporal lobe epilepsy (MTLE) with HS were selected. Clinical data were assessed pre-operatively and surgical outcome in the first year post surgery. One block of mid hippocampal body was selected for HS classification according to ILAE criteria. NeuN-immunoreactive cell bodies were counted within hippocampal subfields, in four randomly visual fields, and cell densities were transformed into z-score values. FreeSurfer processing of 1.5T brain structural images was used for subcortical and cortical volumetric estimation of the ipsilateral hippocampus. Univariate analysis of variance and Pearson's correlation test were applied for statistical analyses. Sixty-two cases (31 female, 32 right HS) were included. ILAE type 1 HS was identified in 48 patients, type 2 in eight, type 3 in two, and four had no-HS. Better results regarding seizure control, i.e. ILAE 1, were achieved by patients with type 1 HS (58.3%). Patients with types 1 and 2 had smaller hippocampal volumes compared to those with no-HS (p<0.001 and p=0.004, respectively). Positive correlation was encountered between hippocampal volumes and CA1, CA3, CA4, and total estimated neuronal densities. CA2 was the only sector which did not correlate its neuronal density with hippocampal volume (p=0.390). This is the first study correlating hippocampal volume on MRI submitted to FreeSurfer processing with ILAE patterns of HS and neuronal loss within each hippocampal subfield, a fundamental finding to anticipate surgical prognosis for patients with drug-resistant MTLE and HS. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Dentate network activity is necessary for spatial working memory by supporting CA3 sharp-wave ripple generation and prospective firing of CA3 neurons.

    Science.gov (United States)

    Sasaki, Takuya; Piatti, Verónica C; Hwaun, Ernie; Ahmadi, Siavash; Lisman, John E; Leutgeb, Stefan; Leutgeb, Jill K

    2018-02-01

    Complex spatial working memory tasks have been shown to require both hippocampal sharp-wave ripple (SWR) activity and dentate gyrus (DG) neuronal activity. We therefore asked whether DG inputs to CA3 contribute to spatial working memory by promoting SWR generation. Recordings from DG and CA3 while rats performed a dentate-dependent working memory task on an eight-arm radial maze revealed that the activity of dentate neurons and the incidence rate of SWRs both increased during reward consumption. We then found reduced reward-related CA3 SWR generation without direct input from dentate granule neurons. Furthermore, CA3 cells with place fields in not-yet-visited arms preferentially fired during SWRs at reward locations, and these prospective CA3 firing patterns were more pronounced for correct trials and were dentate-dependent. These results indicate that coordination of CA3 neuronal activity patterns by DG is necessary for the generation of neuronal firing patterns that support goal-directed behavior and memory.

  1. Hippocampal Atrophy Is Associated with Altered Hippocampus-Posterior Cingulate Cortex Connectivity in Mesial Temporal Lobe Epilepsy with Hippocampal Sclerosis.

    Science.gov (United States)

    Shih, Y C; Tseng, C E; Lin, F-H; Liou, H H; Tseng, W Y I

    2017-03-01

    Unilateral mesial temporal lobe epilepsy and hippocampal sclerosis have structural and functional abnormalities in the mesial temporal regions. To gain insight into the pathophysiology of the epileptic network in mesial temporal lobe epilepsy with hippocampal sclerosis, we aimed to clarify the relationships between hippocampal atrophy and the altered connection between the hippocampus and the posterior cingulate cortex in patients with mesial temporal lobe epilepsy with hippocampal sclerosis. Fifteen patients with left mesial temporal lobe epilepsy with hippocampal sclerosis and 15 healthy controls were included in the study. Multicontrast MR imaging, including high-resolution T1WI, diffusion spectrum imaging, and resting-state fMRI, was performed to measure the hippocampal volume, structural connectivity of the inferior cingulum bundle, and intrinsic functional connectivity between the hippocampus and the posterior cingulate cortex, respectively. Compared with controls, patients had decreased left hippocampal volume (volume ratio of the hippocampus and controls, 0.366% ± 0.029%; patients, 0.277% ± 0.063%, corrected P = .002), structural connectivity of the bilateral inferior cingulum bundle (generalized fractional anisotropy, left: controls, 0.234 ± 0.020; patients, 0.193 ± 0.022, corrected P = .0001, right: controls, 0.226 ± 0.022; patients, 0.208 ± 0.017, corrected P = .047), and intrinsic functional connectivity between the left hippocampus and the left posterior cingulate cortex (averaged z-value: controls, 0.314 ± 0.152; patients, 0.166 ± 0.062). The left hippocampal volume correlated with structural connectivity positively (standardized β = 0.864, P = .001), but it had little correlation with intrinsic functional connectivity (standardized β = -0.329, P = .113). On the contralesional side, the hippocampal volume did not show any significant correlation with structural connectivity or intrinsic functional connectivity ( F 2,12 = 0.284, P = .757, R 2

  2. Tau protein and adult hippocampal neurogenesis

    Directory of Open Access Journals (Sweden)

    Almudena eFuster-Matanzo

    2012-07-01

    Full Text Available Tau protein is a microtubule associated protein found in the axonal compartment that stabilizes neuronal microtubules under normal physiological conditions. Tau metabolism has attracted much attention because of its role in neurodegenerative disorders called tauopathies, mainly Alzheimer disease. Here, we review recent findings suggesting that axonal outgrowth in subgranular zone during adult hippocampal neurogenesis requires a dynamic microtubule network and tau protein facilitates to maintain that dynamic cytoskeleton. Those functions are carried out in part by tau isoform with only three microtubule-binding domains (without exon 10 and by presence of hypherphosphorylated tau forms. Thus, tau is a good marker and a valuable tool to study new axons in adult neurogenesis.

  3. Spatial relational memory requires hippocampal adult neurogenesis.

    Directory of Open Access Journals (Sweden)

    David Dupret

    Full Text Available The dentate gyrus of the hippocampus is one of the few regions of the mammalian brain where new neurons are generated throughout adulthood. This adult neurogenesis has been proposed as a novel mechanism that mediates spatial memory. However, data showing a causal relationship between neurogenesis and spatial memory are controversial. Here, we developed an inducible transgenic strategy allowing specific ablation of adult-born hippocampal neurons. This resulted in an impairment of spatial relational memory, which supports a capacity for flexible, inferential memory expression. In contrast, less complex forms of spatial knowledge were unaltered. These findings demonstrate that adult-born neurons are necessary for complex forms of hippocampus-mediated learning.

  4. Gene-environment effects on hippocampal neurodevelopment

    DEFF Research Database (Denmark)

    Rosenthal, Eva Helga

    Mental disorders like schizophrenia and autism put a heavy load on today’s societies, creating a steady call for revealing underlying disease mechanisms and the development of effective treatments. The etiology of major psychiatric illnesses is complex involving gene by environment susceptibility...... factors. Hence, a deeper understanding is needed of how cortical neurodevelopmental deficiencies can arise from such gene-environment interactions. The convergence of genetic and environmental risk factors is a recent field of research. It is now clear that disease, infection and stress factors may...... and antipsychotics mediate their effects on hippocampal neurodevelopment through deregulation of the Zbtb20 gene. A short presentation of the status of this work will shown....

  5. Hummingbirds have a greatly enlarged hippocampal formation.

    Science.gov (United States)

    Ward, Brian J; Day, Lainy B; Wilkening, Steven R; Wylie, Douglas R; Saucier, Deborah M; Iwaniuk, Andrew N

    2012-08-23

    Both field and laboratory studies demonstrate that hummingbirds (Apodiformes, Trochilidae) have exceptional spatial memory. The complexity of spatial-temporal information that hummingbirds must retain and use daily is probably subserved by the hippocampal formation (HF), and therefore, hummingbirds should have a greatly expanded HF. Here, we compare the relative size of the HF in several hummingbird species with that of other birds. Our analyses reveal that the HF in hummingbirds is significantly larger, relative to telencephalic volume, than any bird examined to date. When expressed as a percentage of telencephalic volume, the hummingbird HF is two to five times larger than that of caching and non-caching songbirds, seabirds and woodpeckers. This HF expansion in hummingbirds probably underlies their ability to remember the location, distribution and nectar content of flowers, but more detailed analyses are required to determine the extent to which this arises from an expansion of HF or a decrease in size of other brain regions.

  6. Sharps injury reduction: a six-year, three-phase study comparing use of a small patient-room sharps disposal container with a larger engineered container.

    Science.gov (United States)

    Grimmond, T; Naisoro, W

    2014-09-01

    A 350-bed Sydney hospital noted excessive container-associated sharps injuries (CASI) using small sharps containers and compared the effect from 2004 to 2010 of using a larger container engineered to reduce CASI. In Phase 1 (Ph1), disposable 1.4L containers (BD Australia) were carried to/from patients' rooms. In Phase 2 (Ph2), this stopped and a safety-engineered 32L reusable container (the Device; Sharpsmart, SteriHealth) was mounted in medication stations only and sharps were carried to and from patient rooms using kidney dishes. In Phase 3 (Ph3), the Device was wall-mounted in patient rooms. Sharps injuries were categorised as 'during-procedure', 'after-procedure but before disposal', 'CASI', and 'improper disposal SI'. Disposal-related SI comprised CASI plus improper-disposal SI. Injuries per 100 full-time-equivalent staff were analysed using Chi 2 ; p ≤ 0.05; and relative risk and 95% confidence limits were calculated. In Ph1 (small containers) 19.4% of SI were CASI and transport injuries were zero. In Ph2 (Device in medication station) CASI fell 94.9% ( p <0.001); Disposal-related SI fell 71.1% ( p =0.002) but transport injuries rose significantly. In Ph3 (Device in patient room) zero CASI occurred ( p <0.001); Disposal-related SI fell 83.1% ( p =0.001). Recapping SI fell 85.1% ( p =0.01) with the Device. The Device's volume, large aperture, passive overfill-protection and close-at-hand siting are postulated as SI reduction factors.

  7. Glucocorticoid effects on hippocampal protein synthesis

    International Nuclear Information System (INIS)

    Schlatter, L.K.

    1988-01-01

    Following subcutaneous injection of rats with 5 mg corticosterone, hippocampal slices in vitro show increased [ 35 S]-methionine labeling of a cytosolic protein with an apparent molecular weight (M r ) of 35,000 and an isoelectric point (IEP) of 6.6. This labeling is temporally consistent with a transcriptional event, and is steroid- and tissue-specific. The pear serum concentration of steroid occurs one hour or less following the injection. Maximal labeling of this protein is reached whenever serum corticosterone values are approximately 100 ng/ml. When endogenous corticosterone levels are elevated to 100 ng/ml through stressors or exogenous ACTH injections the same maximal increase in synthesis of the 35,000 M r protein is observed. Adrenalectomy prevents the observed response from occurring following stressor application or ACTH injections. Comparison of the increases observed after administration of the type 2 receptor agonist RU 28362 and aldosterone, which has a higher affinity for the type 1 receptor, shows a 50-fold greater sensitivity of the response to the type 2 receptor agonist. Synthesis of this protein following serum increases of steroid possibly correlates to the theorized function of the type 2 receptor feedback regulation. The similar protein in the liver has an IEP of 6.8 and a slightly higher M r . A second hippocampal protein with an M r of 46,000 and an IEP of 6.2 is also increased in labeling. Two additional liver proteins, one of Mr 53,000 (IEP of 6.2) and the other with an M r of 45,000 (IEP of 8.7-7.8) are increased in the liver following glucocorticoid administration

  8. Bilateral reorganization of the dentate gyrus in hippocampal sclerosis: a postmortem study.

    Science.gov (United States)

    Thom, M; Martinian, L; Catarino, C; Yogarajah, M; Koepp, M J; Caboclo, L; Sisodiya, S M

    2009-09-29

    Hippocampal sclerosis (HS) is the most common surgical pathology associated with mesial temporal lobe epilepsy (MTLE). HS is typically characterized by mossy fiber sprouting (MFS) and reorganization of neuropeptide Y (NPY) fiber networks in the dentate gyrus. One potential cause of postoperative seizure recurrence following temporal lobe surgery may be the presence of seizure-associated bilateral hippocampal damage. We aimed to investigate patterns of hippocampal abnormalities in a postmortem series as identified by NPY and dynorphin immunohistochemistry. Analysis of dentate gyrus fiber reorganization, using dynorphin (to demonstrate MFS) and NPY immunohistochemistry, was carried out in a postmortem epilepsy series of 25 cases (age range 21-96 years). In 9 patients, previously refractory seizures had become well controlled for up to 34 years prior to death. Bilateral MFS or abnormal NPY patterns were seen in 15 patients including those with bilateral symmetric, asymmetric, and unilateral HS by conventional histologic criteria. MFS and NPY reorganization was present in all classical HS cases, more variably in atypical HS, present in both MTLE and non-MTLE syndromes and with seizure histories of up to 92 years, despite seizure remission in some patients. Synaptic reorganization in the dentate gyrus may be a bilateral, persistent process in epilepsy. It is unlikely to be sufficient to generate seizures and more likely to represent a seizure-induced phenomenon.

  9. Parkia biglobosa Improves Mitochondrial Functioning and Protects against Neurotoxic Agents in Rat Brain Hippocampal Slices

    Directory of Open Access Journals (Sweden)

    Kayode Komolafe

    2014-01-01

    Full Text Available Objective. Methanolic leaf extracts of Parkia biglobosa, PBE, and one of its major polyphenolic constituents, catechin, were investigated for their protective effects against neurotoxicity induced by different agents on rat brain hippocampal slices and isolated mitochondria. Methods. Hippocampal slices were preincubated with PBE (25, 50, 100, or 200 µg/mL or catechin (1, 5, or 10 µg/mL for 30 min followed by further incubation with 300 µM H2O2, 300 µM SNP, or 200 µM PbCl2 for 1 h. Effects of PBE and catechin on SNP- or CaCl2-induced brain mitochondrial ROS formation and mitochondrial membrane potential (ΔΨm were also determined. Results. PBE and catechin decreased basal ROS generation in slices and blunted the prooxidant effects of neurotoxicants on membrane lipid peroxidation and nonprotein thiol contents. PBE rescued hippocampal cellular viability from SNP damage and caused a significant boost in hippocampus Na+, K+-ATPase activity but with no effect on the acetylcholinesterase activity. Both PBE and catechin also mitigated SNP- or CaCl2-dependent mitochondrial ROS generation. Measurement by safranine fluorescence however showed that the mild depolarization of the ΔΨm by PBE was independent of catechin. Conclusion. The results suggest that the neuroprotective effect of PBE is dependent on its constituent antioxidants and mild mitochondrial depolarization propensity.

  10. Memory-related hippocampal functioning in ecstasy and amphetamine users: a prospective fMRI study.

    Science.gov (United States)

    Becker, Benjamin; Wagner, Daniel; Koester, Philip; Bender, Katja; Kabbasch, Christoph; Gouzoulis-Mayfrank, Euphrosyne; Daumann, Jörg

    2013-02-01

    Recreational use of ecstasy (3,4-methylenedioxymethamphetamine [MDMA]) has been associated with memory impairments. Functional neuroimaging studies with cross-sectional designs reported altered memory-related hippocampal functioning in ecstasy-polydrug users. However, differences might be pre-existing or related to the concomitant use of amphetamine. To prospectively investigate the specific effects of ecstasy on memory-related hippocampal functioning. We used an associative memory task and functional magnetic resonance imaging (fMRI) in 40 ecstasy and/or amphetamine users at baseline (t1) and after 12 months (t2). At t1, all subjects had very limited amphetamine and/or ecstasy experience (less than 5 units lifetime dose). Based on the reported drug use at t2, subjects with continued ecstasy and/or amphetamine use (n = 17) were compared to subjects who stopped use after t1 (n = 12). Analysis of repeated measures revealed that encoding-related activity in the left parahippocampal gyrus changed differentially between the groups. Activity in this region increased in abstinent subjects from t1 to t2, however, decreased in subjects with continued use. Decreases within the left parahippocampal gyrus were associated with the use of ecstasy, but not amphetamine, during the follow-up period. However, there were no significant differences in memory performance. The current findings suggest specific effects of ecstasy use on memory-related hippocampal functioning. However, alternative explanations such as (sub-)acute cannabis effects are conceivable.

  11. Neonatal hypoxia, hippocampal atrophy, and memory impairment: evidence of a causal sequence.

    Science.gov (United States)

    Cooper, Janine M; Gadian, David G; Jentschke, Sebastian; Goldman, Allan; Munoz, Monica; Pitts, Georgia; Banks, Tina; Chong, W Kling; Hoskote, Aparna; Deanfield, John; Baldeweg, Torsten; de Haan, Michelle; Mishkin, Mortimer; Vargha-Khadem, Faraneh

    2015-06-01

    Neonates treated for acute respiratory failure experience episodes of hypoxia. The hippocampus, a structure essential for memory, is particularly vulnerable to such insults. Hence, some neonates undergoing treatment for acute respiratory failure might sustain bilateral hippocampal pathology early in life and memory problems later in childhood. We investigated this possibility in a cohort of 40 children who had been treated neonatally for acute respiratory failure but were free of overt neurological impairment. The cohort had mean hippocampal volumes (HVs) significantly below normal control values, memory scores significantly below the standard population means, and memory quotients significantly below those predicted by their full scale IQs. Brain white matter volume also fell below the volume of the controls, but brain gray matter volumes and scores on nonmnemonic neuropsychological tests were within the normal range. Stepwise linear regression models revealed that the cohort's HVs were predictive of degree of memory impairment, and gestational age at treatment was predictive of HVs: the younger the age, the greater the atrophy. We conclude that many neonates treated for acute respiratory failure sustain significant hippocampal atrophy as a result of the associated hypoxia and, consequently, show deficient memory later in life. © The Author 2013. Published by Oxford University Press.

  12. Aerobic fitness relates to learning on a virtual morris water task and hippocampal volume in adolescents

    Science.gov (United States)

    Herting, Megan M.; Nagel, Bonnie J.

    2012-01-01

    In rodents, exercise increases hippocampal neurogenesis and allows for better learning and memory performance on water maze tasks. While exercise has also been shown to be beneficial for the brain and behavior in humans, no study has examined how exercise impacts spatial learning using a directly translational water maze task, or if these relationships exist during adolescence – a developmental period which the animal literature has shown to be especially vulnerable to exercise effects. In this study, we investigated the influence of aerobic fitness on hippocampal size and subsequent learning and memory, including visuospatial memory using a human analogue of the Morris Water Task, in 34 adolescents. Results showed that higher aerobic fitness predicted better learning on the virtual Morris Water Task and larger hippocampal volumes. No relationship between virtual Morris Water Task memory recall and aerobic fitness was detected. Aerobic fitness, however, did not relate to global brain volume, or verbal learning, which might suggest some specificity of the influence of aerobic fitness on the adolescent brain. This study provides a direct translational approach to the existing animal literature on exercise, as well as adds to the sparse research that exists on how aerobic exercise impacts the developing human brain and memory. PMID:22610054

  13. Concentration-dependent effects of fullerenol on cultured hippocampal neuron viability

    Directory of Open Access Journals (Sweden)

    Zha YY

    2012-06-01

    Full Text Available Ying-ying Zha,1 Bo Yang,1 Ming-liang Tang,2 Qiu-chen Guo,1 Ju-tao Chen,1 Long-ping Wen,3 Ming Wang11CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, University of Science and Technology of China, Hefei, 2Suzhou Institute of NanoTech and NanoBionics, Chinese Academy of Sciences, Suzhou, 3Laboratory of Nano-biology, School of Life Sciences, University of Science and Technology of China, Hefei, People's Republic of ChinaBackground: Recent studies have shown that the biological actions and toxicity of the water-soluble compound, polyhydroxyfullerene (fullerenol, are related to the concentrations present at a particular site of action. This study investigated the effects of different concentrations of fullerenol on cultured rat hippocampal neurons.Methods and results: Fullerenol at low concentrations significantly enhanced hippocampal neuron viability as tested by MTT assay and Hoechst 33342/propidium iodide double stain detection. At high concentrations, fullerenol induced apoptosis confirmed by Comet assay and assessment of caspase proteins.Conclusion: These findings suggest that fullerenol promotes cell death and protects against cell damage, depending on the concentration present. The concentration-dependent effects of fullerenol were mainly due to its influence on the reduction-oxidation pathway.Keywords: fullerenol, nanomaterial, neurotoxicity, neuroprotection, hippocampal neuron

  14. Hippocampal NMDA receptors are involved in rats' spontaneous object recognition only under high memory load condition.

    Science.gov (United States)

    Sugita, Manami; Yamada, Kazuo; Iguchi, Natsumi; Ichitani, Yukio

    2015-10-22

    The possible involvement of hippocampal N-methyl-D-aspartate (NMDA) receptors in spontaneous object recognition was investigated in rats under different memory load conditions. We first estimated rats' object memory span using 3-5 objects in "Different Objects Task (DOT)" in order to confirm the highest memory load condition in object recognition memory. Rats were allowed to explore a field in which 3 (3-DOT), 4 (4-DOT), or 5 (5-DOT) different objects were presented. After a delay period, they were placed again in the same field in which one of the sample objects was replaced by another object, and their object exploration behavior was analyzed. Rats could differentiate the novel object from the familiar ones in 3-DOT and 4-DOT but not in 5-DOT, suggesting that rats' object memory span was about 4. Then, we examined the effects of hippocampal AP5 infusion on performance in both 2-DOT (2 different objects were used) and 4-DOT. The drug treatment before the sample phase impaired performance only in 4-DOT. These results suggest that hippocampal NMDA receptors play a critical role in spontaneous object recognition only when the memory load is high. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. A mental retardation gene, motopsin/neurotrypsin/prss12, modulates hippocampal function and social interaction.

    Science.gov (United States)

    Mitsui, Shinichi; Osako, Yoji; Yokoi, Fumiaki; Dang, Mai T; Yuri, Kazunari; Li, Yuqing; Yamaguchi, Nozomi

    2009-12-01

    Motopsin is a mosaic serine protease secreted from neuronal cells in various brain regions, including the hippocampus. The loss of motopsin function causes nonsyndromic mental retardation in humans and impairs long-term memory formation in Drosophila. To understand motopsin's function in the mammalian brain, motopsin knockout (KO) mice were generated. Motopsin KO mice did not have significant deficits in memory formation, as tested using the Morris water maze, passive avoidance and Y-maze tests. A social recognition test showed that the motopsin KO mice had the ability to recognize two stimulator mice, suggesting normal social memory. In a social novelty test, motopsin KO mice spent a longer time investigating a familiar mouse than wild-type (WT) mice did. In a resident-intruder test, motopsin KO mice showed prolonged social interaction as compared with WT mice. Consistent with the behavioral deficit, spine density was significantly decreased on apical dendrites, but not on basal dendrites, of hippocampal pyramidal neurons of motopsin KO mice. In contrast, pyramidal neurons at the cingulate cortex showed normal spine density. Spatial learning and social interaction induced the phosphorylation of cAMP-responsive element-binding protein (CREB) in hippocampal neurons of WT mice, whereas the phosphorylation of CREB was markedly decreased in mutant mouse brains. Our results indicate that an extracellular protease, motopsin, preferentially affects social behaviors, and modulates the functions of hippocampal neurons.

  16. Accelerated Age-Dependent Hippocampal Volume Loss in Parkinson Disease With Mild Cognitive Impairment.

    Science.gov (United States)

    Schneider, Christine B; Donix, Markus; Linse, Katharina; Werner, Annett; Fauser, Mareike; Klingelhoefer, Lisa; Löhle, Matthias; von Kummer, Rüdiger; Reichmann, Heinz; Storch, Alexander

    2017-09-01

    Patients with Parkinson disease are at high risk of developing dementia. During the course of the disease, a substantial number of patients will experience a cognitive decline, indicating the dynamics of the underlying neuropathology. Magnetic resonance imaging (MRI) has become increasingly useful for identifying structural characteristics in radiological brain anatomy existing prior to clinical symptoms. Whether these changes reflect pathology, whether they are aging related, or both often remains unclear. We hypothesized that aging-associated brain structural changes would be more pronounced in the hippocampal region among patients with Parkinson disease having mild cognitive deficits relative to cognitively unimpaired patients. Using MRI, we investigated 30 cognitively healthy patients with Parkinson disease and 33 patients with nondemented Parkinson disease having mild cognitive impairment. All participants underwent structural MRI scanning and extensive clinical and neuropsychological assessments. Irrespective of the study participants' cognitive status, older age was associated with reduced cortical thickness in various neocortical regions. Having mild cognitive impairment was not associated with an increased rate of cortical thinning or volume loss in these regions, except in the hippocampus bilaterally. Patients with Parkinson disease having mild cognitive impairment show an accelerated age-dependent hippocampal volume loss when compared with cognitively healthy patients with Parkinson disease. This may indicate pathological processes in a key region for memory functioning in patients with Parkinson disease at risk of developing dementia. Structural MRI of the hippocampal region could potentially contribute to identifying patients who should receive early treatment aimed at delaying the clinical onset of dementia.

  17. Subcellular localization of Patched and Smoothened, the receptors for Sonic hedgehog signaling, in the hippocampal neuron.

    Science.gov (United States)

    Petralia, Ronald S; Schwartz, Catherine M; Wang, Ya-Xian; Mattson, Mark P; Yao, Pamela J

    2011-12-15

    Cumulative evidence suggests that, aside from patterning the embryonic neural tube, Sonic hedgehog (Shh) signaling plays important roles in the mature nervous system. In this study, we investigate the expression and localization of the Shh signaling receptors, Patched (Ptch) and Smoothened (Smo), in the hippocampal neurons of young and mature rats. Reverse transcriptase-polymerase chain reaction and immunoblotting analyses show that the expression of Ptch and Smo remains at a moderate level in young postnatal and adult brains. By using immunofluorescence light microscopy and immunoelectron microscopy, we examine the spatial distribution of Ptch and Smo within the hippocampal neurons. In young developing neurons, Ptch and Smo are present in the processes and are clustered at their growth cones. In mature neurons, Ptch and Smo are concentrated in dendrites, spines, and postsynaptic sites. Synaptic Ptch and Smo often co-exist with unusual structures-synaptic spinules and autophagosomes. Our results reveal the anatomical organization of the Shh receptors within both the young and the mature hippocampal neurons. Copyright © 2011 Wiley-Liss, Inc.

  18. Aerobic fitness relates to learning on a virtual Morris Water Task and hippocampal volume in adolescents.

    Science.gov (United States)

    Herting, Megan M; Nagel, Bonnie J

    2012-08-01

    In rodents, exercise increases hippocampal neurogenesis and allows for better learning and memory performance on water maze tasks. While exercise has also been shown to be beneficial for the brain and behavior in humans, no study has examined how exercise impacts spatial learning using a directly translational water maze task, or if these relationships exist during adolescence--a developmental period which the animal literature has shown to be especially vulnerable to exercise effects. In this study, we investigated the influence of aerobic fitness on hippocampal size and subsequent learning and memory, including visuospatial memory using a human analogue of the Morris Water Task, in 34 adolescents. Results showed that higher aerobic fitness predicted better learning on the virtual Morris Water Task and larger hippocampal volumes. No relationship between virtual Morris Water Task memory recall and aerobic fitness was detected. Aerobic fitness, however, did not relate to global brain volume or verbal learning, which might suggest some specificity of the influence of aerobic fitness on the adolescent brain. This study provides a direct translational approach to the existing animal literature on exercise, as well as adds to the sparse research that exists on how aerobic exercise impacts the developing human brain and memory. Published by Elsevier B.V.

  19. Isoflurane induced cognitive impairment in aged rats through hippocampal calcineurin/NFAT signaling

    Energy Technology Data Exchange (ETDEWEB)

    Ni, Cheng; Li, Zhengqian; Qian, Min; Zhou, Yang; Wang, Jun; Guo, Xiangyang, E-mail: puthmzk@163.com

    2015-05-15

    Calcineurin (CaN) over-activation constrains synaptic plasticity and memory formation. Upon CaN activation, NFAT imports into the nucleus and guides its downstream genes, which also affect neuronal and synaptic function. Aberrant CaN/NFAT signaling involves in neurotoxicity and cognitive impairment in neurological disorders such as Alzheimer's disease, but its role in postoperative cognitive dysfunction (POCD) remains uninvestigated. Inhaled anesthetic isoflurane facilitates the development of POCD, and the present study investigated the role of CaN/NFAT signaling in isoflurane induced cognitive impairment of aged rats, and the therapeutic effects of CaN inhibitor cyclosporine A (CsA). The results indicated that hippocampal CaN activity increased and peaked at 6 h after isoflurane exposure, and NFAT, especially NFATc4, imported into the nucleus following CaN activation. Furthermore, phamacological inhibition of CaN by CsA markedly attenuated isoflurane induced aberrant CaN/NFATc4 signaling in the hippocampus, and rescued relevant spatial learning and memory impairment of aged rats. Overall, the study suggests hippocampal CaN/NFAT signaling as the upstream mechanism of isoflurane induced cognitive impairment, and provides potential therapeutic target and possible treatment methods for POCD. - Highlights: • Isoflurane induces hippocampal calcineurin activation. • Isoflurane induces hippocampal NFAT, especially NFATc4, nuclear import. • Cyclosporine A attenuates isoflurane induced aberrant calcineurin/NFAT signaling. • Cyclosporine A rescues isoflurane induced cognitive impairment. • Calcineurin/NFAT signaling is the upstream mechanism of isoflurane induced synaptic dysfunction and cognitive impairment.

  20. Estrogen administration modulates hippocampal GABAergic subpopulations in the hippocampus of trimethyltin-treated rats

    Directory of Open Access Journals (Sweden)

    Valentina eCorvino

    2015-11-01

    Full Text Available Given the well-documented involvement of estrogens in the modulation of hippocampal functions in both physiological and pathological conditions, the present study investigates the effects of 17-beta estradiol (E2 administration in the rat model of hippocampal neurodegeneration induced by trimethyltin (TMT administration (8mg/kg, characterized by loss of pyramidal neurons in CA1, CA3/hilus hippocampal subfields associated with astroglial and microglial activation, seizures and cognitive impairment. After TMT/saline treatment, ovariectomized animals received two doses of E2 (0.2 mg/kg i.p. or vehicle, and were sacrificed 48h or 7 days after TMT-treatment. Our results indicate that in TMT-treated animals E2 administration induces the early (48h upregulation of genes involved in neuroprotection and synaptogenesis, namely Bcl2, trkB, Cadherin and cyclin-dependent-kinase-5. Increased expression levels of glutamic acid decarboxylase (gad 67, neuropeptide Y (Npy, parvalbumin , Pgc-1α and Sirtuin 1genes, the latter involved in parvalbumin (PV synthesis, were also evident. Unbiased stereology performed on rats sacrificed 7 days after TMT treatment showed that although E2 does not significantly influence the extent of TMT-induced neuronal death, significantly enhances the TMT-induced modulation of GABAergic interneuron population size in selected hippocampal subfields. In particular, E2 administration causes, in TMT treated rats, a significant increase in the number of GAD67-expressing interneurons in CA1 stratum oriens, CA3 pyramidal layer, hilus and dentate gyrus, accompanied by a parallel increase in NPY-expressing cells, essentially in the same regions, and of PV-positive cells in CA1 pyramidal layer. The present results add information concerning the role of in vivo E2 administration on mechanisms involved in cellular plasticity in the adult brain.

  1. The influence of cold temperature on cellular excitability of hippocampal networks.

    Science.gov (United States)

    de la Peña, Elvira; Mälkiä, Annika; Vara, Hugo; Caires, Rebeca; Ballesta, Juan J; Belmonte, Carlos; Viana, Felix

    2012-01-01

    The hippocampus plays an important role in short term memory, learning and spatial navigation. A characteristic feature of the hippocampal region is its expression of different electrical population rhythms and activities during different brain states. Physiological fluctuations in brain temperature affect the activity patterns in hippocampus, but the underlying cellular mechanisms are poorly understood. In this work, we investigated the thermal modulation of hippocampal activity at the cellular network level. Primary cell cultures of mouse E17 hippocampus displayed robust network activation upon light cooling of the extracellular solution from baseline physiological temperatures. The activity generated was dependent on action potential firing and excitatory glutamatergic synaptic transmission. Involvement of thermosensitive channels from the transient receptor potential (TRP) family in network activation by temperature changes was ruled out, whereas pharmacological and immunochemical experiments strongly pointed towards the involvement of temperature-sensitive two-pore-domain potassium channels (K(2P)), TREK/TRAAK family. In hippocampal slices we could show an increase in evoked and spontaneous synaptic activity produced by mild cooling in the physiological range that was prevented by chloroform, a K(2P) channel opener. We propose that cold-induced closure of background TREK/TRAAK family channels increases the excitability of some hippocampal neurons, acting as a temperature-sensitive gate of network activation. Our findings in the hippocampus open the possibility that small temperature variations in the brain in vivo, associated with metabolism or blood flow oscillations, act as a switch mechanism of neuronal activity and determination of firing patterns through regulation of thermosensitive background potassium channel activity.

  2. Involvement of hippocampal NMDA receptors in retrieval of spontaneous object recognition memory in rats.

    Science.gov (United States)

    Iwamura, Etsushi; Yamada, Kazuo; Ichitani, Yukio

    2016-07-01

    The involvement of hippocampal N-methyl-d-aspartate (NMDA) receptors in the retrieval process of spontaneous object recognition memory was investigated. The spontaneous object recognition test consisted of three phases. In the sample phase, rats were exposed to two identical objects several (2-5) times in the arena. After the sample phase, various lengths of delay intervals (24h-6 weeks) were inserted (delay phase). In the test phase in which both the familiar and the novel objects were placed in the arena, rats' novel object exploration behavior under the hippocampal treatment of NMDA receptor antagonist, AP5, or vehicle was observed. With 5 exposure sessions in the sample phase (experiment 1), AP5 treatment in the test phase significantly decreased discrimination ratio when the delay was 3 weeks but not when it was one week. On the other hand, with 2 exposure sessions in the sample phase (experiment 2) in which even vehicle-injected control animals could not discriminate the novel object from the familiar one with a 3 week delay, AP5 treatment significantly decreased discrimination ratio when the delay was one week, but not when it was 24h. Additional experiment (experiment 3) showed that the hippocampal treatment of an α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist, NBQX, decreased discrimination ratio with all delay intervals tested (24h-3 weeks). Results suggest that hippocampal NMDA receptors play an important role in the retrieval of spontaneous object recognition memory especially when the memory trace weakens. Copyright © 2016. Published by Elsevier B.V.

  3. Isoflurane induced cognitive impairment in aged rats through hippocampal calcineurin/NFAT signaling

    International Nuclear Information System (INIS)

    Ni, Cheng; Li, Zhengqian; Qian, Min; Zhou, Yang; Wang, Jun; Guo, Xiangyang

    2015-01-01

    Calcineurin (CaN) over-activation constrains synaptic plasticity and memory formation. Upon CaN activation, NFAT imports into the nucleus and guides its downstream genes, which also affect neuronal and synaptic function. Aberrant CaN/NFAT signaling involves in neurotoxicity and cognitive impairment in neurological disorders such as Alzheimer's disease, but its role in postoperative cognitive dysfunction (POCD) remains uninvestigated. Inhaled anesthetic isoflurane facilitates the development of POCD, and the present study investigated the role of CaN/NFAT signaling in isoflurane induced cognitive impairment of aged rats, and the therapeutic effects of CaN inhibitor cyclosporine A (CsA). The results indicated that hippocampal CaN activity increased and peaked at 6 h after isoflurane exposure, and NFAT, especially NFATc4, imported into the nucleus following CaN activation. Furthermore, phamacological inhibition of CaN by CsA markedly attenuated isoflurane induced aberrant CaN/NFATc4 signaling in the hippocampus, and rescued relevant spatial learning and memory impairment of aged rats. Overall, the study suggests hippocampal CaN/NFAT signaling as the upstream mechanism of isoflurane induced cognitive impairment, and provides potential therapeutic target and possible treatment methods for POCD. - Highlights: • Isoflurane induces hippocampal calcineurin activation. • Isoflurane induces hippocampal NFAT, especially NFATc4, nuclear import. • Cyclosporine A attenuates isoflurane induced aberrant calcineurin/NFAT signaling. • Cyclosporine A rescues isoflurane induced cognitive impairment. • Calcineurin/NFAT signaling is the upstream mechanism of isoflurane induced synaptic dysfunction and cognitive impairment

  4. Focal CA3 hippocampal subfield atrophy following LGI1 VGKC-complex antibody limbic encephalitis.

    Science.gov (United States)

    Miller, Thomas D; Chong, Trevor T-J; Aimola Davies, Anne M; Ng, Tammy W C; Johnson, Michael R; Irani, Sarosh R; Vincent, Angela; Husain, Masud; Jacob, Saiju; Maddison, Paul; Kennard, Christopher; Gowland, Penny A; Rosenthal, Clive R

    2017-05-01

    Magnetic resonance imaging has linked chronic voltage-gated potassium channel (VGKC) complex antibody-mediated limbic encephalitis with generalized hippocampal atrophy. However, autoantibodies bind to specific rodent hippocampal subfields. Here, human hippocampal subfield (subiculum, cornu ammonis 1-3, and dentate gyrus) targets of immunomodulation-treated LGI1 VGKC-complex antibody-mediated limbic encephalitis were investigated using in vivo ultra-high resolution (0.39 × 0.39 × 1.0 mm3) 7.0 T magnetic resonance imaging [n = 18 patients, 17 patients (94%) positive for LGI1 antibody and one patient negative for LGI1/CASPR2 but positive for VGKC-complex antibodies, mean age: 64.0 ± 2.55 years, median 4 years post-limbic encephalitis onset; n = 18 controls]. First, hippocampal subfield quantitative morphometry indicated significant volume loss confined to bilateral CA3 [F(1,34) = 16.87, P 3 months from symptom onset) were associated with CA3 atrophy. Third, whole-brain voxel-by-voxel morphometry revealed no significant grey matter loss. Fourth, CA3 subfield atrophy was associated with severe episodic but not semantic amnesia for postmorbid autobiographical events that was predicted by variability in CA3 volume. The results raise important questions about the links with histopathology, the impact of the observed focal atrophy on other CA3-mediated reconstructive and episodic mechanisms, and the role of potential antibody-mediated pathogenicity as part of the pathophysiology cascade in humans. © The Author (2017). Published by Oxford University Press on behalf of the Guarantors of Brain.

  5. Short-term sleep deprivation stimulates hippocampal neurogenesis in rats following global cerebral ischemia/reperfusion.

    Directory of Open Access Journals (Sweden)

    Oumei Cheng

    Full Text Available Sleep deprivation (SD plays a complex role in central nervous system (CNS diseases. Recent studies indicate that short-term SD can affect the extent of ischemic damage. The aim of this study was to investigate whether short-term SD could stimulate hippocampal neurogenesis in a rat model of global cerebral ischemia/reperfusion (GCIR.One hundred Sprague-Dawley rats were randomly divided into Sham, GCIR and short-term SD groups based on different durations of SD; the short-term SD group was randomly divided into three subgroups: the GCIR+6hSD*3d-treated, GCIR+12hSD-treated and GCIR+12hSD*3d-treated groups. The GCIR rat model was induced via the bilateral occlusion of the common carotid arteries and hemorrhagic hypotension. The rats were sleep-deprived starting at 48 h following GCIR. A Morris water maze test was used to assess learning and memory ability; cell proliferation and differentiation were analyzed via 5-bromodeoxyuridine (BrdU and neuron-specific enolase (NSE, respectively, at 14 and 28 d; the expression of hippocampal BDNF was measured after 7 d.The different durations of short-term SD designed in our experiment exhibited improvement in cognitive function as well as increased hippocampal BDNF expression. Additionally, the short-term SD groups also showed an increased number of BrdU- and BrdU/NSE-positive cells compared with the GCIR group. Of the three short-term SD groups, the GCIR+12hSD*3d-treated group experienced the most substantial beneficial effects.Short-term SD, especially the GCIR+12hSD*3d-treated method, stimulates neurogenesis in the hippocampal dentate gyrus (DG of rats that undergo GCIR, and BDNF may be an underlying mechanism in this process.

  6. SHARP: A multi-mission artificial intelligence system for spacecraft telemetry monitoring and diagnosis

    Science.gov (United States)

    Lawson, Denise L.; James, Mark L.

    1989-01-01

    The Spacecraft Health Automated Reasoning Prototype (SHARP) is a system designed to demonstrate automated health and status analysis for multi-mission spacecraft and ground data systems operations. Telecommunications link analysis of the Voyager 2 spacecraft is the initial focus for the SHARP system demonstration which will occur during Voyager's encounter with the planet Neptune in August, 1989, in parallel with real time Voyager operations. The SHARP system combines conventional computer science methodologies with artificial intelligence techniques to produce an effective method for detecting and analyzing potential spacecraft and ground systems problems. The system performs real time analysis of spacecraft and other related telemetry, and is also capable of examining data in historical context. A brief introduction is given to the spacecraft and ground systems monitoring process at the Jet Propulsion Laboratory. The current method of operation for monitoring the Voyager Telecommunications subsystem is described, and the difficulties associated with the existing technology are highlighted. The approach taken in the SHARP system to overcome the current limitations is also described, as well as both the conventional and artificial intelligence solutions developed in SHARP.

  7. SHARP: A multi-mission AI system for spacecraft telemetry monitoring and diagnosis

    Science.gov (United States)

    Lawson, Denise L.; James, Mark L.

    1989-01-01

    The Spacecraft Health Automated Reasoning Prototype (SHARP) is a system designed to demonstrate automated health and status analysis for multi-mission spacecraft and ground data systems operations. Telecommunications link analysis of the Voyager II spacecraft is the initial focus for the SHARP system demonstration which will occur during Voyager's encounter with the planet Neptune in August, 1989, in parallel with real-time Voyager operations. The SHARP system combines conventional computer science methodologies with artificial intelligence techniques to produce an effective method for detecting and analyzing potential spacecraft and ground systems problems. The system performs real-time analysis of spacecraft and other related telemetry, and is also capable of examining data in historical context. A brief introduction is given to the spacecraft and ground systems monitoring process at the Jet Propulsion Laboratory. The current method of operation for monitoring the Voyager Telecommunications subsystem is described, and the difficulties associated with the existing technology are highlighted. The approach taken in the SHARP system to overcome the current limitations is also described, as well as both the conventional and artificial intelligence solutions developed in SHARP.

  8. Consideration of vision and picture quality: psychological effects induced by picture sharpness

    Science.gov (United States)

    Kusaka, Hideo

    1989-08-01

    A psychological hierarchy model of human vision(1)(2) suggests that the visual signals are processed in a serial manner from lower to higher stages: that is "sensation" - "perception" - "emotion." For designing a future television system, it is important to find out what kinds of physical factors affect the "emotion" experienced by an observer in front of the display. This paper describes the psychological effects induced by the sharpness of the picture. The subjective picture quality was evaluated for the same pictures with five different levels of sharpness. The experiment was performed on two kinds of printed pictures: (A) a woman's face, and (B) a town corner. From these experiments, it was found that the amount of high-frequency peaking (physical value of the sharpness) which psychologically gives the best picture quality, differs between pictures (A) and (B). That is, the optimum picture sharpness differs depending on the picture content. From these results, we have concluded that the psychophysical sharpness of the picture is not only determined at the stage of "perception" (e.g., resolution or signal to noise ratio, which everyone can judge immediately), but also at the stage of "emotion" (e.g., sensation of reality or beauty).

  9. Objective assessment of knife sharpness over a working day cutting meat.

    Science.gov (United States)

    Savescu, Adriana; Cuny-Guerrier, Aude; Wild, Pascal; Reno, Gilles; Aublet-Cuvelier, Agnès; Claudon, Laurent

    2018-04-01

    Knife sharpness is one of multiple factors involved in musculoskeletal disorders in industrial meat cutting. The aim of this study was to objectively evaluate, in real working situations, how knife sharpness changed over a working day cutting meat, and to analyse the impact of sharpening, steeling and meat-cutting activities on these variations. Twenty-two meat-cutting workers from three different companies participated in the study. The methods included measurements of knife sharpness in relation to real work situations and consideration of the way meat-cutting and sharpening operations were organised. Results showed that the type of meat-cutting activities, the steeling strategy adopted by the worker, including the types of tool used, and the overall organisation of the sharpening task all had a significant influence on how knife sharpness evolved over a 2-h period and over an entire working day. To improve MSD prevention, sharpening and steeling operations should not be considered as independent activities, but taken into account as a continuity of working actions. Appropriate assessment of knife sharpness by meat cutters affects how they organise meat-cutting and sharpening tasks. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Hippocampal damage and memory impairment in congenital cyanotic heart disease.

    Science.gov (United States)

    Muñoz-López, Mónica; Hoskote, Aparna; Chadwick, Martin J; Dzieciol, Anna M; Gadian, David G; Chong, Kling; Banks, Tina; de Haan, Michelle; Baldeweg, Torsten; Mishkin, Mortimer; Vargha-Khadem, Faraneh

    2017-04-01

    Neonatal hypoxia can lead to hippocampal atrophy, which can lead, in turn, to memory impairment. To test the generalizability of this causal sequence, we examined a cohort of 41 children aged 8-16, who, having received the arterial switch operation to correct for transposition of the great arteries, had sustained significant neonatal cyanosis but were otherwise neurodevelopmentally normal. As predicted, the cohort had significant bilateral reduction of hippocampal volumes relative to the volumes of 64 normal controls. They also had significant, yet selective, impairment of episodic memory as measured by standard tests of memory, despite relatively normal levels of intelligence, academic attainment, and verbal fluency. Across the cohort, degree of memory impairment was correlated with degree of hippocampal atrophy suggesting that even as early as neonatal life no other structure can fully compensate for hippocampal injury and its special role in serving episodic long term memory. © 2017 Wiley Periodicals, Inc. © 2017 The Authors. Hippocampus Published by Wiley Periodicals, Inc.

  11. Extent of hippocampal atrophy predicts degree of deficit in recall.

    Science.gov (United States)

    Patai, Eva Zita; Gadian, David G; Cooper, Janine M; Dzieciol, Anna M; Mishkin, Mortimer; Vargha-Khadem, Faraneh

    2015-10-13

    Which specific memory functions are dependent on the hippocampus is still debated. The availability of a large cohort of patients who had sustained relatively selective hippocampal damage early in life enabled us to determine which type of mnemonic deficit showed a correlation with extent of hippocampal injury. We assessed our patient cohort on a test that provides measures of recognition and recall that are equated for difficulty and found that the patients' performance on the recall tests correlated significantly with their hippocampal volumes, whereas their performance on the equally difficult recognition tests did not and, indeed, was largely unaffected regardless of extent of hippocampal atrophy. The results provide new evidence in favor of the view that the hippocampus is essential for recall but not for recognition.

  12. DEVELOPMENTAL HYPOTHYROIDISM IMPAIRS HIPPOCAMPAL LEARNING AND SYNAPTIC TRANSMISSION IN VIVO.

    Science.gov (United States)

    A number of environmental chemicals have been reported to alter thyroid hormone (TH) function. It is well established that severe hypothyroidism during critical periods of brain development leads to alterations in hippocampal structure and learning deficits, yet evaluation of ...

  13. Erythropoietin enhances hippocampal response during memory retrieval in humans

    DEFF Research Database (Denmark)

    Miskowiak, Kamilla; O'Sullivan, Ursula; Harmer, Catherine J

    2007-01-01

    Although erythropoietin (Epo) is best known for its effects on erythropoiesis, recent evidence suggests that it also has neurotrophic and neuroprotective properties in animal models of hippocampal function. Such an action in humans would make it an intriguing novel compound for the treatment....... This is consistent with upregulation of hippocampal BDNF and neurotrophic actions found in animals and highlights Epo as a promising candidate for treatment of psychiatric disorders....

  14. Damage of hippocampal neurons in rats with chronic alcoholism

    OpenAIRE

    Du, Ailin; Jiang, Hongbo; Xu, Lei; An, Na; Liu, Hui; Li, Yinsheng; Zhang, Ruiling

    2014-01-01

    Chronic alcoholism can damage the cytoskeleton and aggravate neurological deficits. However, the effect of chronic alcoholism on hippocampal neurons remains unclear. In this study, a model of chronic alcoholism was established in rats that were fed with 6% alcohol for 42 days. Endogenous hydrogen sulfide content and cystathionine-beta-synthase activity in the hippocampus of rats with chronic alcoholism were significantly increased, while F-actin expression was decreased. Hippocampal neurons i...

  15. The effects of hormones and physical exercise on hippocampal structural plasticity.

    Science.gov (United States)

    Triviño-Paredes, Juan; Patten, Anna R; Gil-Mohapel, Joana; Christie, Brian R

    2016-04-01

    The hippocampus plays an integral role in certain aspects of cognition. Hippocampal structural plasticity and in particular adult hippocampal neurogenesis can be influenced by several intrinsic and extrinsic factors. Here we review how hormones (i.e., intrinsic modulators) and physical exercise (i.e., an extrinsic modulator) can differentially modulate hippocampal plasticity in general and adult hippocampal neurogenesis in particular. Specifically, we provide an overview of the effects of sex hormones, stress hormones, and metabolic hormones on hippocampal structural plasticity and adult hippocampal neurogenesis. In addition, we also discuss how physical exercise modulates these forms of hippocampal plasticity, giving particular emphasis on how this modulation can be affected by variables such as exercise regime, duration, and intensity. Understanding the neurobiological mechanisms underlying the modulation of hippocampal structural plasticity by intrinsic and extrinsic factors will impact the design of new therapeutic approaches aimed at restoring hippocampal plasticity following brain injury or neurodegeneration. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Hippocampal lesions, contextual retrieval, and autoshaping in pigeons.

    Science.gov (United States)

    Richmond, Jenny; Colombo, Michael

    2002-02-22

    Both pigeons and rats with damage to the hippocampus are slow to acquire an autoshaped response and emit fewer overall responses than control animals. Experiment 1 explored the possibility that the autoshaping deficit was due to an impairment in contextual retrieval. Pigeons were trained for 14 days on an autoshaping task in which a red stimulus was followed by reinforcement in context A, and a green stimulus was followed by reinforcement in context B. On day 15, the subjects were given a context test in which the red and green stimuli were presented simultaneously in context A and then later in context B. Both control and hippocampal animals showed context specificity, that is, they responded more to the red stimulus in context A and to the green stimulus in context B. In Experiment 2 we video-recorded the control and hippocampal animals performing the autoshaping task. Hippocampal animals tended to miss-peck the key more often than control animals. In addition, the number of missed pecks increased across days for hippocampal animals but not for control animals, suggesting that while the control animals increased their pecking accuracy, the hippocampal animals actually decreased their pecking accuracy. Our findings suggest that impairments in moving through space may underlie the hippocampal autoshaping deficit.

  17. Influence of phase transformations on the asymptotic residual stress distribution arising near a sharp V-notch tip

    International Nuclear Information System (INIS)

    Ferro, P

    2012-01-01

    In this work, the residual stress distribution induced by the solidification and cooling of a fusion zone in the vicinity of a sharp V-notch tip is investigated. The intensity of the residual asymptotic stress fields, quantified by the notch stress intensity factors, was studied for two different V-notch specimen geometries under generalized plane-strain conditions. In order to analyze the influence of phase transformations on the obtained results, simulations with and without the effects of phase transformation were carried out on ASTM SA 516 steel plates. Thanks to the possibilities of numerical modelling, additional analyses were performed without taking into account the transformation plasticity phenomenon. It was found that phase transformation effects (both volume change and transformation plasticity) have a great influence on the intensity and sign of the asymptotic stress fields at the sharp V-notch tips. This result is believed to be very important for the correct numerical determination (and future applications) of notch stress intensity factors resulting from asymptotic residual stress distributions induced by transient thermal loads. The analyses were performed with the finite element code SYSWELD. (paper)

  18. Effects of Phytoplankton Growth Phase on Delayed Settling Behavior of Marine Snow Aggregates at Sharp Density Transitions

    Science.gov (United States)

    Proctor, K. W.; Montgomery, Q. W.; Prairie, J. C.

    2016-02-01

    Marine snow aggregates play a fundamental role in the marine carbon cycle. Since marine snow aggregates are larger and thus sink faster than individual phytoplankton, aggregates often dominate carbon flux. Previous studies have shown that marine snow aggregates will significantly decrease their settling velocity when passing through sharp density transitions within the ocean, a phenomenon defined as delayed settling. Given the importance of aggregate settling to carbon export, these small-scale changes in aggregate settling dynamics may have significant impacts on the efficiency of the biological pump. However, there is still a lack of knowledge about how different physical properties of aggregates can affect this delayed settling. In this study, we investigated the effect of phytoplankton growth phase on delayed settling behavior. Using phytoplankton cultures stopped at four different growth phases, we formed marine snow aggregates in the laboratory in rotating cylindrical tanks. We then observed individual aggregates as they settled through a stratified tank. We will present data which illustrates that aggregates experience greatly reduced settling rates when passing through sharp density gradients and that the growth phase of the phytoplankton used to form these aggregates has a significant effect on this delayed settling behavior. A thorough understanding of the impact of phytoplankton growth phase on the delayed settling behavior of marine snow will offer insight into the way phytoplankton growth phase may influence the efficiency of the biological pump, carbon flux, and the carbon cycle as a whole.

  19. Summer High School Apprenticeship Research Program (SHARP) of the National Aeronautics and Space Administration

    Science.gov (United States)

    1984-01-01

    A total of 125 talented high school students had the opportunity to gain first hand experience about science and engineering careers by working directly with a NASA scientist or engineer during the summer. This marked the fifth year of operation for NASA's Summer High School Apprenticehsip Research Program (SHARP). Ferguson Bryan served as the SHARP contractor and worked closely with NASA staff at Headquarters and the eight participating sites to plan, implement, and evaluate the Program. The main objectives were to strengthen SHARP and expand the number of students in the Program. These eight sites participated in the Program: Ames Research Center North, Ames' Dryden Flight Research Facility, Goddard Space Flight Center, Goddard's Wallops Flight Facility, Kennedy Space Center, Langley Research Center, Lewis Research Center, and Marshall Space Flight Center.

  20. Interactions between entorhinal axons and target hippocampal neurons: a role for glutamate in the development of hippocampal circuitry.

    Science.gov (United States)

    Mattson, M P; Lee, R E; Adams, M E; Guthrie, P B; Kater, S B

    1988-11-01

    A coculture system consisting of input axons from entorhinal cortex explants and target hippocampal pyramidal neurons was used to demonstrate that glutamate, released spontaneously from afferent axons, can influence both dendritic geometry of target neurons and formation of presumptive synaptic sites. Dendritic outgrowth was reduced in hippocampal neurons growing on entorhinal axons when compared with neurons growing off the axons. Presumptive presynaptic sites were observed in association with hippocampal neuron dendrites and somas. HPLC analysis showed that glutamate was released from the explants in an activity- and Ca2(+)-dependent manner. The general glutamate receptor antagonist D-glutamylglycine significantly increased dendritic outgrowth in pyramidal neurons associated with entorhinal axons and reduced presumptive presynaptic sites. Tetrodotoxin and reduction of extracellular Ca2+ also promoted dendritic outgrowth and reduced the formation of presumptive synaptic sites. The results suggest that the neurotransmitter glutamate may play important roles in the development of hippocampal circuitry.

  1. The Pecularities of Feeding Foreign Students in the Conditions of Adaptation to the Sharp Continental Climate of Russia

    Directory of Open Access Journals (Sweden)

    Severin Aleksandr Evgenyevich

    2014-04-01

    Full Text Available The authors discuss the physiological aspects of Indian students adaptation to the conditions of sharp continental climate of Russia, the questions of maintaining the heat homeostasis in the process of the functional rebuild of a human organism during the adaptation to the unaccustomed environment. The article reviews the dependence of adaptation on the climate of the Indian State the students come from, of the peculiarities of feeding of Indian students. The problem of Indian students’ health maintaining is observed and it is determined by optimization of adaptation terms. For this purpose antropometric and thermometric investigations of 173 Indian students in comparison with 60 Russian students were made. The investigation of the students was realized in autumn and spring periods. According to the results of the research, the transition to the animal albumin and fat type of the feeding of the Indian students is necessary.

  2. Low-dose sevoflurane promotes hippocampal neurogenesis and facilitates the development of dentate gyrus-dependent learning in neonatal rats.

    Science.gov (United States)

    Chen, Chong; Shen, Feng-Yan; Zhao, Xuan; Zhou, Tao; Xu, Dao-Jie; Wang, Zhi-Ru; Wang, Ying-Wei

    2015-01-01

    Huge body of evidences demonstrated that volatile anesthetics affect the hippocampal neurogenesis and neurocognitive functions, and most of them showed impairment at anesthetic dose. Here, we investigated the effect of low dose (1.8%) sevoflurane on hippocampal neurogenesis and dentate gyrus-dependent learning. Neonatal rats at postnatal day 4 to 6 (P4-6) were treated with 1.8% sevoflurane for 6 hours. Neurogenesis was quantified by bromodeoxyuridine labeling and electrophysiology recording. Four and seven weeks after treatment, the Morris water maze and contextual-fear discrimination learning tests were performed to determine the influence on spatial learning and pattern separation. A 6-hour treatment with 1.8% sevoflurane promoted hippocampal neurogenesis and increased the survival of newborn cells and the proportion of immature granular cells in the dentate gyrus of neonatal rats. Sevoflurane-treated rats performed better during the training days of the Morris water maze test and in contextual-fear discrimination learning test. These results suggest that a subanesthetic dose of sevoflurane promotes hippocampal neurogenesis in neonatal rats and facilitates their performance in dentate gyrus-dependent learning tasks. © The Author(s) 2015.

  3. Fluoxetine Increases Hippocampal Neurogenesis and Induces Epigenetic Factors But Does Not Improve Functional Recovery after Traumatic Brain Injury

    Science.gov (United States)

    Wang, Yonggang; Neumann, Melanie; Hansen, Katharina; Hong, Shuwhey M.; Kim, Sharon; Noble-Haeusslein, Linda J.

    2011-01-01

    Abstract The selective serotonin reuptake inhibitor fluoxetine induces hippocampal neurogenesis, stimulates maturation and synaptic plasticity of adult hippocampal neurons, and reduces motor/sensory and memory impairments in several CNS disorders. In the setting of traumatic brain injury (TBI), its effects on neuroplasticity and function have yet to be thoroughly investigated. Here we examined the efficacy of fluoxetine after a moderate to severe TBI, produced by a controlled cortical impact. Three days after TBI or sham surgery, mice were treated with fluoxetine (10 mg/kg/d) or vehicle for 4 weeks. To evaluate the effects of fluoxetine on neuroplasticity, hippocampal neurogenesis and epigenetic modification were studied. Stereologic analysis of the dentate gyrus revealed a significant increase in doublecortin-positive cells in brain-injured animals treated with fluoxetine relative to controls, a finding consistent with enhanced hippocampal neurogenesis. Epigenetic modifications, including an increase in histone 3 acetylation and induction of methyl-CpG-binding protein, a transcription factor involved in DNA methylation, were likewise seen by immunohistochemistry and quantitative Western immunoblots, respectively, in brain-injured animals treated with fluoxetine. To determine if fluoxetine improves neurological outcomes after TBI, gait function and spatial learning and memory were assessed by the CatWalk-assisted gait test and Barnes maze test, respectively. No differences in these parameters were seen between fluoxetine- and vehicle-treated animals. Thus while fluoxetine enhanced neuroplasticity in the hippocampus after TBI, its chronic administration did not restore locomotor function or ameliorate memory deficits. PMID:21175261

  4. Low-Dose Sevoflurane Promotes Hippocampal Neurogenesis and Facilitates the Development of Dentate Gyrus-Dependent Learning in Neonatal Rats

    Directory of Open Access Journals (Sweden)

    Chong Chen

    2015-04-01

    Full Text Available Huge body of evidences demonstrated that volatile anesthetics affect the hippocampal neurogenesis and neurocognitive functions, and most of them showed impairment at anesthetic dose. Here, we investigated the effect of low dose (1.8% sevoflurane on hippocampal neurogenesis and dentate gyrus-dependent learning. Neonatal rats at postnatal day 4 to 6 (P4–6 were treated with 1.8% sevoflurane for 6 hours. Neurogenesis was quantified by bromodeoxyuridine labeling and electrophysiology recording. Four and seven weeks after treatment, the Morris water maze and contextual-fear discrimination learning tests were performed to determine the influence on spatial learning and pattern separation. A 6-hour treatment with 1.8% sevoflurane promoted hippocampal neurogenesis and increased the survival of newborn cells and the proportion of immature granular cells in the dentate gyrus of neonatal rats. Sevoflurane-treated rats performed better during the training days of the Morris water maze test and in contextual-fear discrimination learning test. These results suggest that a subanesthetic dose of sevoflurane promotes hippocampal neurogenesis in neonatal rats and facilitates their performance in dentate gyrus-dependent learning tasks.

  5. Decreased hippocampal 5-HT2A receptors in post mortem tissue from schizophrenic but not bipolar subjects

    International Nuclear Information System (INIS)

    Scarr, E.; Pavey, G.; Bradbury, R.; Copolov, D.L.; Dean, B.

    2001-01-01

    Full text: The hippocampus is important in cognition and sensory gating,both of which are thought to be impaired in schizophrenia. Since 5HT has also been implicated in cognition we investigated the hippocampal serotonergic system in subjects with either schizophrenia or bipolar mood disorder. Using autoradiography,we found significant (p 3 H] ketanserin binding in the CA3 (Mean ±SEM:29.6 ± 4.0 vs.46.6 ± 4.2 fmol/mgETE), the stratum radiatum (27.3 ± 2.7 vs.38.7 ± 3.9 fmol/mgETE) and pyramidal cell layer (35.6 ± 3.4 vs.51.4 ± 2.7 fmol/ mgETE) of CA1 as well as the outer (8.3 ± 1.5 vs.12.2 ± 1.4 fmol/mgETE) and pyramidal cell layer (16.4 ± 2.5 vs.32.1 ± 3.2 fmol/mgETE) of the subiculum in hippocampal tissue from schizophrenic subjects. No such differences were found in the dentate gyrus or CA2 region from schizophrenia subjects or in any hippocampal region from bipolar subjects. The lack of change in the bipolar cohort suggests that the decreased density of hippocampal 5-HT 2A receptors is disease specific and not a result of neuroleptic treatment, which both cohorts received. Copyright (2001) Australian Neuroscience Society

  6. Estradiol treatment in preadolescent females enhances adolescent spatial memory and differentially modulates hippocampal region-specific phosphorylated ERK labeling.

    Science.gov (United States)

    Wartman, Brianne C; Keeley, Robin J; Holahan, Matthew R

    2012-10-24

    Estrogen levels in rats are positively correlated with enhanced memory function and hippocampal dendritic spine density. There is much less work on the long-term effects of estradiol manipulation in preadolescent rats. The present work examined how injections of estradiol during postnatal days 19-22 (p19-22; preadolescence) affected water maze performance and hippocampal phosphorylated ERK labeling. To investigate this, half of the estradiol- and vehicle-treated female rats were trained on a water maze task 24h after the end of estradiol treatment (p23-27) while the other half was not trained. All female rats were tested on the water maze from p40 to p44 (adolescence) and hippocampal pERK1/2 labeling was assessed as a putative marker of neuronal plasticity. During adolescence, preadolescent-trained groups showed lower latencies than groups without preadolescent training. Retention data revealed lower latencies in both estradiol groups, whether preadolescent trained or not. Immunohistochemical detection of hippocampal pERK1/2 revealed elevations in granule cell labeling associated with the preadolescent trained groups and reductions in CA1 labeling associated with estradiol treatment. These results show a latent beneficial effect of preadolescent estradiol treatment on adolescent spatial performance and suggest an organizational effect of prepubescent exogenously applied estradiol. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  7. Inference for the Sharpe Ratio Using a Likelihood-Based Approach

    Directory of Open Access Journals (Sweden)

    Ying Liu

    2012-01-01

    Full Text Available The Sharpe ratio is the prominent risk-adjusted performance measure used by practitioners. Statistical testing of this ratio using its asymptotic distribution has lagged behind its use. In this paper, highly accurate likelihood analysis is applied for inference on the Sharpe ratio. Both the one- and two-sample problems are considered. The methodology has O(n−3/2 distributional accuracy and can be implemented using any parametric return distribution structure. Simulations are provided to demonstrate the method's superior accuracy over existing methods used for testing in the literature.

  8. A rare case of a sharp foreign body on the vocal cord

    Directory of Open Access Journals (Sweden)

    Khairunnisak Misron

    2017-08-01

    Full Text Available A foreign body (FB in the upper aerodigestive tract is a common clinical problem that presents as as acute emergency. Sharp FB, such as fish bone or chicken bone, commonly lodges in the tonsil, base of tongue, vallecula or pyriform fossa. Dislodgement of a FB into the laryngopharynx is very rare and specifically onto the vocal cord is extremely uncommon. This case report illustrates a rare case of a sharp FB that was dislodged into the airway and stuck on to the right vocal cord, which was removed under local anaesthesia.

  9. Comparison of image sharpness metrics and real-time sharpening methods with GPU implementations

    CSIR Research Space (South Africa)

    De Villiers, Johan P

    2010-06-01

    Full Text Available , and not in trying to adjust the image to some fixed sharpness value. With the advent of the increased progammability of Graphics Pro- cessing Units (GPU) and their seemingly ever increasing number of processor cores (the dual-GPU NVidia GTX295 has 480 cores...) Quadro MDS 140M 16 400 64 700 ATI HD 2400XT 40 800 64 700 NVidia 9600GT 64 650 256 900 NVidia GTX280 240 602 512 1107 2 Metric descriptions Three metrics are used to evaluate images for sharpness. The first two are a measure of how much information...

  10. Soft yet Sharp Interfaces in a Vertex Model of Confluent Tissue

    Science.gov (United States)

    Sussman, Daniel M.; Schwarz, J. M.; Marchetti, M. Cristina; Manning, M. Lisa

    2018-01-01

    How can dense biological tissue maintain sharp boundaries between coexisting cell populations? We explore this question within a simple vertex model for cells, focusing on the role of topology and tissue surface tension. We show that the ability of cells to independently regulate adhesivity and tension, together with neighbor-based interaction rules, lets them support strikingly unusual interfaces. In particular, we show that mechanical- and fluctuation-based measurements of the effective surface tension of a cellular aggregate yield different results, leading to mechanically soft interfaces that are nevertheless extremely sharp.

  11. Needlesticks and Sharps Injuries Among the Personnel of Baharlou Hospital in Tehran, Iran

    Directory of Open Access Journals (Sweden)

    Izadi

    2015-10-01

    Full Text Available Background The prevalence and incidence of needlesticks and sharps injuries (NSSIs have not been well documented in Iran. In most previous studies, the data were obtained through anonymous, self-reporting questionnaires, which are subjected to bias. Objectives The focus of this study was to investigate the frequency and causes of NSSIs among health care workers (HCWs in collaboration with an occupational health office and to compare these data with related previous studies. Patients and Methods In this cross-sectional study, all HCWs exposed to NSSIs in Baharlou Hospital, Tehran, Iran, were included. Among 309 studied cases, 83 HCWs who were directly exposed to NSSIs were enrolled in this study. Results The case incidence of NSSIs was 26.86% (83.309. Of all the occupational groups, the nurses had the highest rate of NSSI incidence (63.9%, n = 53.83. Moreover, the incidence rate of NSSIs in the HCWs on rotational shift work (90.4% was higher than that among their counterparts on fixed shift work (9.6%, with the latter chiefly employed on night shift (90.4%, n = 75. NSSIs (83.1%, followed by splash (16.9%, were the most common method of exposure. Conclusions This study confirmed a relatively high incidence of NSSIs among HCWs. Inadequate occupational health and safety measures such as lack of training on occupational health hazards and safety issues, absence of written protocols for reporting NSSIs, and lack of safety instructions were associated with NSSIs. Effective training programs and raising the awareness of HCWs to reduce unsafe behaviors and implementing organizational strategies to prevent exposure are essential.

  12. Influence of pericarp, cotyledon and inhibitory substances on sharp tooth oak (Quercus aliena var. acuteserrata germination.

    Directory of Open Access Journals (Sweden)

    Yan Liu

    Full Text Available In order to explore the mechanism of delayed and uneven germination in sharp tooth oak (Quercus aliena var. acuteserrata (STO, mechanical scarification techniques were used to study STO root and shoot germination and growth. The techniques used were: removing cup scar (RS, removing the pericarp (RP, and cutting off 1/2 (HC and 2/3 (TC cotyledons. Germination percentage and root and shoot length for Chinese cabbage (Beassica pekinensis seeds (CCS were also investigated for CCS cultivated in a Sanyo growth cabinet watered by distilled water and 80% methanol extracts from the acorn embryo, cotyledon and pericarp with concentrations of 1.0 g, 0.8 g, 0.6 g and 0.4 g dry acorn weight per ml methanol. The results showed that the majority of roots and shoots from acorns with RP and HC treatment emerged two weeks earlier, more simultaneously, and their total emergencies were more than 46% and 28% higher, respectively. TC accelerated root and shoot emergence time and root length, but root and shoot germination rate and shoot height had no significant difference from the control. Positive consequences were not observed on all indices of RS treatment. The germination rates of CCS watered by 1.0 g · ml(-1 methanol extracts from the embryo and cotyledon were significantly lower than those from the pericarp, and all concentrations resulted in decreased growth of root and shoot. Methanol extracts from pericarp significantly reduced root length of CCS, but presented little response in germination percentage and shoot length. The inhibitory effect was gradually increased with the increasing concentration of the methanol extract. We conclude that both the mechanical restriction of the pericarp and the presence of germination inhibitors in the embryo, cotyledon and pericarp are the causes for delayed and asynchronous germination of STO acorns.

  13. Sharp Morphological Transitions from Nanoscale Mixed-Anchoring Patterns in Confined Nematic Liquid Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Armas-Pérez, Julio C. [Institute; División; Li, Xiao [Institute; Martínez-González, José A. [Institute; Smith, Coleman [Institute; Hernández-Ortiz, J. P. [Departamento; Nealey, Paul F. [Institute; Materials; de Pablo, Juan J. [Institute; Materials

    2017-08-17

    Liquid crystals are known to be particularly sensitive to orientational cues provided at surfaces or interfaces. In this work, we explore theoretically, computationally, and experimentally the behavior of liquid crystals on isolated nanoscale patterns with controlled anchoring characteristics at small length scales. The orientation of the liquid crystal is controlled through the use of chemically patterned polymer brushes that are tethered to a surface. This system can be engineered with remarkable precision, and the central question addressed here is whether a characteristic length scale exists at which information encoded on a surface is no longer registered by a liquid crystal. To do so, we adopt a tensorial description of the free energy of the hybrid liquidcrystal surface system, and we investigate its morphology in a systematic manner. For long and narrow surface stripes, it is found that the liquid crystal follows the instructions provided by the pattern down to 100 nm widths. This is accomplished through the creation of line defects that travel along the sides of the stripes. We show that a "sharp" morphological transition occurs from a uniform undistorted alignment to a dual uniform/splay-bend morphology. The theoretical and numerical predictions advanced here are confirmed by experimental observations. Our combined analysis suggests that nanoscale patterns can be used to manipulate the orientation of liquid crystals at a fraction of the energetic cost that is involved in traditional liquid crystal-based devices. The insights presented in this work have the potential to provide a new fabrication platform to assemble low power bistable devices, which could be reconfigured upon application of small external fields.

  14. [Effect of Scalp-acupuncture Stimulation on Neurological Function and Expression of ASIC 1 a and ASIC 2 b of Hippocampal CA 1 Region in Cerebral Ischemia Rats].

    Science.gov (United States)

    Tian, Liang; Wang, Jin-Hai; Zhao, Min; Bao, Ying-Cun; Shang, Jun-Fang; Yan, Qi; Zhang, Zhen-Chang; Du, Xiao-Zheng; Jiang, Hua; Sun, Run-Jie; Yuan, Bo; Zhang, Xing-Hua; Zhang, Ting-Zhuo; Li, Xing-Lan

    2016-10-25

    To observe the influence of scalp-acupuncture on the expression of acid-sensing ion channels (ASICs) 1 a and 2 b of hippocampal CA 1 region in cerebral ischemia (CI) rats, so as to investigate its mechanism underlying improvement of ischemic stroke. Thirty-two male SD rats were randomly allocated to normal control, model, scalp-acupuncture and Amiloride group ( n =8 in each group). The model of focal CI was established by middle cerebral artery occlusion (MCAO). Scalp acupuncture stimulation was applied to bilateral Dingnieqianxiexian (MS 6) and Dingniehouxiexian (MS 7), once daily for 7 days. Rats of the Amiloride group were fed with Amiloride solution, twice a day for 7 days, and those of the normal control and model groups were grabbled and fixed in the same way with the acupuncture and Amiloride groups. The neurological deficit score was given according to Longa's method. The expression of hippocampal ASIC 1 a and ASIC 2 b was detected by immunohistochemistry, and the Ca 2+ concentration in the hippocampal tissue assayed using flowing cytometry. After the intervention, the neurological deficit score of both the scalp-acupuncture and Amiloride groups were significantly decreased in comparison with pre-treatment ( P ASIC 1 a and ASIC 2 b in the hippocampal CA 1 region and hip-pocampal Ca 2+ concentration were significantly up-regulated in the model group compared with the normal control group ( P ASIC 1 a and ASIC 2 b expression and Ca 2+ concentration ( P >0.05). Scalp-acupuncture stimulation can improve neurological function in CI rats, which may be related to its effects in suppressing the increased expression of hippocampal ASIC 1 a and ASIC 2 b proteins and in reducing calcium overload in hip-pocampal neurocytes.

  15. A pilot study of hippocampal volume and N-acetylaspartate (NAA) as response biomarkers in riluzole-treated patients with GAD.

    Science.gov (United States)

    Abdallah, Chadi G; Coplan, Jeremy D; Jackowski, Andrea; Sato, João R; Mao, Xiangling; Shungu, Dikoma C; Mathew, Sanjay J

    2013-04-01

    Anxiolytic benefit following chronic treatment with the glutamate modulating agent riluzole in patients with generalized anxiety disorder (GAD) was previously associated with differential changes in hippocampal NAA concentrations. Here, we investigated the association between hippocampal volume and hippocampal NAA in the context of riluzole response in GAD. Eighteen medication-free adult patients with GAD received 8-week of open-label riluzole. Ten healthy subjects served as a comparison group. Participants underwent magnetic resonance imaging and spectroscopy at baseline and at the end of Week 8. GAD patients who completed all interventions were classified as remitters (n=7) or non-remitters (n=6), based on final Hamilton Anxiety Rating Scale (HAM-A) scores ≤7. At baseline, GAD patients had a significant reduction in total hippocampal volume compared to healthy subjects (F(1,21)=6.55, p=0.02). This reduction was most pronounced in the remitters, compared to non-remitters and healthy subjects. Delta (final-baseline) hippocampal volume was positively correlated with delta NAA in GAD. This positive association was highly significant in the right hippocampus in GAD [r=0.81, p=0.002], with no significant association in healthy subjects [Fisher r-to-z p=0.017]. Across all GAD patients, delta hippocampal volume was positively associated with improvement in HAM-A (rspearman=0.62, p=0.03). These preliminary findings support hippocampal NAA and volume as neural biomarkers substantially associated with therapeutic response to a glutamatergic drug. Copyright © 2012 Elsevier B.V. and ECNP. All rights reserved.

  16. Change in hippocampal theta oscillation associated with multiple lever presses in a bimanual two-lever choice task for robot control in rats.

    Directory of Open Access Journals (Sweden)

    Norifumi Tanaka

    Full Text Available Hippocampal theta oscillations have been implicated in working memory and attentional process, which might be useful for the brain-machine interface (BMI. To further elucidate the properties of the hippocampal theta oscillations that can be used in BMI, we investigated hippocampal theta oscillations during a two-lever choice task. During the task body-restrained rats were trained with a food reward to move an e-puck robot towards them by pressing the correct lever, ipsilateral to the robot several times, using the ipsilateral forelimb. The robot carried food and moved along a semicircle track set in front of the rat. We demonstrated that the power of hippocampal theta oscillations gradually increased during a 6-s preparatory period before the start of multiple lever pressing, irrespective of whether the correct lever choice or forelimb side were used. In addition, there was a significant difference in the theta power after the first choice, between correct and incorrect trials. During the correct trials the theta power was highest during the first lever-releasing period, whereas in the incorrect trials it occurred during the second correct lever-pressing period. We also analyzed the hippocampal theta oscillations at the termination of multiple lever pressing during the correct trials. Irrespective of whether the correct forelimb side was used, the power of hippocampal theta oscillations gradually decreased with the termination of multiple lever pressing. The frequency of theta oscillation also demonstrated an increase and decrease, before and after multiple lever pressing, respectively. There was a transient increase in frequency after the first lever press during the incorrect trials, while no such increase was observed during the correct trials. These results suggested that hippocampal theta oscillations reflect some aspects of preparatory and cognitive neural activities during the robot controlling task, which could be used for BMI.

  17. The hippocampal continuation (indusium griseum): its connectivity in the hedgehog tenrec and its status within the hippocampal formation of higher vertebrates.

    Science.gov (United States)

    Künzle, H

    2004-06-01

    The indusium griseum and its precallosal extension are usually considered poorly differentiated portions of the hippocampus. The connections of this so-called 'hippocampal continuation' (HCt) have only been analyzed so far in rodents, which show one of the least-developed HCt among mammals. In this study we have investigated the relatively well differentiated HCt of the small Madagascan hedgehog tenrec (Afrotheria) using histochemical and axonal transport techniques. The tenrec's HCt shows associative and commissural connections. It receives laminar specific afferents from the entorhinal cortex (collaterals from neurons projecting to the dentate area), the anterior and posterior piriform cortices as well as the supramammillary region. A few fibers also originate in the olfactory bulb and the dentate hilus. Among these input areas only the dentate hilus receives a significant reciprocal projection from the HCt. Additional HCt efferents are directed to the subcallosal septum (presumed septohippocampal nucleus), the olfactory tubercle and the islands of Calleja. With the exception of the supramammillary afferents and possible efferents to the supraoptic nucleus we failed, however, to demonstrate distinct thalamic and hypothalamic connections. A comparison of the connections of the HCt with those of the hippocampal subdivisions reveal some similarity between the HCt and the dentate area, but the overall pattern of connectivity does not permit a correlation of the HCt with the dentate area, let alone the cornu ammonis and the subiculum. This view is supported by histochemical findings in the tenrec (immunoreactivity to calcium binding proteins) as well as the rat (data taken from the literature). The HCt is therefore considered a region in its own right within the hippocampal formation. It may be tentatively correlated with the medial cortex of reptiles, while the dentate area and the cornu ammonis may have evolved de novo in mammals.

  18. Ketamine Protects Gamma Oscillations by Inhibiting Hippocampal LTD

    Science.gov (United States)

    Huang, Lanting; Yang, Xiu-Juan; Huang, Ying; Sun, Eve Y.

    2016-01-01

    NMDA receptors have been widely reported to be involved in the regulation of synaptic plasticity through effects on long-term potentiation (LTP) and long-term depression (LTD). LTP and LTD have been implicated in learning and memory processes. Besides synaptic plasticity, it is known that the phenomenon of gamma oscillations is critical in cognitive functions. Synaptic plasticity has been widely studied, however it is still not clear, to what degree synaptic plasticity regulates the oscillations of neuronal networks. Two NMDA receptor antagonists, ketamine and memantine, have been shown to regulate LTP and LTD, to promote cognitive functions, and have even been reported to bring therapeutic effects in major depression and Alzheimer’s disease respectively. These compounds allow us to investigate the putative interrelationship between network oscillations and synaptic plasticity and to learn more about the mechanisms of their therapeutic effects. In the present study, we have identified that ketamine and memantine could inhibit LTD, without impairing LTP in the CA1 region of mouse hippocampus, which may underlie the mechanism of these drugs’ therapeutic effects. Our results suggest that NMDA-induced LTD caused a marked loss in the gamma power, and pretreatment with 10 μM ketamine prevented the oscillatory loss via its inhibitory effect on LTD. Our study provides a new understanding of the role of NMDA receptors on hippocampal plasticity and oscillations. PMID:27467732

  19. Functional clustering in hippocampal cultures: relating network structure and dynamics

    International Nuclear Information System (INIS)

    Feldt, S; Dzakpasu, R; Olariu, E; Żochowski, M; Wang, J X; Shtrahman, E

    2010-01-01

    In this work we investigate the relationship between gross anatomic structural network properties, neuronal dynamics and the resultant functional structure in dissociated rat hippocampal cultures. Specifically, we studied cultures as they developed under two conditions: the first supporting glial cell growth (high glial group), and the second one inhibiting it (low glial group). We then compared structural network properties and the spatio-temporal activity patterns of the neurons. Differences in dynamics between the two groups could be linked to the impact of the glial network on the neuronal network as the cultures developed. We also implemented a recently developed algorithm called the functional clustering algorithm (FCA) to obtain the resulting functional network structure. We show that this new algorithm is useful for capturing changes in functional network structure as the networks evolve over time. The FCA detects changes in functional structure that are consistent with expected dynamical differences due to the impact of the glial network. Cultures in the high glial group show an increase in global synchronization as the cultures age, while those in the low glial group remain locally synchronized. We additionally use the FCA to quantify the amount of synchronization present in the cultures and show that the total level of synchronization in the high glial group is stronger than in the low glial group. These results indicate an interdependence between the glial and neuronal networks present in dissociated cultures

  20. Hippocampal morphology mediates biased memories of chronic pain

    Science.gov (United States)

    Berger, Sara E.; Vachon-Presseau, Étienne; Abdullah, Taha B.; Baria, Alex T.; Schnitzer, Thomas J.; Apkarian, A. Vania

    2018-01-01

    Experiences and memories are often mismatched. While multiple studies have investigated psychological underpinnings of recall error with respect to emotional events, the neurobiological mechanisms underlying the divergence between experiences and memories remain relatively unexplored in the domain of chronic pain. Here we examined the discrepancy between experienced chronic low back pain (CBP) intensity (twice daily ratings) and remembered pain intensity (n = 48 subjects) relative to psychometric properties, hippocampus morphology, memory capabilities, and personality traits related to reward. 77% of CBP patients exaggerated remembered pain, which depended on their strongest experienced pain and their most recent mood rating. This bias persisted over nearly 1 year and was related to reward memory bias and loss aversion. Shape displacement of a specific region in the left posterior hippocampus mediated personality effects on pain memory bias, predicted pain memory bias in a validation CBP group (n = 21), and accounted for 55% of the variance of pain memory bias. In two independent groups (n = 20/group), morphology of this region was stable over time and unperturbed by the development of chronic pain. These results imply that a localized hippocampal circuit, and personality traits associated with reward processing, largely determine exaggeration of daily pain experiences in chronic pain patients. PMID:29080714

  1. The association of visual memory with hippocampal volume.

    Science.gov (United States)

    Zammit, Andrea R; Ezzati, Ali; Katz, Mindy J; Zimmerman, Molly E; Lipton, Michael L; Sliwinski, Martin J; Lipton, Richard B

    2017-01-01

    In this study we investigated the role of hippocampal volume (HV) in visual memory. Participants were a subsample of older adults (> = 70 years) from the Einstein Aging Study. Visual performance was measured using the Complex Figure (CF) copy and delayed recall tasks from the Repeatable Battery for the Assessment of Neuropsychological Status. Linear regressions were fitted to study associations between HV and visual tasks. Participants' (n = 113, mean age = 78.9 years) average scores on the CF copy and delayed recall were 17.4 and 11.6, respectively. CF delayed recall was associated with total (β = .031, p = 0.001) and left (β = 0.031, p = 0.001) and right HVs (β = 0.24, p = 0.012). CF delayed recall remained significantly associated with left HV even after we also included right HV (β = 0.27, p = 0.025) and the CF copy task (β = 0.30, p = 0.009) in the model. CF copy did not show any significant associations with HV. Our results suggest that left HV contributes in retrieval of visual memory in older adults.

  2. Exposure of rat hippocampal astrocytes to Ziram increases oxidative stress.

    Science.gov (United States)

    Matei, Ann-Marie; Trombetta, Louis D

    2016-04-01

    Pesticides have been shown in several studies to be the leading candidates of environmental toxins and may contribute to the pathogenesis of several neurodegenerative diseases. Ziram (zinc-bis(dimethyldithiocarbamate)) is an agricultural dithiocarbamate fungicide that is used to treat a variety of plant diseases. In spite of their generally acknowledged low toxicity, dithiocarbamates are known to cause a wide range of neurobehavioral effects as well as neuropathological changes in the brain. Astrocytes play a key role in normal brain physiology and in the pathology of the nervous system. This investigation studied the effects of 1.0 µM Ziram on rat hippocampal astrocytes. The thiobarbituric acid reactive substance assay performed showed a significant increase in malondialdehyde, a product of lipid peroxidation, in the Ziram-treated cells. Biochemical analysis also revealed a significant increase in the induction of 70 kDa heat shock and heme oxygenase 1 stress proteins. In addition, an increase of glutathione peroxidase (GPx) and a significant increase in oxidized glutathione (GSSG) were observed in the Ziram-treated cells. The ratio GSH to GSSG calculated from the treated cells was also decreased. Light and transmission electron microscopy supported the biochemical findings in Ziram-treated astrocytes. This data suggest that the cytotoxic effects observed with Ziram treatments may be related to the increase of oxidative stress. © The Author(s) 2013.

  3. Effects of Sun ginseng on memory enhancement and hippocampal neurogenesis.

    Science.gov (United States)

    Lee, Chang Hwan; Kim, Jong Min; Kim, Dong Hyun; Park, Se Jin; Liu, Xiaotong; Cai, Mudan; Hong, Jin Gyu; Park, Jeong Hill; Ryu, Jong Hoon

    2013-09-01

    Panax ginseng C.A. Meyer has been used in traditional herb prescriptions for thousands of years. A heat-processing method has been used to increase the efficacy of ginseng, yielding what is known as red ginseng. In addition, recently, a slightly modified heat-processing method was applied to ginseng, to obtain a new type of processed ginseng with increased biological activity; this new form of ginseng is referred to as Sun ginseng (SG). The aim of this study was to investigate the effect of SG on memory enhancement and neurogenesis in the hippocampal dentate gyrus (DG) region. The subchronic administration of SG (for 14 days) significantly increased the latency time in the passive avoidance task relative to the administration of the vehicle control (P memory-enhancing activities and that these effects are mediated, in part, by the increase in the levels of pERK and pAkt and by the increases in cell proliferation and cell survival. Copyright © 2012 John Wiley & Sons, Ltd.

  4. The association of visual memory with hippocampal volume.

    Directory of Open Access Journals (Sweden)

    Andrea R Zammit

    Full Text Available In this study we investigated the role of hippocampal volume (HV in visual memory.Participants were a subsample of older adults (> = 70 years from the Einstein Aging Study. Visual performance was measured using the Complex Figure (CF copy and delayed recall tasks from the Repeatable Battery for the Assessment of Neuropsychological Status. Linear regressions were fitted to study associations between HV and visual tasks.Participants' (n = 113, mean age = 78.9 years average scores on the CF copy and delayed recall were 17.4 and 11.6, respectively. CF delayed recall was associated with total (β = .031, p = 0.001 and left (β = 0.031, p = 0.001 and right HVs (β = 0.24, p = 0.012. CF delayed recall remained significantly associated with left HV even after we also included right HV (β = 0.27, p = 0.025 and the CF copy task (β = 0.30, p = 0.009 in the model. CF copy did not show any significant associations with HV.Our results suggest that left HV contributes in retrieval of visual memory in older adults.

  5. Acetylcholine release and inhibitory interneuron activity in hippocampal CA1

    Directory of Open Access Journals (Sweden)

    A. Rory McQuiston

    2014-09-01

    Full Text Available Acetylcholine release in the central nervous system (CNS has an important role in attention, recall and memory formation. One region influenced by acetylcholine is the hippocampus, which receives inputs from the medial septum and diagonal band of Broca complex (MS/DBB. Release of acetylcholine from the MS/DBB can directly affect several elements of the hippocampus including glutamatergic and GABAergic neurons, presynaptic terminals, postsynaptic receptors and astrocytes. A significant portion of acetylcholine’s effect likely results from the modulation of GABAergic inhibitory interneurons, which have crucial roles in controlling excitatory inputs, synaptic integration, rhythmic coordination of principal neurons and outputs in the hippocampus. Acetylcholine affects interneuron function in large part by altering their membrane potential via muscarinic and nicotinic receptor activation. This minireview describes recent data from mouse hippocampus that investigated changes in CA1 interneuron membrane potentials following acetylcholine release. The interneuron subtypes affected, the receptor subtypes activated, and the potential outcome on hippocampal CA1 network function is discussed.

  6. Hand gestures support word learning in patients with hippocampal amnesia.

    Science.gov (United States)

    Hilverman, Caitlin; Cook, Susan Wagner; Duff, Melissa C

    2018-06-01

    Co-speech hand gesture facilitates learning and memory, yet the cognitive and neural mechanisms supporting this remain unclear. One possibility is that motor information in gesture may engage procedural memory representations. Alternatively, iconic information from gesture may contribute to declarative memory representations mediated by the hippocampus. To investigate these alternatives, we examined gesture's effects on word learning in patients with hippocampal damage and declarative memory impairment, with intact procedural memory, and in healthy and in brain-damaged comparison groups. Participants learned novel label-object pairings while producing gesture, observing gesture, or observing without gesture. After a delay, recall and object identification were assessed. Unsurprisingly, amnesic patients were unable to recall the labels at test. However, they correctly identified objects at above chance levels, but only if they produced a gesture at encoding. Comparison groups performed well above chance at both recall and object identification regardless of gesture. These findings suggest that gesture production may support word learning by engaging nondeclarative (procedural) memory. © 2018 Wiley Periodicals, Inc.

  7. Under what conditions is recognition spared relative to recall after selective hippocampal damage in humans?

    Science.gov (United States)

    Holdstock, J S; Mayes, A R; Roberts, N; Cezayirli, E; Isaac, C L; O'Reilly, R C; Norman, K A

    2002-01-01

    The claim that recognition memory is spared relative to recall after focal hippocampal damage has been disputed in the literature. We examined this claim by investigating object and object-location recall and recognition memory in a patient, YR, who has adult-onset selective hippocampal damage. Our aim was to identify the conditions under which recognition was spared relative to recall in this patient. She showed unimpaired forced-choice object recognition but clearly impaired recall, even when her control subjects found the object recognition task to be numerically harder than the object recall task. However, on two other recognition tests, YR's performance was not relatively spared. First, she was clearly impaired at an equivalently difficult yes/no object recognition task, but only when targets and foils were very similar. Second, YR was clearly impaired at forced-choice recognition of object-location associations. This impairment was also unrelated to difficulty because this task was no more difficult than the forced-choice object recognition task for control subjects. The clear impairment of yes/no, but not of forced-choice, object recognition after focal hippocampal damage, when targets and foils are very similar, is predicted by the neural network-based Complementary Learning Systems model of recognition. This model postulates that recognition is mediated by hippocampally dependent recollection and cortically dependent familiarity; thus hippocampal damage should not impair item familiarity. The model postulates that familiarity is ineffective when very similar targets and foils are shown one at a time and subjects have to identify which items are old (yes/no recognition). In contrast, familiarity is effective in discriminating which of similar targets and foils, seen together, is old (forced-choice recognition). Independent evidence from the remember/know procedure also indicates that YR's familiarity is normal. The Complementary Learning Systems model can

  8. Neuroprotective effects of ginsenoside Rg1 against oxygen-glucose deprivation in cultured hippocampal neurons.

    Science.gov (United States)

    He, Qing; Sun, Jianguo; Wang, Qin; Wang, Wei; He, Bin

    2014-03-01

    Ginsenoside Rg1 (Rg1) is believed to be one of the main active principles in ginseng, a traditional Chinese medicine extensively used to enhance stamina and deal with fatigue as well as physical stress. It has been reported that Rg1 performs multiple biological activities, including neuroprotective activity. In this study, we investigated the efficacy of ginsenoside Rg1 on ischemia-reperfusion injury in cultured hippocampal cells and also probed its possible mechanisms. To establish a model of oxygen-glucose deprivation (OGD) and reperfusion, cultured hippocampal neurons were exposed to OGD for 2.5 hours, followed by a 24-hour reoxygenation. Cultured hippocampal neurons were randomly divided into control group, model group (vehicle), and ginsenoside Rg1 treatment groups (5μM, 20μM, 60μM). At 24 hours post-OGD, the intracellular free calcium concentration was detected using Furo-3/AM-loaded hippocampal neurons deprived of oxygen and glucose. Neuronal nitric oxide synthase (nNOS) activity was measured by chemical colorimetry. Cell apoptosis was evaluated by Hoechst staining, and the neuron viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Excitotoxic neuronal injury of OGD was demonstrated by the increase of intracellular free calcium concentrations and elevated nNOS activity in the model group compared with the control group. The intracellular free calcium concentrations and the nNOS activity in the groups receiving intermediate and high dose of ginsenoside Rg1 were significantly lower than those of the control group (p cell viability loss (p cell apoptosis induced by OGD. Ginsenoside Rg1 has neuroprotective effect on ischemia-reperfusion injury in cultured hippocampal cells mediated by blocking calcium over-influx into neuronal cells and decreasing the nNOS activity after OGD exposure. We infer that ginsenoside Rg1 may serve as a potential therapeutic agent for cerebral ischemia injury. Copyright © 2014

  9. Structural and functional biological materials: Abalone nacre, sharp materials, and abalone foot adhesion

    Science.gov (United States)

    Lin, Albert Yu-Min

    A three-part study of lessons from nature is presented through the examination of various biological materials, with an emphasis on materials from the mollusk Haliotis rufescens, commonly referred to as the red abalone. The three categories presented are: structural hierarchy, self-assembly, and functionality. Ocean mollusk shells are composed of aragonite/calcite crystals interleaved with layers of a visco-elastic protein, having dense, tailored structures with excellent mechanical properties. The complex nano-laminate structure of this bio-composite material is characterized and related to its mechanical properties. Three levels of structural hierarchy are identified: macroscale mesolayers separating larger regions of tiled aragonite, microscale organization of 0.5 mum by 10 mum aragonite bricks; nanoscale mineral bridges passing through 30 nm layers of organic matrix separating individual aragonite tiles. Composition and growth mechanisms of this nanostructure were observed through close examination of laboratory-grown samples using scanning electron microscopy (SEM), Raman spectroscopy, and transmission electron microscopy (TEM). Glass slides and nacre pucks were implanted onto the growth surface of living abalone and removed periodically to observe trends in nacre deposition. Various deproteinization and demineralization experiments are used to explore the inorganic and organic components of the nacre's structure. The organic component of the shell is characterized by atomic force microscopy (AFM). The functionality of various biological materials is described and investigated. Two specific types of functionality are characterized, the ability of some materials to cut and puncture through sharp designs, and the ability for some materials to be used as attachment devices. Aspects of cutting materials employed by a broad range of animals were characterized and compared. In respect to the attachment mechanisms the foot of the abalone and the tree frog were

  10. Longitudinal study of hippocampal volumes in heavy cannabis users.

    Science.gov (United States)

    Koenders, L; Lorenzetti, V; de Haan, L; Suo, C; Vingerhoets, Wam; van den Brink, W; Wiers, R W; Meijer, C J; Machielsen, Mwj; Goudriaan, A E; Veltman, D J; Yücel, M; Cousijn, J

    2017-08-01

    Cannabis exposure, particularly heavy cannabis use, has been associated with neuroanatomical alterations in regions rich with cannabinoid receptors such as the hippocampus in some but not in other (mainly cross-sectional) studies. However, it remains unclear whether continued heavy cannabis use alters hippocampal volume, and whether an earlier age of onset and/or a higher dosage exacerbate these changes. Twenty heavy cannabis users (mean age 21 years, range 18-24 years) and 23 matched non-cannabis using healthy controls were submitted to a comprehensive psychological assessment and magnetic resonance imaging scan at baseline and at follow-up (average of 39 months post-baseline; standard deviation=2.4). Cannabis users started smoking around 16 years and smoked on average five days per week. A novel aspect of the current study is that hippocampal volume estimates were obtained from manual tracing the hippocampus on T1-weighted anatomical magnetic resonance imaging scans, using a previously validated protocol. Compared to controls, cannabis users did not show hippocampal volume alterations at either baseline or follow-up. Hippocampal volumes increased over time in both cannabis users and controls, following similar trajectories of increase. Cannabis dose and age of onset of cannabis use did not affect hippocampal volumes. Continued heavy cannabis use did not affect hippocampal neuroanatomical changes in early adulthood. This contrasts with prior evidence on alterations in this region in samples of older adult cannabis users. In young adults using cannabis at this level, cannabis use may not be heavy enough to affect hippocampal neuroanatomy.

  11. Computer simulation of radiographic images sharpness in several system of image record

    International Nuclear Information System (INIS)

    Silva, Marcia Aparecida; Schiable, Homero; Frere, Annie France; Marques, Paulo M.A.; Oliveira, Henrique J.Q. de; Alves, Fatima F.R.; Medeiros, Regina B.

    1996-01-01

    A method to predict the influence of the record system on radiographic images sharpness by computer simulation is studied. The method intend to previously show the image to be obtained for each type of film or screen-film combination used during the exposure

  12. Load modeling for sharp V-cutter cutting litchi ( Litchi chinensis Sonn ...

    African Journals Online (AJOL)

    harvesting. Cutting load is a key parameter for 'hand-held auto-picker' operation. However, there is still no suitable model for cutting load setting. Hence, a model describing the relationship among cutting load, blade angle and friction coefficient was developed for cutting operation by sharp V-cutters. The model was based ...

  13. Conformal coating by photoresist of sharp corners of anisotropically etched through-holes in silicon

    DEFF Research Database (Denmark)

    Heschel, Matthias; Bouwstra, Siebe

    1997-01-01

    The authors describe a photoresist treatment yielding conformal coating of three-dimensional silicon structures. This even includes the sharp corners of through-holes obtained by anisotropic etching in (100)-silicon. Resist reflow from these corners is avoided by replacing the common baking...

  14. A new species of the genus Linoderus Sharp, 1885 (Coleoptera, Staphylinidae, Philonthina) from the Colombian Andes.

    Science.gov (United States)

    López-García, Margarita M; Méndez-Rojas, Diana M

    2014-05-09

    The monotypic genus Linoderus Sharp, 1885 was described based on a species from Panama and since the original description nearly nothing has been added to its taxonomical knowledge. The aim of the present paper is to describe a new species of the genus from Colombia and to report the genus for the first time from South America, adding some biological notes of the species.

  15. Intercomparison of field measurements of nitrous acid (HONO) during the SHARP Campaign

    Science.gov (United States)

    Because of the importance of HONO as a radical reservoir, consistent and accurate measurements of its concentration are needed. As part of the SHARP (Study of Houston Atmospheric Radical Precursors), time series of HONO were obtained by five different measurement techniques on th...

  16. Sharp Central Venous Recanalization in Hemodialysis Patients: A Single-Institution Experience

    Energy Technology Data Exchange (ETDEWEB)

    Arabi, Mohammad, E-mail: marabi2004@hotmail.com; Ahmed, Ishtiaq; Mat’hami, Abdulaziz [Prince Sultan Military Medical City (PSMMC), Division of Endovascular Interventional Radiology, Department of Medical Imaging (Saudi Arabia); Ahmed, Dildar; Aslam, Naveed [Prince Sultan Military Medical City (PSMMC), Department of Nephrology (Saudi Arabia)

    2016-06-15

    PurposeWe report our institutional experience with sharp central venous recanalization in chronic hemodialysis patients who failed standard techniques.Materials and MethodsSince January 2014, a series of seven consecutive patients (four males and three females), mean age 35 years (18–65 years), underwent sharp central venous recanalization. Indications included obtaining hemodialysis access (n = 6) and restoration of superior vena cava (SVC) patency to alleviate occlusion symptoms and restore fistula function (n = 1). The transseptal needle was used for sharp recanalization in six patients, while it could not be introduced in one patient due to total occlusion of the inferior vena cava. Instead, transmediastinal SVC access using Chiba needle was obtained.ResultsTechnical success was achieved in all cases. SVC recanalization achieved symptoms’ relief and restored fistula function in the symptomatic patient. One patient underwent arteriovenous fistula creation on the recanalized side 3 months after the procedure. The remaining catheters were functional at median follow-up time of 9 months (1–14 months). Two major complications occurred including a right hemothorax and a small hemopericardium, which were managed by covered stent placement across the perforated SVC.ConclusionSharp central venous recanalization using the transseptal needle is feasible technique in patients who failed standard recanalization procedures. The potential high risk of complications necessitates thorough awareness of anatomy and proper technical preparedness.

  17. Development of the Children's Scale of Hostility and Aggression: Reactive/Proactive (C-SHARP)

    Science.gov (United States)

    Farmer, Cristan A.; Aman, Michael G.

    2009-01-01

    Whereas some scales exist for assessing aggression in typically developing children, they do not give a detailed analysis, and none is available for populations with developmental disabilities (DD). Parents of 365 children with DD completed the Children's Scale of Hostility and Aggression: Reactive/Proactive (C-SHARP), which surveys the severity…

  18. Cryptic species of sharp-nosed reed frogs in the Hyperolius nasutus ...

    African Journals Online (AJOL)

    The sharp-nosed reed frog is widespread in Africa. Although currently recognized as one species, suggestions have been made that more than one species might exist. We analysed 237 calls of 69 males from 19 localities in the western to southern parts of Africa. Calls fall into three groups, which we recognize as cryptic ...

  19. Space-time adaptive hp-FEM for problems with traveling sharp fronts

    Czech Academy of Sciences Publication Activity Database

    Šolín, Pavel; Korous, L.

    2013-01-01

    Roč. 95, č. 1 (2013), S709-S722 ISSN 0010-485X Institutional support: RVO:61388998 Keywords : adaptive hp-FEM * transient problems * sharp fronts Subject RIV: BA - General Mathematics Impact factor: 1.055, year: 2013

  20. A sharp Rogers–Shephard type inequality for Orlicz-difference body ...

    Indian Academy of Sciences (India)

    Abstract. In this paper, we prove a sharp Rogers–Shephard type inequality for the Orlicz-difference body of planar convex bodies, which extend the works of Bianchini and Colesanti (Proc. Amer. Math. Soc. 138(7) (2008) 2575–2582).

  1. Hydrovatus caraibus Sharp, 1882 (Dytiscidae, Hydroporinae, Hydrovatini new for the fauna of South America

    Directory of Open Access Journals (Sweden)

    Benetti, C. J.

    2003-11-01

    Full Text Available The species Hydrovatus caraibus Sharp, 1882 is recorded for the first time for South America, after the recollection of specimens of this species in the municipality of Gramado, State of Rio Grande do Sul, Brazil. The range of distribution of the species, previously restricted to the Caribbean, is now extended to the latitude 29º 26’ South, approximately.

  2. Proliferation of sharp kinks on cosmic (super)string loops with junctions

    International Nuclear Information System (INIS)

    Binetruy, P.; Bohe, A.; Hertog, T.; Steer, D. A.

    2010-01-01

    Motivated by their effect on the gravitational wave signal emitted by cosmic strings, we study the dynamics of kinks on strings of different tensions meeting at junctions. The propagation of a kink through a Y junction leads to the formation of three 'daughter' kinks. Assuming a uniform distribution of the incoming wave vectors at the junction, we find there is a significant region of configuration space in which the sharpness of at least one of the daughter kinks is enhanced relative to the sharpness of the initial kink. For closed loops with junctions we show this leads to an exponential growth in time of very sharp kinks. Using numerical simulations of realistic, evolving cosmic string loops with junctions to calculate the distribution of kink amplitudes as a function of time, we show that loops of this kind typically develop several orders of magnitude of very sharp kinks before the two junctions collide. This collision, or other effects such as gravitational backreaction, may end the proliferation.

  3. Sharp Central Venous Recanalization in Hemodialysis Patients: A Single-Institution Experience

    International Nuclear Information System (INIS)

    Arabi, Mohammad; Ahmed, Ishtiaq; Mat’hami, Abdulaziz; Ahmed, Dildar; Aslam, Naveed

    2016-01-01

    PurposeWe report our institutional experience with sharp central venous recanalization in chronic hemodialysis patients who failed standard techniques.Materials and MethodsSince January 2014, a series of seven consecutive patients (four males and three females), mean age 35 years (18–65 years), underwent sharp central venous recanalization. Indications included obtaining hemodialysis access (n = 6) and restoration of superior vena cava (SVC) patency to alleviate occlusion symptoms and restore fistula function (n = 1). The transseptal needle was used for sharp recanalization in six patients, while it could not be introduced in one patient due to total occlusion of the inferior vena cava. Instead, transmediastinal SVC access using Chiba needle was obtained.ResultsTechnical success was achieved in all cases. SVC recanalization achieved symptoms’ relief and restored fistula function in the symptomatic patient. One patient underwent arteriovenous fistula creation on the recanalized side 3 months after the procedure. The remaining catheters were functional at median follow-up time of 9 months (1–14 months). Two major complications occurred including a right hemothorax and a small hemopericardium, which were managed by covered stent placement across the perforated SVC.ConclusionSharp central venous recanalization using the transseptal needle is feasible technique in patients who failed standard recanalization procedures. The potential high risk of complications necessitates thorough awareness of anatomy and proper technical preparedness.

  4. Tactile modulation of hippocampal place fields.

    Science.gov (United States)

    Gener, Thomas; Perez-Mendez, Lorena; Sanchez-Vives, Maria V

    2013-12-01

    Neural correlates of spatial representation can be found in the activity of the hippocampal place cells. These neurons are characterized by firing whenever the animal is located in a particular area of the space, the place field. Place fields are modulated by sensory cues, such as visual, auditory, or olfactory cues, being the influence of visual inputs the most thoroughly studied. Tactile information gathered by the whiskers has a prominent representation in the rat cerebral cortex. However, the influence of whisker-detected tactile cues on place fields remains an open question. Here we studied place fields in an enriched tactile environment where the remaining sensory cues were occluded. First, place cells were recorded before and after blockade of tactile transmission by means of lidocaine applied on the whisker pad. Following tactile deprivation, the majority of place cells decreased their firing rate and their place fields expanded. We next rotated the tactile cues and 90% of place fields rotated with them. Our results demonstrate that tactile information is integrated into place cells at least in a tactile-enriched arena and when other sensory cues are not available. Copyright © 2013 Wiley Periodicals, Inc.

  5. D-serine increases adult hippocampal neurogenesis

    Directory of Open Access Journals (Sweden)

    Sebastien eSultan

    2013-08-01

    Full Text Available Adult hippocampal neurogenesis results in the continuous formation of new neurons and is a process of brain plasticity involved in learning and memory. The neurogenic niche regulates the stem cell proliferation and the differentiation and survival of new neurons and a major contributor to the neurogenic niche are astrocytes. Among the molecules secreted by astrocytes, D-serine is an important gliotransmitter and is a co-agonist of the glutamate, N-methyl-D-aspartate (NMDA receptor. D-serine has been shown to enhance the proliferation of neural stem cells in vitro, but its effect on adult neurogenesis in vivo is unknown. Here, we tested the effect of exogenous administration of D-serine on adult neurogenesis in the mouse dentate gyrus. We found that 1 week of treatment with D-serine increased cell proliferation in vivo and in vitro and increased the density of neural stem cells and transit amplifying progenitors. Furthermore, D-serine increased the survival of newborn neurons. Together, these results indicate that D-serine treatment resulted in the improvement of several steps of adult neurogenesis in vivo.

  6. Active hippocampal networks undergo spontaneous synaptic modification.

    Directory of Open Access Journals (Sweden)

    Masako Tsukamoto-Yasui

    Full Text Available The brain is self-writable; as the brain voluntarily adapts itself to a changing environment, the neural circuitry rearranges its functional connectivity by referring to its own activity. How the internal activity modifies synaptic weights is largely unknown, however. Here we report that spontaneous activity causes complex reorganization of synaptic connectivity without any external (or artificial stimuli. Under physiologically relevant ionic conditions, CA3 pyramidal cells in hippocampal slices displayed spontaneous spikes with bistable slow oscillations of membrane potential, alternating between the so-called UP and DOWN states. The generation of slow oscillations did not require fast synaptic transmission, but their patterns were coordinated by local circuit activity. In the course of generating spontaneous activity, individual neurons acquired bidirectional long-lasting synaptic modification. The spontaneous synaptic plasticity depended on a rise in intracellular calcium concentrations of postsynaptic cells, but not on NMDA receptor activity. The direction and amount of the plasticity varied depending on slow oscillation patterns and synapse locations, and thus, they were diverse in a network. Once this global synaptic refinement occurred, the same neurons now displayed different patterns of spontaneous activity, which in turn exhibited different levels of synaptic plasticity. Thus, active networks continuously update their internal states through ongoing synaptic plasticity. With computational simulations, we suggest that with this slow oscillation-induced plasticity, a recurrent network converges on a more specific state, compared to that with spike timing-dependent plasticity alone.

  7. Trafficking of astrocytic vesicles in hippocampal slices

    International Nuclear Information System (INIS)

    Potokar, Maja; Kreft, Marko; Lee, So-Young; Takano, Hajime; Haydon, Philip G.; Zorec, Robert

    2009-01-01

    The increasingly appreciated role of astrocytes in neurophysiology dictates a thorough understanding of the mechanisms underlying the communication between astrocytes and neurons. In particular, the uptake and release of signaling substances into/from astrocytes is considered as crucial. The release of different gliotransmitters involves regulated exocytosis, consisting of the fusion between the vesicle and the plasma membranes. After fusion with the plasma membrane vesicles may be retrieved into the cytoplasm and may continue to recycle. To study the mobility implicated in the retrieval of secretory vesicles, these structures have been previously efficiently and specifically labeled in cultured astrocytes, by exposing live cells to primary and secondary antibodies. Since the vesicle labeling and the vesicle mobility properties may be an artifact of cell culture conditions, we here asked whether the retrieving exocytotic vesicles can be labeled in brain tissue slices and whether their mobility differs to that observed in cell cultures. We labeled astrocytic vesicles and recorded their mobility with two-photon microscopy in hippocampal slices from transgenic mice with fluorescently tagged astrocytes (GFP mice) and in wild-type mice with astrocytes labeled by Fluo4 fluorescence indicator. Glutamatergic vesicles and peptidergic granules were labeled by the anti-vesicular glutamate transporter 1 (vGlut1) and anti-atrial natriuretic peptide (ANP) antibodies, respectively. We report that the vesicle mobility parameters (velocity, maximal displacement and track length) recorded in astrocytes from tissue slices are similar to those reported previously in cultured astrocytes.

  8. Ipsilateral hippocampal atrophy is associated with long-term memory dysfunction after ischemic stroke in young adults.

    Science.gov (United States)

    Schaapsmeerders, Pauline; van Uden, Inge W M; Tuladhar, Anil M; Maaijwee, Noortje A M; van Dijk, Ewoud J; Rutten-Jacobs, Loes C A; Arntz, Renate M; Schoonderwaldt, Hennie C; Dorresteijn, Lucille D A; de Leeuw, Frank-Erik; Kessels, Roy P C

    2015-07-01

    Memory impairment after stroke in young adults is poorly understood. In elderly stroke survivors memory impairments and the concomitant loss of hippocampal volume are usually explained by coexisting neurodegenerative disease (e.g., amyloid pathology) in interaction with stroke. However, neurodegenerative disease, such as amyloid pathology, is generally absent at young age. Accumulating evidence suggests that infarction itself may cause secondary neurodegeneration in remote areas. Therefore, we investigated the relation between long-term memory performance and hippocampal volume in young patients with first-ever ischemic stroke. We studied all consecutive first-ever ischemic stroke patients, aged 18-50 years, admitted to our academic hospital center between 1980 and 2010. Episodic memory of 173 patients was assessed using the Rey Auditory Verbal Learning Test and the Rey Complex Figure and compared with 87 stroke-free controls. Hippocampal volume was determined using FSL-FIRST, with manual correction. On average 10 years after stroke, patients had smaller ipsilateral hippocampal volumes compared with controls after left-hemispheric stroke (5.4%) and right-hemispheric stroke (7.7%), with most apparent memory dysfunctioning after left-hemispheric stroke. A larger hemispheric stroke was associated with a smaller ipsilateral hippocampal volume (b=-0.003, Pstroke (b=-0.028 ml, P=0.002) and right-hemispheric stroke (b=-0.015 ml, P=0.03). Our results suggest that infarction is associated with remote injury to the hippocampus, which may lower or expedite the threshold for cognitive impairment or even dementia later in life. © 2015 Wiley Periodicals, Inc.

  9. Quercetin ameliorates chronic unpredicted stress-induced behavioral dysfunction in male Swiss albino mice by modulating hippocampal insulin signaling pathway.

    Science.gov (United States)

    Mehta, Vineet; Singh, Tiratha Raj; Udayabanu, Malairaman

    2017-12-01

    Chronic stress is associated with impaired neurogenesis, neurodegeneration and behavioral dysfunction, whereas the mechanism underlying stress-mediated neurological complications is still not clear. In the present study, we aimed to investigate whether chronic unpredicted stress (CUS) mediated neurological alterations are associated with impaired hippocampal insulin signaling or not, and studied the effect of quercetin in this scenario. Male Swiss albino mice were subjected to 21day CUS, during which 30mg/kg quercetin treatment was given orally. After 21days, behavioral functions were evaluated in terms of locomotor activity (Actophotometer), muscle coordination (Rota-rod), depression (Tail Suspension Test (TST), Forced Swim Test (FST)) and memory performance (Passive-avoidance step-down task (PASD)). Further, hippocampal insulin signaling was evaluated in terms of protein expression of insulin, insulin receptor (IR) and glucose transporter 4 (GLUT-4) and neurogenesis was evaluated in terms of doublecortin (DCX) expression. 21day CUS significantly impaired locomotion and had no effect on muscle coordination. Stressed animals were depressed and showed markedly impaired memory functions. Quercetin treatment significantly improvement stress-mediated behavior dysfunction as indicated by improved locomotion, lesser immobility time and greater frequency of upward turning in TST and FST and increased transfer latency on the day 2 (short-term memory) and day 5 (long-term memory) in PASD test. We observed significantly higher IR expression and significantly lower GLUT-4 expression in the hippocampus of stressed animals, despite of nonsignificant difference in insulin levels. Further, chronic stress impaired hippocampal neurogenesis, as indicated by the significantly reduced levels of hippocampal DCX expression. Quercetin treatment significantly lowered insulin and IR expression and significantly enhanced GLUT-4 and DCX expression in the hippocampus, when compared to CUS. In

  10. Notes on breeding sharp-shinned hawks and cooper’s hawks in Barnwell County, South Carolina

    Science.gov (United States)

    Mark Vukovich; John C. Kilgo

    2009-01-01

    Breeding records of Accipiter striatus (Sharp-shinned Hawks) in the southeastern US are scattered and isolated. We documented a Sharp-shinned Hawk and Accipiter cooperii (Cooper’s Hawk) nest while conducting a telemetry study on Melanerpes erythrocephalus (Red-headed Woodpeckers) in Barnwell County, SC in 2006 and 2007. We report the first known nest of a Sharp-shinned...

  11. Cannula Versus Sharp Needle for Placement of Soft Tissue Fillers: An Observational Cadaver Study.

    Science.gov (United States)

    van Loghem, Jani A J; Humzah, Dalvi; Kerscher, Martina

    2017-12-13

    Soft-tissue fillers have become important products for facial rejuvenation. Deep fat compartments and facial bones lose volume during the natural aging process. For the most natural-looking results, deep volumetric injections at strategic sites are therefore preferred. Supraperiosteal placement is performed with a sharp needle or a non-traumatic cannula. The primary objective was to determine whether there is a difference in precision between supraperiosteal placement with a sharp needle compared with a non-traumatic cannula in cadaver specimens. A secondary objective was to analyze the safety profiles of both injection techniques. Cadaver heads were injected with dye material and soft-tissue fillers at multiple aesthetic facial sites on the supraperiosteum and subsequently dissected for observation of dye and filler placement. The non-traumatic cannula technique resulted in product being confined to the deep anatomic layers. In contrast, with the sharp needle technique, material was placed in multiple anatomic layers, from the periosteum to more superficial skin layers. For both techniques results were consistent for all facial sites. Although direct extrapolation from cadavers to the in vivo situation cannot be made, cannulae showed more precision in placement of product. With the sharp needle, the material was injected on the periosteum, and then migrated in a retrograde direction along the trajectory of the needle path, ending up in multiple anatomic layers. The sharp needle technique also showed a higher complication risk with intra-arterial injection occurring, even though the needle tip was positioned on the periosteum and the product was injected with the needle in constant contact with the periosteum. © 2016 The American Society for Aesthetic Plastic Surgery, Inc. Reprints and permission: journals.permissions@oup.com

  12. Hippocampal memory consolidation during sleep: a comparison of mammals and birds.

    Science.gov (United States)

    Rattenborg, Niels C; Martinez-Gonzalez, Dolores; Roth, Timothy C; Pravosudov, Vladimir V

    2011-08-01

    The transition from wakefulness to sleep is marked by pronounced changes in brain activity. The brain rhythms that characterize the two main types of mammalian sleep, slow-wave sleep (SWS) and rapid eye movement (REM) sleep, are thought to be involved in the functions of sleep. In particular, recent theories suggest that the synchronous slow-oscillation of neocortical neuronal membrane potentials, the defining feature of SWS, is involved in processing information acquired during wakefulness. According to the Standard Model of memory consolidation, during wakefulness the hippocampus receives input from neocortical regions involved in the initial encoding of an experience and binds this information into a coherent memory trace that is then transferred to the neocortex during SWS where it is stored and integrated within preexisting memory traces. Evidence suggests that this process selectively involves direct connections from the hippocampus to the prefrontal cortex (PFC), a multimodal, high-order association region implicated in coordinating the storage and recall of remote memories in the neocortex. The slow-oscillation is thought to orchestrate the transfer of information from the hippocampus by temporally coupling hippocampal sharp-wave/ripples (SWRs) and thalamocortical spindles. SWRs are synchronous bursts of hippocampal activity, during which waking neuronal firing patterns are reactivated in the hippocampus and neocortex in a coordinated manner. Thalamocortical spindles are brief 7-14 Hz oscillations that may facilitate the encoding of information reactivated during SWRs. By temporally coupling the readout of information from the hippocampus with conditions conducive to encoding in the neocortex, the slow-oscillation is thought to mediate the transfer of information from the hippocampus to the neocortex. Although several lines of evidence are consistent with this function for mammalian SWS, it is unclear whether SWS serves a similar function in birds, the only

  13. Training labels for hippocampal segmentation based on the EADC-ADNI harmonized hippocampal protocol.

    Science.gov (United States)