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Sample records for investigating hippocampal sharp

  1. 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.

  2. 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.

  3. Learning-induced plasticity regulates hippocampal sharp wave-ripple drive.

    Science.gov (United States)

    Girardeau, Gabrielle; Cei, Anne; Zugaro, Michaël

    2014-04-09

    Hippocampal sharp wave-ripples (SPW-Rs) and associated place-cell reactivations are crucial for spatial memory consolidation during sleep and rest. However, it remains unclear how learning and consolidation requirements influence and regulate subsequent SPW-R activity. Indeed, SPW-R activity has been observed not only following complex behavioral tasks, but also after random foraging in familiar environments, despite markedly different learning requirements. Because transient increases in SPW-R rates have been reported following training on memory tasks, we hypothesized that SPW-R activity following learning (but not routine behavior) could involve specific regulatory processes related to ongoing consolidation. Interfering with ripples would then result in a dynamic compensatory response only when initial memory traces required consolidation. Here we trained rats on a spatial memory task, and showed that subsequent sleep periods where ripple activity was perturbed by timed electrical stimulation were indeed characterized by increased SPW-R occurrence rates compared with control sleep periods where stimulations were slightly delayed in time and did not interfere with ripples. Importantly, this did not occur following random foraging in a familiar environment. We next showed that this dynamic response was abolished following injection of an NMDA receptor blocker (MK-801) before, but not after training. Our results indicate that NMDA receptor-dependent processes occurring during learning, such as network "tagging" and plastic changes, regulate subsequent ripple-mediated consolidation of spatial memory during sleep.

  4. The hippocampal CA3 region can generate two distinct types of sharp wave-ripple complexes, in vitro.

    Science.gov (United States)

    Hofer, Katharina T; Kandrács, Ágnes; Ulbert, István; Pál, Ildikó; Szabó, Csilla; Héja, László; Wittner, Lucia

    2015-02-01

    Hippocampal sharp wave-ripples (SPW-Rs) occur during slow wave sleep and behavioral immobility and are thought to play an important role in memory formation. We investigated the cellular and network properties of SPW-Rs with simultaneous laminar multielectrode and intracellular recordings in a rat hippocampal slice model, using physiological bathing medium. Spontaneous SPW-Rs were generated in the dentate gyrus (DG), CA3, and CA1 regions. These events were characterized by a local field potential gradient (LFPg) transient, increased fast oscillatory activity and increased multiple unit activity (MUA). Two types of SPW-Rs were distinguished in the CA3 region based on their different LFPg and current source density (CSD) pattern. Type 1 (T1) displayed negative LFPg transient in the pyramidal cell layer, and the associated CSD sink was confined to the proximal dendrites. Type 2 (T2) SPW-Rs were characterized by positive LFPg transient in the cell layer, and showed CSD sinks involving both the apical and basal dendrites. In both types, consistent with the somatic CSD source, only a small subset of CA3 pyramidal cells fired, most pyramidal cells were hyperpolarized, while most interneurons increased firing rate before the LFPg peak. Different neuronal populations, with different proportions of pyramidal cells and distinct subsets of interneurons were activated during T1 and T2 SPW-Rs. Activation of specific inhibitory cell subsets-with the possible leading role of perisomatic interneurons-seems to be crucial to synchronize distinct ensembles of CA3 pyramidal cells finally resulting in the expression of different SPW-R activities. This suggests that the hippocampus can generate dynamic changes in its activity stemming from the same excitatory and inhibitory circuits, and so, might provide the cellular and network basis for an input-specific and activity-dependent information transmission. © 2014 Wiley Periodicals, Inc.

  5. 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.

  6. Hippocampal sharp wave bursts coincide with neocortical “up-state” transitions

    OpenAIRE

    Battaglia, Francesco P.; Sutherland, Gary R.; McNaughton, Bruce L.

    2004-01-01

    The sleeping neocortex shows nested oscillatory activity in different frequency ranges, characterized by fluctuations between “up-states” and “down-states.” High-density neuronal ensemble recordings in rats now reveal the interaction between synchronized activity in the hippocampus and neocortex: Electroencephalographic sharp waves in the hippocampus were more probable during down-states than during up-states, and tended to coincide with transitions from down-states to up-states. The form of ...

  7. 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.

  8. 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.

  9. [Somewhere in tertiary hospital clinical laboratory in pursuance of personnel sharp injury incidence status investigation and relative factor analysis].

    Science.gov (United States)

    Ding, E; Li, W H; Wang, P; Jian, X D

    2016-07-20

    Objective: Investigation in tertiary hospital clinical laboratory in pursuance of the current state of the sharp injury incidence and influencing factors, analyze the causes and discuss the control strategy. Methods: Application of cross-sectional survey method, according to the unified investigation questionnaire investigation, with chi-square test and the multi-factor Logistic regression analysis methods to analyze research data. Results: The work environment exit contact with injection needles, glass and other sharps, contact with noise, contact with chemicals, contact the patient's blood and other biological specimens, high-risk groups, the patient and family to negative emotions, by patients and their families complain or abuse related influencing factors. In the organization and management factors, in order to work strength is insufficient for the most dissatisfied, protective equipment, medical staff personal cognitive factors of occupational exposure, failing to abide by the medical care standard operation and high incidence after exposure to failed to report. Somewhere in tertiary hospital clinical laboratory in pursuance of the incidence of sharps injuries associated with five factors: different jobs, working strength, protective equipment perfect or not, sharp instrument use and disposal of medical wastes. Conclusion: Tertiary hospital clinical laboratory in pursuance of the incidence of sharp injury related to many factors, Hospitals should formulate corresponding rules and regulations, improve the working environment, the standard safety operation, reduced the incidence of sharps injuries.

  10. Investigating the synchronization of hippocampal neural network in response to acute nicotine exposure

    Directory of Open Access Journals (Sweden)

    Akay Metin

    2010-07-01

    Full Text Available Abstract Previous studies suggested that γ oscillations in the brain are associated with higher order cognitive function including selective visual attention, motor task planning, sensory perception, working memory and dreaming REM sleep. These oscillations are mainly observed in cortical regions and also occur in neocortical and subcortical areas and the hippocampus. In this paper, we investigate the influence of acute exposure to nicotine on the complexity of hippocampal γ oscillations. Using the approximate entropy method, the influence of acute nicotine exposure on the hippocampal γ oscillations was investigated. The hippocampal γ oscillations have been generated in response to the 100 Hz stimulus and isolated using the visual inspection and spectral analysis method. Our central hypothesis is that acute exposure to nicotine significantly reduces the complexity of hippocampal γ oscillations. We used brain-slice recordings and the approximate entropy method to test this hypothesis. The approximate entropy (complexity values of the hippocampal γ oscillations are estimated from the 14 hippocampal slices. Our results show that it takes at least 100 msec to see any hippocampal activities in response to the 100 Hz stimulus. These patterns noticeably changed after 100 msec until 300 msec after the stimulus Finally, they were less prominent after 300 msec. We have analyzed the isolated hippocampal γ oscillations (between 150 and 250 msec after the stimulus using the approximate entropy (ApEn method. Our results showed that the ApEn (complexity values of hippocampal γ oscillations during nicotine exposure were reduced compared to those of hippocampal γ oscillations during control, and washout. This reduction was much more significant in response to acute nicotine exposure (p

  11. Investigation of Patients with Hippocampal Sclerosis Associated with Unusual Epileptic Activities

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    Ebru Nur Vanlı Yavuz

    2016-06-01

    Full Text Available INTRODUCTION: Hippocampal sclerosis (HS is usually associated with typical anterior temporal spikes/sharp waves in the electroencephalography (EEG. We aimed to investigate the clinical, electrophysiologic differences, and prognosis between HS patients with unusual epileptic foci in comparison with patients with typical foci. METHODS: Patients diagnosed who were diagnosed as having mesial temporal lobe epilepsy with HS in our center were included. All magnetic resonance imaging (MRI results were investigated for the presence of two major criteria of HS diagnosis, namely T1 atrophy and T2 hyperintensity. All EEG and video-EEG investigations (a total of 496 were re-evaluated for unusual epileptic activities except T1/2, F7/8, T3/4 foci. Clinical and other laboratory data were retrospectively reevaluated by two investigators and the groups with usual and unusual epileptic activities for this syndrome were statistically compared. RESULTS: A total of 124 patients including 20 (16.1% with unusual epileptic activities (group 1 and 104 patients with typical foci (group 2 were evaluated. We observed 11 posterior temporal (T5/T6, four frontal (F3/F4, four frontopolar (Fp1/2, two occipital (O1/O2, three central (CP/FC unusual foci, and two generalized epileptiform discharges in these 20 patients. Impaired background activity, nonspecific interictal diffuse slowing, and atypical seizure offset patterns were more frequently observed in group 1. Forty-nine patients underwent surgery after appropriate preoperative diagnostics; there was no significant difference in the postoperative outcome between the groups despite a tendency to better prognosis in group 2. DISCUSSION AND CONCLUSION: Our study showed that unusual epileptic foci could be seen in 16.1% of patients with HS. Although some patients with HS have these atypical interictal EEG findings, they might obtain good post-operative outcomes when preoperative diagnostics are appropriately planned.

  12. 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.

  13. 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...

  14. 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 (K ATP ) channels, vesicular glutamate transporter (VGLUT), pannexin channels and adenosine receptors underlying ketogenic diet and other forms of metabolic therapy.

  15. 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

  16. 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.

  17. 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

  18. 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.

  19. Investigating the role of hippocampal BDNF in anxiety vulnerability using classical eyeblink conditioning

    Directory of Open Access Journals (Sweden)

    Kellie L Janke

    2015-07-01

    Full Text Available Dysregulation of brain-derived neurotrophic factor (BDNF, behavioral inhibition temperament (BI and small hippocampal volume have been linked to anxiety disorders. Individuals with BI show facilitated acquisition of the classically conditioned eyeblink response (CCER as compared to non-BI individuals, and a similar pattern is seen in an animal model of BI, the Wistar-Kyoto (WKY rat. The present study examined the role of hippocampal BDNF in the facilitated delay CCER of WKY rats. Consistent with earlier work, acquisition was facilitated in WKY rats compared to the SD rats. Facilitated acquisition was associated with increased BDNF, TrkB, and Arc mRNA in the dentate gyrus of SD rats, but learning-induced increases in BDNF and Arc mRNA were significantly smaller in WKY rats. To determine if reduced hippocampal BDNF in WKY rats was a contributing factor for their facilitated CCER, BDNF or saline infusions were given bilaterally into the dentate gyrus region one hour prior to training. BDNF infusion did not alter the acquisition of SD rats, but significantly dampened the acquisition of CCER in the WKY rats, such that acquisition was similar to SD rats. Together, these results suggest that inherent differences in the BDNF system play a critical role in the facilitated associative learning exhibited by WKY rats, and potentially individuals with BI. Facilitated associative learning may represent a vulnerability factor in the development of anxiety disorders.

  20. 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.

  1. 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.

  2. 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....

  3. An investigation of the effects of exercise on hippocampal function in young, middle-aged and aged rats

    OpenAIRE

    O'Callaghan, Rachel

    2008-01-01

    The hippocampus is a brain structure that is important for higher cognitive functions, possesses a high degree of plasticity, and is particularly vulnerable to the aging process (Burke & Barnes, 2006). Symptoms of hippocampal dysfunction and cognitive alteration are seen with both severe cognitive decline such as that associated with Alzheimer’s disease and other forms of dementia (Small et al, 1999). Given that demographic trends suggest the elderly population is increasing (Miller & O’Calla...

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

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

    African Journals Online (AJOL)

    2010-07-10

    Jul 10, 2010 ... respondents who sustained injuries (59.0%) received post-exposure prophylaxis (Table. 5). The mode of disposal of sharps for most respondents. (85.4%, n 35) was into special containers (Table 6). Discussion. Sharps injuries potentially expose workers to deadly vi- ruses and other bloodborne pathogens.

  11. Hippocampal sclerosis and chronic epilepsy following posterior reversible encephalopathy syndrome.

    Science.gov (United States)

    Kapina, Viktoria; Vargas, Maria-Isabel; Wohlrab, Gabriele; Vulliemoz, Serge; Fluss, Joel; Seeck, Margitta

    2013-12-01

    Chronic epilepsy has rarely been reported after posterior reversible encephalopathy syndrome (PRES) and the association with hippocampal sclerosis has been suggested only once before. We report the case of a girl admitted at the age of 8 years with idiopathic nephrotic syndrome. On the second day of admission, she presented with focal complex seizures and cerebral MRI showed posterior encephalopathy and no hippocampal sclerosis. MRI after one month confirmed the diagnosis of PRES. The seizures recurred and the girl developed pharmacoresistant epilepsy and was admitted to our hospital for further investigation. Cerebral MRI three years after the diagnosis of PRES showed hippocampal sclerosis which was not present on the initial MRI. We conclude that there is a triggering role of PRES in the development of hippocampal sclerosis. Hippocampal sclerosis may have resulted from seizure-associated damage, alternatively, hypertensive encephalopathy may have led to hippocampal damage via a vascular mechanism.

  12. 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

  13. 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.

  14. The Sharpe ratio of estimated efficient portfolios

    OpenAIRE

    Kourtis, Apostolos

    2016-01-01

    Investors often adopt mean-variance efficient portfolios for achieving superior risk-adjusted returns. However, such portfolios are sensitive to estimation errors, which affect portfolio performance. To understand the impact of estimation errors, I develop simple and intuitive formulas of the squared Sharpe ratio that investors should expect from estimated efficient portfolios. The new formulas show that the expected squared Sharpe ratio is a function of the length of the available data, the ...

  15. 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

  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. 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.

  18. 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.

  19. A sharp cutting liposuction cannula for gynecomastia.

    Science.gov (United States)

    Hamas, R S; Williams, C W

    1998-01-01

    Liposuction is often used for the treatment of gynecomastia. Blunt liposuction cannulas can remove the fat but are not very effective in fibrous breast tissue, which requires open excision. Ultrasound-assisted lipoplasty has been advocated for gynecomastia because it effectively removes the fat from fibrous areas. An alternative treatment is a sharp cutting liposuction cannula that easily penetrates and removes the fibrous breast tissue along with the fatty component. The early experience of 22 surgeons who used this cannula in 88 cases of gynecomastia is reported. For 19 of the 22 surgeons, liposuction with sharp cutting cannulas alone gave a satisfactory result in 81% of their patients.

  20. Closed-Loop Interruption of Hippocampal Ripples through Fornix Stimulation in the Non-Human Primate.

    Science.gov (United States)

    Talakoub, Omid; Gomez Palacio Schjetnan, Andrea; Valiante, Taufik A; Popovic, Milos R; Hoffman, Kari L

    Hippocampal sharp-wave ripples (SWRs) arising from synchronous bursting in CA3 pyramidal cells and propagating to CA1 are thought to facilitate memory consolidation. Stimulation of the CA3 axon collaterals comprising the hippocampal commissure in rats interrupts sharp-wave ripples and leads to memory impairment. In primates, however, these commissural collaterals are limited. Other hippocampal fiber pathways, like the fornix, may be potential targets for modulating ongoing hippocampal activity, with the short latencies necessary to interrupt ripples. The aim of this study is to determine the efficacy of closed-loop stimulation adjacent to the fornix for interrupting hippocampal ripples. Stimulating electrodes were implanted bilaterally alongside the fornix in the macaque, together with microelectrodes targeting the hippocampus for recording SWRs. We first verified that fornix stimulation reliably and selectively evoked a response in the hippocampus. We then implemented online detection and stimulation as hippocampal ripples occurred. The closed-loop interruption method was effective in interrupting ripples as well as the associated hippocampal multi-unit activity, demonstrating the feasibility of ripple interruption using fornix stimulation in primates. Analogous to murine research, such an approach will likely be useful in understanding the role of SWRs in memory formation in macaques and other primates sharing these pathways, such as humans. More generally, closed-loop stimulation of the fornix may prove effective in interrogating hippocampal-dependent memory processes. Finally, this rapid, contingent-DBS approach may be a means for modifying pathological high-frequency events within the hippocampus, and potentially throughout the extended hippocampal circuit. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  1. 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.

  2. 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.

  3. Sharp inequalities for tangent function with applications.

    Science.gov (United States)

    Lv, Hui-Lin; Yang, Zhen-Hang; Luo, Tian-Qi; Zheng, Shen-Zhou

    2017-01-01

    In the article, we present new bounds for the function [Formula: see text] on the interval [Formula: see text] 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.

  4. Sharp embeddings of Besov-type spaces

    Czech Academy of Sciences Publication Activity Database

    Gurka, P.; Opic, Bohumír

    2007-01-01

    Roč. 208, č. 1 (2007), s. 1-43 ISSN 0377-0427 R&D Projects: GA ČR GA201/05/2033 Institutional research plan: CEZ:AV0Z10190503 Keywords : Besov spaces with slowly varying smoothness * Lorentz-Karamata spaces * sharp embeddings Subject RIV: BA - General Mathematics Impact factor: 0.943, year: 2007

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

    African Journals Online (AJOL)

    Objective To assess the prevalence of sharp injury among Cameroonian dental professionals. Materials and Methods A cross-sectional study of 41 dental professionals recruited from 4 out of 10 provinces in Cameroon was conducted in the second half of 2009. A self-administered questionnaire was used to capture ...

  6. 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.

  7. Hippocampal Offline Reactivation Consolidates Recently Formed Cell Assembly Patterns during Sharp Wave-Ripples

    OpenAIRE

    van de Ven, Gido M.; Trouche, Stéphanie; McNamara, Colin G.; Allen, Kevin; Dupret, David

    2016-01-01

    Summary The ability to reinstate neuronal assemblies representing mnemonic information is thought to require their consolidation through offline reactivation during sleep/rest. To test this, we detected cell assembly patterns formed by repeated neuronal co-activations in the mouse hippocampus during exploration of spatial environments. We found that the reinstatement of assembly patterns representing a novel, but not a familiar, environment correlated with their offline reactivation and was i...

  8. Rhinal-hippocampal EEG coherence is reduced during human sleep.

    NARCIS (Netherlands)

    Fell, J.; Staedtgen, M.; Burr, W.; Kockelmann, E.; Helmstaedter, C.; Schaller, C.; Elger, C.E.; Fernandez, G.S.E.

    2003-01-01

    The deficiency of declarative memory compared with waking state is an often overlooked characteristic of sleep. Here, we investigated whether rhinal-hippocampal coherence, an electrophysiological correlate of declarative memory formation, is significantly altered during sleep as compared with waking

  9. Aerobic fitness, hippocampal viscoelasticity, and relational memory performance.

    Science.gov (United States)

    Schwarb, Hillary; Johnson, Curtis L; Daugherty, Ana M; Hillman, Charles H; Kramer, Arthur F; Cohen, Neal J; Barbey, Aron K

    2017-06-01

    The positive relationship between hippocampal structure, aerobic fitness, and memory performance is often observed among children and older adults; but evidence of this relationship among young adults, for whom the hippocampus is neither developing nor atrophying, is less consistent. Studies have typically relied on hippocampal volumetry (a gross proxy of tissue composition) to assess individual differences in hippocampal structure. While volume is not specific to microstructural tissue characteristics, microstructural differences in hippocampal integrity may exist even among healthy young adults when volumetric differences are not diagnostic of tissue health or cognitive function. Magnetic resonance elastography (MRE) is an emerging noninvasive imaging technique for measuring viscoelastic tissue properties and provides quantitative measures of tissue integrity. We have previously demonstrated that individual differences in hippocampal viscoelasticity are related to performance on a relational memory task; however, little is known about health correlates to this novel measure. In the current study, we investigated the relationship between hippocampal viscoelasticity and cardiovascular health, and their mutual effect on relational memory in a group of healthy young adults (N=51). We replicated our previous finding that hippocampal viscoelasticity correlates with relational memory performance. We extend this work by demonstrating that better aerobic fitness, as measured by VO 2 max, was associated with hippocampal viscoelasticity that mediated the benefits of fitness on memory function. Hippocampal volume, however, did not account for individual differences in memory. Therefore, these data suggest that hippocampal viscoelasticity may provide a more sensitive measure to microstructural tissue organization and its consequences to cognition among healthy young adults. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  10. SHARP/PRONGHORN Interoperability: Mesh Generation

    Energy Technology Data Exchange (ETDEWEB)

    Avery Bingham; Javier Ortensi

    2012-09-01

    Progress toward collaboration between the SHARP and MOOSE computational frameworks has been demonstrated through sharing of mesh generation and ensuring mesh compatibility of both tools with MeshKit. MeshKit was used to build a three-dimensional, full-core very high temperature reactor (VHTR) reactor geometry with 120-degree symmetry, which was used to solve a neutron diffusion critical eigenvalue problem in PRONGHORN. PRONGHORN is an application of MOOSE that is capable of solving coupled neutron diffusion, heat conduction, and homogenized flow problems. The results were compared to a solution found on a 120-degree, reflected, three-dimensional VHTR mesh geometry generated by PRONGHORN. The ability to exchange compatible mesh geometries between the two codes is instrumental for future collaboration and interoperability. The results were found to be in good agreement between the two meshes, thus demonstrating the compatibility of the SHARP and MOOSE frameworks. This outcome makes future collaboration possible.

  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. Acupuncture reversed hippocampal mitochondrial dysfunction in vascular dementia rats.

    Science.gov (United States)

    Li, Hui; Liu, Yi; Lin, Li-Ting; Wang, Xue-Rui; Du, Si-Qi; Yan, Chao-Qun; He, Tian; Yang, Jing-Wen; Liu, Cun-Zhi

    2016-01-01

    Hippocampal mitochondrial dysfunction due to oxidative stress has been considered to play a major role in the pathogenesis of vascular dementia (VD). Previous studies suggested that acupuncture could improve cerebral hypoperfusion-induced cognitive impairments. However, whether hippocampal mitochondria are associated with this cognitive improvement remains unclear. In this study, an animal model of VD was established via bilateral common carotid arteries occlusion (BCCAO) to investigate the alterations of cognitive ability and hippocampal mitochondrial function. BCCAO rats showed impairments in hippocampal mitochondrial function, overproduction of reactive oxygen species (ROS) and learning and memory deficits. After two-week acupuncture treatment, BCCAO-induced spatial learning and memory impairments as shown in Morris water maze were ameliorated. Hippocampal mitochondrial respiratory complex enzymes (complex I, II, IV) activities and cytochrome c oxidase IV expression significantly increased, which might contribute to the reduction of hippocampal ROS generation. In addition, acupuncture significantly improve mitochondrial bioenergy parameters such as mitochondrial respiratory control rate and membrane potential not PDH A1 expression. Placebo-acupuncture did not produce similar therapeutic effects. These findings suggested that acupuncture reversed BCCAO-induced hippocampal mitochondrial dysfunction, which might contribute to its prevention on cognitive deficits. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Resveratrol: A Potential Hippocampal Plasticity Enhancer.

    Science.gov (United States)

    Dias, Gisele Pereira; Cocks, Graham; do Nascimento Bevilaqua, Mário Cesar; Nardi, Antonio Egidio; Thuret, Sandrine

    2016-01-01

    The search for molecules capable of restoring altered hippocampal plasticity in psychiatric and neurological conditions is one of the most important tasks of modern neuroscience. It is well established that neural plasticity, such as the ability of the postnatal hippocampus to continuously generate newly functional neurons throughout life, a process called adult hippocampal neurogenesis (AHN), can be modulated not only by pharmacological agents, physical exercise, and environmental enrichment, but also by "nutraceutical" agents. In this review we focus on resveratrol, a phenol and phytoalexin found in the skin of grapes and red berries, as well as in nuts. Resveratrol has been reported to have antioxidant and antitumor properties, but its effects as a neural plasticity inducer are still debated. The current review examines recent evidence implicating resveratrol in regulating hippocampal neural plasticity and in mitigating the effects of various disorders and diseases on this important brain structure. Overall, findings show that resveratrol can improve cognition and mood and enhance hippocampal plasticity and AHN; however, some studies report opposite effects, with resveratrol inhibiting aspects of AHN. Therefore, further investigation is needed to resolve these controversies before resveratrol can be established as a safe coadjuvant in preventing and treating neuropsychiatric conditions.

  14. Schizophrenia polygenic risk score predicts mnemonic hippocampal activity.

    Science.gov (United States)

    Chen, Qiang; Ursini, Gianluca; Romer, Adrienne L; Knodt, Annchen R; Mezeivtch, Karleigh; Xiao, Ena; Pergola, Giulio; Blasi, Giuseppe; Straub, Richard E; Callicott, Joseph H; Berman, Karen F; Hariri, Ahmad R; Bertolino, Alessandro; Mattay, Venkata S; Weinberger, Daniel R

    2018-02-03

    The use of polygenic risk scores has become a practical translational approach to investigating the complex genetic architecture of schizophrenia, but the link between polygenic risk scores and pathophysiological components of this disorder has been the subject of limited research. We investigated in healthy volunteers whether schizophrenia polygenic risk score predicts hippocampal activity during simple memory encoding, which has been proposed as a risk-associated intermediate phenotype of schizophrenia. We analysed the relationship between polygenic risk scores and hippocampal activity in a discovery sample of 191 unrelated healthy volunteers from the USA and in two independent replication samples of 76 and 137 healthy unrelated participants from Europe and the USA, respectively. Polygenic risk scores for each individual were calculated as the sum of the imputation probability of reference alleles weighted by the natural log of odds ratio from the recent schizophrenia genome-wide association study. We examined hippocampal activity during simple memory encoding of novel visual stimuli assessed using blood oxygen level-dependent functional MRI. Polygenic risk scores were significantly associated with hippocampal activity in the discovery sample [P = 0.016, family-wise error (FWE) corrected within Anatomical Automatic Labeling (AAL) bilateral hippocampal-parahippocampal mask] and in both replication samples (P = 0.033, FWE corrected within AAL right posterior hippocampal-parahippocampal mask in Bari sample, and P = 0.002 uncorrected in the Duke Neurogenetics Study sample). The relationship between polygenic risk scores and hippocampal activity was consistently negative, i.e. lower hippocampal activity in individuals with higher polygenic risk scores, consistent with previous studies reporting decreased hippocampal-parahippocampal activity during declarative memory tasks in patients with schizophrenia and in their healthy siblings. Polygenic risk scores accounted for

  15. Convex Regression with Interpretable Sharp Partitions.

    Science.gov (United States)

    Petersen, Ashley; Simon, Noah; Witten, Daniela

    2016-06-01

    We consider the problem of predicting an outcome variable on the basis of a small number of covariates, using an interpretable yet non-additive model. We propose convex regression with interpretable sharp partitions (CRISP) for this task. CRISP partitions the covariate space into blocks in a data-adaptive way, and fits a mean model within each block. Unlike other partitioning methods, CRISP is fit using a non-greedy approach by solving a convex optimization problem, resulting in low-variance fits. We explore the properties of CRISP, and evaluate its performance in a simulation study and on a housing price data set.

  16. After an exposure to sharps or body fluids

    Science.gov (United States)

    ... htm After an exposure to sharps or body fluids To use the sharing features on this page, ... JavaScript. Being exposed to sharps (needles) or body fluids means that another person's blood or other body ...

  17. Sharp injuries among hospital waste handlers.

    Science.gov (United States)

    Olaitan, P B; Odu, O O; Olaitan, J O; Oseni, O G

    2012-01-01

    Health care workers are generally predisposed to injuries from sharps as a health hazard. This is more pronounced among waste handlers. It is therefore important to assess these injuries among this group of people with a view to identifying the risk factors and suggesting preventive methods. Questionnaires were administered to People handling wastes in our hospital to assess their level of education on injury prevention, immunization status and preventive methods used by them to prevent these injuries and subsequent infections. Forty three waste handlers were interviewed. Twenty eight (65.8%) of them received training before commencing on the job while 14 (32.5%) never received any training. Only thirty nine (90.7%) of them always use hand gloves before carrying wastes. Only three (7.0%) of the respondents have been screened for Hepatitis B, 19 (44.2%) for HIV, while 10 (23.3%) were screened for Hepatitis B, C, and HIV. Eleven (25.6%) of them have been injured with sharps. The finger was the most injured in 7 (93%) of them. Training and re-training of health workers is important and should be encouraged. All health workers should have pre-employment immunization against Hepatitis B, 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.

  18. 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.

  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. Strategic Management Plan for Columbian Sharp-Tailed Grouse 2002

    OpenAIRE

    State of Utah, Department of Natural Resoures, Division of Wildlife Resources

    2002-01-01

    The Columbian Sharp-tailed Grouse (Tympanuchus phasianellus columbianus) is one of seven subspecies of Sharp-tailed Grouse. Historically, Columbian Sharp-tailed Grouse occurred within sagebrush-native bunch grass habitat throughout the intermountain region, extending from British Columbia, Washington, Idaho and Montana south through portions of Oregon, California, Nevada, Utah, Wyoming, Colorado and New Mexico. Sharp-tailed Grouse populations range-wide began declining during 1880-1920 (Bart ...

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

    African Journals Online (AJOL)

    Key words: Sharps waste, sharps waste container, overfilled safety box, sharps waste proportion, infectious waste, incinerator ash, fuel effectiveness. .... cost consideration, efficacy of treatment method, skills requirements and availability of ..... A Preliminary Study of Medical Waste. Management in Lagos Metropolis, Nigeria.

  2. The SHARP Program: Giving Kids Chances to Excel

    Science.gov (United States)

    Kenney, Rich

    2007-01-01

    In this article, the author describes the Sports, Habilitation, and Recreation Program (SHARP), a program of the Foundation for Blind Children in Phoenix, Arizona. The SHARP program aims to help children, who have visual impairments, achieve goals, develop independence, and make friends. One of the unique features of the SHARP program is that it…

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

    African Journals Online (AJOL)

    Sharps waste is part of infectious waste generated in health facilities, management of which is critical. This study aimed at assessing the sharps waste management practices in a referral hospital. The study was conducted at Muhimbili National Hospital (MNH) in Dar es Salaam, Tanzania. Data on sharps waste containers ...

  4. Sharp Vision Reveals Intimacy of Stars

    Science.gov (United States)

    2005-11-01

    Sharp Vision Reveals Intimacy of Stars AMBER instrument on VLTI Probes Environment of Stars Using the newly installed AMBER instrument on ESO's Very Large Telescope Interferometer, which combines the light from two or three 8.2-m Unit Telescopes thereby amounting to observe with a telescope of 40 to 90 metres in diameter, two international teams of astronomers observed with unprecedented detail the environment of two stars. One is a young, still-forming star and the new results provide useful information on the conditions leading to the creation of planets. The other is on the contrary a star entering the latest stages of its life. The astronomers found, in both cases, evidence for a surrounding disc. ESO PR Photo 36a/05 ESO PR Photo 36a/05 The Young Stellar Object MWC 297 (Artist's View) [Preview - JPEG: 400 x 502 pix - 50k] [Normal - JPEG: 800 x 1004 pix - 330k] A first group of astronomers [1], led by Fabien Malbet from the Laboratoire d'Astrophysique de Grenoble, France, studied the young 10-solar mass stellar object MWC 297, which is still in the very early stage of its life [2]. "This scientific breakthrough opens the doors to an especially detailed scrutiny of the very close environment of young stars and will bring us invaluable knowledge on how planets form", says Malbet. It is amazing to see the amount of details the astronomers could achieve while observing an object located more than 800 light-years away and hidden by a large amount of gas and dust. They found the object to be surrounded by a proto-planetary disc extending to about the size of our Solar System, but truncated in his inner part until about half the distance between the Earth and the Sun. Moreover, the scientists found the object to be surrounded by an outflowing wind, the velocity of which increased by a factor 9, from about 70 km/s near the disc to 600 km/s in the polar regions [3]. "The reason why the inner part of the disc should be truncated is not clear", adds Malbet. "This raises

  5. 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...

  6. Hippocampal correlates of depression in healthy elderly adults.

    Science.gov (United States)

    Ezzati, Ali; Zimmerman, Molly E; Katz, Mindy J; Lipton, Richard B

    2013-12-01

    Mixed findings have been reported on the relationship between hippocampal integrity and major depression in clinical populations. Few neuroimaging studies have investigated associations between hippocampal measures and depressive symptoms in nondemented older adults. Here, we address this issue by imaging 36 nondemented adults over age 70 from the Einstein Aging Study, a community-based sample from the Bronx, NY. Depressive symptoms were assessed using the 15-item Geriatric Depression scale (GDS). Clinically significant depression was defined using a cut-off score of 5 or greater. Hippocampal data included MRI-derived volume data normalized to midsagittal area and MRS-derived N-acetylaspartate to creatine ratios (NAA/Cr). Our result indicates that smaller total hippocampal volume was associated with higher GDS scores, but there were no significant association between hippocampal NAA/Cr and GDS score. These effects were consistent after controlling for age, education, and gender. Reduction in hippocampal volume could represent a risk factor or a consequence of depression in older adults. Further studies are needed to better understand the role of the hippocampus in the development and experience of depression in older adults. Copyright © 2013 Wiley Periodicals, Inc.

  7. Two reentrant pathways in the hippocampal-entorhinal system.

    Science.gov (United States)

    Kloosterman, Fabian; van Haeften, Theo; Lopes da Silva, Fernando H

    2004-01-01

    The entorhinal cortex has long been recognized as an important interface between the hippocampal formation and the neocortex. The notion of bidirectional connections between the entorhinal cortex and the hippocampal formation have led to the suggestion that hippocampal output originating in CA1 and subiculum may reenter hippocampal subfields via the entorhinal cortex. To investigate this, we used simultaneous multi-site field potential recordings and current source density analysis in the entorhinal cortex and hippocampal formation of the rat in vivo. Under ketamine/xylazine anesthesia, we found that repetitive stimulation of subiculum or Schaffer collaterals facilitated entorhinal responses, such that a population spike appeared in layer III. In addition, a current sink in stratum lacunosum-moleculare of area CA1 was found, that followed responses in the entorhinal cortex, indicating reentrance into this area. Responses indicating reentrance in the dentate gyrus were not found under ketamine/xylazine anesthesia, but were readily evoked under urethane anesthesia. Reentrance into CA1 was also encountered under urethane anesthesia. These results suggest that parallel, but possibly functionally distinct, connections are present between the output of the hippocampal formation and cells in layers III and II of the entorhinal cortex that project to area CA1 and the dentate gyrus, respectively. 2004 Wiley-Liss, Inc.

  8. Unexceptional sharpness of frequency tuning in the human cochlea

    Science.gov (United States)

    Ruggero, Mario A.; Temchin, Andrei N.

    2005-12-01

    The responses to sound of auditory-nerve fibers are well known in many animals but are topics of conjecture for humans. Some investigators have claimed that the auditory-nerve fibers of humans are more sharply tuned than are those of various experimental animals. Here we invalidate such claims. First, we show that forward-masking psychophysical tuning curves, which were used as the principal support for those claims, greatly overestimate the sharpness of cochlear tuning in experimental animals and, hence, also probably in humans. Second, we calibrate compound action potential tuning curves against the tuning of auditory-nerve fibers in experimental animals and use compound action potential tuning curves recorded in humans to show that the sharpness of tuning in human cochleae is not exceptional and that it is actually similar to tuning in all mammals and birds for which comparisons are possible. Third, we note that the similarity of frequency of tuning across species with widely diverse cochlear lengths and auditory bandwidths implies that for any given stimulus frequency the "cochlear amplifier" is confined to a highly localized region of the cochlea. auditory nerve | basilar membrane | masking | compound action potential | psychophysical tuning curve

  9. Near-field edge fringes at sharp material boundaries.

    Science.gov (United States)

    Babicheva, V E; Gamage, S; Stockman, M I; Abate, Y

    2017-10-02

    We have studied the formation of near-field fringes when sharp edges of materials are imaged using scattering-type scanning near-field optical microscope (s-SNOM). The materials we have investigated include dielectrics, metals, a near-perfect conductor, and those that possess anisotropic permittivity and hyperbolic dispersion. For our theoretical analysis, we use a technique that combines full-wave numerical simulations of tip-sample near-field interaction and signal demodulation at higher orders akin to what is done in typical s-SNOM experiments. Unlike previous tip-sample interaction near-field models, our advanced technique allows simulation of the realistic tip and sample structure. Our analysis clarifies edge imaging of recently emerged layered materials such as hexagonal boron nitride and transition metal dichalcogenides (in particular, molybdenum disulfide), as well as traditional plasmonic materials such as gold. Hexagonal boron nitride is studied at several wavelengths, including the wavelength where it possesses excitation of phonon-polaritons and hyperbolic dispersion. Based on our results of s-SNOM imaging in different demodulation orders, we specify resonant and non-resonant types of edges and describe the edge fringes for each case. We clarify near-field edge-fringe formation at material sharp boundaries, both outside bright fringes and the low-contrast region at the edge, and elaborate on the necessity of separating them from propagating waves on the surface of polaritonic materials.

  10. SHARP-2 gene silencing by lentiviral-based short hairpin RNA interference prolonged rat kidney transplant recipients' survival time.

    Science.gov (United States)

    Shou, Z; Xiao, H; Xu, Y; Wang, Y; Yang, Y; Jiang, H; Chen, J; Yamada, K; Miyamoto, K

    2009-01-01

    Split- and hairy-related protein-2 (SHARP-2) controls the expression of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma), which both play a key role in transplant rejection. This study was designed to investigate whether SHARP-2 short hairpin RNA interference (shRNAi) could prolong the survival of rat kidney transplant recipients. A lentiviral-based shRNAi construct, LV-SHARP-2iC, showed a SHARP-2 gene silencing efficiency of 84% in normal rat kidney cells. In activated T-cells, SHARP-2 gene silencing with the LV-SHARP-2iC construct resulted in 61% and 69% down-regulation of IL-2 and IFN-gamma, respectively, compared with a scramble control construct. When donor kidney was perfused with 5 x 10(7) transforming units of the LV-SHARP-2iC construct, the median survival time of the transplant recipients was prolonged by 4 - 5 days compared with control groups. In conclusion, recombinant lentiviral LV-SHARP-2iC construct effectively silenced SHARP-2 gene expression, which reduced IL-2 and IFN-gamma mRNA expression and prolonged rat kidney transplant recipients' survival.

  11. Diagenetic Crystal Clusters and Dendrites, Lower Mount Sharp, Gale Crater

    Science.gov (United States)

    Kah, L. C.; Kronyak, R.; Van Beek, J.; Nachon, M.; Mangold, N.; Thompson, L.; Wiens, R.; Grotzinger, J.; Farmer, J.; Minitti, M.; hide

    2015-01-01

    Since approximately Sol 753 (to sol 840+) the Mars Science Laboratory Curiosity rover has been investigating the Pahrump locality. Mapping of HiRise images suggests that the Pahrup locality represents the first occurrence of strata associated with basal Mount Sharp. Considerable efforts have been made to document the Pahrump locality in detail, in order to constrain both depositional and diagenetic facies. The Pahrump succession consists of approximately 13 meters of recessive-weathering mudstone interbedded with thin (decimeter-scale) intervals of more erosionally resistant mudstone, and crossbedded sandstone in the upper stratigraphic levels. Mudstone textures vary from massive, to poorly laminated, to well-laminated. Here we investigate the distribution and structure of unusual diagenetic features that occur in the lowermost portion of the Pahrump section. These diagenetic features consist of three dimensional crystal clusters and dendrites that are erosionally resistant with respect to the host rock.

  12. 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

  13. 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

  14. Update on Hippocampal Sclerosis.

    Science.gov (United States)

    Dutra, Juliana R; Cortés, Etty P; Vonsattel, Jean Paul G

    2015-10-01

    The diagnostic hallmarks of hippocampal sclerosis (HS) are severe volume loss of the hippocampus, severe neuronal loss, and reactive gliosis involving primarily two especially vulnerable fields, CA1 and the subiculum. Occasionally, HS may be the only neuropathological change detected in older individuals with dementia and is known as pure HS. In the majority of cases, HS occurs in the setting of other degenerative changes, usually Alzheimer's disease (AD). In these cases, it is classified as combined HS. Although a clinical profile for HS has been identified, its similarities with AD make the diagnosis during life quite challenging; thus, the diagnosis is often made postmortem. The pathogenesis of HS is not completely understood, but the strong association with transactive response DNA-binding protein 43 (TDP-43), in approximately 90%, and the recent discovery of genetic risk factors are important contributions to a better understanding of the disease process.

  15. 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.

  16. Stress, depression and hippocampal damage

    Indian Academy of Sciences (India)

    adrenocortical (HPA) axis which regulates secretion of the stress responsive corticosteroids. The hippocampus is known to provide an inhibitory feedback to the HPA axis. Hippocampal damage then would result in disinhibition of the HPA axis ...

  17. Fimbria-fornix (FF)-transected hippocampal extracts induce the activation of astrocytes in vitro.

    Science.gov (United States)

    Zou, Linqing; Li, Haoming; Jin, Guohua; Tian, Meiling; Qin, Jianbing; Zhao, Heyan

    2014-03-01

    Hippocampus is one of the neurogenesis areas in adult mammals, but the function of astrocytes in this area is still less known. In our previous study, the fimbria-fornix (FF)-transected hippocampal extracts promoted the proliferation and neuronal differentiation of radial glial cells in vitro. To explore the effects of hippocampal extracts on gliogenesis, the hippocampal astrocytes were treated by normal or ff-transected hippocampal extracts in vitro. The cells were immunostained by brain lipid-binding protein (BLBP), nestin, and SOX2 to assess their state of activation. The effects of astrocyte-conditioned medium on the neuronal differentiation of hippocampal neural stem cells (NSCs) were also investigated. After treatment of FF-transected hippocampal extracts, the number of BLBP, nestin, and Sox-positive cells were obviously more than the cells which treated by normal hippocampal extracts, these cells maintained a state of activation and the activated astrocyte-conditioned medium also promoted the differentiation of NSCs into more neurons. These findings suggest that the astrocytes can be activated by FF-transected hippocampal extracts and these activated cells also can promote the neuronal differentiation of hippocampal NSCs in vitro.

  18. 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.

  19. NT-3 Facilitates Hippocampal Plasticity and Learning and Memory by Regulating Neurogenesis

    Science.gov (United States)

    Sakata, Kazuko; Akbarian, Schahram; Bates, Brian; Jaenisch, Rudolf; Lu, Bai; Shimazu, Kazuhiro; Zhao, Mingrui

    2006-01-01

    In the adult brain, the expression of NT-3 is largely confined to the hippocampal dentate gyrus (DG), an area exhibiting significant neurogenesis. Using a conditional mutant line in which the "NT-3" gene is deleted in the brain, we investigated the role of NT-3 in adult neurogenesis, hippocampal plasticity, and memory. Bromodeoxyuridine…

  20. Vitamin D and hippocampal development-the story so far.

    Science.gov (United States)

    Lardner, Anne L

    2015-01-01

    Epidemiological studies suggest that vitamin D insufficiency may be prevalent in young as well as older populations. The pleiotropic effects of vitamin D are now beyond dispute and a growing number of studies provide accumulating evidence of a role for vitamin D in brain development and function. A number of studies to date have investigated the effects of early-life vitamin D deprivation on adult hippocampus in animals and humans, and there is a growing body of evidence to suggest a role for this hormone in the development of selected hippocampal functions such as latent inhibition and hole board habituation in rats. There are few studies to date of vitamin D deprivation or supplementation on early hippocampal development in vivo. However, a small number of studies, mostly in vitro, point to a role for vitamin D in differentiation and development of hippocampal neurons. There is also limited evidence that supplementation with vitamin D following a period of deprivation is capable of restoring cellular activity and later function. Further avenues of future research are outlined including animal studies on the effects of vitamin D deprivation and inadequacy on early hippocampal biochemistry and function, e.g., measurement of BDNF levels, GABAergic activity, long-term potentiation (LTP) and spatial navigation. It also remains to be established if there are critical developmental windows during which vitamin D is required. In light of the importance of the hippocampus in LTP and spatial learning, further investigations on the early effects of vitamin D deprivation on hippocampal development are warranted.

  1. Neuropathologic correlates of hippocampal atrophy in the elderly: a clinical, pathologic, postmortem MRI study.

    Directory of Open Access Journals (Sweden)

    Robert J Dawe

    Full Text Available The volume of the hippocampus measured with structural magnetic resonance imaging (MRI is increasingly used as a biomarker for Alzheimer's disease (AD. However, the neuropathologic basis of structural MRI changes in the hippocampus in the elderly has not been directly assessed. Postmortem MRI of the aging human brain, combined with histopathology, could be an important tool to address this issue. Therefore, this study combined postmortem MRI and histopathology in 100 elderly subjects from the Rush Memory and Aging Project and the Religious Orders Study. First, to validate the information contained in postmortem MRI data, we tested the hypothesis that postmortem hippocampal volume is smaller in subjects with clinically diagnosed Alzheimer's disease compared to subjects with mild or no cognitive impairment, as observed in antemortem imaging studies. Subsequently, the relations of postmortem hippocampal volume to AD pathology, Lewy bodies, amyloid angiopathy, gross infarcts, microscopic infarcts, and hippocampal sclerosis were examined. It was demonstrated that hippocampal volume was smaller in persons with a clinical diagnosis of AD compared to those with no cognitive impairment (P = 2.6 × 10(-7 or mild cognitive impairment (P = 9.6 × 10(-7. Additionally, hippocampal volume was related to multiple cognitive abilities assessed proximate to death, with its strongest association with episodic memory. Among all pathologies investigated, the most significant factors related to lower hippocampal volume were shown to be AD pathology (P = 0.0018 and hippocampal sclerosis (P = 4.2 × 10(-7. Shape analysis allowed for visualization of the hippocampal regions most associated with volume loss for each of these two pathologies. Overall, this investigation confirmed the relation of hippocampal volume measured postmortem to clinical diagnosis of AD and measures of cognition, and concluded that both AD pathology and hippocampal sclerosis affect hippocampal

  2. 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.

  3. 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:

  4. 'Sharpe', a new Armillaria resistant rootstock for peach

    Science.gov (United States)

    Sharpe clonal rootstock for peach is jointly released for grower trial by the U.S. Department of Agriculture, Agricultural Research Service (Byron, GA) and Florida Agricultural Experiment Station. Sharpe, previously tested as FLA1-1, was discovered in the wild and appears to be a hybrid of Chickasa...

  5. Sharp compared with blunt fascial incision at cesarean delivery

    DEFF Research Database (Denmark)

    Aabakke, Anna J M; Hare, Kristine J; Krebs, Lone

    2014-01-01

    OBJECTIVE: To compare patient preference for either sharp incision with scissors or blunt manual cleavage of the fascia at cesarean delivery in a randomized controlled trial in which each woman was her own control. STUDY DESIGN: Women undergoing primary cesarean delivery (n=34) were randomized...... to side distribution of sharp or blunt incision of the fascia (sharp right and blunt left or blunt right and sharp left) and followed three months postoperatively. The primary outcome was patient preference for the right or left side of the scar 3 months postoperatively and modeled by polytomous logistic...... difference was found in patient preference with regard to sharp or blunt incision of the fascia, nor was there a significant difference in postoperative pain scores. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov: www.clinicaltrials.org;NCT01297725....

  6. Hippocampal polysynaptic computation.

    Science.gov (United States)

    Kimura, Rie; Kang, Siu; Takahashi, Naoya; Usami, Atsushi; Matsuki, Norio; Fukai, Tomoki; Ikegaya, Yuji

    2011-09-14

    Neural circuitry is a self-organizing arithmetic device that converts input to output and thereby remodels its computational algorithm to produce more desired output; however, experimental evidence regarding the mechanism by which information is modified and stored while propagating across polysynaptic networks is sparse. We used functional multineuron calcium imaging to monitor the spike outputs from thousands of CA1 neurons in response to the stimulation of two independent sites of the dentate gyrus in rat hippocampal networks ex vivo. Only pyramidal cells were analyzed based on post hoc immunostaining. Some CA1 pyramidal cells were observed to fire action potentials only when both sites were simultaneously stimulated (AND-like neurons), whereas other neurons fired in response to either site of stimulation but not to concurrent stimulation (XOR-like neurons). Both types of neurons were interlaced in the same network and altered their logical operation depending on the timing of paired stimulation. Repetitive paired stimulation for brief periods induced a persistent reorganization of AND and XOR operators, suggesting a flexibility in parallel distributed processing. We simulated these network functions in silico and found that synaptic modification of the CA3 recurrent excitation is pivotal to the shaping of logic plasticity. This work provides new insights into how microscopic synaptic properties are associated with the mesoscopic dynamics of complex microcircuits.

  7. 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); V.M. Strike (Vanessa); 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

  8. 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

  9. Characterization of two novel nuclear BTB/POZ domain zinc finger isoforms. Association with differentiation of hippocampal neurons, cerebellar granule cells, and macroglia

    DEFF Research Database (Denmark)

    Mitchelmore, Cathy; Kjaerulff, Karen M; Pedersen, Hans C

    2002-01-01

    progenitors as well as in differentiated glia. During embryonic development of the murine cerebral cortex, HOF expression is restricted to the hippocampal subdivision. Expression coincides with early differentiation of presumptive CA1 and CA3 pyramidal neurons and dentate gyrus granule cells, with a sharp...

  10. 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 ...

  11. 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

  12. Hippocampal activity during the transverse patterning task declines with cognitive competence but not with age

    Directory of Open Access Journals (Sweden)

    Leirer Vera M

    2010-09-01

    Full Text Available Abstract Background The hippocampus is a brain region that is particularly affected by age-related morphological changes. It is generally assumed that a loss in hippocampal volume results in functional deficits that contribute to age-related cognitive decline. In a combined cross-sectional behavioural and magnetoencephalography (MEG study we investigated whether hippocampal-associated neural current flow during a transverse patterning task - which requires learning relational associations between stimuli - correlates with age and whether it is modulated by cognitive competence. Results Better performance in several tests of verbal memory, verbal fluency and executive function was indeed associated with higher hippocampal neural activity. Age, however, was not related to the strength of hippocampal neural activity: elderly participants responded slower than younger individuals but on average produced the same neural mass activity. Conclusions Our results suggest that in non-pathological aging, hippocampal neural activity does not decrease with age but is rather related to cognitive competence.

  13. Modulation of hippocampal activity with fornix Deep Brain Stimulation.

    Science.gov (United States)

    Stypulkowski, Paul H; Stanslaski, Scott R; Giftakis, Jonathon E

    Deep Brain Stimulation (DBS) within the Papez circuit is under investigation as a treatment for epilepsy and Alzheimer's disease. We previously reported the effects of stimulation at nodes within this network (anterior thalamic nucleus and hippocampus) on hippocampal activity in a large animal model, using a chronic implantable, clinical-grade system that permits concurrent stimulation and recording. In this study we extended earlier work to compare the effects of fornix DBS on evoked potentials (EPs) and local field potential (LFP) activity within the hippocampus, and to assess closed-loop stimulation. Unilateral fornix and hippocampal DBS leads were implanted in three ovine subjects using image-guided, frameless stereotaxy. Chronic, awake recordings of EPs and LFPs in response to fornix and hippocampal stimulation were collected with the implanted device and analyzed off-line. Stimulation of the fornix produced robust, short latency hippocampal EPs. High frequency fornix stimulation generated parameter-dependent effects. At low amplitudes, short lasting inhibition of LFP activity occurred. Above a specific amplitude threshold, DBS elicited pronounced bursts of theta activity, followed by a marked state shift in hippocampal activity. These effects persisted for minutes post-DBS and were reflected as changes in LFP spectral content and phase-amplitude coupling. Real-time modulation of hippocampal activity via the implanted device was demonstrated using LFPs as the control signal for closed-loop stimulation. The current results expand earlier findings and demonstrate target-specific effects produced by DBS within this neural circuit. These changes in network activity may provide insights into stimulation targets and parameter selection for clinical investigations. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  14. 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…

  15. Input from the medial septum regulates adult hippocampal neurogenesis

    NARCIS (Netherlands)

    Van der Borght, Karin; Mulder, Jan; Keijser, Jan N; Eggen, Bart J L; Luiten, Paul G.M.; Van der Zee, Eddy A; Keijser, Johannes

    2005-01-01

    Neural progenitors in the subgranular zone of the hippocampal formation form a continuously proliferating cell population, generating new granule neurons throughout adult life. Between 10 days and 1 month after their formation, many of the newly generated cells die. The present study investigated

  16. 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.

  17. 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.

  18. 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)

  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. Revision of the Genus Piestoneus SHARP (Coleoptera : Staphylinidae) from Japan

    OpenAIRE

    ShunIchiro, NAOMI; Natural History Museum and Institute

    1995-01-01

    This is the fourth part on a series of the taxonomic studies of the subfamily Piestinae from Japan, and the genus Piestoneus SHARP is treated. Three new species, Piestoneus deboiseae, P. monticola and P. oharai are described. The lectotype is designated for P. lewisii SHARP. A key to the species is provided. The important characters for the definition of the genus and the aedeagi for identification are illustrated.

  1. A Sharpe-ratio-based measure for currencies

    Directory of Open Access Journals (Sweden)

    Javier Prado-Dominguez

    2015-06-01

    Full Text Available The Sharpe Ratio offers an excellent summary of the excess return required per unit of risk invested. This work presents an adaptation of the ex-ante Sharpe Ratio for currencies where we consider a random walk approach for the currency behavior and implied volatility as a proxy for market expectations of future realized volatility. The outcome of the proposed measure seems to gauge some information on the expected required return attached to the “peso problem”.

  2. 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

  3. The three-dimensional organization of the hippocampal formation: a review of anatomical data.

    Science.gov (United States)

    Amaral, D G; Witter, M P

    1989-01-01

    In the early 1970s, Andersen and colleagues proposed that the principal excitatory pathways of the hippocampal formation were organized in a lamellar fashion. This proposition, based heavily on the physiological studies of the proponents, indicated that "a point source of entorhinal activity projects its impulses through the four membered pathway (of the hippocampal formation) along a slice or lamella, of hippocampal tissue oriented normally to the alvear surface" [Anderson P., Bliss V.P. and Skrede K. K. (1971) Expl Brain Res. 13, 222-238] and perpendicular to the long axis of the hippocampus. Andersen et al. further suggested that, "By means of this lamellar organization, small strips of the hippocampal cortex may operate as independent functional units, although excitatory and inhibitory transverse connections may modify the behavior of neighboring lamellae." The "lamellar hypothesis" of hippocampal anatomical organization has had tremendous influence on the conceptualization of hippocampal information processing and was largely responsible for prompting the establishment of the in vitro hippocampal slice technology. While the "lamellar hypothesis" was consistent with the known neuroanatomy, subsequent neuroanatomical investigations, using a variety of modern tracing techniques, have invariably demonstrated that all of the major hippocampal projections, except for those arising from the granule cells of the dentate gyrus, are much more divergent than would be consistent with a strict interpretation of the lamellar hypothesis. This has become particularly clear in ongoing studies of the intrinsic hippocampal projections using the recently introduced anterograde tracer, Phaseolus vulgaris leucoagglutinin. Citing the conclusions from several papers dealing with the anatomical organization of the hippocampal formation and using examples from recent Phaseolus vulgaris leucoagglutinin mapping studies, the following are demonstrated. (1) That the major hippocampal

  4. 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

  5. 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, pmemory. 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.

  6. 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

  7. Sleep benefits subsequent hippocampal functioning

    NARCIS (Netherlands)

    van der Werf, Y.D.; Altena, E.; Schoonheim, M.M.; Sanz-Arigita, E.J.; Vis, J.C.; de Rijke, W.; van Someren, E.J.

    2009-01-01

    Sleep before learning benefits memory encoding through unknown mechanisms. We found that even a mild sleep disruption that suppressed slow-wave activity and induced shallow sleep, but did not reduce total sleep time, was sufficient to affect subsequent successful encoding-related hippocampal

  8. Hippocampal Sclerosis: Causes and Prevention.

    Science.gov (United States)

    Walker, Matthew Charles

    2015-06-01

    Hippocampal sclerosis is the commonest cause of drug-resistant epilepsy in adults, and is associated with alterations to structures and networks beyond the hippocampus.In addition to being a cause of epilepsy, the hippocampus is vulnerable to damage from seizure activity. In particular, prolonged seizures (status epilepticus) can result in hippocampal sclerosis. The hippocampus is also vulnerable to other insults including traumatic brain injury, and inflammation. Hippocampal sclerosis can occur in association with other brain lesions; the prevailing view is that it is probably a secondary consequence. In such instances, successful surgical treatment usually involves the resection of both the lesion and the involved hippocampus. Experimental data have pointed to numerous neuroprotective strategies to prevent hippocampal sclerosis. Initial neuroprotective strategies aimed at glutamate receptors may be effective, but later, metabolic pathways, apoptosis, reactive oxygen species, and inflammation are involved, perhaps necessitating the use of interventions aimed at multiple targets. Some of the therapies that we use to treat status epilepticus may neuroprotect. However, prevention of neuronal death does not necessarily prevent the later development of epilepsy or cognitive deficits. Perhaps, the most important intervention is the early, aggressive treatment of seizure activity, and the prevention of prolonged seizures. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  9. Hippocampal-Prefrontal Reactivation during Learning Is Stronger in Awake Compared with Sleep States.

    Science.gov (United States)

    Tang, Wenbo; Shin, Justin D; Frank, Loren M; Jadhav, Shantanu P

    2017-12-06

    Hippocampal sharp-wave ripple (SWR) events occur during both behavior (awake SWRs) and slow-wave sleep (sleep SWRs). Awake and sleep SWRs both contribute to spatial learning and memory, thought to be mediated by the coordinated reactivation of behavioral experiences in hippocampal-cortical circuits seen during SWRs. Current hypotheses suggest that reactivation contributes to memory consolidation processes, but whether awake and sleep reactivation are suited to play similar or different roles remains unclear. Here we addressed that issue by examining the structure of hippocampal (area CA1) and prefrontal (PFC) activity recorded across behavior and sleep stages in male rats learning a spatial alternation task. We found a striking state difference: prefrontal modulation during awake and sleep SWRs was surprisingly distinct, with differing patterns of excitation and inhibition. CA1-PFC synchronization was stronger during awake SWRs, and spatial reactivation, measured using both pairwise and ensemble measures, was more structured for awake SWRs compared with post-task sleep SWRs. Stronger awake reactivation was observed despite the absence of coordination between network oscillations, namely hippocampal SWRs and cortical delta and spindle oscillations, which is prevalent during sleep. Finally, awake CA1-PFC reactivation was enhanced most prominently during initial learning in a novel environment, suggesting a key role in early learning. Our results demonstrate significant differences in awake and sleep reactivation in the hippocampal-prefrontal network. These findings suggest that awake SWRs support accurate memory storage and memory-guided behavior, whereas sleep SWR reactivation is better suited to support integration of memories across experiences during consolidation. SIGNIFICANCE STATEMENT Hippocampal sharp-wave ripples (SWRs) occur both in the awake state during behavior and in the sleep state after behavior. Awake and sleep SWRs are associated with memory

  10. The Formation and Erosion History of Mt. Sharp

    Science.gov (United States)

    Allen, Carlton C.; Dapremont, Angela M.

    2014-01-01

    The Curiosity rover is exploring 155 km diameter Gale crater and Mt. Sharp, Gale's 5 km high central mound (Fig. 1). This study addresses the formation and erosion history of Mt. Sharp. Gale lies on the topographic dichotomy between the southern highlands and the northern plains - a drop of over 2 km [1,2]. Altitude differences between the north and south rim reflect this regional slope, as do altitude differences between the deep annulus north of Mt. Sharp and the southern crater floor. Orbiter and rover images demonstrate that most exposed areas on Mt. Sharp consist of thin, sub-parallel units interpreted as sedimentary layers [3]. Gale is typical of the 50 large martian craters that have been totally or partially filled with such layers [4,5]. In many craters these sediments have been deeply eroded. Central Peak and Peak Ring: The highest point on Mt. Sharp, near the crater's center, is interpreted as a central peak [6]. The peak has a massive lower portion and a thin, smooth capping deposit (Fig. 2). Gale's size is transitional between martian craters with single central peaks and craters with peak rings approximately half the crater's diameter [2,6]. The boundaries of Mt. Sharp, as well as an arc of hills to the southeast of the mountain, closely match a circle approximately 80 km in diameter (Fig. 3). This morphology suggests that the Gale impact may have formed both a central peak and a partial peak ring, which is covered by the sediments of Mt. Sharp in the north and possibly exposed in the arc of eroded hills in the southeast quadrant (Figs. 3,4).

  11. 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.

  12. 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.

  13. 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.

  14. Vitamin D and hippocampal development-the story so far.

    Directory of Open Access Journals (Sweden)

    Anne L Lardner

    2015-10-01

    Full Text Available Epidemiological studies suggest that vitamin D insufficiency may be prevalent in young as well as older populations. The pleiotropic effects of vitamin D are now beyond dispute and a growing number of studies provide accumulating evidence of a role for vitamin D in brain development and function. A number of studies to date have investigated the effects of early-life vitamin D deprivation on adult hippocampus in animals and humans, and there is a growing body of evidence to suggest a role for this hormone in the development of selected hippocampal functions such as latent inhibition and hole board habituation in rats. There are few studies to date of vitamin D deprivation or supplementation on early hippocampal development in vivo. However, a small number of studies, mostly in vitro, point to a role for vitamin D in differentiation and development of hippocampal neurons. There is also limited evidence that supplementation with vitamin D following a period of deprivation is capable of restoring cellular activity and later function. Further avenues of future research are outlined including animal studies on the effects of vitamin D deprivation and inadequacy on early hippocampal biochemistry and function e.g. measurement of BDNF levels, GABAergic activity, long-term potentiation and spatial navigation,. It also remains to be established if there are critical developmental windows during which vitamin D is required. In light of the importance of the hippocampus in LTP and spatial learning, further investigations on the early effects of vitamin D deprivation on hippocampal development are warranted

  15. HIPPOCAMPAL CONTRIBUTIONS TO THE PROCESSING OF SOCIAL EMOTIONS

    OpenAIRE

    Immordino-Yang, Mary Helen; Singh, Vanessa

    2011-01-01

    Inducing and experiencing emotions about others’ mental and physical circumstances is thought to involve self-relevant processing and personal memories of similar experiences. The hippocampus is important for self-referential processing during recall and prospection; however, its contributions during social emotions have not been systematically investigated. We use event-related averaging and Granger causal connectivity mapping to investigate hippocampal contributions during the processing of...

  16. 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.

  17. Hippocampal GABA transporter distribution in patients with temporal lobe epilepsy and hippocampal sclerosis.

    Science.gov (United States)

    Schijns, Olaf; Karaca, Ümit; Andrade, Pablo; de Nijs, Laurence; Küsters, Benno; Peeters, Andrea; Dings, Jim; Pannek, Heinz; Ebner, Alois; Rijkers, Kim; Hoogland, Govert

    2015-10-01

    To determine hippocampal expression of neuronal GABA-transporter (GAT-1) and glial GABA-transporter (GAT-3) in patients with temporal lobe epilepsy (TLE) and hippocampal sclerosis (HS). Hippocampal sections were immunohistochemically stained for GABA-transporter 1 and GABA-transporter-3, followed by quantification of the immunoreactivity in the hilus by optical density measurements. GABA-transporter 3 positive hilar cells were counted and GABA-transporter protein expression in sections that included all hippocampal subfields was quantified by Western blot. The hilar GABA-transporter 1 expression of patients with severe hippocampal sclerosis was about 7% lower compared to that in the mild hippocampal sclerosis/control group (psclerosis group than in the mild hippocampal sclerosis/control group (non-significant). Also, severe hippocampal sclerosis samples contained 34% less (non-significant) GABA-transporter 3 positive cells compared to that of controls. Protein expression as assessed by Western blot showed that GABA-transporter 1 was equally expressed in mild and severe hippocampal sclerosis samples, whereas GABA-transporter 3 was reduced by about 62% in severe hippocampal sclerosis samples (psclerosis. Implications for the use of GABAergic antiepileptic therapies in hippocampal sclerosis vs non-hippocampal sclerosis patients remain to be studied. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. 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.

  19. Stress and adolescent hippocampal neurogenesis: diet and exercise as cognitive modulators.

    Science.gov (United States)

    Hueston, C M; Cryan, J F; Nolan, Y M

    2017-04-04

    Adolescence is a critical period for brain maturation. Deciphering how disturbances to the central nervous system at this time affect structure, function and behavioural outputs is important to better understand any long-lasting effects. Hippocampal neurogenesis occurs during development and continues throughout life. In adulthood, integration of these new cells into the hippocampus is important for emotional behaviour, cognitive function and neural plasticity. During the adolescent period, maturation of the hippocampus and heightened levels of hippocampal neurogenesis are observed, making alterations to neurogenesis at this time particularly consequential. As stress negatively affects hippocampal neurogenesis, and adolescence is a particularly stressful time of life, it is important to investigate the impact of stressor exposure at this time on hippocampal neurogenesis and cognitive function. Adolescence may represent not only a time for which stress can have long-lasting effects, but is also a critical period during which interventions, such as exercise and diet, could ameliorate stress-induced changes to hippocampal function. In addition, intervention at this time may also promote life-long behavioural changes that would aid in fostering increased hippocampal neurogenesis and cognitive function. This review addresses both the acute and long-term stress-induced alterations to hippocampal neurogenesis and cognition during the adolescent period, as well as changes to the stress response and pubertal hormones at this time which may result in differential effects than are observed in adulthood. We hypothesise that adolescence may represent an optimal time for healthy lifestyle changes to have a positive and long-lasting impact on hippocampal neurogenesis, and to protect against stress-induced deficits. We conclude that future research into the mechanisms underlying the susceptibility of the adolescent hippocampus to stress, exercise and diet and the consequent effect

  20. Vitamin A status regulates glucocorticoid availability in Wistar rats: consequences on cognitive functions and hippocampal neurogenesis ?

    Directory of Open Access Journals (Sweden)

    Damien eBonhomme

    2014-02-01

    Full Text Available A disruption of the vitamin A signaling pathway has been involved in age-related memory decline and hippocampal plasticity alterations. Using vitamin A deficiency (VAD, a nutritional model leading to a hyposignaling of the retinoid pathway, we have recently demonstrated that retinoic acid (RA, the active metabolite of vitamin A, is efficient to reverse VAD-induced spatial memory deficits and adult hippocampal neurogenesis alterations. Besides, excess of glucocorticoids (GCs occurring with aging is known to strongly inhibit hippocampal plasticity and functions and few studies report on the counteracting effects of RA signaling pathway on GCs action. Here, we have addressed whether the modulation of brain GCs availability could be one of the biological mechanisms involved in the effects of vitamin A status on hippocampal plasticity and functions. Thus, we have studied the effects of a vitamin A-free diet for 14 weeks and a 4-week vitamin A supplementation on plasma and hippocampal corticosterone (CORT levels in Wistar rats. We have also investigated corticosteroid binding globulin (CBG binding capacity and 11beta-Hydrosteroid Dehydrogenase type 1 (11β-HSD1 activity, both important modulators of CORT availability at the peripheral and hippocampal levels respectively. Interestingly, we show that the vitamin A status regulates levels of free plasma CORT and hippocampal CORT levels, by acting through a regulation of CBG binding capacity and 11β-HSD1 activity. Moreover, our results suggest that increased CORT levels in VAD rats could have some deleterious consequences on spatial memory, anxiety-like behavior and adult hippocampal neurogenesis whereas these effects could be corrected by a vitamin A supplementation. Thus, the modulation of GCs availability by vitamin A status is an important biological mechanism that should be taken into account in order to prevent age-related cognitive decline and hippocampal plasticity alterations.

  1. Vitamin A status regulates glucocorticoid availability in Wistar rats: consequences on cognitive functions and hippocampal neurogenesis?

    Science.gov (United States)

    Bonhomme, Damien; Minni, Amandine M; Alfos, Serge; Roux, Pascale; Richard, Emmanuel; Higueret, Paul; Moisan, Marie-Pierre; Pallet, Véronique; Touyarot, Katia

    2014-01-01

    A disruption of the vitamin A signaling pathway has been involved in age-related memory decline and hippocampal plasticity alterations. Using vitamin A deficiency (VAD), a nutritional model leading to a hyposignaling of the retinoid pathway, we have recently demonstrated that retinoic acid (RA), the active metabolite of vitamin A, is efficient to reverse VAD-induced spatial memory deficits and adult hippocampal neurogenesis alterations. Besides, excess of glucocorticoids (GCs) occurring with aging is known to strongly inhibit hippocampal plasticity and functions and few studies report on the counteracting effects of RA signaling pathway on GCs action. Here, we have addressed whether the modulation of brain GCs availability could be one of the biological mechanisms involved in the effects of vitamin A status on hippocampal plasticity and functions. Thus, we have studied the effects of a vitamin A-free diet for 14 weeks and a 4-week vitamin A supplementation on plasma and hippocampal corticosterone (CORT) levels in Wistar rats. We have also investigated corticosteroid binding globulin (CBG) binding capacity and 11beta-Hydrosteroid Dehydrogenase type 1 (11β-HSD1) activity, both important modulators of CORT availability at the peripheral and hippocampal levels respectively. Interestingly, we show that the vitamin A status regulates levels of free plasma CORT and hippocampal CORT levels, by acting through a regulation of CBG binding capacity and 11β-HSD1 activity. Moreover, our results suggest that increased CORT levels in VAD rats could have some deleterious consequences on spatial memory, anxiety-like behavior and adult hippocampal neurogenesis whereas these effects could be corrected by a vitamin A supplementation. Thus, the modulation of GCs availability by vitamin A status is an important biological mechanism that should be taken into account in order to prevent age-related cognitive decline and hippocampal plasticity alterations.

  2. Protracted hippocampal development is associated with age-related improvements in memory during early childhood.

    Science.gov (United States)

    Riggins, Tracy; Geng, Fengji; Botdorf, Morgan; Canada, Kelsey; Cox, Lisa; Hancock, Gregory R

    2018-03-05

    The hippocampus is a structure that is critical for memory. Previous studies have shown that age-related differences in specialization along the longitudinal axis of this structure (i.e., subregions) and within its internal circuitry (i.e., subfields) relate to age-related improvements in memory in school-age children and adults. However, the influence of age on hippocampal development and its relations with memory ability earlier in life remains under-investigated. This study examined effects of age and sex on hippocampal subregion (i.e., head, body, tail) and subfield (i.e., subiculum, CA1, CA2-4/DG) volumes, and their relations with memory, using a large sample of 4- to 8-year-old children. Results examining hippocampal subregions suggest influences of both age and sex on the hippocampal head during early childhood. Results examining subfields within hippocampal head suggest these age effects may arise from CA1, whereas sex differences may arise from subiculum and CA2-4/DG. Memory ability was not associated with hippocampal subregion volume but was associated with subfield volume. Specifically, within the hippocampal head, relations between memory and CA1 were moderated by age; in younger children bigger was better, whereas in older children smaller was superior. Within the hippocampal body, smaller CA1 and larger CA2-4/DG contributed to better memory performance across all ages. Together, these results shed light on hippocampal development during early childhood and support claims that the prolonged developmental trajectory of the hippocampus contributes to memory development early in life. Copyright © 2018. Published by Elsevier Inc.

  3. Retinoic acid restores adult hippocampal neurogenesis and reverses spatial memory deficit in vitamin a deprived rats

    OpenAIRE

    Bonnet, Emilie; Touyarot, katia; Alfos, Serge; Pallet, Véronique; Higueret, Paul; Abrous, Djoher Nora

    2008-01-01

    A dysfunction of retinoid hippocampal signaling pathway has been involved in the appearance of affective and cognitive disorders. However, the underlying neurobiological mechanisms remain unknown. Hippocampal granule neurons are generated throughout life and are involved in emotion and memory. Here, we investigated the effects of vitamin A deficiency (VAD) on neurogenesis and memory and the ability of retinoic acid (RA) treatment to prevent VAD-induced impairments. Adult retinoid-deficient ra...

  4. 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...

  5. 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

  6. Dedicated Hippocampal Inhibitory Networks for Locomotion and Immobility.

    Science.gov (United States)

    Arriaga, Moises; Han, Edward B

    2017-09-20

    Network activity is strongly tied to animal movement; however, hippocampal circuits selectively engaged during locomotion or immobility remain poorly characterized. Here we examined whether distinct locomotor states are encoded differentially in genetically defined classes of hippocampal interneurons. To characterize the relationship between interneuron activity and movement, we used in vivo , two-photon calcium imaging in CA1 of male and female mice, as animals performed a virtual-reality (VR) track running task. We found that activity in most somatostatin-expressing and parvalbumin-expressing interneurons positively correlated with locomotion. Surprisingly, nearly one in five somatostatin or one in seven parvalbumin interneurons were inhibited during locomotion and activated during periods of immobility. Anatomically, the somata of somatostatin immobility-activated neurons were smaller than those of movement-activated neurons. Furthermore, immobility-activated interneurons were distributed across cell layers, with somatostatin-expressing cells predominantly in stratum oriens and parvalbumin-expressing cells mostly in stratum pyramidale. Importantly, each cell's correlation between activity and movement was stable both over time and across VR environments. Our findings suggest that hippocampal interneuronal microcircuits are preferentially active during either movement or immobility periods. These inhibitory networks may regulate information flow in "labeled lines" within the hippocampus to process information during distinct behavioral states. SIGNIFICANCE STATEMENT The hippocampus is required for learning and memory. Movement controls network activity in the hippocampus but it's unclear how hippocampal neurons encode movement state. We investigated neural circuits active during locomotion and immobility and found interneurons were selectively active during movement or stopped periods, but not both. Each cell's response to locomotion was consistent across time

  7. Sharp Adams-type inequality invoking Hardy inequalities

    Indian Academy of Sciences (India)

    Mohamed Khalil Zghal

    2018-03-22

    Mar 22, 2018 ... and they proved independently that the maximal growth is of exponential type. Thereafter,. Moser improved these works by establishing a sharp result known as the Trudinger–Moser inequality (see [22]) and since then, this subject has continued to interest researchers and Trudinger–Moser inequality has ...

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

    African Journals Online (AJOL)

    incinerator is more effective in weight reduction, rated at 94.6% efficient. Key words: .... wastes incinerated, for example plastic materials, drinking .... consumption costs. Fuel control is an important area to consider during incineration of medical waste containing sharps waste. High fuel consumption occurs when burning ...

  9. Ultrathin 90-degree sharp bends for spoof surface plasmon polaritons

    DEFF Research Database (Denmark)

    Yang, Yihao; Chen, Hongsheng; Xiao, Sanshui

    2015-01-01

    surface plasmons around 90-degree sharp bends on ultrathin metallic films in the microwave regime. We demonstrate that by judiciously engineering the structure, the dispersion relation can be designed to reduce the scattering. Furthermore, the reflection can be suppressed by proper structural decoration...

  10. Study of sharp bends in anisotropic potassium double tungstate waveguides

    NARCIS (Netherlands)

    Dubbink, T.; Sefünç, Mustafa; Pollnau, Markus; García Blanco, Sonia Maria

    Rare earth ion doped potassium double tungstate gain materials have recently shown a great promise for the development of waveguide amplifiers and lasers exhibiting excellent performance. To enable the use of this material in larger nanophotonic platforms, sharp bends are required. In this work we

  11. 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.

  12. SHARP: the SHARC-II polarimeter for CSO

    Science.gov (United States)

    Li, H.; Attard, M.; Dowell, C. D.; Hildebrand, R. H.; Houde, M.; Kirby, L.; Novak, G.; Vaillancourt, J. E.

    2006-06-01

    SHARC-II is a 32 × 12 pixel submillimeter camera that is used with the ten-meter diameter Caltech Submillimeter Observatory (CSO) on Mauna Kea. This camera can be operated at either 350 or 450 microns. We developed a module that is installed at the CSO Nasmyth focus in order to convert SHARC-II into a sensitive imaging polarimeter, which we refer to as "SHARP". SHARP splits the incident beam into two orthogonal polarized beams that are then re-imaged onto different halves of the SHARC-II bolometer array. When this removable polarimetry module is in use, SHARC-II becomes a dual-beam 12 × 12 pixel polarimeter. Sky noise is a significant source of error for submillimeter continuum observations. Because SHARP will simultaneously observe two orthogonal polarization components, we are able to eliminate or greatly reduce this source of error. Here we describe the design of SHARP and report preliminary results of tests and observations carried out during our first two runs at CSO in August 2005 and January 2006.

  13. The Management of Sharp Wastes in a Tertiary Health Care ...

    African Journals Online (AJOL)

    ... with two-handed recapping of used needles very common. In view of the importance of the standards to occupational safety and community health, strict enforcement is advocated, especially the education of relevant health workers, and the provision of needed supplies. Keywords: Injection safety, sharps management, ...

  14. 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

  15. Homicide by sharp force in two Scandinavian capitals

    DEFF Research Database (Denmark)

    Rogde, S; Hougen, H P; Poulsen, K

    2000-01-01

    In the Oslo and Copenhagen capital areas, 141 homicides by sharp force were committed in the ten-year period 1985-1994. This method accounted for 33% of the homicides in this period. Thirty-five percent of the victims were female, and most of the victims were between 20 and 50 years of age...

  16. Transverse patterning dissociates human EEG theta power and hippocampal BOLD activation.

    Science.gov (United States)

    Meltzer, Jed A; Fonzo, Greg A; Constable, R Todd

    2009-01-01

    Theta oscillations (4-8 Hz) are often modulated in human electroencephalogram (EEG) studies of memory, whereas overlapping frequencies dominate rodent hippocampal EEG. An emerging parallelism between theta reactivity and hippocampal functional magnetic resonance imaging activation has suggested a homology between theta activity in humans and rodents, representing a process of cortico-hippocampal interaction involved in memory. In the present study, we investigated EEG reactivity during performance of a relational memory task that induces a negative hippocampal blood oxygenation level dependent (BOLD) signal change, compared to a nonrelational control condition. Relational trials induced theta increases and alpha decreases. Low Resolution Electromagnetic Brain Tomography estimates localized theta and alpha modulation to frontal midline and parietal midline cortices, respectively, both of which exhibit negative BOLD responses in this task. Thus, theta and alpha dynamics are dissociable from positive BOLD activation, and may, in fact, colocalize with negative BOLD responses.

  17. Colchicine induces apoptosis in organotypic hippocampal slice cultures

    DEFF Research Database (Denmark)

    Kristensen, Bjarne W; Noer, Helle; Gramsbergen, Jan Bert

    2003-01-01

    The microtubule-disrupting agent colchicine is known to be particular toxic for certain types of neurons, including the granule cells of the dentate gyrus. In this study we investigated whether colchicine could induce such neuron-specific degeneration in developing (1 week in vitro) and mature (3...... weeks in vitro) organotypic hippocampal slice cultures and whether the induced cell death was apoptotic and/or necrotic. When applied to 1-week-old cultures for 48 h, colchicine induced primarily apoptotic, but also a minor degree of necrotic cell death in the dentate granule cells, as investigated...... the formation of active caspase 3 protein and apoptotic nuclei induced by colchicine, but the formation of necrotic nuclei increased correspondingly and the PI uptake was unaffected. We conclude that colchicine induces caspase 3-dependent apoptotic cell death of dentate granule cells in hippocampal brain slice...

  18. 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.

  19. 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.

  20. 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.

  1. 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...

  2. 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.

  3. 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.

  4. Spatial bistability generates hunchback expression sharpness in the Drosophila embryo.

    Directory of Open Access Journals (Sweden)

    Francisco J P Lopes

    2008-09-01

    Full Text Available During embryonic development, the positional information provided by concentration gradients of maternal factors directs pattern formation by providing spatially dependent cues for gene expression. In the fruit fly, Drosophila melanogaster, a classic example of this is the sharp on-off activation of the hunchback (hb gene at midembryo, in response to local concentrations of the smooth anterior-posterior Bicoid (Bcd gradient. The regulatory region for hb contains multiple binding sites for the Bcd protein as well as multiple binding sites for the Hb protein. Some previous studies have suggested that Bcd is sufficient for properly sharpened Hb expression, yet other evidence suggests a need for additional regulation. We experimentally quantified the dynamics of hb gene expression in flies that were wild-type, were mutant for hb self-regulation or Bcd binding, or contained an artificial promoter construct consisting of six Bcd and two Hb sites. In addition to these experiments, we developed a reaction-diffusion model of hb transcription, with Bcd cooperative binding and hb self-regulation, and used Zero Eigenvalue Analysis to look for multiple stationary states in the reaction network. Our model reproduces the hb developmental dynamics and correctly predicts the mutant patterns. Analysis of our model indicates that the Hb sharpness can be produced by spatial bistability, in which hb self-regulation produces two stable levels of expression. In the absence of self-regulation, the bistable behavior vanishes and Hb sharpness is disrupted. Bcd cooperative binding affects the position where bistability occurs but is not itself sufficient for a sharp Hb pattern. Our results show that the control of Hb sharpness and positioning, by hb self-regulation and Bcd cooperativity, respectively, are separate processes that can be altered independently. Our model, which matches the changes in Hb position and sharpness observed in different experiments, provides a

  5. A Nonlinear Model for Hippocampal Cognitive Prosthesis: Memory Facilitation by Hippocampal Ensemble Stimulation

    Science.gov (United States)

    Hampson, Robert E.; Song, Dong; Chan, Rosa H.M.; Sweatt, Andrew J.; Riley, Mitchell R.; Gerhardt, Gregory A.; Shin, Dae C.; Marmarelis, Vasilis Z.; Berger, Theodore W.; Deadwyler, Samuel A.

    2012-01-01

    Collaborative investigations have characterized how multineuron hippocampal ensembles encode memory necessary for subsequent successful performance by rodents in a delayed nonmatch to sample (DNMS) task and utilized that information to provide the basis for a memory prosthesis to enhance performance. By employing a unique nonlinear dynamic multi-input/multi-output (MIMO) model, developed and adapted to hippocampal neural ensemble firing patterns derived from simultaneous recorded CA1 and CA3 activity, it was possible to extract information encoded in the sample phase necessary for successful performance in the nonmatch phase of the task. The extension of this MIMO model to online delivery of electrical stimulation delivered to the same recording loci that mimicked successful CA1 firing patterns, provided the means to increase levels of performance on a trial-by-trial basis. Inclusion of several control procedures provides evidence for the specificity of effective MIMO model generated patterns of electrical stimulation. Increased utility of the MIMO model as a prosthesis device was exhibited by the demonstration of cumulative increases in DNMS task performance with repeated MIMO stimulation over many sessions on both stimulation and nonstimulation trials, suggesting overall system modification with continued exposure. Results reported here are compatible with and extend prior demonstrations and further support the candidacy of the MIMO model as an effective cortical prosthesis. PMID:22438334

  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. Optimizing 3D Triangulations to Recapture Sharp Edges

    DEFF Research Database (Denmark)

    Bærentzen, Jakob Andreas

    2006-01-01

    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......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...... terrain models. It is demonstrated how the method has been able to recapture sharp edges which are clearly present in the data but not reflected by the original triangulation of the elevation points....

  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. 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.

  10. Ketamine Affects the Neurogenesis of the Hippocampal Dentate Gyrus in 7-Day-Old Rats.

    Science.gov (United States)

    Huang, He; Liu, Cun-Ming; Sun, Jie; Hao, Ting; Xu, Chun-Mei; Wang, Dan; Wu, Yu-Qing

    2016-08-01

    Ketamine has been reported to cause neonatal neurotoxicity via a neuronal apoptosis mechanism; however, no in vivo research has reported whether ketamine could affect postnatal neurogenesis in the hippocampal dentate gyrus (DG). A growing number of experiments suggest that postnatal hippocampal neurogenesis is the foundation of maintaining normal hippocampus function into adulthood. Therefore, this study investigated the effect of ketamine on hippocampal neurogenesis. Male Sprague-Dawley rats were divided into two groups: the control group (equal volume of normal saline), and the ketamine-anesthesia group (40 mg/kg ketamine in four injections at 1 h intervals). The S-phase marker 5-bromodeoxyuridine (BrdU) was administered after ketamine exposure to postnatal day 7 (PND-7) rats, and the neurogenesis in the hippocampal DG was assessed using single- or double-immunofluorescence staining. The expression of GFAP in the hippocampal DG was measured by western blot analysis. Spatial reference memory was tested by Morris water maze at 2 months after PND-7 rats exposed to ketamine treatment. The present results showed that neonatal ketamine exposure significantly inhibited neural stem cell (NSC) proliferation, decreased astrocytic differentiation, and markedly enhanced neuronal differentiation. The disruptive effect of ketamine on the proliferation and differentiation of NSCs lasted at least 1 week and disappeared by 2 weeks after ketamine exposure. Moreover, the migration of newborn neurons in the granule cell layer and the growth of astrocytes in the hippocampal DG were inhibited by ketamine on PND-37 and PND-44. Finally, ketamine caused a deficit in hippocampal-dependent spatial reference memory tasks at 2 months old. Our results suggested that ketamine may interfere with hippocampal neurogenesis and long-term neurocognitive function in PND-7 rats. These findings may provide a new perspective to explain the adult neurocognitive dysfunction induced by neonatal

  11. 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.

  12. 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

  13. 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

  14. 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

  15. Endogenous acetylcholine rescues NMDA-induced long-lasting hippocampal cell damage via stimulation of muscarinic M(1) receptors: elucidation using organic hippocampal slice cultures.

    Science.gov (United States)

    Inada, Chikako; Thi Le, Xoan; Tsuneyama, Koichi; Fujiwara, Hironori; Miyata, Takeshi; Matsumoto, Kinzo

    2013-01-15

    This study aimed to investigate a recuing role of cholinergic systems in the excitotoxicity-induced hippocampal cell damage. Organotypic hippocampal slice cultures (OHSCs) were prepared from 7-day-old mice and exposed to N-methyl-d-aspartate (NMDA) for 24h. After washing out the NMDA, OHSCs were incubated in medium containing test drugs for 0-6 days. Hippocampal cell damage was evaluated by propidium iodide staining, immunofluorescence, and Western blotting. NMDA (1-10 μM) dose-dependently damaged hippocampal cells. The toxic effect of 3 μM NMDA was also observed at 3-6 days, even after washing out NMDA, and was blocked by MK-801 from day 3 to day 6. Post-treatments with tacrine, donepezil, and galantamine reduced the NMDA-induced long-lasting hippocampal cell damage. The effect of tacrine was induced in a manner dependent on the incubation period after NMDA treatment and was confirmed by Nissl staining and immunostaining with NeuN, a marker of mature neurons. The effect of tacrine was attenuated by scopolamine and a muscarinic M(1) receptor antagonist, pirenzepine, but not by a muscarinic M(3) receptor antagonist, darifenacin, or a nicotinic receptor antagonist, mecamylamine. The protein kinase C inhibitor Ro-31-8220 abolished the effect of tacrine. The pretreatment with 3 μM NMDA had no effect on the expression level of presynaptic cholinergic markers, choline acetyltransferase and vesicular acetylcholine transporter, in OHSCs. These results suggest that a low concentration of NMDA causes long-lasting hippocampal cell damage and that endogenous acetylcholine plays, via muscarinic M(1) receptor, a rescuing role in the excitotoxicity-induced long-lasting hippocampal cell damage. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Hippocampal neurogenesis dysfunction linked to depressive-like behaviors in a neuroinflammation induced model of depression.

    Science.gov (United States)

    Tang, Ming-Ming; Lin, Wen-Juan; Pan, Yu-Qin; Guan, Xi-Ting; Li, Ying-Cong

    2016-07-01

    Our previous work found that triple central lipopolysaccharide (LPS) administration could induce depressive-like behaviors and increased central pro-inflammatory cytokines mRNA, hippocampal cytokine mRNA in particular. Since several neuroinflammation-associated conditions have been reported to impair neurogenesis, in this study, we further investigated whether the neuroinflammation induced depression would be associated with hippocampal neurogenesis dysfunction. An animal model of depression induced by triple central lipopolysaccharide (LPS) administration was used. In the hippocampus, the neuroinflammatory state evoked by LPS was marked by an increased production of pro-inflammatory cytokines, including interleukin-1β, interleukin-6, and tumor necrosis factor-α. It was found that rats in the neuroinflammatory state exhibited depressive-like behaviors, including reduced saccharin preference and locomotor activity as well as increased immobility time in the tail suspension test and latency to feed in the novelty suppressed feeding test. Adult hippocampal neurogenesis was concomitantly inhibited, including decreased cell proliferation and newborn cell survival. We also demonstrated that the decreased hippocampal neurogenesis in cell proliferation was significantly correlated with the depressive-like phenotypes of decreased saccharine preference and distance travelled, the core and characteristic symptoms of depression, under neuro inflammation state. These findings provide the first evidence that hippocampal neurogenesis dysfunction is correlated with neuroinflammation-induced depression, which suggests that hippocampal neurogenesis might be one of biological mechanisms underlying depression induced by neruoinflammation. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. 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.

  18. 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.

  19. 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)

  20. APOE ε4 is associated with disproportionate progressive hippocampal atrophy in AD.

    Directory of Open Access Journals (Sweden)

    Emily N Manning

    Full Text Available To investigate whether APOE ε4 carriers have higher hippocampal atrophy rates than non-carriers in Alzheimer's disease (AD, mild cognitive impairment (MCI and controls, and if so, whether higher hippocampal atrophy rates are still observed after adjusting for concurrent whole-brain atrophy rates.MRI scans from all available visits in ADNI (148 AD, 307 MCI, 167 controls were used. MCI subjects were divided into "progressors" (MCI-P if diagnosed with AD within 36 months or "stable" (MCI-S if a diagnosis of MCI was maintained. A joint multi-level mixed-effect linear regression model was used to analyse the effect of ε4 carrier-status on hippocampal and whole-brain atrophy rates, adjusting for age, gender, MMSE and brain-to-intracranial volume ratio. The difference in hippocampal rates between ε4 carriers and non-carriers after adjustment for concurrent whole-brain atrophy rate was then calculated.Mean adjusted hippocampal atrophy rates in ε4 carriers were significantly higher in AD, MCI-P and MCI-S (p≤0.011, all tests compared with ε4 non-carriers. After adjustment for whole-brain atrophy rate, the difference in mean adjusted hippocampal atrophy rate between ε4 carriers and non-carriers was reduced but remained statistically significant in AD and MCI-P.These results suggest that the APOE ε4 allele drives atrophy to the medial-temporal lobe region in AD.

  1. 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.

  2. 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.

  3. 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.

  4. Altered hippocampal arteriole structure and function in a rat model of preeclampsia: Potential role in impaired seizure-induced hyperemia.

    Science.gov (United States)

    Johnson, Abbie C; Cipolla, Marilyn J

    2017-08-01

    We investigated the effect of experimental preeclampsia on hyperemia during seizure in the hippocampus and vascular function and structure of hippocampal arterioles using Sprague Dawley rats (n = 14/group) that were nonpregnant, pregnant (d20), or had experimental preeclampsia (induced by a high cholesterol diet d7-20). Hyperemia was measured via hydrogen clearance basally and during pentylenetetrazol-induced seizure (40-130 mg/kg i.v.). Reactivity of isolated and pressurized hippocampal arterioles to KCl, nitric oxide synthase inhibition with NG-nitro-L-arginine methyl ester and the nitric oxide donor sodium nitroprusside were investigated. Capillary density was quantified via immunohistochemistry. Cerebral blood flow increased during seizure vs. baseline in pregnant (118 ± 14 vs. 87 ± 9 mL/100 g/min; p  0.05), suggesting impaired seizure-induced hyperemia in preeclampsia. Hippocampal arterioles from preeclamptic rats had less basal tone, and dilated less to 15 mM KCl (9 ± 8%) vs. pregnant (61 ± 27%) and nonpregnant rats (20 ± 11%). L-NAME had no effect on hippocampal arterioles in any group, but dilation to sodium nitroprusside was similar. Structurally, hippocampal arterioles from preeclamptic rats underwent inward hypotrophic remodeling and capillary rarefaction. Impaired seizure-induced hyperemia, vascular dysfunction, and limited vasodilatory reserve of hippocampal arterioles could potentiate hippocampal injury in preeclampsia especially during eclampsia.

  5. Hippocampal substructural vulnerability to sleep disturbance and cognitive impairment in patients with chronic primary insomnia: magnetic resonance imaging morphometry.

    Science.gov (United States)

    Joo, Eun Yeon; Kim, Hosung; Suh, Sooyeon; Hong, Seung Bong

    2014-07-01

    Despite compelling evidence from animal studies indicating hippocampal subfield-specific vulnerability to poor sleep quality and related cognitive impairment, there have been no human magnetic resonance imaging (MRI) studies investigating the relationship between hippocampal subfield volume and sleep disturbance. Our aim was to investigate the pattern of volume changes across hippocampal subfields in patients with primary insomnia relative to controls. Pointwise morphometry allowed for volume measurements of hippocampal regions on T1-weighted MRI. University hospital. Twenty-seven unmedicated patients (age: 51.2 ± 9.6 y) and 30 good sleepers as controls (50.4 ± 7.1 y). N/A. We compared hippocampal subfield volumes between patients and controls and correlated volume with clinical and neuropsychological features in patients. Patients exhibited bilateral atrophy across all hippocampal subfields (P sleep quality (higher Pittsburgh Sleep Quality Index and higher arousal index of polysomnography) (r 0.45, P sleep fragmentation and related chronic stress condition. Atrophy in the CA3-4-DG region was associated with impaired cognitive functions in patients. These observations may provide insight into pathophysiological mechanisms that make patients with chronic sleep disturbance vulnerable to cognitive impairment. Joo EY, Kim H, Suh S, Hong SB. Hippocampal substructural vulnerability to sleep disturbance and cognitive impairment in patients with chronic primary insomnia: magnetic resonance imaging morphometry.

  6. A comparison of accurate automatic hippocampal segmentation methods.

    Science.gov (United States)

    Zandifar, Azar; Fonov, Vladimir; Coupé, Pierrick; Pruessner, Jens; Collins, D Louis

    2017-07-15

    The hippocampus is one of the first brain structures affected by Alzheimer's disease (AD). While many automatic methods for hippocampal segmentation exist, few studies have compared them on the same data. In this study, we compare four fully automated hippocampal segmentation methods in terms of their conformity with manual segmentation and their ability to be used as an AD biomarker in clinical settings. We also apply error correction to the four automatic segmentation methods, and complete a comprehensive validation to investigate differences between the methods. The effect size and classification performance is measured for AD versus normal control (NC) groups and for stable mild cognitive impairment (sMCI) versus progressive mild cognitive impairment (pMCI) groups. Our study shows that the nonlinear patch-based segmentation method with error correction is the most accurate automatic segmentation method and yields the most conformity with manual segmentation (κ=0.894). The largest effect size between AD versus NC and sMCI versus pMCI is produced by FreeSurfer with error correction. We further show that, using only hippocampal volume, age, and sex as features, the area under the receiver operating characteristic curve reaches up to 0.8813 for AD versus NC and 0.6451 for sMCI versus pMCI. However, the automatic segmentation methods are not significantly different in their performance. Copyright © 2017. Published by Elsevier Inc.

  7. 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.

  8. Acupuncture modulates resting state hippocampal functional connectivity in Alzheimer disease.

    Directory of Open Access Journals (Sweden)

    Zhiqun Wang

    Full Text Available Our objective is to clarify the effects of acupuncture on hippocampal connectivity in patients with Alzheimer disease (AD using functional magnetic resonance imaging (fMRI. Twenty-eight right-handed subjects (14 AD patients and 14 healthy elders participated in this study. Clinical and neuropsychological examinations were performed on all subjects. MRI was performed using a SIEMENS verio 3-Tesla scanner. The fMRI study used a single block experimental design. We first acquired baseline resting state data during the initial 3 minutes and then performed acupuncture stimulation on the Tai chong and He gu acupoints for 3 minutes. Last, we acquired fMRI data for another 10 minutes after the needle was withdrawn. The preprocessing and data analysis were performed using statistical parametric mapping (SPM5 software. Two-sample t-tests were performed using data from the two groups in different states. We found that during the resting state, several frontal and temporal regions showed decreased hippocampal connectivity in AD patients relative to control subjects. During the resting state following acupuncture, AD patients showed increased connectivity in most of these hippocampus related regions compared to the first resting state. In conclusion, we investigated the effect of acupuncture on AD patients by combing fMRI and traditional acupuncture. Our fMRI study confirmed that acupuncture at Tai chong and He gu can enhance the hippocampal connectivity in AD patients.

  9. 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.

  10. Hippocampal harms, protection and recovery following regular cannabis use

    Science.gov (United States)

    Yücel, M; Lorenzetti, V; Suo, C; Zalesky, A; Fornito, A; Takagi, M J; Lubman, D I; Solowij, N

    2016-01-01

    Shifting policies towards legalisation of cannabis for therapeutic and recreational use raise significant ethical issues for health-care providers seeking evidence-based recommendations. We investigated whether heavy cannabis use is associated with persistent harms to the hippocampus, if exposure to cannabidiol offers protection, and whether recovery occurs with abstinence. To do this, we assessed 111 participants: 74 long-term regular cannabis users (with an average of 15.4 years of use) and 37 non-user healthy controls. Cannabis users included subgroups of participants who were either exposed to Δ9-tetrahydrocannabinol (THC) but not to cannabidiol (CBD) or exposed to both, and former users with sustained abstinence. Participants underwent magnetic resonance imaging from which three measures of hippocampal integrity were assessed: (i) volume; (ii) fractional anisotropy; and (iii) N-acetylaspartate (NAA). Three curve-fitting models across the entire sample were tested for each measure to examine whether cannabis-related hippocampal harms are persistent, can be minimised (protected) by exposure to CBD or recovered through long-term abstinence. These analyses supported a protection and recovery model for hippocampal volume (P=0.003) and NAA (P=0.001). Further pairwise analyses showed that cannabis users had smaller hippocampal volumes relative to controls. Users not exposed to CBD had 11% reduced volumes and 15% lower NAA concentrations. Users exposed to CBD and former users did not differ from controls on any measure. Ongoing cannabis use is associated with harms to brain health, underpinned by chronic exposure to THC. However, such harms are minimised by CBD, and can be recovered with extended periods of abstinence. PMID:26756903

  11. 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

  12. 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.

  13. Homicide by sharp force in two Scandinavian capitals

    DEFF Research Database (Denmark)

    Rogde, S; Hougen, H P; Poulsen, K

    2000-01-01

    In the Oslo and Copenhagen capital areas, 141 homicides by sharp force were committed in the ten-year period 1985-1994. This method accounted for 33% of the homicides in this period. Thirty-five percent of the victims were female, and most of the victims were between 20 and 50 years of age......% of the males were killed in their own home. The most common circumstance was family row when the victim was female, while a fight was the most common circumstance when the victim was male. Three offenders committed suicide after having committed homicide(s) (seven victims; three offenders)....

  14. Sharp nonlinear stability for centrifugal filtration convection in magnetizable media.

    Science.gov (United States)

    Saravanan, S; Brindha, D

    2011-11-01

    A nonlinear stability theory is adopted to study centrifugal thermal convection in a magnetic-fluid-saturated and differentially heated porous layer placed in a zero-gravity environment. The axis of rotation of the layer is placed within its boundaries that leads to an alternating direction of the centrifugal body force. An analysis through the variational principles is made to find the unconditional and sharp nonlinear limits. The compound matrix method is employed to solve the eigenvalue problems of the nonlinear and corresponding linear theories. The importance of nonlinear theory is established by demonstrating the failure of the linear theory in capturing the physics of the onset of convection.

  15. 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...

  16. 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.

  17. Effects of hippocampal state-contingent trial presentation on hippocampus-dependent nonspatial classical conditioning and extinction.

    Science.gov (United States)

    Nokia, Miriam S; Wikgren, Jan

    2014-04-23

    Hippocampal local field potentials are characterized by two mutually exclusive states: one characterized by regular θ oscillations (∼4-8 Hz) and the other by irregular sharp-wave ripples. Presenting stimuli during dominant θ oscillations leads to expedited learning, suggesting that θ indexes a state in which encoding is most effective. However, ripple-contingent training also expedites learning, suggesting that any discrete brain state, much like the external context, can affect learning. We trained adult rabbits in trace eyeblink conditioning, a hippocampus-dependent nonspatial task, followed by extinction. Trials were delivered either in the presence or absence of θ or regardless of hippocampal state. Conditioning in the absence of θ led to more animals learning, although learning was slower compared with a yoked control group. Contrary to expectations, conditioning in the presence of θ did not affect learning. However, extinction was expedited both when it was conducted contingent on θ and when it was conducted in a state contrary to that used to trigger trials during conditioning. Strong phase-locking of hippocampal θ-band responses to the conditioned stimulus early on during conditioning predicted good learning. No such connection was observed during extinction. Our results suggest that any consistent hippocampal oscillatory state can potentially be used to regulate learning. However, the effects depend on the specific state and task at hand. Finally, much like the external environment, the ongoing neural state appears to act as a context for learning and memory retrieval.

  18. Hippocampal synaptic plasticity, spatial memory and anxiety

    OpenAIRE

    Bannerman, David M.; Sprengel, Rolf; Sanderson, David J.; McHugh, Stephen B.; Rawlins, J. Nicholas P.; Monyer, Hannah; Seeburg, Peter H.

    2014-01-01

    Recent studies using transgenic mice lacking NMDA receptors in the hippocampus challenge the long-standing hypothesis that hippocampal long-term potentiation-like mechanisms underlie the encoding and storage of associative long-term spatial memories. However, it may not be the synaptic plasticity-dependent memory hypothesis that is wrong; instead, it may be the role of the hippocampus that needs to be re-examined. We present an account of hippocampal function that explains its role in both me...

  19. 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.)

  20. Hippocampal correlates of aversive mibdrain stimulation.

    Science.gov (United States)

    Routtenberg, A; Kramis, R C

    1968-06-21

    Hippocampal synchronization during aversive dorsal midbrain stimulation was observed in rats both in a conditioning procedure and under d-tubo-curarine paralysis. The results restrict the generality of previous reports which correlated hippocampal synchronization and desynchronization with approach and withdrawal behavior, respectively. Relative to the condition of free movement, curarization reduced the frequency of both "spontaneous" and dorsal midbrain-evoked synchronization, thus suggesting possible direct and indirect effects of d-tubocurarine on subcortical structures.

  1. 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

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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)

  7. 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.

  8. Hippocampal EEG and behaviour in dog. II. Hippocampal EEG correlates with elementary motor acts

    NARCIS (Netherlands)

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

    A positive correlation has been shown between the speed of forced stepping on a conveyor belt and the amplitude and frequency of the concomitant hippocampal EEG. Significant modulation in the spectral properties of the dog's hippocampal EEG has been found in relation to 3 elementary motor acts:

  9. 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.

  10. 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.

  11. Cannabidiol inhibits synaptic transmission in rat hippocampal cultures and slices via multiple receptor pathways

    Science.gov (United States)

    Ledgerwood, CJ; Greenwood, SM; Brett, RR; Pratt, JA; Bushell, TJ

    2011-01-01

    BACKGROUND AND PURPOSE Cannabidiol (CBD) has emerged as an interesting compound with therapeutic potential in several CNS disorders. However, whether it can modulate synaptic activity in the CNS remains unclear. Here, we have investigated whether CBD modulates synaptic transmission in rat hippocampal cultures and acute slices. EXPERIMENTAL APPROACH The effect of CBD on synaptic transmission was examined in rat hippocampal cultures and acute slices using whole cell patch clamp and standard extracellular recordings respectively. KEY RESULTS Cannabidiol decreased synaptic activity in hippocampal cultures in a concentration-dependent and Pertussis toxin-sensitive manner. The effects of CBD in culture were significantly reduced in the presence of the cannabinoid receptor (CB1) inverse agonist, LY320135 but were unaffected by the 5-HT1A receptor antagonist, WAY100135. In hippocampal slices, CBD inhibited basal synaptic transmission, an effect that was abolished by the proposed CB1 receptor antagonist, AM251, in addition to LY320135 and WAY100135. CONCLUSIONS AND IMPLICATIONS Cannabidiol reduces synaptic transmission in hippocampal in vitro preparations and we propose a role for both 5-HT1A and CB1 receptors in these CBD-mediated effects. These data offer some mechanistic insights into the effects of CBD and emphasize that further investigations into the actions of CBD in the CNS are required in order to elucidate the full therapeutic potential of CBD. PMID:20825410

  12. 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.

  13. 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.

  14. 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...

  15. 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

  16. The differences of the precommissural and postcommissural fornix in the hippocampal location: a diffusion tensor tractography study

    OpenAIRE

    Jang, Sung Ho; Yeo, Sang Seok

    2017-01-01

    Purpose The precommissural fornix and postcommissural fornix have different connections to the basal forebrain and septal region, and mammillary body, respectively. However, little is known about the differences of the precommissural fornix and postcommissural fornix in the hippocampal location. In this study, using diffusion tensor tractography, we investigated the differences of the precommissural fornix and postcommissural fornix in the hippocampal location. Methods We recruited 25 healthy...

  17. 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

  18. Hippocampal hyperactivation in presymptomatic familial Alzheimer's disease.

    Science.gov (United States)

    Quiroz, Yakeel T; Budson, Andrew E; Celone, Kim; Ruiz, Adriana; Newmark, Randall; Castrillón, Gabriel; Lopera, Francisco; Stern, Chantal E

    2010-12-01

    The examination of individuals who carry fully penetrant genetic alterations that result in familial Alzheimer's disease (FAD) provides a unique model for studying the early presymptomatic disease stages. In AD, deficits in episodic and associative memory have been linked to structural and functional changes within the hippocampal system. This study used functional MRI (fMRI) to examine hippocampal function in a group of healthy, young, cognitively-intact presymptomatic individuals (average age 33.7 years) who carry the E280A presenilin-1 (PS1) genetic mutation for FAD. These PS1 subjects will go on to develop the first symptoms of the disease around the age of 45 years. Our objective was to examine hippocampal function years before the onset of clinical symptoms. Twenty carriers of the Alzheimer's-associated E280A PS1 mutation and 19 PS1-negative control subjects participated. Both groups were matched for age, sex, education level, and neuropsychological test performance. All participants performed a face-name associative encoding task while in a Phillips 1.5T fMRI scanner. Analysis focused on the hippocampal system. Despite identical behavioral performance, presymptomatic PS1 mutation carriers exhibited increased activation of the right anterior hippocampus during encoding of novel face-name associations compared to matched controls. Our results demonstrate that functional changes within the hippocampal memory system occur years before cognitive decline in FAD. These presymptomatic changes in hippocampal physiology in FAD suggest that hippocampal fMRI patterns during associative encoding may also provide a preclinical biomarker in sporadic AD.

  19. Timbral Sharpness and Modulations in Frequency and Amplitude: Implications for the Fusion of Musical Sounds.

    Science.gov (United States)

    Goad, Pamela Joy

    The fusion of musical voices is an important aspect of musical blend, or the mixing of individual sounds. Yet, little research has been done to explicitly determine the factors involved in fusion. In this study, the similarity of timbre and modulation were examined for their contribution to the fusion of sounds. It is hypothesized that similar timbres will fuse better than dissimilar timbres, and, voices with the same kind of modulation will fuse better than voices of different modulations. A perceptually-based measure, known as sharpness was investigated as a measure of timbre. The advantages of using sharpness are that it is based on hearing sensitivities and masking phenomena of inner ear processing. Five musical instrument families were digitally recorded in performances across a typical playing range at two extreme dynamic levels. Analyses reveal that sharpness is capable of uncovering subtle changes in timbre including those found in musical dynamics, instrument design, and performer-specific variations. While these analyses alone are insufficient to address fusion, preliminary calculations of timbral combinations indicate that sharpness has the potential to predict the fusion of sounds used in musical composition. Three experiments investigated the effects of modulation on the fusion of a harmonic major sixth interval. In the first experiment using frequency modulation, stimuli varied in deviation about a mean fundamental frequency and relative modulation phase between the two tones. Results showed smaller frequency deviations promoted fusion and relative phase differences had a minimal effect. In a second experiment using amplitude modulation, stimuli varied in deviation about a mean amplitude level and relative phase of modulation. Results showed smaller amplitude deviations promoted better fusion, but unlike frequency modulation, relative phase differences were also important. In a third experiment, frequency modulation, amplitude modulation and mixed

  20. Simulation-Based Analysis of Reentry Dynamics for the Sharp Atmospheric Entry Vehicle

    Science.gov (United States)

    Tillier, Clemens Emmanuel

    1998-01-01

    This thesis describes the analysis of the reentry dynamics of a high-performance lifting atmospheric entry vehicle through numerical simulation tools. The vehicle, named SHARP, is currently being developed by the Thermal Protection Materials and Systems branch of NASA Ames Research Center, Moffett Field, California. The goal of this project is to provide insight into trajectory tradeoffs and vehicle dynamics using simulation tools that are powerful, flexible, user-friendly and inexpensive. Implemented Using MATLAB and SIMULINK, these tools are developed with an eye towards further use in the conceptual design of the SHARP vehicle's trajectory and flight control systems. A trajectory simulator is used to quantify the entry capabilities of the vehicle subject to various operational constraints. Using an aerodynamic database computed by NASA and a model of the earth, the simulator generates the vehicle trajectory in three-dimensional space based on aerodynamic angle inputs. Requirements for entry along the SHARP aerothermal performance constraint are evaluated for different control strategies. Effect of vehicle mass on entry parameters is investigated, and the cross range capability of the vehicle is evaluated. Trajectory results are presented and interpreted. A six degree of freedom simulator builds on the trajectory simulator and provides attitude simulation for future entry controls development. A Newtonian aerodynamic model including control surfaces and a mass model are developed. A visualization tool for interpreting simulation results is described. Control surfaces are roughly sized. A simple controller is developed to fly the vehicle along its aerothermal performance constraint using aerodynamic flaps for control. This end-to-end demonstration proves the suitability of the 6-DOF simulator for future flight control system development. Finally, issues surrounding real-time simulation with hardware in the loop are discussed.

  1. Evaluation of postoperative sharp waveforms through EEG and magnetoencephalography.

    Science.gov (United States)

    Lee, Jong Woo; Tanaka, Naoaki; Shiraishi, Hideaki; Milligan, Tracey A; Dworetzky, Barbara A; Khoshbin, Shahram; Stufflebeam, Steven M; Bromfield, Edward B

    2010-02-01

    EEGs obtained after craniotomy are difficult to read because of a breach rhythm consisting of unfiltered sharply contoured physiologic waveforms that can mimic interictal epileptiform discharges. Magnetoencephalography (MEG) is less affected by the skull breach. The postcraniotomy EEG and MEG scans of 20 patients were reviewed by two experienced electroencephalographers. Larger interrater variability was found for EEG as compared with MEG. Review of patients who had postoperative seizures suggested that EEG was more sensitive but less specific than MEG in detecting interictal epileptiform discharges. Furthermore, several instances of sharp waveforms that were difficult to evaluate on EEG were found to be more easily interpretable on MEG. MEG may also help determine whether asymmetries in physiologic rhythms on EEG result from the skull defect or are pathologic. MEG should be considered as an adjunctive study in patients with a breach rhythm for evaluation of interictal epileptiform discharges and cerebral dysfunction.

  2. 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.

  3. 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.

  4. Taking a SHARP look at mask 3D effects

    Science.gov (United States)

    Benk, Markus P.; Chao, Weilun; Miyakawa, Ryan; Goldberg, Kenneth; Naulleau, Patrick

    2017-10-01

    Mask 3D effects are an area of active research in EUV mask technology. Mask-side numerical aperture, illumination, feature size and absorber thickness are key factors modulating mask 3D effects and affecting printability and process window. Variable mask-side NA and flexible illumination make the SHARP actinic EUV microscope a powerful instrument for the study of mask 3D effects. We show an application example, comparing mask 3D effects for a standard Tantalum Nitride absorber and a thinner, 40-nm Nickel absorber. Data is presented for 0.33 4xNA and anamorphic 0.55 4x/8xNA. The influence of different illumination settings on mask 3D effects is discussed.

  5. 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.

  6. Optimization of sharp and viewing-angle-independent structural color.

    Science.gov (United States)

    Hsu, Chia Wei; Miller, Owen D; Johnson, Steven G; Soljačić, Marin

    2015-04-06

    Structural coloration produces some of the most brilliant colors in nature and has many applications. Motivated by the recently proposed transparent displays that are based on wavelength-selective scattering, here we consider the new problem of transparent structural color, where objects are transparent under omnidirectional broad-band illumination but scatter strongly with a directional narrow-band light source. Transparent structural color requires two competing properties, narrow bandwidth and broad viewing angle, that have not been demonstrated simultaneously previously. Here, we use numerical optimization to discover geometries where a sharp 7% bandwidth in scattering is achieved, yet the peak wavelength varies less than 1%, and the peak height and peak width vary less than 6% over broad viewing angles (0-90°) under a directional illumination. Our model system consists of dipole scatterers arranged into several rings; interference among the scattered waves is optimized to yield the wavelength-selective and angle-insensitive response.

  7. 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

  8. 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

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

    Science.gov (United States)

    Hartley, Tom; Harlow, Rachel

    2012-01-01

    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.

  11. Effects of ultrasound-combined microbubbles on hippocampal AchE fibers in rats.

    Science.gov (United States)

    Gong, Zi-Li; Luo, Chun-Mei; Wu, Sheng-Zheng; Ran, Hong; Zhu, Jie; Zheng, Jian

    2014-05-01

    To investigate the protective effect of ultrasound-combined microbubbles on hippocampal acetylcholinesterase (AchE) fibers in rats. According to random digits table, 60 SD rats were divided into two groups, marrow stromal cells (MSCs) intracranial transplantation group and MSCs intracranial transplantation + ultrasonic microbubbles group. Marrow stromal cells were cultivated and isolated in vitro; 12 weeks after transplantation, spatial learning and memorizing abilities of rats were assessed by Morris water maze; AchE staining method was used to observe changes in density and appearance of AchE staining positive fibers in hippocampal CA1 region. There was a significant increase in spatial learning and memorizing abilities of rats in MSCs intracranial transplantation + ultrasonic microbubbles group. Hippocampal AchE staining suggested an increase in the density of AchE staining positive fibers in MSCs intracranial transplantation group; the fibers were regular, intact and dense. Density of hippocampal AchE positive fibers was negatively correlated with the escape latent period and was positively correlated with percentage of the time needed to cross each platform quadrant. Better promotion of spatial learning and memorizing abilities of rats in MSCs intracranial transplantation + ultrasonic microbubbles group may be related with the protective effect of ultrasound-combined microbubbles on hippocampal acetylcholine fibers. Copyright © 2014 Hainan Medical College. Published by Elsevier B.V. All rights reserved.

  12. 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.

  13. [Effects of subchronic benzo[a]pyrene exposure on hippocampal cholinergic system in rats].

    Science.gov (United States)

    Guo, Liang; Wang, Xin; Li, Jin-yan; Liang, Hua-shan; Jiang, Yong; Chang, Shan-shan; Song, Yu-jing; Cheng, Li; Zheng, Jin-ping

    2013-02-01

    To observe the effects of subchronic benzo[a]pyrene (B[a]P) exposure on the neurobehavior and hippocampal acetylcholine (Ach) level, acetylcholinesterase (AChE) activity, and mRNA and protein expression of nicotinic acetylcholine receptor α7 subtype (nAChR α7) in rats, and to investigate the neurotoxic mechanism of B[a]P. Sixty healthy male SD rats were randomly divided into blank control group, solvent control group, and B [a]P exposure groups. Each rat in the exposure groups was intraperitoneally injected with B[a]P at 1.0, 2.5, or 6.25 mg/kg once every other day for 90 days. The learning and memory ability of the rats was examined by Morris water maze test and step-down test; the hippocampal Ach level was measured by alkaline hydroxylamine method; the AChE activity was measured by DNTB method; the mRNA and protein expression levels of hippocampal nAChR α7 were measured by quantitative PCR and Western blot. The 2.5 and 6.25 mg/kg B[a]P exposure groups showed significantly lower learning and memory abilities than the blank control group and solvent control group (P 0.05). The hippocampal Ach level was negatively correlated with the mean escape latency period and total distance travelled (r = -0.567, P memory ability in rats, which is related to the downregulation of hippocampal Ach level.

  14. Photoperiodic regulation of hippocampal neurogenesis in adult male white-footed mice (Peromyscus leucopus).

    Science.gov (United States)

    Walton, James C; Aubrecht, Taryn G; Weil, Zachary M; Leuner, Benedetta; Nelson, Randy J

    2014-08-01

    Photoperiodic organisms monitor environmental day length to engage in seasonally appropriate adaptions in physiology and behavior. Among these adaptations are changes in brain volume and neurogenesis, which have been well described in multiple species of birds, yet few studies have described such changes in the brains of adult mammals. White-footed mice (Peromyscus leucopus) are an excellent species in which to investigate the effects of day length on adult hippocampal neurogenesis, as males, in addition to having reduced hippocampal volume in short days (SD) with concomitant impairments in hippocampus-mediated behaviors, have photoperiod-dependent changes in olfactory bulb neurogenesis. We performed the current experiment to assess the effects of photoperiod on hippocampal neurogenesis longitudinally, using the thymidine analog bromodeoxyuridine at multiple time points across 10 weeks of SD exposure. Compared with counterparts held in long day (LD) lengths, across the first 8 weeks of SD exposure hippocampal neurogenesis was reduced. However, at 10 weeks in SD lengths neurogenic levels in the hippocampus were elevated above those levels in mice held in LD lengths. The current findings are consistent with the natural photoperiodic cycle of hippocampal function in male white-footed mice, and may help to inform research on photoperiodic plasticity in neurogenesis and provide insight into how the complex interplay among the environment, genes and adaptive responses to changing day lengths affects brain structure, function and behavior at multiple levels. © 2014 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  15. 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.

  16. 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.)

  17. 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.)

  18. 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.

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

    Science.gov (United States)

    Sadowski, Josef H.L.P.; Jones, Matthew W.; Mellor, Jack R.

    2016-01-01

    Summary 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. PMID:26904941

  20. [Protective effect of valsartan or/and ligustrazine on hippocampal neuronal loss in rats with vascular dementia].

    Science.gov (United States)

    Qin, Da-lian; Deng, Sha; Zhang, Zhuo; Zhou, Miao; Li, Hua

    2011-01-01

    To investigate the effect of Valsartan and Ligustrazine on hippocampal neuronal loss and the ability of learning and memory of rats with vascular dementia. Vascular dementia was induced in rats by blocking bilateral carotid artery repeatedly and intraperitoneal injection of sodium nitroprusside. The vacuity learning and memory of the rats were measured with Morris water maze. The plasma AVP and ANGII were determined by radio-immunity methods. The activities of SOD, GSH-Px and MDA in hippocampal tissues were detected by chemistry colorimetry. The hippocampal neuronal loss was observe with light microscope. Both valsartan and ligustrazine shortened escape latency (P drugs alone in all of the indicators except for plasma AVP. Valsartan or/and Ligustrazine have protective effect on hippocampal neuronal loss in rats with vascular dementia, possibly through inhibiting RAS activation and free radical formation induced by cerebral ischemia-reperfusion.

  1. 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.

  2. 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...

  3. Methamphetamine-induced changes in the mice hippocampal neuropeptide Y system: implications for memory impairment

    DEFF Research Database (Denmark)

    Gonçalves, J; Baptista, S; Olesen, MV

    2012-01-01

    , being involved in learning and memory processing. It has been demonstrated that METH induces significant alteration in mice striatal NPY, Y(1) and Y(2) receptor mRNA levels. However, the impact of this drug on the hippocampal NPY system and its consequences remain unknown. Thus, in this study, we...... investigated the effect of METH intoxication on mouse hippocampal NPY levels, NPY receptors function, and memory performance. Results show that METH increased NPY, Y(2) and Y(5) receptor mRNA levels, as well as total NPY binding accounted by opposite up- and down-regulation of Y(2) and Y(1) functional binding......, respectively. Moreover, METH-induced impairment in memory performance and AKT/mammalian target of rapamycin pathway were both prevented by the Y(2) receptor antagonist, BIIE0246. These findings demonstrate that METH interferes with the hippocampal NPY system, which seems to be associated with memory failure...

  4. Protective effect of naringenin on glutamate-induced neurotoxicity in cultured hippocampal cells

    Directory of Open Access Journals (Sweden)

    Xu Xiao-Hui

    2015-01-01

    Full Text Available Monosodium glutamate induces excitotoxicity in the central nervous system through hyperactivation of both ionotropic and metabotropic glutamate receptors, which leads to neuronal cell death. In this study, we investigated the neuroprotective effects of naringenin on excitotoxicity induced by glutamate in primary hippocampal neurons of neonatal mice. The expression levels of apoptosis-inducing proteins and as well as ischemic factors were observed by Western blot analysis. Immunocytochemistry and morphometric analysis of hippocampal cells with or without glutamate and naringenin treatment were performed. We observed that naringenin regulated Erk1/2 and Akt phosphorylation and reduced the demise of dendrites due to glutamate exposure in cultured hippocampal neurons. Furthermore, naringenin induced the brain-derived neurotrophic factor and other neuroprotective cytokines, and markedly improved the survival rates of the neurons 24 h following glutamate exposure. The observed results suggest that the naturally occurring bioflavonoid (naringenin exerts neuroprotective effects via highly specific molecular targets in neurons.

  5. Maternal Vitamin C Deficiency during Pregnancy Persistently Impairs Hippocampal Neurogenesis in Offspring of Guinea Pigs.

    OpenAIRE

    Tveden-Nyborg Pernille; Vogt Lucile; Schjoldager Janne G; Jeannet Natalie; Hasselholt Stine; Paidi Maya D; Christen Stephan; Lykkesfeldt Jens

    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...

  6. Hippocampal volume changes in healthy subjects at risk of unipolar depression

    DEFF Research Database (Denmark)

    Baaré, William F C; Vinberg, Maj; Knudsen, Gitte M

    2010-01-01

    of major psychiatric disorder. High-risk twins had smaller hippocampal volumes than low-risk twins (pglobal brain tissue volumes or regional tissue volumes assessed in exploratory voxel-wise whole cerebrum analyses. In conclusion......, hippocampal volume reduction may index a predisposition to develop depression and thus may be predictive of future onset of the disorder. Further studies are needed to elucidate the role of (shared) environmental and genetic factors.......Unipolar depression is moderately heritable. It is unclear whether structural brain changes associated with unipolar depression are present in healthy persons at risk of the disorder. Here we investigated whether a genetic predisposition to unipolar depression is associated with structural brain...

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. Unusually sharp paramagnetic phase transition in thin film Fe3Pt invar

    Science.gov (United States)

    Drisko, Jasper; Cumings, John

    2013-03-01

    Invar alloys, typically 3d transition metal rich systems, are most commonly known for their extremely low coefficients of thermal expansion (CTE) over a wide range of temperatures close to room temperature. This anomalous behavior in the CTE lends Invar to a variety of important applications in precision mechanical devices, scientific instruments, and sensors, among others. Many theoretical models of Invar have been proposed over the years, the most promising of which is a system described by two coexisting phases, one high-spin high-volume and the other low-spin low-volume, that compete to stabilize the volume of the material as the temperature is changed. However, no theory has yet been able to explain all experimental observations across the range of Invar alloys, especially at finite temperature. We have fabricated thin films of a Fe3Pt Invar alloy and investigate them using Lorentz Transmission Electron Microscopy (TEM). 23nm films are deposited onto SiN membrane substrates via radio-frequency magnetron sputtering from a pure Fe target decorated with Pt pieces. We observe novel magnetic domain structures and an unusually sharp phase transition between ferromagnetic (FM) and paramagnetic (PM) regions of the film under a temperature gradient. This sharp transition suggests that the FM-to-PM transition may be first order, perhaps containing a structural-elastic component to the order parameter. However, electron diffraction reveals that both the FM and PM regions have the same FCC crystal structure.

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

    Directory of Open Access Journals (Sweden)

    Paulus Januar

    2010-09-01

    Full Text Available 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 crossover design. The subjects were 65 dental students, divided into two groups for comparing the 2 types of  toothbrush. On the 1st day, the allocated toothbrushes were distributedto each group according to their designation, and the subjects were instructed to use the toothbrushes according their normal daily practices. On the 1st, 7th, and 14th day, the subjects were scored using the patient hygiene performance index (PHP index and the gingival index. Based on cross over design, the same procedure was repeated during the 2 week second test periods using different type of toothbrush respectively. Results: The mean scores of the 2 groups showed no significant difference on the beginning the study. Though minor differences were observed in the effectiveness of toothbrush, but the comparison of the two types of toothbrush showed no statistically significant differences on 7th and 14th day. Conclusion: There were no significant differences between sharp end and rounded end bristle toot brusher. There is no manual toothbrush superiorly designed than the others single superior design of manual toothbrush.Latar belakang: Berbagai jenis desain sikat gigi saat ini terdapat di pasaran, dengan masing-masing menyatakan keunggulannya dalam membersihkan plak. Penelitian ini dilakukan terhadap dua jenis sikat gigi manual yaitu sikat gigi dengan ujung bulu sikat runcing dan ujung bulus sikat bulat. Tujuan: Penelitian ini dilakukan untuk membandingkan efektivitas membersihkan

  13. 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.

  14. 3T MRI quantification of hippocampal volume and signal in mesial temporal lobe epilepsy improves detection of hippocampal sclerosis.

    Science.gov (United States)

    Coan, A C; Kubota, B; Bergo, F P G; Campos, B M; Cendes, F

    2014-01-01

    In mesial temporal lobe epilepsy, MR imaging quantification of hippocampal volume and T2 signal can improve the sensitivity for detecting hippocampal sclerosis. However, the current contributions of these analyses for the diagnosis of hippocampal sclerosis in 3T MRI are not clear. Our aim was to compare visual analysis, volumetry, and signal quantification of the hippocampus for detecting hippocampal sclerosis in 3T MRI. Two hundred three patients with mesial temporal lobe epilepsy defined by clinical and electroencephalogram criteria had 3T MRI visually analyzed by imaging epilepsy experts. As a second step, we performed automatic quantification of hippocampal volumes with FreeSurfer and T2 relaxometry with an in-house software. MRI of 79 healthy controls was used for comparison. Visual analysis classified 125 patients (62%) as having signs of hippocampal sclerosis and 78 (38%) as having normal MRI findings. Automatic volumetry detected atrophy in 119 (95%) patients with visually detected hippocampal sclerosis and in 10 (13%) with visually normal MR imaging findings. Relaxometry analysis detected hyperintense T2 signal in 103 (82%) patients with visually detected hippocampal sclerosis and in 15 (19%) with visually normal MR imaging findings. Considered together, volumetry plus relaxometry detected signs of hippocampal sclerosis in all except 1 (99%) patient with visually detected hippocampal sclerosis and in 22 (28%) with visually normal MR imaging findings. In 3T MRI visually inspected by experts, quantification of hippocampal volume and signal can increase the detection of hippocampal sclerosis in 28% of patients with mesial temporal lobe epilepsy.

  15. 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

  16. 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; Ayan-Oshodi, Mosun; Ayhan, Murat; Sumana, B. V.; Babic, Tomislav; Baek, Young; Bagepally, Bhavani; Baird, Geoffrey; Baker, John; Baker, Suzanne; Bakker, Arnold; Barbash, Shahar; Bard, Jonathan; Barker, Warren; Bartlett, Jonathan; Baruchin, Andrea; Battaglini, Iacopo; Bauer, Corinna; Bayley, Peter; Beck, Irene; Becker, James; Becker, J. Alex; Beckett, Laurel; Bednar, Martin; Bedner, Arkadiusz; Beg, Mirza Faisal; Bekris, Lynn; Belaroussi, Boubakeur; Belloch, Vicente; Belmokhtar, Nabil; Ben Ahmed, Olfa; Bender, J. Dennis; Benois-Pineau, Jenny; Bhaskar, Uday; Bienkowska, Katarzyna; Biffi, Alessandro; Bigler, Erin; Bilgic, Basar; Bishop, Courtney; Bittner, Daniel; Black, Sandra; Bloss, Cinnamon; Bocti, Christian; Bohorquez, Adriana; Bokde, Arun; Boone, John; Boppana, Madhu; Borrie, Michael; Bouttout, Haroune; Bowes, Mike; Bowman, DuBois; Bowman, Gene; Bracard, Serge; Braskie, Meredith; Braunewell, Karl; Breitner, Joihn; Bresell, Anders; Brewer, James; Brickhouse, Michael; Brickman, Adam; Britschgi, Markus; Broadbent, Steve; Brogren, Jacob; Brunton, Simon; Buchsbaum, Monte; Buckley, Chris; Buerger, Katharina; Bunce, David; Burnham, Samantha; Burns, Jeffrey; Burton, David; Burzykowski, Tomasz; Butler, Tracy; Cabeza, Rafael; Caffery, Terrell; Cairns, Nigel; Callhoff, Johanna; Calvini, Piero; Carbotti, Angela; Carle, Adam; Carmasin, Jeremy; Carmichael, Owen; Carvalho, Janessa; Casabianca, Jodi; Casanova, Ramon; Casey, Anne; Cash, David; Cataldo, Rosella; Cedarbaum, Jesse; Cella, Massimo; Celsis, Pierre; Chakravarty, Mallar; Chang, Ih; Chao, Linda; Charil, Arnaud; Chang, Che-Wei; Chemali, Zeina; Chen, Kewei; Chen, Shuzhong; Chen, Rong; Chen, Qiang; Chen, Jung-Tai; Chen, Gang; Chen, Jake; Chen, Wei; Cheng, Wei-Chen; Cheng, Xi; Cherkas, Yauheniya; Chertkow, Howard; Cheung, Vinci; Cheung, Charlton; Chiang, Gloria; Chiao, Ping; chibane, Mouatez Billah; Chida, Noriko; Chin, Simon; Ching, Christopher; Chisholm, Jane; Cho, Claire; Cho, Youngsang; Choe, John; Choubey, Suresh; Chowbina, Sudhir; Christensen, Anette Luther; Ciocia, Gianluigi; Clark, David; Clark, Chris; Clarkson, Matt; Clerc, Stephanie; Clunie, David; Coen, Michael; Ciombra, Alexandre; Compton, David; Coppola, Giovanni; Coubard, Olivier; Coulin, Samuel; Cover, Keith S.; Crane, Paul; Crans, Gerald; Croop, Robert; Crowther, Daniel; Crum, William; Cui, Yue; Curry, Charles; Cutter, Gary; Da, Long; Daliri, Mohammad Reza; Damato, Vito Domenico; Darby, Eveleen; Darkner, Sune; Davatzikos, Christos; DavidPrakash, Bhaskaran; Davidson, Christopher; Davis, Melissa; de Bruijne, Marleen; de Meyer, Geert; de Nunzio, Giorgio; Decarli, Charles; Dechairo, Bryan; DeDuck, Kristina; Dehghan, Hossein; Delfino, Manuel; Della Rosa, Pasquale Anthony; Dellavedova, Luca; Delpassand, Ebrahim; Delrieu, Julien; DeOrchis, Vincent; Dépy Carron, Delphine; Desjardins, Benoit; deToledo-Morrell, Leyla; Devanand, Davangere; Devanarayan, Viswanath; Devier, Deidre; DeVous, Michael; Dgetluck, Nancy; Di, Jianing; Di, Xin; Diaz-Arrastia, Ramon; Dickerson, Bradford; Dickie, David Alexander; Dill, Vanderson; Ding, Xiaobo; Dinov, Ivo; Dobosh, Brian; Dobson, Howard; Dodge, Hiroko; Dolman, Andrew; Dolmo, Bess-Carolina; Donohue, Michael; Dore, Vincent; Dorflinger, Ernest; Dowling, Maritza; Dragicevic, Natasa; Dubal, Dena; Duchesne, Simon; Duff, Kevin; Dukart, Jürgen; Durazzo, Timothy; Dutta, Joyita; DWors, Robert; Earl, Nancy; Edula, Goutham; Elcoroaristizabal, Xabier; Emahazion, Tesfai; Endres, Christopher; Epstein, Noam; Ereshefsky, Larry; Eskildsen, Simon; Espinosa, Ana; Esposito, Mario; Ewers, Michael; Falcone, Guido; Fan, Yong; Fan, Jing; Fan, Lingzhong; Farahibozorg, Seyedehrezvan; Farb, Norman; Fardo, David; Farias, Sarah; Farnum, Michael; Farrer, Lindsay; Fatke, Bastian; Faux, Noel; Feldman, Howard; Feldman, Susan; Feldman, Betsy; Félix, Zandra; Fennema-Notestine, Christine; Fernandes, Michel; Fernandez, Elsa; Ferreira, Manuel Joao; Ferrer, Eugene; Fetterman, Bob; Figurski, Michal; Fillit, Howard; Finch, Stephen; Fiot, Jean-Baptiste; Flenniken, Derek; Fletcher, Evan; Flores, Christopher; Longmire, Crystal Flynn; Focke, Niels; Forman, Mark; Forsythe, Alan; Fox, Steven; Fox-Bosetti, Sabrina; Foxhall, Suzanne; Franko, Edit; Freeman, Roderick; Friedrich, Christoph M.; Friesenhahn, Michel; Frisoni, Giovanni; Fritzsche, Klaus; Fujimoto, Yoko; Fujiwara, Ken; Fullerton, Terence; Gaffour, Yacine; Galvin, Ben; Gamst, Anthony; Gao, Sujuan; Garg, Gaurav; Gaser, Christian; Gastineau, Edward; Gattaz, Wagner; Gaubert, Malo; Gauthier, Serge; Gavett, Brandon; Ge, Tian; Gemme, Gianluca; Geraci, Joseph; Gholipour, Farhad; Ghosh, Debashis; Ghosh, Satrajit; Gieschke, Ronald; Gill, Ryan; Gillespie, William; Gitelman, Darren; Gkontra, Xenia; Gleason, Carey; Glymour, M. Maria; Godbey, Michael; Gold, Brian; Goldberg, Terry; Goldman, Jennifer; Gonzalez-Beltran, Alejandra; Goodro, Robert; Gore, Chris; Gorriz, Juan Manuel; Goto, Masami; Grachev, Igor; Gradkowski, Wojciech; Grandey, Emily; Grasela, Thaddeus; Gray, Katherine; Greenberg, Barry; Greicius, Michael; Grill, Joshua; Gross, Alden; Gross, Alan; Grydeland, Håkon; Guignot, Isabelle; Guo, Qimiao; Guo, Liang-Hao; Guo, Hongbin; Gupta, Vinay; Guyot, Jennifer; Habeck, Christian; Habte, Frezghi; Haight, Thaddeus; Hajaj, Chen; Hajiesmaeili, Maryam; Hajjar, Ihab; Hammarstrom, Per; Hampel, Harald; Han, Duke; Han, Jian; Han, Zhaoying; Hanna, Yousef; Hao, Yongfu; Hardy, Peter; Harvey, Danielle; Hasan, Md Kamrul; Hayashi, Toshihiro; Haynes, John-Dylan; He, Huiguang; He, Yong; Head, Denise; Heckemann, Rolf; Heegaard, Niels; Heidebrink, Judith; Hellyer, Peter; Helwig, Michael; Henderson, David; Herholz, Karl; Herskovits, A. 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Richard; Jenq, John; Jessen, Walter; Jia, Fucang; Jiang, Tianzi; Jiao, Yun; Jing, Huang; Johnson, Kent; Johnson, Sterling; Johnson, David K.; Johnson, Julene; Jones, Gareth; Jones, Mark; Jones, Richard; Joshi, Shantanu; Jouvent, Eric; Juengling, Freimut; Julin, Per; Junjie, Zhuo; Kabilan, Meena; Kadish, Bill; Kairui, Zhang; Kam, Hye Jin; Kamboh, M. Ilyas; Kamer, Angela; Kanakaraj, Sithara; Kanchev, Vladimir; Kaneko, Tomoki; Kaneta, Tomohiro; Kang, Hyunseok; Kang, Ju Hee; Kang, Jian; Karageorgiou, Elissaios; Karantzoulis, Stella; Karlawish, Jason; Katz, Elyse; Kaushik, Sandeep S.; Kauwe, John; Kawakami, Hirofumi; Kawashima, Shoji; Kaye, Edward; Kazemi, Samaneh; Ke, Han; Kelleher, Thomas; Kennedy, Richard; Keogh, Bart; Kerchner, Geoffrey; Kerr, Daniel; Keshava, Nirmal; Khalil, Iya; Khalil, Andre; Khondker, Zakaria; Kihara, Takeshi; Killeen, Neil; Killiany, Ron; Kim, Dajung; Kim, Hyoungkyu; Kim, Seongkyun; Kim, Jong Hun; Kim, Ana; Kim, Jung-Hyun; Kimberg, Daniel; Kimura, Tokunori; King, Richard; Kirby, Justin; Kirsch, Wolff; Klimas, Michael; Kline, Richard; Kling, Mitchel; Klopfenstein, Erin; Koen, Joshua; Koikkalainen, Juha; Kokomoor, Anders; Kong, Xiangnan; Koppel, Jeremy; Korolev, Igor; Kotran, Nickolas; Kowalczyk, Adam; Krahnke, Tillmann; Krams, Michael; Kuceyeski, Amy; Kuhl, Donald; Kumar, Vinod; Roy, P. 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A.; Pa, Judy; Palanisamy, Preethi; Pan, Sarah; Pan, Zhifang; Pande, Yogesh; Pardo, Jose; Pardoe, Heath; Park, Sang hyun; Park, Sujin; Park, Lovingly; Park, Hyunjin; Park, Moon Ho; Parker, Christopher; Patel, Yogen; Patil, Amol; Patil, Manasi; Pawlak, Mikolaj; Payoux, Pierre; Pearson, Jim; Pell, Gaby; Peng, Yahong; Pennec, Xavier; Pepin, Jean louis; Pereira, Francisco; Perneczky, Robert; Petitti, Diana; Petrella, Jeffrey; Peyrat, Jean-Marc; Ngoc, Phuong Trinh Pham; Phillips, Justin; Phillips, Nicole; Pian, Wen-ting; Pierson, Ronald; Piovezan, Mauro; Pipitone, Jon; Pirraglia, Elizabeth; Planes, Xavi; Podhorski, Adam; Pollari, Mika; Pomara, Nunzio; Pontecorvo, Michael; Popov, Veljko; Poppenk, Jordan; Posner, Holly; Potkin, Steven; Potter, Guy; Potter, Elizabeth; Poulin, Stephane; Prastawa, Marcel; Prince, Jerry; Priya, Anandh; Pruessner, Jens; Qiu, Wendy; Qu, Annie; Qualls, Constance Dean; Quarg, Peter; Quinlan, Judith; Rabbia, Michael; Rajagovindan, Rajasimhan; Rajeesh, Rajeesh; Rallabandi, V. P. Subramanyam; Ramadubramani, Vanamamalai; Ramage, Amy; Ramirez, Alfredo; Randolph, Chrstopher; Rao, Anil; Rao, Hengyi; Rao, Divya; Raubertas, Richard; Ray, Debashis; Razak, Hana; Reed, Bruce; Reid, Andrew; Reihac, Anthonin; Reiner, Peggy; Reinsberger, Claus; Restrepo, Lucas; Retico, Alessandra; Rhatigan, Lewis; Rhinn, Herve; Rhoades, Earl; Ribbens, Annemie; Richard, Edo; Richards, John; Richter, Mirco; Riddle, William; Ridgway, Gerard; Ries, Michele; Ringman, John; Rischall, Matt; Rizk-Jackson, Angela; Rizzi, Massimo; Robieson, Weining; Rodriguez, Laura; Rodriguez-Vieitez, Elena; Rogalski, Emily; Rogers, Elizabeth; Balderrama, Javier Rojas; Rokicki, Jaroslav; Romero, Klaus; Rorden, Chris; Rosand, Jonathan; Rosen, Ori; Rosenberg, Paul; Roubini, Eli; Rousseau, François; Rowe, Christopher; Rubin, Daniel; Rubright, Jonathan; Rucinski, Marek; Ruiz, Agustin; Rulseh, Aaron; Rusinek, Henry; Ryan, Laurie; Saad, Ahmed; Sabuncu, Mert; Sahuquillo, Juan; Said, Yasmine; Saito, Naomi; Sakata, Muneyuki; 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Q.; Yu, Peng; Yuan, Ying; Yuan, Kai; Yuan, Guihong; Yuen, Bob; Yushkevich, Paul; Zaborszky, Laszlo; Zagorodnov, Vitali; Zagorski, Michael; Zahodne, Laura; Zarei, Mojtaba; Zawadzki, Rezi; Zeitzer, Jamie; Zelinski, Elizabeth; Zeskind, Benjamin; Zhan, Shu; Zhang, Jing; Zhang, Lijun; Zhang, Zhiguo; Zhang, Linda; Zhang, Zhe; Zhang, Daoqiang; Zhang, Huixiong; Zhang, Xin; Zhang, Tianhao; Zhang, Ping; Zhao, Jim; Zhao, Qinying; Zhao, Peng; Zhen, Xiantong; Zhijun, Yao; Zhou, Luping; Zhou, Bin; Zhou, Yongxia; Zhou, Sheng; Zhu, Hongtu; Zhu, Wen; Zhu, Wanlin; Zhu, Xuyan; Ziegler, Gabriel; Zilka, Samantha; Zisserman, Andrew; Zito, Giancarlo; Zu, Chen; Zulfigar, Annam

    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

  17. Organotypic hippocampal slice cultures for studies of brain damage, neuroprotection and neurorepair

    DEFF Research Database (Denmark)

    Noraberg, Jens; Poulsen, Frantz Rom; Blaabjerg, Morten

    2005-01-01

    Slices of developing brain tissue can be grown for several weeks as so-called organotypic slice cultures. Here we summarize and review studies using hippocampal slice cultures to investigate mechanisms and treatment strategies for the neurodegenerative disorders like stroke (cerebral ischemia), A...

  18. 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...

  19. Sharps Injuries and Other Blood and Body Fluid Exposures Among Home Health Care Nurses and Aides

    Science.gov (United States)

    Markkanen, Pia K.; Galligan, Catherine J.; Kriebel, David; Chalupka, Stephanie M.; Kim, Hyun; Gore, Rebecca J.; Sama, Susan R.; Laramie, Angela K.; Davis, Letitia

    2009-01-01

    Objectives. We quantified risks of sharp medical device (sharps) injuries and other blood and body fluid exposures among home health care nurses and aides, identified risk factors, assessed the use of sharps with safety features, and evaluated underreporting in workplace-based surveillance. Methods. We conducted a questionnaire survey and workplace-based surveillance, collaborating with 9 home health care agencies and 2 labor unions from 2006 to 2007. Results. Approximately 35% of nurses and 6.4% of aides had experienced at least 1 sharps injury during their home health care career; corresponding figures for other blood and body fluid exposures were 15.1% and 6.7%, respectively. Annual sharps injuries incidence rates were 5.1 per 100 full-time equivalent (FTE) nurses and 1.0 per 100 FTE aides. Medical procedures contributing to sharps injuries were injecting medications, administering fingersticks and heelsticks, and drawing blood. Other contributing factors were sharps disposal, contact with waste, and patient handling. Sharps with safety features frequently were not used. Underreporting of sharps injuries to the workplace-based surveillance system was estimated to be about 50%. Conclusions. Sharps injuries and other blood and body fluid exposures are serious hazards for home health care nurses and aides. Improvements in hazard intervention are needed. PMID:19890177

  20. Nonspecific effects of the gap junction blocker mefloquine on fast hippocampal network oscillations in the adult rat in vitro.

    Science.gov (United States)

    Behrens, C J; Ul Haq, R; Liotta, A; Anderson, M L; Heinemann, U

    2011-09-29

    It has been suggested that gap junctions are involved in the synchronization during high frequency oscillations as observed during sharp wave-ripple complexes (SPW-Rs) and during recurrent epileptiform discharges (REDs). Ripple oscillations during SPW-Rs, possibly involved in memory replay and memory consolidation, reach frequencies of up to 200 Hz while ripple oscillations during REDs display frequencies up to 500 Hz. These fast oscillations may be synchronized by intercellular interactions through gap junctions. In area CA3, connexin 36 (Cx36) proteins are present and potentially sensitive to mefloquine. Here, we used hippocampal slices of adult rats to investigate the effects of mefloquine, which blocks Cx36, Cx43 and Cx50 gap junctions on both SPW-Rs and REDs. SPW-Rs were induced by high frequency stimulation in the CA3 region while REDs were recorded in the presence of the GABA(A) receptor blocker bicuculline (5 μM). Both, SPW-Rs and REDs were blocked by the gap junction blocker carbenoxolone. Mefloquine (50 μM), which did not affect stimulus-induced responses in area CA3, neither changed SPW-Rs nor superimposed ripple oscillations. During REDs, 25 and 50 μM mefloquine exerted only minor effects on the expression of REDs but significantly reduced the amplitude of superimposed ripples by ∼17 and ∼54%, respectively. Intracellular recordings of CA3 pyramidal cells revealed that mefloquine did not change their resting membrane potential and input resistance but significantly increased the afterhyperpolarization following evoked action potentials (APs) resulting in reduced probability of AP firing during depolarizing current injection. Similarly, mefloquine caused a reduction in AP generation during REDs. Together, our data suggest that mefloquine depressed RED-related ripple oscillations by reducing high frequency discharges and not necessarily by blocking electrical coupling. Copyright © 2011 IBRO. Published by Elsevier Ltd. All rights reserved.

  1. Sharp transition towards shared vocabularies in multi-agent systems

    Science.gov (United States)

    Baronchelli, Andrea; Felici, Maddalena; Loreto, Vittorio; Caglioti, Emanuele; Steels, Luc

    2006-06-01

    What processes can explain how very large populations are able to converge on the use of a particular word or grammatical construction without global coordination? Answering this question helps to understand why new language constructs usually propagate along an S-shaped curve with a rather sudden transition towards global agreement. It also helps to analyse and design new technologies that support or orchestrate self-organizing communication systems, such as recent social tagging systems for the web. The article introduces and studies a microscopic model of communicating autonomous agents performing language games without any central control. We show that the system undergoes a disorder/order transition, going through a sharp symmetry breaking process to reach a shared set of conventions. Before the transition, the system builds up non-trivial scale-invariant correlations, for instance in the distribution of competing synonyms, which display a Zipf-like law. These correlations make the system ready for the transition towards shared conventions, which, observed on the timescale of collective behaviours, becomes sharper and sharper with system size. This surprising result not only explains why human language can scale up to very large populations but also suggests ways to optimize artificial semiotic dynamics.

  2. Effect of sharp maximum in ion diffusivity for liquid xenon

    Science.gov (United States)

    Lankin, A. V.; Orekhov, M. A.

    2016-11-01

    Ion diffusion in a liquid usually could be treated as a movement of an ion cluster in a viscous media. For small ions this leads to a special feature: diffusion coefficient is either independent of the ion size or increases with it. We find a different behavior for small ions in liquid xenon. Calculation of the dependence of an ion diffusion coefficient in liquid xenon on the ion size is carried out. Classical molecular dynamics method is applied. Calculated dependence of the ion diffusion coefficient on its radius has sharp maximums at the ion radiuses 1.75 and 2 Å. Every maximum is placed between two regions with different stable ion cluster configurations. This leads to the instability of these configurations in a small region between them. Consequently ion with radius near 1.75 or 2 Å could jump from one configuration to another. This increases the speed of the diffusion. A simple qualitative model for this effect is suggested. The decomposition of the ion movement into continuous and jump diffusion shows that continuous part of the diffusion is the same as for the ion cluster in the stable region.

  3. 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.

  4. 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.

  5. Hippocampal remapping is constrained by sparseness rather than capacity.

    Directory of Open Access Journals (Sweden)

    Axel Kammerer

    2014-12-01

    Full Text Available Grid cells in the medial entorhinal cortex encode space with firing fields that are arranged on the nodes of spatial hexagonal lattices. Potential candidates to read out the space information of this grid code and to combine it with other sensory cues are hippocampal place cells. In this paper, we investigate a population of grid cells providing feed-forward input to place cells. The capacity of the underlying synaptic transformation is determined by both spatial acuity and the number of different spatial environments that can be represented. The codes for different environments arise from phase shifts of the periodical entorhinal cortex patterns that induce a global remapping of hippocampal place fields, i.e., a new random assignment of place fields for each environment. If only a single environment is encoded, the grid code can be read out at high acuity with only few place cells. A surplus in place cells can be used to store a space code for more environments via remapping. The number of stored environments can be increased even more efficiently by stronger recurrent inhibition and by partitioning the place cell population such that learning affects only a small fraction of them in each environment. We find that the spatial decoding acuity is much more resilient to multiple remappings than the sparseness of the place code. Since the hippocampal place code is sparse, we thus conclude that the projection from grid cells to the place cells is not using its full capacity to transfer space information. Both populations may encode different aspects of space.

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

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    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

  7. 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.

  8. Mixed neurotransmission in the hippocampal mossy fibers

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    Agnieszka eMuenster-Wandowski

    2013-11-01

    Full Text Available The hippocampal mossy fibers (MFs, the axons of the granule cells of the dentate gyrus, innervate mossy cells and interneurons in the hilus on its way to CA3 where they innervate interneurons and pyramidal cells. Synapses on each target cell have distinct anatomical and functional characteristics. In recent years, the paradigmatic view of the MF synapses being only glutamatergic and, thus, excitatory has been questioned. Several laboratories have provided data supporting the hypothesis that the MFs can transiently release GABA during development and, in the adult, after periods of enhanced excitability. This transient glutamate-GABA co-transmission coincides with the transient expression of the machinery for the synthesis and release of GABA in the glutamatergic granule cells. Although some investigators have deemed this evidence controversial, new data has appeared with direct evidence of co-release of glutamate and GABA from single, identified MF boutons. However, this must still be confirmed by other groups and with other methodologies. A second, intriguing observation is that MF activation produced fast spikelets followed by excitatory postsynaptic potentials in a number of pyramidal cells, which, unlike the spikelets, underwent frequency potentiation and were strongly depressed by activation of metabotropic glutamate receptors. The spikelets persisted during blockade of chemical transmission and were suppressed by the gap junction blocker carbenoxolone. These data is consistent with the hypothesis of mixed electrical-chemical synapses between MFs and some pyramidal cells. Dye coupling between these types of principal cells and ultrastructural studies showing the co-existence of AMPA receptors and connexin 36 in this synapse corroborate their presence. A deeper consideration of mixed neurotransmission taking place in this synapse may expand our search and understanding of communication channels between different regions of the mammalian CNS.

  9. Norepinephrine but not serotonin reuptake inhibitors enhance theta and gamma activity of the septo-hippocampal system.

    Science.gov (United States)

    Hajós, Mihály; Hoffmann, William E; Robinson, Deborah D; Yu, Jen H; Hajós-Korcsok, Eva

    2003-05-01

    Current neurobiological concepts attribute a central role of the hippocampal formation in cognitive and affective processes. Recent studies indicate that the hippocampus is affected in human depression, and antidepressant drugs induce hippocampal adaptive changes that are thought to be associated with their therapeutic action. In the present study, we investigated the action of various antidepressant drugs on the activity of the septo-hippocampal system, its oscillatory activity in particular. The acute effects of the norepinephrine (NE) reuptake inhibitors reboxetine and desipramine, and the selective serotonin reuptake inhibitor fluvoxamine were evaluated. Extracellular single-unit recordings were performed from the medial septum/diagonal band of Broca (MS/DBv), with simultaneous hippocampal EEG recordings of anesthetized rats. Systemic administration of reboxetine synchronized hippocampal EEG, resulting in a significant increase in power at theta frequency, and an increase in frequency and power of gamma-wave activity. Parallel to EEG synchrony, reboxetine induced or enhanced theta oscillation of MS/DBv neurons. Oscillatory frequencies of MS/DBv neurons were identical, and phase locked to the corresponding hippocamapal theta frequencies. Under the same experimental conditions, reboxetine induced a two-fold increase in extracellular NE (but not serotonin) levels in the hippocampus as revealed by microdialysis. Desipramine, but not the serotonin reuptake inhibitor fluvoxamine, evoked responses similar to those of reboxetine regarding septo-hippocampal theta activity. The present findings indicate that even though both NE and serotonin reuptake inhibitors are clinically effective antidepressant drugs, their action on the septo-hippocampal oscillatory behavior is different. It is presumed that selective NE reuptake inhibitors could modulate various cognitive processes associated with hippocampal oscillatory activity.

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. 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

  15. Glucocorticoid receptor knockdown and adult hippocampal neurogenesis

    NARCIS (Netherlands)

    Hooijdonk, Leonarda Wilhelmina Antonia van

    2010-01-01

    The research in this thesis is aimed at the elucidation of the role of the glucocorticoid receptor (GR) in hippocampal neuroplasticity and functioning. To achieve this, we have developed a novel method to specifically knockdown GR in a discrete cell population of the mouse brain. In this thesis I

  16. 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

  17. Stimulus Configuration, Classical Conditioning, and Hippocampal Function.

    Science.gov (United States)

    Schmajuk, Nestor A.; DiCarlo, James J.

    1991-01-01

    The participation of the hippocampus in classical conditioning is described in terms of a multilayer network portraying stimulus configuration. A model of hippocampal function is presented, and computer simulations are used to study neural activity in the various brain areas mapped according to the model. (SLD)

  18. 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.)

  19. Nocturnal mnemonics: sleep and hippocampal memory processing.

    Science.gov (United States)

    Saletin, Jared M; Walker, Matthew P

    2012-01-01

    As critical as waking brain function is to learning and memory, an established literature now describes an equally important yet complementary role for sleep in information processing. This overview examines the specific contribution of sleep to human hippocampal memory processing; both the detriments caused by a lack of sleep, and conversely, the proactive benefits that develop following the presence of sleep. First, a role for sleep before learning is discussed, preparing the hippocampus for initial memory encoding. Second, a role for sleep after learning is considered, modulating the post-encoding consolidation of hippocampal-dependent memory. Third, a model is outlined in which these encoding and consolidation operations are symbiotically accomplished, associated with specific NREM sleep physiological oscillations. As a result, the optimal network outcome is achieved: increasing hippocampal independence and hence overnight consolidation, while restoring next-day sparse hippocampal encoding capacity for renewed learning ability upon awakening. Finally, emerging evidence is considered suggesting that, unlike previous conceptions, sleep does not universally consolidate all information. Instead, and based on explicit as well as saliency cues during initial encoding, sleep executes the discriminatory offline consolidation only of select information. Consequently, sleep promotes the targeted strengthening of some memories while actively forgetting others; a proposal with significant theoretical and clinical ramifications.

  20. Nocturnal Mnemonics: Sleep and Hippocampal Memory Processing

    Directory of Open Access Journals (Sweden)

    Jared M. Saletin

    2012-05-01

    Full Text Available As critical as waking brain function is to learning and memory, an established literature now describes an equally important yet complementary role for sleep in information processing. This overview examines the specific contribution of sleep to human hippocampal memory processing; both the detriments caused by a lack of sleep, and conversely, the proactive benefits that develop following the presence of sleep. First, a role for sleep before learning is discussed, preparing the hippocampus for initial memory encoding. Second, a role for sleep after learning is considered, modulating the post-encoding consolidation of hippocampal-dependent memory. Third, a model is outlined in which these encoding and consolidation operations are symbiotically accomplished, associated with specific NREM sleep physiological oscillations. As a result, the optimal network outcome is achieved, increasing hippocampal independence and hence overnight consolidation, while restoring next-day sparse hippocampal encoding capacity for renewed learning ability upon awakening. Finally, emerging evidence is considered suggesting that, unlike previous conceptions, sleep does not universally consolidate all information equally. Instead, and based on explicit as well as motivational cues during initial encoding, sleep executes the discriminatory offline consolidation only of select information. Consequently, sleep promotes the targeted strengthening of some memories while actively forgetting others; a proposal with significant theoretical and clinical ramifications.

  1. Klotho regulates CA1 hippocampal synaptic plasticity.

    Science.gov (United States)

    Li, Qin; Vo, Hai T; Wang, Jing; Fox-Quick, Stephanie; Dobrunz, Lynn E; King, Gwendalyn D

    2017-04-07

    Global klotho overexpression extends lifespan while global klotho-deficiency shortens it. As well, klotho protein manipulations inversely regulate cognitive function. Mice without klotho develop rapid onset cognitive impairment before they are 2months old. Meanwhile, adult mice overexpressing klotho show enhanced cognitive function, particularly in hippocampal-dependent tasks. The cognitive enhancing effects of klotho extend to humans with a klotho polymorphism that increases circulating klotho and executive function. To affect cognitive function, klotho could act in or on the synapse to modulate synaptic transmission or plasticity. However, it is not yet known if klotho is located at synapses, and little is known about its effects on synaptic function. To test this, we fractionated hippocampi and detected klotho expression in both pre and post-synaptic compartments. We find that loss of klotho enhances both pre and post-synaptic measures of CA1 hippocampal synaptic plasticity at 5weeks of age. However, a rapid loss of synaptic enhancement occurs such that by 7weeks, when mice are cognitively impaired, there is no difference from wild-type controls. Klotho overexpressing mice show no early life effects on synaptic plasticity, but decreased CA1 hippocampal long-term potentiation was measured at 6months of age. Together these data suggest that klotho affects cognition, at least in part, by regulating hippocampal synaptic plasticity. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

  2. Measuring grinding surface roughness based on the sharpness evaluation of colour images

    International Nuclear Information System (INIS)

    Huaian, Y I; Jian, L I U; Enhui, L U; Peng, A O

    2016-01-01

    Current machine vision-based detection methods for metal surface roughness mainly use the grey values of images for statistical analysis but do not make full use of the colour information and ignore the subjective judgment of the human vision system. To address these problems, this paper proposes a method to measure surface roughness through the sharpness evaluation of colour images. Based on the difference in sharpness of virtual images of colour blocks that are formed on grinding surfaces with different roughness, an algorithm for evaluating the sharpness of colour images that is based on the difference of the RGB colour space was used to develop a correlation model between the sharpness and the surface roughness. The correlation model was analysed under two conditions: constant illumination and varying illumination. The effect of the surface textures of the grinding samples on the image sharpness was also considered, demonstrating the feasibility of the detection method. The results show that the sharpness is strongly correlated with the surface roughness; when the illumination and the surface texture have the same orientation, the sharpness clearly decreases with increasing surface roughness. Under varying illumination, this correlation between the sharpness and surface roughness was highly robust, and the sharpness of each virtual image increased linearly with the illumination. Relative to the detection method for surface roughness using gray level co-occurrence matrix or artificial neural network, the proposed method is convenient, highly accurate and has a wide measurement range. (paper)

  3. 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

  4. Imaging diagnostics of pulsed plasma discharges in saline generated with various sharp pin powered electrodes

    Science.gov (United States)

    Asimakoulas, L.; Karim, M. L.; Dostal, L.; Krcma, F.; Graham, W. G.; Field, T. A.

    2016-09-01

    Plasmas formed by 1 ms pulses of between 180 and 300 V applied to sharp pin-like electrodes immersed in saline solution have been imaged with a Photron SA-X2 fast framing camera and an Andor iStar 510 ICCD camera. Stainless steel, Tungsten and Gold electrodes were investigated with tip diameters of 30 μm, 1 μm and volume, which appears to move about, but remains close to the tip. In the case of Tungsten with higher voltages or longer pulses the tip of the needle can heat up to incandescent temperatures. At higher voltages shock wave fronts appear to be observed as the vapour layer collapses at the end of the voltage pulse. Backlighting and no lighting to observe bubble/vapour layer formation and emission due to plasma formation were employed. Sometimes at higher voltages a thicker vapour layer engulfs the tip and no plasma emission/current is observed.

  5. On the Photometric Variability of Very Sharp-lined Cool mCP Stars

    Science.gov (United States)

    Pyper, Diane M.; Adelman, Saul J.

    2017-10-01

    We investigate the photometric variability of very sharp-lined cool mCP stars from a list published in 1970 by Dr. George W. Preston who suggested that some belonged to the long-period tail of the period distribution. In this study, we discuss our Strömgren uvby observations obtained with the Four College Automated Photometric Telescope (FCAPT) at the Fairborn Observatory for 22 of the stars in Preston’s list. We improved the periods of 11 stars. Further, we discuss results from the literature concerning the light, magnetic, and spectrum variability of these stars. Eleven of the stars are found to have periods longer than 20 days, and all but one of these stars display variations in the u and v filters that cannot be explained by the simple oblique rotator theory. We discuss some possible causes of this behavior.

  6. 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.

  7. [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.

  8. Insular and hippocampal contributions to remembering people with an impression of bad personality

    Science.gov (United States)

    Shigemune, Yayoi; Nouchi, Rui; Kambara, Toshimune; Kawashima, Ryuta

    2013-01-01

    Our impressions of other people are formed mainly from the two possible factors of facial attractiveness and trustworthiness. Previous studies have shown the importance of orbitofrontal–hippocampal interactions in the better remembering of attractive faces, and psychological data have indicated that faces giving an impression of untrustworthiness are remembered more accurately than those giving an impression of trustworthiness. However, the neural mechanisms of the latter effect are largely unknown. To investigate this issue, we investigated neural activities with event-related fMRI while the female participants rated their impressions of the personalities of men in terms of trustworthiness. After the rating, memory for faces was tested to identify successful encoding activity. As expected, faces that gave bad impressions were remembered better than those that gave neutral or good impressions. In fMRI data, right insular activity reflected an increasing function of bad impressions, and bilateral hippocampal activities predicted subsequent memory success. Additionally, correlation between these insular and hippocampal regions was significant only in the encoding of faces associated with a bad impression. Better memory for faces associated with an impression of bad personality could reflect greater interaction between the avoidance-related insular region and the encoding-related hippocampal region. PMID:22349799

  9. Treadmill Exercise Induces Hippocampal Astroglial Alterations in Rats

    Directory of Open Access Journals (Sweden)

    Caren Bernardi

    2013-01-01

    Full Text Available Physical exercise effects on brain health and cognitive performance have been described. Synaptic remodeling in hippocampus induced by physical exercise has been described in animal models, but the underlying mechanisms remain poorly understood. Changes in astrocytes, the glial cells involved in synaptic remodeling, need more characterization. We investigated the effect of moderate treadmill exercise (20 min/day for 4 weeks on some parameters of astrocytic activity in rat hippocampal slices, namely, glial fibrillary acidic protein (GFAP, glutamate uptake and glutamine synthetase (GS activities, glutathione content, and S100B protein content and secretion, as well as brain-derived neurotrophic factor (BDNF levels and glucose uptake activity in this tissue. Results show that moderate treadmill exercise was able to induce a decrease in GFAP content (evaluated by ELISA and immunohistochemistry and an increase in GS activity. These changes could be mediated by corticosterone, whose levels were elevated in serum. BDNF, another putative mediator, was not altered in hippocampal tissue. Moreover, treadmill exercise caused a decrease in NO content. Our data indicate specific changes in astrocyte markers induced by physical exercise, the importance of studying astrocytes for understanding brain plasticity, as well as reinforce the relevance of physical exercise as a neuroprotective strategy.

  10. Hippocampal Dendritic Spines Modifications Induced by Perinatal Asphyxia

    Directory of Open Access Journals (Sweden)

    G. E. Saraceno

    2012-01-01

    Full Text Available Perinatal asphyxia (PA affects the synaptic function and morphological organization. In previous works, we have shown neuronal and synaptic changes in rat neostriatum subjected to hypoxia leading to long-term ubi-protein accumulation. Since F-actin is highly concentrated in dendritic spines, modifications in its organization could be related with alterations induced by hypoxia in the central nervous system (CNS. In the present study, we investigate the effects of PA on the actin cytoskeleton of hippocampal postsynaptic densities (PSD in 4-month-old rats. PSD showed an increment in their thickness and in the level of ubiquitination. Correlative fluorescence-electron microscopy photooxidation showed a decrease in the number of F-actin-stained spines in hippocampal excitatory synapses subjected to PA. Although Western Blot analysis also showed a slight decrease in β-actin in PSD in PA animals, the difference was not significant. Taken together, this data suggests that long-term actin cytoskeleton might have role in PSD alterations which would be a spread phenomenon induced by PA.

  11. 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.

  12. Amyloid Beta Peptides Differentially Affect Hippocampal Theta Rhythms In Vitro

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    Armando I. Gutiérrez-Lerma

    2013-01-01

    Full Text Available Soluble amyloid beta peptide (Aβ is responsible for the early cognitive dysfunction observed in Alzheimer's disease. Both cholinergically and glutamatergically induced hippocampal theta rhythms are related to learning and memory, spatial navigation, and spatial memory. However, these two types of theta rhythms are not identical; they are associated with different behaviors and can be differentially modulated by diverse experimental conditions. Therefore, in this study, we aimed to investigate whether or not application of soluble Aβ alters the two types of theta frequency oscillatory network activity generated in rat hippocampal slices by application of the cholinergic and glutamatergic agonists carbachol or DHPG, respectively. Due to previous evidence that oscillatory activity can be differentially affected by different Aβ peptides, we also compared Aβ25−35 and Aβ1−42 for their effects on theta rhythms in vitro at similar concentrations (0.5 to 1.0 μM. We found that Aβ25−35 reduces, with less potency than Aβ1−42, carbachol-induced population theta oscillatory activity. In contrast, DHPG-induced oscillatory activity was not affected by a high concentration of Aβ25−35 but was reduced by Aβ1−42. Our results support the idea that different amyloid peptides might alter specific cellular mechanisms related to the generation of specific neuronal network activities, instead of exerting a generalized inhibitory effect on neuronal network function.

  13. Auditory stimuli elicit hippocampal neuronal responses during sleep

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    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.

  14. Cardiovascular Risk and Hippocampal Thickness in Alzheimer’s Disease

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    Markus Donix

    2013-01-01

    Full Text Available Cardiovascular risk factors influence onset and progression of Alzheimer’s disease. Among cognitively healthy people, changes in brain structure and function associated with high blood pressure, diabetes, or other vascular risks suggest differential regional susceptibility to neuronal damage. In patients with Alzheimer’s disease, hippocampal and medial temporal lobe atrophy indicate early neuronal loss preferentially in key areas for learning and memory. We wanted to investigate whether this regional cortical thinning would be modulated by cardiovascular risk factors. We utilized high-resolution magnetic resonance imaging and a cortical unfolding technique to determine the cortical thickness of medial temporal subregions in 30 patients with Alzheimer’s disease. Cardiovascular risk was assessed using a sex-specific multivariable risk score. Greater cardiovascular risk was associated with cortical thinning in the hippocampus CA2/3/dentate gyrus area but not other hippocampal and medial temporal subregions. APOE genotype, a family history of Alzheimer’s disease, and age did not influence cortical thickness. Alzheimer’s disease-related atrophy could mask the influence of genetic risk factors or age on regional cortical thickness in medial temporal lobe regions, whereas the impact of vascular risk factors remains detectable. This highlights the importance of cardiovascular disease prevention and treatment in patients with Alzheimer’s disease.

  15. 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

  16. Sharp-1 regulates TGF-β signaling and skeletal muscle regeneration.

    Science.gov (United States)

    Acharjee, Sujata; Chung, Teng-Kai; Gopinadhan, Suma; Shankar, Shilpa Rani; Wang, Yaju; Li, Li; Vercherat, Cecile; Gulbagci, Neriman Tuba; Rossner, Moritz; Taneja, Reshma

    2014-02-01

    Sharp-1 is a basic helix-loop-helix (bHLH) transcriptional repressor that is involved in a number of cellular processes. Our previous studies have demonstrated that Sharp-1 is a negative regulator of skeletal myogenesis and it blocks differentiation of muscle precursor cells by modulating the activity of MyoD. In order to understand its role in pre- and post-natal myogenesis, we assessed skeletal muscle development and freeze-injury-induced regeneration in Sharp-1-deficient mice. We show that embryonic skeletal muscle development is not impaired in the absence of Sharp-1; however, post-natally, the regenerative capacity is compromised. Although the initial phases of injury-induced regeneration proceed normally in Sharp-1(-/-) mice, during late stages, the mutant muscle exhibits necrotic fibers, calcium deposits and fibrosis. TGF-β expression, as well as levels of phosphorylated Smad2 and Smad3, are sustained in the mutant tissue and treatment with decorin, which blocks TGF-β signaling, improves the histopathology of Sharp-1(-/-) injured muscles. In vitro, Sharp-1 associates with Smad3, and its overexpression inhibits TGF-β- and Smad3-mediated expression of extracellular matrix genes in myofibroblasts. These results demonstrate that Sharp-1 regulates muscle regenerative capacity, at least in part, by modulation of TGF-β signaling.

  17. 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.

  18. Multiple sharp force injuries to the head - the crime of passion

    Directory of Open Access Journals (Sweden)

    Nikolić Slobodan

    2015-01-01

    Full Text Available Introduction. The Institute of Forensic Medicine was founded by Professor Milovan Milovanović (1884- 1948 in 1923 as part of School of Medicine of the University of Belgrade, and also established the Institute’s forensic collection worthy of a museum. This paper illustrates the way Professor Milovanović made this collection into a teaching aid for student education. We present a case of crime of passion from the year 1931, from our Institute’s collection. Case Outline. The victim was a 30-year-old woman with multiple stab wounds of the head, neck and arms. It was noted in the case history that the deceased woman was a maid with a wealthy merchant, as well as that she had “dubious morals” for that time, with three wooers at the same time. Injuries to the forearms and the index finger prove that the victim tried to defend herself. In the autopsy record there is a drawn figure of a kitchen knife with a rounded blade tip, which explains the absence of stab wounds to the skull, and the presence of the impression skull fractures and crushed skull bones. It was concluded that the death occurred due to exsanguination, in turn due to transection of the left carotid artery, probably caused by sharp force, while the manner of death was homicide. Some of the most prominent autopsy findings were multiple mutilating overkill sharp force injuries, localized on the head, indicated sexually motivated murder. Conclusion. Combining the museum specimen, diagrams with injuries, drawn figure of the kitchen knife used, and photographs taken during the autopsy and the police investigation, Professor Milovanović was able to properly illustrate this intriguing case to students without a computer or a PowerPoint presentation. [Projekat Ministarstva nauke Republike Srbije, br. 45005

  19. Multiple Sharp Force Injuries to the Head - The Crime of Passion.

    Science.gov (United States)

    Nikolić, Slobodan; Živković, Vladimir

    2015-01-01

    The Institute of Forensic Medicine was founded by Professor Milovan Milovanovid (1884-1948) in 1923 as part of School of Medicine of the University of Belgrade, and also established the Institute's forensic collection worthy of a museum.This paper illustrates the way Professor Milovanovie made this collection into a teaching aid for student education. We present a case of crime of passion from the year 1931, from our Institute's collection. The victim was a 30-year-old woman with multiple stab wounds of the head, neck and arms. It was noted in the case history that the deceased woman was a maid with a wealthy merchant, as well as that she had "dubious morals" for that time, with three wooers at the same time. Injuries to the forearms and the index finger prove that the victim tried to defend herself. In the autopsy record there is a drawn figure of a kitchen knife with a rounded blade tip, which explains the absence of stab wounds to the skull, and the presence of the impression skull fractures and crushed skull bones. It was concluded that the death occurred due to exsanguination, in turn due to transection of the left carotid artery, probably caused by sharp force, while the manner of death was homicide. Some of the most prominent autopsy findings were multiple mutilating overkill sharp force injuries, localized on the head, indicated sexually motivated murder. Combining the museum specimen, diagrams with injuries, drawn figure of the kitchen knife used, and photographs taken during the autopsy and the police investigation, Professor Milovanovie was able to properly illustrate this intriguing case to students without a computer or a PowerPoint presentation.

  20. Hippocampal volume and cognitive function in anorexia nervosa.

    Science.gov (United States)

    Connan, Frances; Murphy, Fay; Connor, Steve E J; Rich, Phil; Murphy, Tara; Bara-Carill, Nuria; Landau, Sabine; Krljes, Sanya; Ng, Virginia; Williams, Steve; Morris, Robin G; Campbell, Iain C; Treasure, Janet

    2006-03-31

    We hypothesised that hippocampal volume would be reduced in underweight anorexia nervosa (AN) and associated with impaired hippocampus-dependent cognitive function. Hippocampal and whole brain volumes were measured in 16 women with AN and 16 matched healthy women using magnetic resonance imaging (MRI) and a manual tracing method. Participants also completed the Doors and People Test of hippocampus-dependent memory and an IQ test. After adjustment for total cerebral volume, there was significant bilateral reduction in hippocampal volume in the AN group (8.2% right; 7.5% left). There was no evidence of impaired hippocampus-dependent cognitive function and no evidence of a relationship between hippocampal volume and clinical features of AN. The reduced hippocampal volume in anorexia nervosa is not associated with changes in cognitive function. To understand the cause and consequence of hippocampal size and function, it will be important to integrate endocrine, neuropsychological and neuroimaging studies.

  1. Magnolol Enhances Hippocampal Neurogenesis and Exerts Antidepressant-Like Effects in Olfactory Bulbectomized Mice.

    Science.gov (United States)

    Matsui, Nobuaki; Akae, Haruka; Hirashima, Nana; Kido, Yuki; Tanabe, Satoshi; Koseki, Mayumi; Fukuyama, Yoshiyasu; Akagi, Masaaki

    2016-11-01

    Magnolol is the main constituent of Magnolia bark and has been reported to exhibit antidepressant effects in rodent models. Hippocampal neurogenesis and neurotrophins such as brain-derived neurotrophic factor are integrally involved in the action of conventional antidepressants. Here, we investigated the effects of magnolol on depressive behaviours, impaired hippocampal neurogenesis and neurotrophin-related signal transduction in an olfactory bulbectomy (OBX) mouse model of depression. Mice were submitted to OBX to induce depressive behaviour, which was evaluated in the tail suspension test. Magnolol was administered orally by gavage needle. Neurogenesis was assessed by analysis of cells expressing NeuN, a neuronal marker, and 5-bromo-2'-deoxyuridine (BrdU) uptake. Phosphorylation levels of protein kinase B (Akt), extracellular signal-regulated kinase and cyclic AMP-responsive element-binding protein were evaluated by Western blot. Fourteen day treatment with magnolol (50 or 100 mg/kg/day) significantly improved OBX-induced depressive behaviour in tail suspension test. In agreement, magnolol significantly rescued impairments of hippocampal neurogenesis. Moreover, single treatments with magnolol (50 mg/kg) significantly increased phosphorylation of Akt, extracellular signal-regulated kinase and cyclic AMP-responsive element-binding protein after 3 h. The present data indicate that magnolol exerts antidepressant-like effects on behaviours by enhancing hippocampal neurogenesis and neurotrophin-related intracellular signalling in OBX mice. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  2. Postnatal stimulation of the pups counteracts prenatal stress-induced deficits in hippocampal neurogenesis.

    Science.gov (United States)

    Lemaire, Valerie; Lamarque, Stephanie; Le Moal, Michel; Piazza, Pier-Vincenzo; Abrous, Djoher Nora

    2006-05-01

    Prenatal stress constitutes a developmental risk factor for later psychopathology. The behavioral disorders are sustained by neurobiological alterations including long-term reduction of hippocampal neurogenesis; its deregulation has been involved in cognitive impairments, mood disorders and addiction. A major goal is to define periods in development and strategies for intervening to prevent the effects of early stressful events. We investigated the ability of a postnatal infantile stimulation to prevent prenatal stress-induced alteration in hippocampal neurogenesis. The influence of postnatal handling on prenatal stress-induced changes in hippocampal neurogenesis was examined in 4 and 26 month-old male rats. Three distinct phases of the neurogenesis were studied: proliferation, survival and neuronal differentiation. Prenatal stress reduced hippocampal cell proliferation all throughout life. Furthermore, the survival rate of newborn cells, the number of immature neurons and the number of differentiated new neurons were reduced in young and old prenatally-stressed rats. All those deleterious effects were counteracted by neonatal handling. These data show that finer aspects of brain shaping can be rewired by environmental influences occurring at sensitive phase of development. They also suggest that infantile stimulation may reverse the appearance of behavioral disorders induced by early life stress.

  3. Retinoic Acid Restores Adult Hippocampal Neurogenesis and Reverses Spatial Memory Deficit in Vitamin A Deprived Rats

    Science.gov (United States)

    Alfos, Serge; Pallet, Véronique; Higueret, Paul; Abrous, Djoher Nora

    2008-01-01

    A dysfunction of retinoid hippocampal signaling pathway has been involved in the appearance of affective and cognitive disorders. However, the underlying neurobiological mechanisms remain unknown. Hippocampal granule neurons are generated throughout life and are involved in emotion and memory. Here, we investigated the effects of vitamin A deficiency (VAD) on neurogenesis and memory and the ability of retinoic acid (RA) treatment to prevent VAD-induced impairments. Adult retinoid-deficient rats were generated by a vitamin A-free diet from weaning in order to allow a normal development. The effects of VAD and/or RA administration were examined on hippocampal neurogenesis, retinoid target genes such as neurotrophin receptors and spatial reference memory measured in the water maze. Long-term VAD decreased neurogenesis and led to memory deficits. More importantly, these effects were reversed by 4 weeks of RA treatment. These beneficial effects may be in part related to an up-regulation of retinoid-mediated molecular events, such as the expression of the neurotrophin receptor TrkA. We have demonstrated for the first time that the effect of vitamin A deficient diet on the level of hippoccampal neurogenesis is reversible and that RA treatment is important for the maintenance of the hippocampal plasticity and function. PMID:18941534

  4. 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.

  5. Protective effects of high Tryptophan diet on aging-induced passive avoidance impairment and hippocampal apoptosis.

    Science.gov (United States)

    Musumeci, Giuseppe; Castrogiovanni, Paola; Szychlinska, Marta Anna; Imbesi, Rosa; Loreto, Carla; Castorina, Sergio; Giunta, Salvatore

    2017-01-01

    In our previous work we have shown that L-Tryptophan (TrP) enriched diet prevents the age-induced decline of hippocampal Serotonin (5-HT) production. Considering that loss or reduction in 5-HT neurotransmission may contribute to age-related cognitive decline, here we have investigated the effect of such diet on passive avoidance (PA) behavior, cell death, pro- and anti- apoptotic molecules (BAX, Bcl-2 and Caspase-3) and an important transcription factor involved in synaptic plasticity and memory (CREB). The increase in 5-HT neurotransmission in the Hippocampus (Hp) of aged rats was induced by 1 month of high TrP administration. In the first phase of our study we found that high TrP diet improves PA behaviour of aged rats and this correlated with a decrease of TUNEL positive cells in all hippocampal regions tested (CA1, CA2, CA3, DG). Interestingly, the Hp of aged animals fed with high TrP diet showed a significant downregulation of proapoptotic proteins, caspase-3 and BAX, and an increase of antiapoptotic molecules Bcl-2 as indicated by Western Blot and immunohistochemical analyses. Also, high TrP diet partially rescued the age-induced inhibition of hippocampal CREB phosphorylation. Altogether, our data suggest that enhanced TrP intake, and in consequence a potential increase in 5-HT neurotransmission, might be beneficial in preventing age-related detrimental features by inhibition of hippocampal apoptosis. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. 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.

  7. Retinoic acid restores adult hippocampal neurogenesis and reverses spatial memory deficit in vitamin A deprived rats.

    Directory of Open Access Journals (Sweden)

    Emilie Bonnet

    Full Text Available A dysfunction of retinoid hippocampal signaling pathway has been involved in the appearance of affective and cognitive disorders. However, the underlying neurobiological mechanisms remain unknown. Hippocampal granule neurons are generated throughout life and are involved in emotion and memory. Here, we investigated the effects of vitamin A deficiency (VAD on neurogenesis and memory and the ability of retinoic acid (RA treatment to prevent VAD-induced impairments. Adult retinoid-deficient rats were generated by a vitamin A-free diet from weaning in order to allow a normal development. The effects of VAD and/or RA administration were examined on hippocampal neurogenesis, retinoid target genes such as neurotrophin receptors and spatial reference memory measured in the water maze. Long-term VAD decreased neurogenesis and led to memory deficits. More importantly, these effects were reversed by 4 weeks of RA treatment. These beneficial effects may be in part related to an up-regulation of retinoid-mediated molecular events, such as the expression of the neurotrophin receptor TrkA. We have demonstrated for the first time that the effect of vitamin A deficient diet on the level of hippoccampal neurogenesis is reversible and that RA treatment is important for the maintenance of the hippocampal plasticity and function.

  8. 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.

  9. Sleep deprivation and hippocampal vulnerability: changes in neuronal plasticity, neurogenesis and cognitive function.

    Science.gov (United States)

    Kreutzmann, J C; Havekes, R; Abel, T; Meerlo, P

    2015-11-19

    Despite the ongoing fundamental controversy about the physiological function of sleep, there is general consensus that sleep benefits neuronal plasticity, which ultimately supports brain function and cognition. In agreement with this are numerous studies showing that sleep deprivation (SD) results in learning and memory impairments. Interestingly, such impairments appear to occur particularly when these learning and memory processes require the hippocampus, suggesting that this brain region may be particularly sensitive to the consequences of sleep loss. Although the molecular mechanisms underlying sleep and memory formation remain to be investigated, available evidence suggests that SD may impair hippocampal neuronal plasticity and memory processes by attenuating intracellular cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) signaling which may lead to alterations in cAMP response element binding protein (CREB)-mediated gene transcription, neurotrophic signaling, and glutamate receptor expression. When restricted sleep becomes a chronic condition, it causes a reduction of hippocampal cell proliferation and neurogenesis, which may eventually lead to a reduction in hippocampal volume. Ultimately, by impairing hippocampal plasticity and function, chronically restricted and disrupted sleep contributes to cognitive disorders and psychiatric diseases. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

  10. 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.

  11. 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.

  12. BNDF heterozygosity is associated with memory deficits and alterations in cortical and hippocampal EEG power.

    Science.gov (United States)

    Geist, Phillip A; Dulka, Brooke N; Barnes, Abigail; Totty, Michael; Datta, Subimal

    2017-08-14

    Brain derived neurotrophic factor (BDNF) plays a pivotal role in structural plasticity, learning, and memory. Electroencephalogram (EEG) spectral power in the cortex and hippocampus has also been correlated with learning and memory. In this study, we investigated the effect of globally reduced BDNF levels on learning behavior and EEG power via BDNF heterozygous (KO) rats. We employed several behavioral tests that are thought to depend on cortical and hippocampal plasticity to varying degrees: novel object recognition, a test that is reliant on a variety of cognitive systems; contextual fear, which is highly hippocampal-dependent; and cued fear, which has been shown to be amygdala-dependent. We also examined the effects of BDNF reduction on cortical and hippocampal EEG spectral power via chronically implanted electrodes in the motor cortex and dorsal hippocampus. We found that BDNF KO rats were impaired in novelty recognition and fear memory retention, while hippocampal EEG power was decreased in slow waves and increased in fast waves. Interestingly, our results, for the first time, show sexual dimorphism in each of our tests. These results support the hypothesis that BDNF drives both cognitive plasticity and coordinates EEG activity patterns, potentially serving as a link between the two. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Treadmill exercise induces selective changes in hippocampal histone acetylation during the aging process in rats.

    Science.gov (United States)

    de Meireles, Louisiana Carolina Ferreira; Bertoldi, Karine; Cechinel, Laura Reck; Schallenberger, Bruna Luisa; da Silva, Vanessa Kappel; Schröder, Nadja; Siqueira, Ionara Rodrigues

    2016-11-10

    Physical exercise and the aging process have been shown to induce opposite effects on epigenetic marks, such as histone acetylation. The impact of exercise on hippocampal histone acetylation on specific lysine residues, especially during the aging process, is rarely studied. The aim of this study was to investigate the effect of treadmill exercise (20min/day during 2 weeks) on H3K9, H4K5 and H4K12 acetylation levels in hippocampi of young adult and aged rats. Male Wistar rats aged 3 or 20-21 months were assigned to sedentary and exercise groups. Single-trial step-down inhibitory avoidance conditioning was employed as an aversive memory paradigm. Hippocampal H3K9, H4K5 and H4K12 acetylation was determined by Western blotting. The daily moderate exercise protocol improved the aversive memory performance and increased hipocampal H4K12 acetylation levels in both tested ages. Exercise was also able to increase H3K9 acetylation levels in aged rats. An age-related decline in memory performance was observed, without any effect of the aging process on histone acetylation state. Our data suggest that treadmill exercise can impact hippocampal the histone acetylation profile in an age- and lysine-dependent manner. In addition, higher hippocampal H4K12 acetylation levels at both ages may be related to improvement of aversive memory performance. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  14. 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.

  15. 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.

  16. 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...

  17. 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.

  18. Measurements of system sharpness for two digital breast tomosynthesis systems

    Science.gov (United States)

    Marshall, N. W.; Bosmans, H.

    2012-11-01

    The aim of this work was to propose system sharpness parameters for digital breast tomosynthesis (DBT) systems that include the influence of focus size and focus motion for use in quality assurance protocols. X-ray focus size was measured using a multiple pinhole test object, while detector presampling modulation transfer function (MTF) was measured from projection images of a 10 cm × 10 cm, 1 mm thick steel edge, for the Siemens Inspiration and Hologic Selenia Dimensions DBT systems. The height of the edge above the table was then varied from 1 to 78 mm. The MTF expected from theory for the projection images was calculated from the measured detector MTF, focus size MTF and focus motion MTF and was compared against measured curves. Two methods were used to measure the in-plane MTF in the DBT volume: a tungsten wire of diameter 25 µm and an Al edge 0.2 mm thick, both imaged with a 15 mm thick poly(methyl methacrylate) (PMMA) plate. The in-depth point spread function (PSF) was measured using an angled tungsten wire. The full 3D MTF was estimated with a 0.5 mm diameter aluminium bead held in a 45 mm thick PMMA phantom, with the bead 15 and 65 mm above the table. Inspiration DBT projection images are saved at native detector resolution (85 µm), while the Dimensions re-bins projections to 140 µm pixels (2 × 2 binning); both systems used 2 × 2 binning of projection data before reconstruction. The 50% point for the MTF (MTF0.50) measured in the DBT projection images for the tube-travel direction fell as a function of height above the table from 3.60 to 0.90 mm-1 for the Inspiration system and from 2.50 to 1.20 mm-1 for the Dimensions unit. The maximum deviation of measured MTF0.50 from the calculated value was 13%. MTF0.50 measured in-plane (tube-travel direction) fell as a function of height above the table from 1.66 to 0.97 mm-1 for the Inspiration system and from 2.21 to 1.31 mm-1 for the Dimensions system. The full-width half-maximum for the in-depth PSF was 3

  19. Chronic peripheral inflammation, hippocampal neurogenesis, and behavior.

    Science.gov (United States)

    Chesnokova, Vera; Pechnick, Robert N; Wawrowsky, Kolja

    2016-11-01

    Adult hippocampal neurogenesis is involved in memory and learning, and disrupted neurogenesis is implicated in cognitive impairment and mood disorders, including anxiety and depression. Some long-term peripheral illnesses and metabolic disorders, as well as normal aging, create a state of chronic peripheral inflammation. These conditions are associated with behavioral disturbances linked to disrupted adult hippocampal neurogenesis, such as cognitive impairment, deficits in learning and memory, and depression and anxiety. Pro-inflammatory cytokines released in the periphery are involved in peripheral immune system-to-brain communication by activating resident microglia in the brain. Activated microglia reduce neurogenesis by suppressing neuronal stem cell proliferation, increasing apoptosis of neuronal progenitor cells, and decreasing survival of newly developing neurons and their integration into existing neuronal circuits. In this review, we summarize evolving evidence that the state of chronic peripheral inflammation reduces adult hippocampal neurogenesis, which, in turn, produces the behavioral disturbances observed in chronic inflammatory disorders. As there are no data available on neurogenesis in humans with chronic peripheral inflammatory disease, we focus on animal models and, in parallel, consider the evidence of cognitive disturbance and mood disorders in human patients. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Taurine increases hippocampal neurogenesis in aging mice.

    Science.gov (United States)

    Gebara, Elias; Udry, Florian; Sultan, Sébastien; Toni, Nicolas

    2015-05-01

    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. Copyright © 2015. Published by Elsevier B.V.

  1. Tuberous sclerosis complex coexistent with hippocampal sclerosis.

    Science.gov (United States)

    Lang, Min; Prayson, Richard A

    2016-02-01

    Tuberous sclerosis and hippocampal sclerosis are both well-defined entities associated with medically intractable epilepsy. To our knowledge, there has been only one prior case of these two pathologies being co-existent. We report a 7-month-old boy who presented with intractable seizures at 2 months of age. MRI studies showed diffuse volume loss in the brain with bilateral, multiple cortical tubers and subcortical migration abnormalities. Subependymal nodules were noted without subependymal giant cell astrocytoma. Genetic testing revealed TSC2 and PRD gene deletions. Histopathology of the hippocampus showed CA1 sclerosis marked by loss of neurons in the CA1 region. Sections from the temporal, parietal and occipital lobes showed multiple cortical tubers characterized by cortical architectural disorganization, gliosis, calcifications and increased number of large balloon cells. Focal white matter balloon cells and spongiform changes were also present. The patient underwent resection of the right fronto-parietal lobe and a subsequent resection of the right temporal, parietal and occipital lobes. The patient is free of seizures on anti-epileptic medication 69 months after surgery. Although hippocampal sclerosis is well documented to be associated with coexistent focal cortical dysplasia, the specific co-existence of cortical tubers and hippocampal sclerosis appears to be rare. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Early detection of Alzheimer's disease using MRI hippocampal texture

    DEFF Research Database (Denmark)

    Sørensen, Lauge; Igel, Christian; Hansen, Naja Liv

    2016-01-01

    Cognitive impairment in patients with Alzheimer's disease (AD) is associated with reduction in hippocampal volume in magnetic resonance imaging (MRI). However, it is unknown whether hippocampal texture changes in persons with mild cognitive impairment (MCI) that does not have a change...... in hippocampal volume. We tested the hypothesis that hippocampal texture has association to early cognitive loss beyond that of volumetric changes. The texture marker was trained and evaluated using T1-weighted MRI scans from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database, and subsequently...

  3. Preschool is a sensitive period for the influence of maternal support on the trajectory of hippocampal development

    Science.gov (United States)

    Luby, Joan L.; Belden, Andy; Harms, Michael P.; Tillman, Rebecca; Barch, Deanna M.

    2016-01-01

    Building on well-established animal data demonstrating the effects of early maternal support on hippocampal development and adaptive coping, a few longitudinal studies suggest that early caregiver support also impacts human hippocampal development. How caregiving contributes to human hippocampal developmental trajectories, whether there are sensitive periods for these effects, as well as whether related variation in hippocampal development predicts later childhood emotion functioning are of major public health importance. The current study investigated these questions in a longitudinal study of preschoolers assessed annually for behavioral and emotional development, including observed caregiver support. One hundred and twenty-seven children participated in three waves of magnetic resonance brain imaging through school age and early adolescence. Multilevel modeling of the effects of preschool and school-age maternal support on hippocampal volumes across the three waves was conducted. Hippocampal volume increased faster for those with higher levels of preschool maternal support. Subjects with support 1 SD above the mean had a 2.06 times greater increase in total hippocampus volume across the three scans than those with 1 SD below the mean (2.70% vs. 1.31%). No effect of school-age support was found. Individual slopes of hippocampus volume were significantly associated with emotion regulation at scan 3. The findings demonstrate a significant effect of early childhood maternal support on hippocampal volume growth across school age and early adolescence and suggest an early childhood sensitive period for these effects. They also show that this growth trajectory is associated with later emotion functioning. PMID:27114522

  4. More vulnerability of left than right hippocampal damage in right-handed patients with post-traumatic stress disorder.

    Science.gov (United States)

    Shu, Xi-Ji; Xue, Li; Liu, Wei; Chen, Fu-Yin; Zhu, Cheng; Sun, Xiao-Hai; Wang, Xiao-Ping; Liu, Zhong-Cun; Zhao, Hu

    2013-06-30

    Previous studies have shown hippocampal abnormalities in people with post-traumatic stress disorder (PTSD), but findings of diminished volume in shortages in the hippocampus have been inconsistent. In this study, we investigated changes in hippocampal volume and neuronal metabolites in right-handed PTSD patients to determine their possible relationship(s) with PTSD severity. We performed a case-control study of 11 right-handed PTSD patients and 11 healthy controls using magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy ((1)H MRS). Hippocampal volume and metabolite ratios of N-acetylaspartate (NAA) to creatine (Cr) (NAA/Cr) and choline compounds (Cho) to Cr (Cho/Cr) were calculated. The severity of PTSD was evaluated by the Clinician-Administered PTSD Scale (CAPS). Significantly decreased left and total normalized hippocampal volumes were found in PTSD patients compared with controls (6.6% for the left hippocampus, 5.5% for total hippocampus). Also, the bilateral hippocampal NAA/Cr ratio of PTSD patients was significantly reduced compared with controls. The volume of the left hippocampus was negatively correlated to the CAPS total and CPAS-C scores. The left hippocampal NAA/Cr ratio was negatively correlated to the CAPS-total, CAPS-B, CAPS-C, and CAPS-D scores. The CAPS total and the CAPS-B scores were positively correlated to the Cho/Cr ratio of the right hippocampus. Our results indicate that hippocampal dysfunction is asymmetric in right-handed PTSD patients, with the left side affected more than the right. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  5. Impact of treadmill running and sex on hippocampal neurogenesis in the mouse model of amyotrophic lateral sclerosis.

    Directory of Open Access Journals (Sweden)

    Xiaoxing Ma

    Full Text Available Hippocampal neurogenesis in the subgranular zone (SGZ of dentate gyrus (DG occurs throughout life and is regulated by pathological and physiological processes. The role of oxidative stress in hippocampal neurogenesis and its response to exercise or neurodegenerative diseases remains controversial. The present study was designed to investigate the impact of oxidative stress, treadmill exercise and sex on hippocampal neurogenesis in a murine model of heightened oxidative stress (G93A mice. G93A and wild type (WT mice were randomized to a treadmill running (EX or a sedentary (SED group for 1 or 4 wk. Immunohistochemistry was used to detect bromodeoxyuridine (BrdU labeled proliferating cells, surviving cells, and their phenotype, as well as for determination of oxidative stress (3-NT; 8-OHdG. BDNF and IGF1 mRNA expression was assessed by in situ hybridization. Results showed that: (1 G93A-SED mice had greater hippocampal neurogenesis, BDNF mRNA, and 3-NT, as compared to WT-SED mice. (2 Treadmill running promoted hippocampal neurogenesis and BDNF mRNA content and lowered DNA oxidative damage (8-OHdG in WT mice. (3 Male G93A mice showed significantly higher cell proliferation but a lower level of survival vs. female G93A mice. We conclude that G93A mice show higher hippocampal neurogenesis, in association with higher BDNF expression, yet running did not further enhance these phenomena in G93A mice, probably due to a 'ceiling effect' of an already heightened basal levels of hippocampal neurogenesis and BDNF expression.

  6. 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.

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

    Science.gov (United States)

    Cengiz, Pelin; Kintner, Douglas B; Chanana, Vishal; Yuan, Hui; Akture, Erinc; Kendigelen, Pinar; Begum, Gulnaz; Fidan, Emin; Uluc, Kutluay; Ferrazzano, Peter; Sun, Dandan

    2014-01-01

    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.

  8. 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.

  9. Investigation of the hippocampal information processing in freely moving rats

    OpenAIRE

    Azahara Gonzalez Oliva

    2016-01-01

    Extracellular electrophysiological recordings of the hippocampus were carried out in freely moving Long-Evans rats. Large-scale and high-density electrodes were used to target all subregions simultaneously. We were able to record both local field potentials (LFPs) and single unit activity, which allowed for the analysis of population activity and individual cells, respectively. We recorded the animals while they performed spatial navigational tasks and during sleep in their home cages. We ...

  10. 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.

  11. 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

  12. Long-lasting effects of neonatal pentobarbital administration on spatial learning and hippocampal synaptic plasticity.

    Science.gov (United States)

    Tachibana, Kaori; Hashimoto, Toshikazu; Kato, Rui; Tsuruga, Kenkichi; Ito, Ryoko; Morimoto, Yuji

    2011-05-04

    Exposure of newborn rats to antiepileptics such as barbiturates has long-lasting detrimental effects on the hippocampus and hippocampus-dependent behavior. However, the long-term consequences of neonatal administration with barbiturates on the hippocampal synaptic plasticity remain unresolved. In this study, we investigated the long-lasting effects of a neonatal administration of pentobarbital on spatial memory, paired-pulse plasticity in the population spikes, and long-term potentiation (LTP) in the hippocampal CA1 region of rats in vivo. Eight weeks after administration of pentobarbital (10 or 20mg/kg) on the seventh postnatal day (P7), rats showed impaired induction in LTP. During paired-pulse stimulation, pentobarbital-treated rats exhibited a greater facilitation of the test pulse population spike, suggesting a disruption in the inhibitory GABAergic synaptic transmission. Spatial learning in hidden platform task of the Morris water maze was impaired in pentobarbital-treated rats. Our present findings indicate that neonatal treatment with pentobarbital causes alterations in function of the hippocampal inhibitory synaptic transmission that persist into adulthood, likely contributing to the long-lasting abnormalities in the hippocampal LTP as well as learning ability. We also demonstrated significant respiratory disturbances, i.e., severe hypoxia, hypercapnia, and extracellular acidosis, in rats treated with pentobarbital on P7. Given that extracellular acidosis can also modulate synaptic transmission in the developing hippocampus, this finding led us to speculate regarding the influence of respiratory disturbances in pentobarbital-induced long-lasting hippocampal dysfunctions. Copyright © 2011 Elsevier B.V. All rights reserved.

  13. Hippocampal subregion volume changes associated with antipsychotic treatment in first-episode psychosis.

    Science.gov (United States)

    Rhindress, K; Robinson, D G; Gallego, J A; Wellington, R; Malhotra, A K; Szeszko, P R

    2017-07-01

    Hippocampal dysfunction is considered central to many neurobiological models of schizophrenia, yet there are few longitudinal in vivo neuroimaging studies that have investigated the relationship between antipsychotic treatment and morphologic changes within specific hippocampal subregions among patients with psychosis. A total of 29 patients experiencing a first episode of psychosis with little or no prior antipsychotic exposure received structural neuroimaging examinations at illness onset and then following 12 weeks of treatment with either risperidone or aripiprazole in a double-blind randomized clinical trial. In addition, 29 healthy volunteers received structural neuroimaging examinations at baseline and 12-week time points. We manually delineated six hippocampal subregions [i.e. anterior cornu ammonis (CA) 1-3, posterior CA1-3, subiculum, dentate gyrus/CA4, entorhinal cortex, and fimbria] from 3T magnetic resonance images using an established method with high inter- and intra-rater reliability. Following antipsychotic treatment patients demonstrated significant reductions in dentate gyrus/CA4 volume and increases in subiculum volume. Healthy volunteers demonstrated non-significant volumetric changes in these subregions across the two time points. We observed a significant quadratic (i.e. inverted U) association between changes in dentate gyrus/CA4 volume and cumulative antipsychotic dosage between the scans. This study provides the first evidence to our knowledge regarding longitudinal in vivo volumetric changes within specific hippocampal subregions in patients with psychosis following antipsychotic treatment. The finding of a non-linear relationship between changes in dentate gyrus/CA4 subregion volume and antipsychotic exposure may provide new avenues into understanding dosing strategies for therapeutic interventions relevant to neurobiological models of hippocampal dysfunction in psychosis.

  14. 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

  15. 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...

  16. 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.

  17. 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.

  18. 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.

  19. Automatic calculation of hippocampal atrophy rates using a hippocampal template and the boundary shift integral.

    Science.gov (United States)

    Barnes, J; Boyes, R G; Lewis, E B; Schott, J M; Frost, C; Scahill, R I; Fox, N C

    2007-11-01

    We describe a method of automatically calculating hippocampal atrophy rates on T1-weighted MR images without manual delineation of hippocampi. This method was applied to a group of Alzheimer's disease (AD) (n=36) and control (n=19) subjects and compared with manual methods (manual segmentation of baseline and repeat-image hippocampi) and semi-automated methods (manual segmentation of baseline hippocampi only). In controls, mean (S.D.) atrophy rates for manual, semi-automated, and automated methods were 18.1 (53.5), 15.3 (50.2) and 11.3 (50.4) mm3 loss per year, respectively. In AD patients these rates were 174.6 (106.5) 159.4 (101.2) and 172.1 (123.1) mm3 loss per year, respectively. The automated method was a significant predictor of disease (p=0.001) and gave similar group discrimination compared with both semi-automated and manual methods. The automated hippocampal analysis in this small study took approximately 20 min per hippocampal pair on a 3.4 GHz Intel Xeon server, whereas manual delineation of each hippocampal pair took approximately 90 min of operator-intensive labour. This method may be useful diagnostically or in studies where analysis of many scans may be required.

  20. 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

  1. Localized gene transfer into organotypic hippocampal slice cultures and acute hippocampal slices

    DEFF Research Database (Denmark)

    Casaccia-Bonnefil, P; Benedikz, Eirikur; Shen, H

    1993-01-01

    Viral vectors derived from herpes simplex virus, type-1 (HSV), can transfer and express genes into fully differentiated, post-mitotic neurons. These vectors also transduce cells effectively in organotypic hippocampal slice cultures. Nanoliter quantities of a virus stock of HSVlac, an HSV vector...

  2. 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

  3. Turbulence characteristics in sharp open-channel bends

    NARCIS (Netherlands)

    Blanckaert, K.; De Vriend, H.J.

    2005-01-01

    In spite of its importance, little is known about the turbulence characteristics in open-channel bends. This paper reports on an experimental investigation of turbulence in one cross section of an open-channel bend. Typical flow features are a bicellular pattern of cross-stream circulation

  4. Regional hippocampal involvement and cognitive impairment in pediatric multiple sclerosis.

    Science.gov (United States)

    Rocca, Maria A; Morelli, Maria E; Amato, Maria P; Moiola, Lucia; Ghezzi, Angelo; Veggiotti, Pierangelo; Capra, Ruggero; Pagani, Elisabetta; Portaccio, Emilio; Fiorino, Agnese; Pippolo, Lorena; Pera, Maria C; Comi, Giancarlo; Falini, Andrea; Filippi, Massimo

    2016-04-01

    We assessed global and regional hippocampal volume abnormalities in pediatric multiple sclerosis (MS) patients and their correlations with clinical, neuropsychological and magnetic resonance imaging metrics. From 53 pediatric MS patients and 18 healthy controls, global hippocampal volume was computed using a manual tracing procedure. Regional hippocampal volume modifications were assessed using a radial mapping analysis. MS patients with abnormal performance in three or more tests of a neuropsychological battery for children were classified as cognitively impaired. Global hippocampal volume was reduced in MS patients compared with controls, but did not correlate with clinical, neuropsychological and magnetic resonance imaging measures. Compared to controls, MS patients experienced bilateral radial atrophy of the cornu ammonis, subiculum and dentate gyrus subfields as well as radial hypertrophy of the dentate gyrus subfield. Regional hippocampal volume modifications correlated with brain T2 lesion volume as well as attention and language abilities. Global hippocampal volume did not differ between cognitively impaired (n=12) and cognitively preserved MS patients. Compared to cognitively preserved, cognitively impaired MS patients had atrophy of the subiculum and dentate gyrus subfields of the right hippocampus. Hippocampal subregions have different vulnerability to damage in pediatric MS. Regional rather than global hippocampal involvement contributes to global cognitive impairment as well as to deficits of selected cognitive tests. © The Author(s), 2015.

  5. The Impact of Sleep Loss on Hippocampal Function

    Science.gov (United States)

    Prince, Toni-Moi; Abel, Ted

    2013-01-01

    Hippocampal cellular and molecular processes critical for memory consolidation are affected by the amount and quality of sleep attained. Questions remain with regard to how sleep enhances memory, what parameters of sleep after learning are optimal for memory consolidation, and what underlying hippocampal molecular players are targeted by sleep…

  6. Parameter Estimation of a Ground Moving Target Using Image Sharpness Optimization.

    Science.gov (United States)

    Yu, Jing; Li, Yaan

    2016-06-30

    Motion parameter estimation of a ground moving target is an important issue in synthetic aperture radar ground moving target indication (SAR-GMTI) which has significant applications for civilian and military. The SAR image of a moving target may be displaced and defocused due to the radial and along-track velocity components, respectively. The sharpness cost function presents a measure of the degree of focus of the image. In this work, a new ground moving target parameter estimation algorithm based on the sharpness optimization criterion is proposed. The relationships between the quadratic phase errors and the target's velocity components are derived. Using two-dimensional searching of the sharpness cost function, we can obtain the velocity components of the target and the focused target image simultaneously. The proposed moving target parameter estimation method and image sharpness metrics are analyzed in detail. Finally, numerical results illustrate the effective and superior velocity estimation performance of the proposed method when compared to existing algorithms.

  7. Needles and Other Sharps (Safe Disposal Outside of Health Care Settings)

    Science.gov (United States)

    ... sharps disposal container) in the household or public trash cans or recycling bins, and never flush them down the toilet. This puts trash and sewage workers, janitors, housekeepers, household members, and ...

  8. 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...

  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. 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. A longitudinal study of alterations of hippocampal volumes and serum BDNF levels in association to atypical antipsychotics in a sample of first-episode patients with schizophrenia.

    Directory of Open Access Journals (Sweden)

    Emmanouil Rizos

    Full Text Available BACKGROUND: Schizophrenia is associated with structural and functional abnormalities of the hippocampus, which have been suggested to play an important role in the formation and emergence of schizophrenia syndrome. Patients with schizophrenia exhibit significant bilateral hippocampal volume reduction and progressive hippocampal volume decrease in first-episode patients with schizophrenia has been shown in many neuroimaging studies. Dysfunction of the neurotrophic system has been implicated in the pathophysiology of schizophrenia. The initiation of antipsychotic medication alters the levels of serum Brain Derived Neurotrophic Factor (BDNF levels. However it is unclear whether treatment with antipsychotics is associated with alterations of hippocampal volume and BDNF levels. METHODS: In the present longitudinal study we investigated the association between serum BDNF levels and hippocampal volumes in a sample of fourteen first-episode drug-naïve patients with schizophrenia (FEP. MRI scans, BDNF and clinical measurements were performed twice: at baseline before the initiation of antipsychotic treatment and 8 months later, while the patients were receiving monotherapy with second generation antipsychotics (SGAs. RESULTS: We found that left hippocampal volume was decreased (corrected left HV [t = 2.977, df = 13, p = .011] at follow-up; We also found that the higher the BDNF levels change the higher were the differences of corrected left hippocampus after 8 months of treatment with atypical antipsychotics (Pearson r = 0.597, p = 0.024. CONCLUSIONS: The association of BDNF with hippocampal volume alterations in schizophrenia merits further investigation and replication in larger longitudinal studies.

  12. Neonatal hypoxia, hippocampal atrophy, and memory impairment: evidence of a causal sequence

    OpenAIRE

    Cooper, Janine M.; Gadian, David G.; Jentschke, Sebastian; Goldman, Allan; Muñoz, Monica; Pitts, Gerogia; Banks, Tina; Chong, W. Kling; Hoskote, Aparna; Deanfield, John; Baldeweg, Torsten; de Haan, Michelle; Mishkin, Mortimer; Vargha-Khadem, Faraneh

    2015-01-01

    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 neurol...

  13. Inverse problems and sharp eigenvalue asymptotics for Euler–Bernoulli operators

    International Nuclear Information System (INIS)

    Badanin, Andrey; Korotyaev, Evgeny

    2015-01-01

    We consider Euler–Bernoulli operators with real coefficients on the unit interval. We prove the following results: (i) The Ambarzumyan-type theorem about the inverse problems for the Euler–Bernoulli operator. (ii) The sharp asymptotics of eigenvalues for the Euler–Bernoulli operator when its coefficients converge to the constant function. (iii) The sharp eigenvalue asymptotics for both the Euler–Bernoulli operator and fourth-order operators (with complex coefficients) on the unit interval at high energy. (paper)

  14. Pengembangan Aplikasi E-commerce Dengan Konsep Berorientasi Objek Pada PT Sharp Cabang Semarang

    OpenAIRE

    Rahman, Arifian; Suhartono, Suhartono; Bahtiar, Nurdin

    2012-01-01

    PT Sharp Semarang branch is engage in the marketing of electronic items like air conditioners, refrigerators, televisions, and others. Business competition is increasingly fierce, especially in the electronics field requires the selection of advertising media that can market their goods quickly and easily. E-commerce as a new method that uses the Internet media is the right solution to market their goods easily and quickly. Application E-commerce Sharp Semarang developed using method of objec...

  15. Sharp-front wave of strong magnetic field diffusion in solid metal

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Bo; Gu, Zhuo-wei; Kan, Ming-xian; Wang, Gang-hua; Zhao, Jian-heng [Institute of Fluid Physics, CAEP, P.O. Box 919-105, Mianyang 621900 (China)

    2016-08-15

    When a strong magnetic field diffuses into a solid metal, if the metal's resistance possesses an abrupt rise at some critical temperature and the magnetic field strength is above some critical value, the magnetic field will diffuse into the metal in the form of a sharp-front wave. Formulas for the critical conditions under which a sharp-front magnetic diffusion wave emerges and a formula for the wave-front velocity are derived in this work.

  16. Triheteromeric NMDA Receptors at Hippocampal Synapses

    Science.gov (United States)

    Tovar, Kenneth R.; McGinley, Matthew J.; Westbrook, Gary L.

    2013-01-01

    NMDA receptors are composed of two GluN1 (N1) and two GluN2 (N2) subunits. Constituent N2 subunits control the pharmacological and kinetic characteristics of the receptor. NMDA receptors in hippocampal or cortical neurons are often thought of as diheteromeric, i.e., containing only one type of N2 subunit. However, triheteromeric receptors with more than one type of N2 subunit also have been reported and the relative contribution of di- and triheteromeric NMDA receptors at synapses has been difficult to assess. Because wild-type hippocampal principal neurons express N1, N2A and N2B, we used cultured hippocampal principal neurons from N2A and N2B-knockout mice as templates for diheteromeric synaptic receptors. Summation of N1/N2B and N1/N2A excitatory postsynaptic currents could not account for the deactivation kinetics of wild-type excitatory postsynaptic currents (EPSCs) however. To make a quantitative estimate of NMDA receptor subtypes at wild-type synapses, we used the deactivation kinetics, as well as the effects of the competitive antagonist NVP-AAM077. Our results indicate that three types of NMDA receptors contribute to the wild-type EPSC, with at least two-thirds being triheteromeric receptors. Functional isolation of synaptic triheteromeric receptors revealed deactivation kinetics and pharmacology distinct from either diheteromeric receptor subtype. Because of differences in open probability, synaptic triheteromeric receptors outnumbered N1/N2A receptors by 5.8 to 1 and N1/N2B receptors by 3.2 to 1. Our results suggest that triheteromeric NMDA receptors must be either preferentially assembled or preferentially localized at synapses. PMID:23699525

  17. Physical exercise induces hippocampal neurogenesis and prevents cognitive decline.

    Science.gov (United States)

    Ma, Chun-Lian; Ma, Xiao-Tang; Wang, Jin-Ju; Liu, Hua; Chen, Yan-Fang; Yang, Yi

    2017-01-15

    Accumulating evidence from animal and human research indicate that adult hippocampal neurogenesis plays a key role in cognition. Meanwhile, cognitive decline is well known to associate with ageing-related neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD). Therefore, prevention of hippocampal neurogenesis reduction should be critical for these diseases. Physical exercise, a potent enhancer of adult hippocampal neurogenesis, has emerged as a potential therapy or an adjunctive therapeutic strategy for cognitive decline. In this review, we discuss the recent findings on hippocampal neurogenesis and the incorporation of new born neurons into the neuronal network in humans and in rodents. By focusing on hippocampal neurogenesis, we illustrate the role and possible mechanisms of physical exercise in cognition preservation. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. 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

  19. [Effects of sleep deprivation in hippocampal neurogenesis].

    Science.gov (United States)

    López-Virgen, Verónica; Zárate-López, David; Adirsch, Fabián L; Collas-Aguilar, Jorge; González-Pérez, Óscar

    2015-01-01

    Adult neurogenesis in the dentate gyrus (DG) in the hippocampus is a process that involves proliferation, differentiation, maturation, migration, and integration of young neurons in the granular layer of DG. These newborn neurons mature in three to four weeks and incorporate into neural circuits in the hippocampus. There, these new neurons play a role in cognitive functions, such as acquisition and retention of memory, which are consolidated during sleep period. In this review, we describe recent findings that associate sleep deprivation with changes in hippocampal neurogenesis and cognitive processes. In addition, we describe possible mechanisms implicated in this deterioration such as circadian rhythm, melatonin receptors, and growth factors.

  20. 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.

  1. RBP-Jkappa/SHARP recruits CtIP/CtBP corepressors to silence Notch target genes.

    Science.gov (United States)

    Oswald, Franz; Winkler, Michael; Cao, Ying; Astrahantseff, Kathy; Bourteele, Soizic; Knöchel, Walter; Borggrefe, Tilman

    2005-12-01

    Notch is a transmembrane receptor that determines cell fates and pattern formation in all animal species. After ligand binding, proteolytic cleavage steps occur and the intracellular part of Notch translocates to the nucleus, where it targets the DNA-binding protein RBP-Jkappa/CBF1. In the absence of Notch, RBP-Jkappa represses Notch target genes through the recruitment of a corepressor complex. We and others have identified SHARP as a component of this complex. Here, we functionally demonstrate that the SHARP repression domain is necessary and sufficient to repress transcription and that the absence of this domain causes a dominant negative Notch-like phenotype. We identify the CtIP and CtBP corepressors as novel components of the human RBP-Jkappa/SHARP-corepressor complex and show that CtIP binds directly to the SHARP repression domain. Functionally, CtIP and CtBP augment SHARP-mediated repression. Transcriptional repression of the Notch target gene Hey1 is abolished in CtBP-deficient cells or after the functional knockout of CtBP. Furthermore, the endogenous Hey1 promoter is derepressed in CtBP-deficient cells. We propose that a corepressor complex containing CtIP/CtBP facilitates RBP-Jkappa/SHARP-mediated repression of Notch target genes.

  2. Do the ball-ended probe cause less damage than sharp explorers?-An ultrastructural analysis.

    Science.gov (United States)

    Mattos-Silveira, Juliana; Oliveira, Marina Monreal; Matos, Ronilza; Moura-Netto, Cacio; Mendes, Fausto Medeiros; Braga, Mariana Minatel

    2016-03-22

    No evidence about damage caused by ball-ended probes on tooth is available. No study compared probing defects caused by ball-ended probes with sharp explorers during tactile examinations of primary teeth. This exploratory study aimed to compare ultrastructural defects caused by ball-ended probes with sharp explorers during tactile examinations of primary teeth. Forty-nine primary extracted teeth were tactile examined as performed for caries activity assessment. Surfaces were randomly divided into groups based on probe type (ball-ended probe or sharp explorer). Two examiners probed different surfaces using the sharp explorer and the ball-ended probe. The order for examination was randomly determined. Images were captured using environmental scanning electron microscopy (ESEM) before and after probing. Two external examiners evaluated independently the ESEM images and scored them as: 0) no damage, 1) slight marks, 2) distinct marks, 3) marks with discontinuity, 4) enamel break-offs. Multilevel Poisson regression models were used to analyze associations between probing ultrastructural damage and surface type, baseline condition and probe type. Prevalence ratios (PR) were calculated with 95 % confidence interval (CI). The most common defects observed on the dental surfaces were probing marks without discontinuity (scores 1 and 2). Ball-ended probes caused significantly less severe damage than sharp explorers (PR: 0.28; CI: 0.11-0.76, p = 0.01). Ball-ended probes cause less damage than sharp explorers when probing gently dental surfaces of primary teeth.

  3. Persistent gliosis interferes with neurogenesis in organotypic hippocampal slice cultures

    Directory of Open Access Journals (Sweden)

    Johannes eGerlach

    2016-05-01

    Full Text Available Neurogenesis in the adult hippocampus has become an intensively investigated research topic, as it is essential for proper hippocampal function and considered to bear therapeutic potential for the replacement of pathologically lost neurons. On the other hand, neurogenesis itself is frequently affected by CNS insults. To identify processes leading to the disturbance of neurogenesis, we made use of organotypic hippocampal slice cultures (OHSC, which, for unknown reasons, lose their neurogenic potential during cultivation. In the present study, we show by BrdU/Prox1 double-immunostaining that the generation of new granule cells drops by 90% during the first week of cultivation. Monitoring neurogenesis dynamically in OHSC from POMC-eGFP mice, in which immature granule cells are endogenously labeled, revealed a gradual decay of the eGFP signal, reaching 10% of initial values within seven days of cultivation. Accordingly, RT-qPCR analysis showed the downregulation of the neurogenesis-related genes doublecortin and Hes5, a crucial target of the stem cell-maintaining Notch signaling pathway. In parallel, we demonstrate a strong and long-lasting activation of astrocytes and microglial cells, both, morphologically and on the level of gene expression. Enhancement of astroglial activation by treating OHSC with ciliary neurotrophic factor (CNTF accelerated the loss of neurogenesis, whereas treatment with indomethacin or an antagonist of the purinergic P2Y12 receptor exhibited potent protective effects on the neurogenic outcome. Therefore, we conclude that OHSC rapidly lose their neurogenic capacity due to persistent inflammatory processes taking place after the slice preparation. As inflammation is also considered to affect neurogenesis in many CNS pathologies, OHSC appear as a useful tool to study this interplay and its molecular basis. Furthermore, we propose that modification of glial activation might bear the therapeutic potential of enabling

  4. Semantic congruence affects hippocampal response to repetition of visual associations.

    Science.gov (United States)

    McAndrews, Mary Pat; Girard, Todd A; Wilkins, Leanne K; McCormick, Cornelia

    2016-09-01

    Recent research has shown complementary engagement of the hippocampus and medial prefrontal cortex (mPFC) in encoding and retrieving associations based on pre-existing or experimentally-induced schemas, such that the latter supports schema-congruent information whereas the former is more engaged for incongruent or novel associations. Here, we attempted to explore some of the boundary conditions in the relative involvement of those structures in short-term memory for visual associations. The current literature is based primarily on intentional evaluation of schema-target congruence and on study-test paradigms with relatively long delays between learning and retrieval. We used a continuous recognition paradigm to investigate hippocampal and mPFC activation to first and second presentations of scene-object pairs as a function of semantic congruence between the elements (e.g., beach-seashell versus schoolyard-lamp). All items were identical at first and second presentation and the context scene, which was presented 500ms prior to the appearance of the target object, was incidental to the task which required a recognition response to the central target only. Very short lags 2-8 intervening stimuli occurred between presentations. Encoding the targets with congruent contexts was associated with increased activation in visual cortical regions at initial presentation and faster response time at repetition, but we did not find enhanced activation in mPFC relative to incongruent stimuli at either presentation. We did observe enhanced activation in the right anterior hippocampus, as well as regions in visual and lateral temporal and frontal cortical regions, for the repetition of incongruent scene-object pairs. This pattern demonstrates rapid and incidental effects of schema processing in hippocampal, but not mPFC, engagement during continuous recognition. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Analysis of parahippocampal gyrus in 115 patients with hippocampal sclerosis

    Directory of Open Access Journals (Sweden)

    Ferreira Nelson Fortes

    2003-01-01

    Full Text Available PURPOSE: Analysis of the parahippocampal gyrus (PHG involvement in 115 patients with hippocampal sclerosis (HS by MR imaging. The simultaneous occurrence of ipsilateral fornix (F and mamillary body (MB volume loss was checked also. These findings were correlated with the side of hippocampal involvement, the sex, patient´s age, and the symptoms onset. METHOD: The MR images of 115 patients with HS were studied retrospectively. All the examinations were performed on 1.5 T units (SIGNA, GE, Milwaukee, WI and included high resolution coronal T2-weighted images (3 mm thickness, 0.6 mm gap. RESULTS: The patient's age ranged between 3.5 and 80 years (mean 34.1; 62 (53.9% were female and 53 (46.1% were male. There were HS on the left side in 53 (46.0%, on the right side in 51 (44.3%, and bilateral in 11 (9.7%. In 43 (37.3% cases there were ipsilateral PHG volume loss and signal hyper intensity on T2-weighted imaging. In 29 (25.2% cases there were ipsilateral fornix volume loss and in 10 (34.5% of this there were also ipsilateral MB changes. In abnormal PHG, 23 (53.4% were on the left side, 17 (39.5% were on the right side, and 3 (7.1% were bilateral. There were fornix changes in 15 (34.8% cases and MB volume loss in 5 (11.6% cases. Pertinent clinical data were obtained in only 18 (41.8% of the PHG lesion cases and 11 (61.1% of these patients had epileptic attacks for more than 20 years before the examination. CONCLUSION: PHG involvement must be investigated in patients with HS and we suggest that the term mesial temporal sclerosis should be used only if there are also changes at this anatomical site.

  6. 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...

  7. 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…

  8. Transcriptome differentiation along the dorso-ventral axis in laser-captured microdissected rat hippocampal granular cell layer

    DEFF Research Database (Denmark)

    Christensen, T.; Bisgaard, C.F.; Nielsen, Henrik Bjørn

    2010-01-01

    -related behaviors. Based on such findings our aim was to investigate the molecular differentiation along the dorso-ventral axis of the hippocampal granular cell layer of the rat dentate gyrus. Homogeneous isolation of this specific area was performed by laser-capture microdissection and Illumina microarray chips...

  9. Hippocampal cell proliferation across the day : Increase by running wheel activity, but no effect of sleep and wakefulness

    NARCIS (Netherlands)

    van der Borght, K; Ferrari, F; Klauke, K; Roman, Viktor; Havekes, R; Sgoifo, A; van der Zee, EA; Meerlo, P

    2006-01-01

    The present study investigated whether proliferation of hippocampal progenitors is subject to circadian modulation. Mice were perfused using 3 h intervals throughout the light-dark cycle and brains were stained for Ki-67. Since Ki-67 is not expressed during the G0 phase of the cell cycle, we

  10. 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…

  11. Role of caspase-12 in amyloid beta-peptide-induced toxicity in organotypic hippocampal slices cultured for long periods.

    NARCIS (Netherlands)

    Ishige, K.; Takagi, N.; Imai, T.; Rausch, W.D.; Kosuge, Y.; Kihara, T.; Kusama-Eguchi, K.; Ikeda, H.; Cools, A.R.; Waddington, J.L.; Koshikawa, N.; Ito, Y.

    2007-01-01

    Amyloid beta (Abeta) toxicity has been implicated in cell death in the hippocampus, but its specific mechanisms are poorly understood. In this study, Abeta-induced cell death was investigated in organotypic hippocampal slice cultures (OHCs) that were cultured for various periods in vitro. There were

  12. 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.

  13. The hydraulic mechanism in the hind wing veins of Cybister japonicus Sharp (order: Coleoptera).

    Science.gov (United States)

    Sun, Jiyu; Wu, Wei; Ling, Mingze; Bhushan, Bharat; Tong, Jin

    2016-01-01

    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.

  14. Can Molecular Hippocampal Alterations Explain Behavioral ...

    Science.gov (United States)

    Studies in both humans and animals have shown that prenatal stress can alter cognitive function and other neurological behaviors in adult offspring. One possible underlying mechanism for this may lie with alterations in hippocampal gene expression. The present study examined genotypical outcomes in adult male and female offspring of rats exposed to variable stress during pregnancy. Dams (n=15/treatment) were subjected to several non-chemical stressors including intermittent noise, light, crowding, restraint, and altered circadian lighting, from gestational day (GD) 13 to 20. Tail blood was drawn on GD 12, 16 and 20 to verify a stress response. Corticosterone levels were not different between the stressed and non-stressed dams on GD12 but was significantly increased in stressed dams on GD 16 and 20 compared to controls. Dams gave birth on GD22 (postnatal day or PND 0). Several behavioral tests were used to assess the cognitive and behavioral phenotype of the offspring from PND 49 through 86, including the Morris water maze and novel object recognition. Male and female stressed offspring showed reduced reversal learning on the Morris water maze and stressed females did not show a significant preference for the novel object (57 ± 8%) while control females did (71 ± 3%). This indicates altered cognition in prenatally stressed offspring. On PND 91-92, offspring were necropsied and hippocampal tissue was collected. Genotypic outcomes of prenatal stress w

  15. AFM study of hippocampal cells cultured on silicon wafers with nano-scale surface topograph.

    Science.gov (United States)

    Ma, J; Liu, B F; Xu, Q Y; Cui, F Z

    2005-08-01

    The rat hippocampal cells were selected as model to study the interaction between the neural cells and silicon substrates using atomic force microscopy (AFM). The hippocampal cells show tight adherence on silicon wafers with nano-scale surface topograph. The lateral friction force investigated by AFM shows significant increase on the boundary around the cellular body. It is considered to relate to the cytoskeleton and cellular secretions. After ultrasonic wash in ethanol and acetone step by step, the surface of silicon wafers was observed by AFM sequentially. We have found that the culture leftovers form tight porous networks and a monolayer on the silicon wafers. It is concluded that the leftovers overspreading on the silicon substrates are the base of cell adherence on such smooth inert surfaces.

  16. 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.

  17. Electrophysiology and biochemical analysis of cyclocreatine uptake and effect in hippocampal slices.

    Science.gov (United States)

    Enrico, Adriano; Patrizia, Garbati; Luisa, Perasso; Alessandro, Parodi; Gianluigi, Lunardi; Carlo, Gandolfo; Maurizio, Balestrino

    2013-06-01

    In in vitro mouse hippocampal slices we investigated whether cyclocreatine is capable of entering brain cells independently of the creatine transporter and if it reproduces the neuroprotective effect of creatine. Our study shows that cyclocreatine does not increase the creatine content, but is taken up as such and then phosphorylated to phosphocyclocreatine. This uptake is largely blocked by inactivation of the creatine transporter, however some cyclocreatine is taken up and posphorylated even after such inactivation. Thus, cyclocreatine sets up a cyclocreatine/phosphocyclocreatine system in the brain independently of the creatine transporter. Cyclocreatine did not delay the disappearance of the evoked synaptic potentials during anoxia in hippocampal slices, unlike creatine which exerts a neuroprotective effect.

  18. Falcarindiol inhibits nitric oxide-mediated neuronal death in lipopolysaccharide-treated organotypic hippocampal cultures.

    Science.gov (United States)

    Kim, Jeong Min; Lee, Pyeongjae; Son, Dongwook; Kim, Hocheol; Kim, Sun Yeou

    2003-10-27

    Excessive nitric oxide (NO) release from activated microglia has a predominant role in neuronal death. This study investigated the effect of falcarindiol, which was isolated from Cnidium officinale Makino, on the NO-mediated neuronal death in lipopolysaccharide (LPS)-treated organotypic hippocampal cultures. Falcarindiol dose-dependently reduced inducible NO synthase (iNOS)-mediated NO production without cytotoxic effects on LPS-activated BV-2 and microglia. Predictably, falcarindiol inhibited neuronal death by reducing NO production in the LPS-treated organotypic hippocampal cultures. N-monomethyl-L-arginine (NMMA), an iNOS inhibitor, also inhibited neuronal death at 500 microM. In contrast, massive neuronal death was induced by excessive NO production in the LPS-treated alone cultures. These results suggest that excessive NO production plays an important role in the neurotoxic effect, and falcarindiol is a potential inhibitor in NO-mediated neuronal death.

  19. The role of Bicoid cooperative binding in the patterning of sharp borders in Drosophila melanogaster.

    Science.gov (United States)

    Lopes, Francisco J P; Spirov, Alexander V; Bisch, Paulo M

    2012-10-15

    In Drosophila embryonic development, the Bicoid (Bcd) protein establishes positional information of downstream developmental genes like hunchback (hb), which has a strong anterior expression and a sharp on-off boundary in the mid-embryo. The role of Bcd cooperative binding in the positioning of the Hb pattern has been previously demonstrated. However, there are discrepancies in the reported results about the role of this mechanism in the sharp Hb border. Here, we determined the Hill coefficient (nH) required for Bcd to generate the sharp border of Hb in wild-type (WT) embryos. We found that an n(H) of approximately 6.3 (s.d. 1.4) and 10.8 (s.d. 4.0) is required to account for Hb sharpness at early and late cycle 14A, respectively. Additional mechanisms are possibly required because the high nH is likely unachievable for Bcd binding to the hb promoter. To test this idea, we determined the nH required to pattern the Hb profile of 15 embryos expressing an hb14F allele that is defective in self-activation and found nH to be 3.0 (s.d. 1.0). This result indicates that in WT embryos, the hb self-activation is important for Hb sharpness. Corroborating our results, we also found a progressive increase in the required value of n(H) spanning from 4.0 to 9.2 by determining this coefficient from averaged profiles of eight temporal classes at cycle 14A (T1 to T8). Our results indicate that there is a transition in the mechanisms responsible for the sharp Hb border during cycle 14A: in early stages of this cycle, Bcd cooperative binding is primarily responsible for Hb sharpness; in late cycle 14A, hb self-activation becomes the dominant mechanism. Copyright © 2012 Elsevier Inc. All rights reserved.

  20. Hippocampal brain-derived neurotrophic factor mediates recovery from chronic stress-induced spatial reference memory deficits.

    Science.gov (United States)

    Ortiz, J Bryce; Mathewson, Coy M; Hoffman, Ann N; Hanavan, Paul D; Terwilliger, Ernest F; Conrad, Cheryl D

    2014-11-01

    Chronic restraint stress impairs hippocampal-mediated spatial learning and memory, which improves following a post-stress recovery period. Here, we investigated whether brain-derived neurotrophic factor (BDNF), a protein important for hippocampal function, would alter the recovery from chronic stress-induced spatial memory deficits. Adult male Sprague-Dawley rats were infused into the dorsal hippocampal cornu ammonis (CA)3 region with an adeno-associated viral vector containing the sequence for a short hairpin RNA (shRNA) directed against BDNF or a scrambled sequence (Scr). Rats were then chronically restrained (wire mesh, 6 h/day for 21 days) and assessed for spatial learning and memory using a radial arm water maze (RAWM) either immediately after stressor cessation (Str-Imm) or following a 21-day post-stress recovery period (Str-Rec). All groups learned the RAWM task similarly, but differed on the memory retention trials. Rats in the Str-Imm group, regardless of adeno-associated viral contents, committed more errors in the spatial reference memory domain on the single retention trial during day 3 than did the non-stressed controls. Importantly, the typical improvement in spatial memory following the recovery from chronic stress was blocked with the shRNA against BDNF, as Str-Rec-shRNA performed worse on the RAWM compared with the non-stressed controls or Str-Rec-Scr. The stress effects were specific for the reference memory domain, but knockdown of hippocampal BDNF in unstressed controls briefly disrupted spatial working memory as measured by repeated entry errors on day 2 of training. These results demonstrated that hippocampal BDNF was necessary for the recovery from stress-induced hippocampal-dependent spatial memory deficits in the reference memory domain. © 2014 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  1. NEUROPATHIC PAIN-INDUCED DEPRESSIVE-LIKE BEHAVIOR AND HIPPOCAMPAL NEUROGENESIS AND PLASTICITY ARE DEPENDENT ON TNFR1 SIGNALING

    Science.gov (United States)

    Anna, Dellarole; Paul, Morton; Roberta, Brambilla; Winston, Walters; Spencer, Summer; Danielle, Bernardes; Mariagrazia, Grilli; R, Bethea John

    2014-01-01

    Patients suffering from neuropathic pain have a higher incidence of mood disorders such as depression. Increased expression of tumor necrosis factor (TNF) has been reported in neuropathic pain and depressive-like conditions and most of the pro-inflammatory effects of TNF are mediated by the TNF receptor 1 (TNFR1). Here we sought to investigate: 1) the occurrence of depressive-like behavior in chronic neuropathic pain and the associated forms of hippocampal plasticity, and 2) the involvement of TNFR1-mediated TNF signaling as a possible regulator of such events. Neuropathic pain was induced by chronic constriction injury of the sciatic nerve in wild-type and TNFR1−/− mice. Anhedonia, weight loss and physical state were measured as symptoms of depression. Hippocampal neurogenesis, neuroplasticity, myelin remodeling and TNF/TNFRs expression were analyzed by immunohistochemical analysis and western blot assay. We found that neuropathic pain resulted in the development of depressive symptoms in a time dependent manner and was associated with profound hippocampal alterations such as impaired neurogenesis, reduced expression of neuroplasticity markers and myelin proteins. The onset of depressive-like behavior also coincided with increased hippocampal levels of TNF, and decreased expression of TNF receptor 2 (TNFR2), which were all fully restored after mice spontaneously recovered from pain. Notably, TNFR1−/− mice did not develop depressive-like symptoms after injury, nor were there changes in hippocampal neurogenesis and plasticity. Our data show that neuropathic pain induces a cluster of depressive-like symptoms and profound hippocampal plasticity that are dependent on TNF signaling through TNFR1. PMID:24938671

  2. Prolonged cannabinoid exposure alters GABAA receptor mediated synaptic function in cultured hippocampal neurons

    Science.gov (United States)

    Deshpande, Laxmikant S.; Blair, Robert. E.; DeLorenzo, Robert. J.

    2011-01-01

    Developing cannabinoid based medication along with marijuana’s recreational use makes it important to investigate molecular adaptations the endocannabinoid system undergoes following prolonged use and withdrawal. Repeated cannabinoid administration results in development of tolerance and produces withdrawal symptoms that may include seizures. Here we employed electrophysiological and immunochemical techniques to investigate the effects of prolonged CB1 receptor agonist exposure on cultured hippocampal neurons. Approximately 60% of CB1 receptors colocalize to GABAergic terminals in hippocampal cultures. Prolonged treatment with the cannabinamimetic WIN 55,212-2 (+WIN, 1μM, 24-h) caused profound CB1 receptor downregulation accompanied by neuronal hyperexcitability. Furthermore, prolonged +WIN treatment resulted in increased GABA release as indicated by increased mIPSC frequency, a diminished GABAergic inhibition as indicated by reduction in mIPSC amplitude and a reduction in GABAA channel number. Additionally, surface staining for the GABAA β2/3 receptor subunits was decreased, while no changes in staining for the presynaptic vesicular GABA transporter were observed, indicating that GABAergic terminals remained intact. These findings demonstrate that agonist-induced downregulation of the CB1 receptor in hippocampal cultures results in neuronal hyperexcitability that may be attributed, in part, to alterations in both presynaptic GABA release mechanisms and postsynaptic GABAA receptor function demonstrating a novel role for cannabinoid-dependent presynaptic control of neuronal transmission. PMID:21324315

  3. 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.

  4. 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

  5. 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

  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. 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.

  8. Analysis of regulatory mechanisms of an insulin-inducible SHARP-2 gene by (S)-Equol.

    Science.gov (United States)

    Haneishi, Ayumi; Takagi, Katsuhiro; Asano, Kosuke; Yamamoto, Taichi; Tanaka, Takashi; Nakamura, Soichiro; Noguchi, Tamio; Yamada, Kazuya

    2012-09-01

    Small compounds that activate the insulin-dependent signaling pathway have potential therapeutic applications in controlling type 2 diabetes mellitus. The rat enhancer of split- and hairy-related protein-2 (SHARP-2) is an insulin-inducible transcription factor that decreases expression of the phosphoenolpyruvate carboxykinase gene, a gluconeogenic enzyme gene. In this study, we screened for soybean isoflavones that can induce the rat SHARP-2 gene expression and analyzed their mechanism(s). Genistein and (S)-Equol, a metabolite of daidzein, induced rat SHARP-2 gene expression in H4IIE rat hepatoma cells. The (S)-Equol induction was mediated by both the phosphoinositide 3-kinase- and protein kinase C (PKC)-pathways. When a dominant negative form of atypical PKC lambda (aPKCλ) was expressed, the induction of SHARP-2 mRNA level by (S)-Equol was inhibited. In addition, Western blot analyses showed that (S)-Equol rapidly activated both aPKCλ and classical PKC alpha. Furthermore, the (S)-Equol induction was inhibited by treatment with a RNA polymerase inhibitor or a protein synthesis inhibitor. Finally, a reporter gene assay revealed that the transcriptional stimulation by (S)-Equol was mediated by nucleotide sequences located between -4687 and -4133 of the rat SHARP-2 gene. Thus, we conclude that (S)-Equol is an useful dietary supplement to control type 2 diabetes mellitus. Copyright © 2012 Elsevier Inc. All rights reserved.

  9. SHARP: The SHARC-II polarimeter at the Caltech Submillimeter Observatory

    Science.gov (United States)

    Vaillancourt, John E.; Attard, M.; Dowell, C. D.; Hildebrand, R. H.; Houde, M.; Kirby, L.; Krejny, M.; Li, H.; Novak, G.; Shinnaga, H.

    2006-12-01

    The Submillimeter High Angular Resolution Camera II (SHARC-II) is a 12 × 32 pixel camera used with the 10 meter diameter Caltech Submillimeter Observatory (CSO). We have deployed an optics module between the telescope and camera which converts SHARC-II into a sensitive imaging polarimeter, "SHARP." The camera and polarimeter currently operate at wavelengths of 350 and 450 μm we are planning an additional passband at 620 μm. The incident beam is split into two orthogonally polarized components by the SHARP optics module and re-imaged onto opposite ends of the SHARC-II array. The result is a dual-beam 12 × 12 pixel polarimeter. The modular nature of the optics design allows the user to easily switch between polarimeter and camera modes during a single observing session. Here we review the optical design of SHARP, report on the instrument's performance, and review our data reduction methodology. SHARP will be used to study the magnetic field structure and dust emission properties in young stellar objects, Galactic clouds, and external galaxies. We present the first polarimetric maps of celestial sources made from SHARP observations and compare them to previous results. This work has been supported by NSF grants AST 02-41356 and 05-05230 to Northwestern University and 05-05124 to the University of Chicago.

  10. 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.

  11. Hippocampal-thalamic wiring in medial temporal lobe epilepsy: Enhanced connectivity per hippocampal voxel.

    Science.gov (United States)

    Dinkelacker, Vera; Valabregue, Romain; Thivard, Lionel; Lehéricy, Stéphane; Baulac, Michel; Samson, Séverine; Dupont, Sophie

    2015-08-01

    Medial temporal lobe epilepsy (TLE) with hippocampal sclerosis is often accompanied by widespread changes in ipsilateral and contralateral white matter connectivity. Recent studies have proposed that patients may show pathologically enhanced wiring of the limbic circuits. To better address this issue, we specifically probed connection patterns between hippocampus and thalamus and examined their impact on cognitive function. A group of 44 patients with TLE (22 with right and 22 with left hippocampal sclerosis) and 24 healthy control participants were examined with high-resolution T1 imaging, memory functional magnetic resonance imaging (fMRI) and probabilistic diffusion tractography. Thirty-four patients had further extensive neuropsychological testing. After whole brain segmentation with FreeSurfer, tractography streamline samples were drawn with hippocampus as the seed and thalamus as the target region. Two tractography strategies were applied: The first targeted the anatomic thalamic volume segmented in FreeSurfer and the second a functional region of interest in the mediodorsal thalamus derived from the activation during delayed recognition memory. We found a pronounced enhancement of connectivity between the sclerotic hippocampus and the ipsilateral thalamus both in the right and left TLE as compared to healthy control participants. This finding held for both the anatomically and the functionally defined thalamic target. Although differences were apparent in the number of absolute fibers, they were most pronounced when correcting for hippocampal volume. In terms of cognitive function, the number of hippocampal-thalamic connections was negatively correlated with performance in a variety of executive tasks, notably in the Trail Making Test, thus suggesting that the pathologic wiring did not compensate cognitive curtailing. We suggest that TLE is accompanied by an abnormal and dysfunctional enhancement of connectivity between the hippocampus and the thalamus

  12. Smaller neuron size in schizophrenia in hippocampal subfields that mediate cortical-hippocampal interactions.

    Science.gov (United States)

    Arnold, S E; Franz, B R; Gur, R C; Gur, R E; Shapiro, R M; Moberg, P J; Trojanowski, J Q

    1995-05-01

    The goal of this study was to characterize the hippocampal formation in patients with schizophrenia by measuring neuron density, neuron size, and variability of neuronal axis orientation. Brain tissue was obtained at autopsy from 14 prospectively accrued elderly patients with chronic schizophrenia and 10 age-compatible individuals without psychiatric disorder. Eight hippocampal regions of interest and two internal control regions (primary motor and visual cortices) were identified on Nissl-stained sections. Morphometric measurements were made without knowledge of diagnosis by means of a computer-based image analysis system. The patients exhibited smaller neuron size in the hippocampal regions relative to the control regions, which was significant only for the subiculum, CA1, and layer II of the entorhinal cortex. Neuron size in the control regions was nearly identical in the two groups. No significant differences in neuron density or in variability of neuronal axis orientation were identified for any region. There was no correlation between neuron size in any area and several potentially confounding variables (age, post-mortem interval, neuroleptic exposure, sex, brain hemisphere studied, duration of illness), with the exception of a negative correlation with age in layer II of the entorhinal cortex. Regression analyses indicated that the findings could not be attributed to these age effects. The subiculum, entorhinal cortex, and CA1 are the major subfields of the hippocampal region that maintain the afferent and efferent connections of the hippocampus with widespread cortical and subcortical targets. The smaller size of neurons in these subfields may reflect the presence of structural or functional impairments that disrupt these connections, which in turn could have important behavioral sequelae.

  13. 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

  14. Phosphate Stability in Diagenetic Fluids Constrains the Acidic Alteration Model for Lower Mt. Sharp Sedimentary Rocks in Gale Crater, Mars

    Science.gov (United States)

    Berger, J. A.; Schmidt, M. E.; Izawa, M. R. M.; Gellert, R.; Ming, D. W.; Rampe, E. B.; VanBommel, S. J.; McAdam, A. C.

    2016-01-01

    The Mars rover Curiosity has encountered silica-enriched bedrock (as strata and as veins and associated halos of alteration) in the largely basaltic Murray Fm. of Mt. Sharp in Gale Crater. Alpha Particle X-ray Spectrometer (APXS) investigations of the Murray Fm. revealed decreasing Mg, Ca, Mn, Fe, and Al, and higher S, as silica increased (Fig. 1). A positive correlation between SiO2 and TiO2 (up to 74.4 and 1.7 wt %, respectively) suggests that these two insoluble elements were retained while acidic fluids leached more soluble elements. Other evidence also supports a silica-retaining, acidic alteration model for the Murray Fm., including low trace element abundances consistent with leaching, and the presence of opaline silica and jarosite determined by CheMin. Phosphate stability is a key component of this model because PO4 3- is typically soluble in acidic water and is likely a mobile ion in diagenetic fluids (pH less than 5). However, the Murray rocks are not leached of P; they have variable P2O5 (Fig. 1) ranging from average Mars (0.9 wt%) up to the highest values in Gale Crater (2.5 wt%). Here we evaluate APXS measurements of Murray Fm. bedrock and veins with respect to phosphate stability in acidic fluids as a test of the acidic alteration model for the Lower Mt. Sharp rocks.

  15. Conjugate observation of sharp dynamical boundary in the inner magnetosphere by Cluster and DMSP spacecraft and ground network

    Directory of Open Access Journals (Sweden)

    S. V. Apatenkov

    2008-09-01

    Full Text Available We investigate an unusual sharp boundary separating two plasma populations (inner magnetospheric plasma with high fluxes of energetic particles and plasma sheet observed by the Cluster quartet near its perigee on 16 December 2003. Cluster was in a pearl-on-string configuration at 05:00 MLT and mapped along magnetic field lines to ~8–9 RE in the equatorial plane. It was conjugate to the MIRACLE network and the DMSP F16 spacecraft passed close to Cluster footpoint. The properties of the sharp boundary, repeatedly crossed 7 times by five spacecraft during ~10 min, are: (1 upward FAC sheet at the boundary with ~30 nA/m2 current density at Cluster and ~2000 nA/m2 at DMSP; (2 the boundary had an embedded layered structure with different thickness scales, the electron population transition was at ~20 km scale at Cluster (<7 km at DMSP, proton population had a scale ~100 km, while the FAC sheet thickness was estimated to be ~500 km at Cluster (~100 km at DMSP; (3 the boundary propagated in the earthward-eastward direction at ~8 km/s in situ (equatorward-eastward ~0.8 km/s in ionosphere, and then decelerated and/or stopped. We discuss the boundary formation by the collision of two different plasmas which may include dynamical three-dimensional field-aligned current loops.

  16. A No-Reference Sharpness Metric Based on Structured Ringing for JPEG2000 Images

    Directory of Open Access Journals (Sweden)

    Zhipeng Cao

    2014-01-01

    Full Text Available This work presents a no-reference image sharpness metric based on human blur perception for JPEG2000 compressed image. The metric mainly uses a ringing measure. And a blurring measure is used for compensation when the blur is so severe that ringing artifacts are concealed. We used the anisotropic diffusion for the preliminary ringing map and refined it by considering the property of ringing structure. The ringing detection of the proposed metric does not depend on edge detection, which is suitable for high degraded images. The characteristics of the ringing and blurring measures are analyzed and validated theoretically and experimentally. The performance of the proposed metric is tested and compared with that of some existing JPEG2000 sharpness metrics on three widely used databases. The experimental results show that the proposed metric is accurate and reliable in predicting the sharpness of JPEG2000 images.

  17. 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.

  18. 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.

  19. Gene-environment effects on hippocampal neurodevelopment

    DEFF Research Database (Denmark)

    Rosenthal, Eva Helga

    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...... disrupt the normal function of neurodevelopmental genes. Here, the transcriptional repressor Zbtb20, which we and others have shown is a master regulator of hippocampal neurodevelopment, deserves special interest. We study the possibility that environmental factors such as steroid hormones, cytokines......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...

  20. 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.

  1. 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.

  2. Centella asiatica Attenuates Diabetes Induced Hippocampal Changes in Experimental Diabetic Rats

    Science.gov (United States)

    Srinivasarao, Nelli; Swapna Rekha, Somesula; Muniandy, Sekaran

    2014-01-01

    Diabetes mellitus has been reported to affect functions of the hippocampus. We hypothesized that Centella asiatica, a herb traditionally being used to improve memory, prevents diabetes-related hippocampal dysfunction. Therefore, the aim of this study was to investigate the protective role of C. asiatica on the hippocampus in diabetes. Methods. Streptozotocin- (STZ-) induced adult male diabetic rats received 100 and 200 mg/kg/day body weight (b.w) C. asiatica leaf aqueous extract for four consecutive weeks. Following sacrifice, hippocampus was removed and hippocampal tissue homogenates were analyzed for Na+/K+-, Ca2+- and Mg2+-ATPases activity levels. Levels of the markers of inflammation (tumor necrosis factor, TNF-α; interleukin, IL-6; and interleukin, IL-1β) and oxidative stress (lipid peroxidation product: LPO, superoxide dismutase: SOD, catalase: CAT, and glutathione peroxidase: GPx) were determined. The hippocampal sections were visualized for histopathological changes. Results. Administration of C. asiatica leaf aqueous extract to diabetic rats maintained near normal ATPases activity levels and prevents the increase in the levels of inflammatory and oxidative stress markers in the hippocampus. Lesser signs of histopathological changes were observed in the hippocampus of C. asiatica leaf aqueous extract treated diabetic rats. Conclusions. C. asiatica leaf protects the hippocampus against diabetes-induced dysfunction which could help to preserve memory in this condition. PMID:25161691

  3. 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.

  4. Anti-inflammatory effects of Ginkgo biloba extract against trimethyltin-induced hippocampal neuronal injury.

    Science.gov (United States)

    Kaur, Sukhwinder; Sharma, Neha; Nehru, Bimla

    2018-02-01

    Despite the immense neuromodulatory potentials of Ginkgo biloba extract as a memory enhancer, its underlying mechanism seems inadequate particularly with regard to its anti-inflammatory properties. The objective of the present study is to investigate the protective potentials of Ginkgo biloba extract (GBE) against hippocampal neuronal injury induced by trimethyltin (TMT), a potent neurotoxicant. Male SD rats were administered trimethyltin (8.5 mg kg -1 b.wt) single intraperitoneal (i.p.) injection, followed by Ginkgo biloba extract (100 mg kg -1 b.wt i.p) for 21 days. The co-administration of GBE with TMT showed marked improvement in cognitive functions. Concomitantly, there was a significant decrease in oxidative stress as evident by reduction in MDA and total ROS levels. In addition, there was a marked suppression of astrocyte activation (GFAP), transcription factor NFκB and proinflammatory cytokines (TNF-α, IL-1α, 1L-6), which were found to be elevated by TMT administration. Histopathological observations showed remarkable improvement in hippocampal neuronal injury in the conjunctive group. Therefore, it is suggested that Ginkgo biloba extract is an effective agent against trimethyltin-induced hippocampal neuronal loss owing to its antioxidative as well as anti-inflammatory properties.

  5. Astaxanthin supplementation enhances adult hippocampal neurogenesis and spatial memory in mice.

    Science.gov (United States)

    Yook, Jang Soo; Okamoto, Masahiro; Rakwal, Randeep; Shibato, Junko; Lee, Min Chul; Matsui, Takashi; Chang, Hyukki; Cho, Joon Yong; Soya, Hideaki

    2016-03-01

    There is a growing necessity for efficacious natural supplements with antioxidant effects on the brain, in particular, hippocampal function. One such compound, which also has a neuroprotective effect, is the carotenoid astaxanthin (ASX). Despite ASX's potential benefit to the brain, very little is known about its effect on hippocampal plasticity and cognition. Thus, we investigated the effect of ASX on adult hippocampal neurogenesis (AHN) and spatial memory using a mouse model. Dose-response was examined in mice fed ASX-supplemented diets (0, 0.02, 0.1, and 0.5%) to define the effect of ASX on AHN. In conjunction with AHN results, hippocampus-dependent cognitive function was assessed. We delineated molecular mechanisms associated with ASX-enhanced AHN using DNA microarray analysis. Results revealed that ASX enhanced cell proliferation and survival at 0.1% and 0.5% doses. Newborn mature neurons were higher only with 0.5% ASX, which also enhanced spatial memory. Transcriptomic profiling revealed potential AHN-associated molecules (Prl, Itga4, and Il4) that were ASX induced. Their downstream factors, identified through Ingenuity Pathway Analysis, were positively correlated with ASX-induced increases in spatial memory. ASX supplementation enhanced AHN and spatial memory, and a DNA microarray approach provided, for the first time, novel molecular insights into ASX action. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. The Effect of Vitamin D Treatment On Nerve Growth Factor (NGF) Release From Hippocampal Neurons.

    Science.gov (United States)

    Gezen-Ak, Duygu; Dursun, Erdinç; Yilmazer, Selma

    2014-06-01

    Vitamin D, the main function of which is thought to be the maintenance of calcium and phosphate homeostasis and bone structure, has been shown in recent studies to have important roles in brain development as well. A certain vitamin D receptor (VDR) gene haplotype was reported, for the first time by our group, to increase the risk of developing Alzheimer's disease. Our studies also showed that vitamin D prevents beta amyloid-induced calcium elevation and toxicity that target nerve growth factor (NGF) release in cortical neurons; beta amyloid suppresses VDR expression and the disruption of vitamin D-VDR pathway mimics beta amyloid-induced neurodegeneration. In this study, our aim was to investigate the effects of vitamin D on the NGF release from hippocampal neurons. Primary hippocampal neuron cultures that were prepared from 18-day-old Sprague-Dawley rat embryos were treated with vitamin D for 48 hours. The alteration in the NGF release was determined with ELISA. Cytotoxicity tests were also performed for all groups. The NGF release in vitamin D-treated group was significantly higher than in untreated control group. The protective effect of vitamin D against cytotoxicity was also observed. Our results indicated that vitamin D regulates the release of NGF, a very important molecule for neuronal survival of hippocampal neurons as well as cortical neurons.

  7. Hippocampal neurogenesis and pattern separation: A meta-analysis of behavioral data.

    Science.gov (United States)

    França, Thiago F A; Bitencourt, Alexandre M; Maximilla, Naiana R; Barros, Daniela M; Monserrat, José M

    2017-09-01

    The generation of new neurons in the hippocampus of adult mammals has become a widely accepted phenomenon, but the functional significance of the adult neurogenesis in the hippocampus is not fully understood. One of the main hypotheses currently investigated suggests that neurogenesis contributes to pattern separation in the dentate gyrus. Many behavioral studies were conducted aiming to test this hypothesis using rodents as animal model. In those studies, researches ablated neurogenesis in the animals and subsequently evaluate them in tests of behavioral pattern separation, that is, behaviors that are thought to rely on the computational process of pattern separation. The results of these studies are varied, with most supporting a role for neurogenesis in pattern separation, but some others not. To address this controversy we performed a systematic review and meta-analysis of studies evaluating the effect of neurogenesis ablation on behavioral pattern separation. Analysis results indicated that most of the literature in the topic is surprisingly consistent and, although there are two studies with divergent results, the bulk of the literature supports an effect of hippocampal neurogenesis on behavioral pattern separation. We discuss those findings in light of other behavioral effects of hippocampal neurogenesis ablation, limitations of behavioral data and other lines of evidence about the effect of hippocampal neurogenesis in the dentate gyrus. © 2017 Wiley Periodicals, Inc.

  8. 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

  9. 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.

  10. Impact of neonatal anoxia on adult rat hippocampal volume, neurogenesis and behavior.

    Science.gov (United States)

    Takada, Silvia Honda; Motta-Teixeira, Lívia Clemente; Machado-Nils, Aline Vilar; Lee, Vitor Yonamine; Sampaio, Carlos Alberto; Polli, Roberson Saraiva; Malheiros, Jackeline Moraes; Takase, Luiz Fernando; Kihara, Alexandre Hiroaki; Covolan, Luciene; Xavier, Gilberto Fernando; Nogueira, Maria Inês

    2016-01-01

    Neonates that suffer oxygen deprivation during birth can have long lasting cognitive deficits, such as memory and learning impairments. Hippocampus, one of the main structures that participate in memory and learning processes, is a plastic and dynamic structure that conserves during life span the property of generating new cells which can become neurons, the so-called neurogenesis. The present study investigated whether a model of rat neonatal anoxia, that causes only respiratory distress, is able to alter the hippocampal volume, the neurogenesis rate and has functional implications in adult life. MRI analysis revealed significant hippocampal volume decrease in adult rats who had experienced neonatal anoxia compared to control animals for rostral, caudal and total hippocampus. In addition, these animals also had 55.7% decrease of double-labelled cells to BrdU and NeuN, reflecting a decrease in neurogenesis rate. Finally, behavioral analysis indicated that neonatal anoxia resulted in disruption of spatial working memory, similar to human condition, accompanied by an anxiogenic effect. The observed behavioral alterations caused by oxygen deprivation at birth might represent an outcome of the decreased hippocampal neurogenesis and volume, evidenced by immunohistochemistry and MRI analysis. Therefore, based on current findings we propose this model as suitable to explore new therapeutic approaches. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Being overweight is associated with hippocampal atrophy: the PATH Through Life Study.

    Science.gov (United States)

    Cherbuin, N; Sargent-Cox, K; Fraser, M; Sachdev, P; Anstey, K J

    2015-10-01

    The prevalence of obesity has increased dramatically in the past two decades, with major implications for individual well-being, population health and the economy. Of particular concern is the risk obesity presents for brain health and its consequences in an ageing population. These associations and their time course are not well understood, particularly after middle age. The aim of this study was to investigate whether being overweight/obese or having an increasing body weight is associated with hippocampal atrophy in early old age. Participants were 420 unimpaired (Mini-Mental State Examination >26) individuals aged 60-64 years, living in the community and taking part in a large prospective study of ageing over an 8 year follow-up. Magnetic resonance imaging scans were collected at three assessments and the hippocampus was manually traced by expert neuroscientists. Multi-level analyses assessing the relationship between body mass index (BMI) and hippocampal atrophy over 8 years while controlling for important covariates were conducted. Analyses showed that BMI was negatively associated with left (coefficient: -10.65 mm(3); s.e. 4.81; P=0.027) and right (coefficient: -8.18 mm(3); s.e. 4.91; P=0.097) hippocampal volume at the first assessment. Over the follow-up period, those with a higher BMI experienced greater hippocampal atrophy and more so in the left (P=0.001) than in the right (P=0.058) hippocampus. The findings from this study provide important evidence indicating that being overweight or obese is associated with poorer brain health. These results are consistent with those of previous animal and human studies and further stress the importance of reducing the rate of obesity through education, population health interventions and policy.

  16. 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.

  17. 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

  18. Preserved learning about allocentric cues but impaired flexible memory expression in rats with hippocampal lesions.

    Science.gov (United States)

    Ramos, Juan M J

    2010-05-01

    Several studies have shown that slight modifications in the standard reference spatial memory procedure normally used for allocentric learning in the Morris water maze and the radial maze, can overcome the classic deficit in allocentric navigation typically observed in rats with hippocampal damage. In these special paradigms, however, there is only intramaze manipulation of a salient stimulus. The present study was designed to investigate whether extramaze manipulations produce a similar outcome. With this aim a four-arm plus-shaped maze and a reference spatial memory paradigm were used, in which the goal arm was marked in two ways: by a prominent extramaze cue (intermittent light), which maintained a constant relation with the goal, and by the extramaze constellation of stimuli around the maze. Experiment 1 showed that, unlike the standard version of the task, using this special training procedure hippocampally-damaged rats could learn a place response as quickly as control animals; importantly, one day after reaching criterion, lesioned and control subjects performed the task perfectly during a transfer test in which the salient extramaze stimulus used during the acquisition was removed. However, although acquisition deficit was overcomed in these lesioned animals, a profound deficit in retention was detected 15 days later. Experiment 2 suggests that although under our special paradigm hippocampal rats can learn a place response, spatial memory only can be expressed when the requisites of behavioral flexibility are minimal. These findings suggest that, under certain circumstances, extrahippocampal structures are sufficient for building a coherent allocentric representation of space; however, flexible memory expression is dependent, fundamentally, on hippocampal functioning. Copyright 2010 Elsevier Inc. All rights reserved.

  19. Acute Fornix Deep Brain Stimulation Improves Hippocampal Glucose Metabolism in Aged Mice.

    Science.gov (United States)

    Wang, Xiu; Hu, Wen-Han; Zhang, Kai; Zhou, Jun-Jian; Liu, De-Feng; Zhang, Mei-Yu; Zhang, Jian-Guo

    2018-03-05

    A beneficial memory effect of acute fornix deep brain stimulation (DBS) has been reported in clinical studies. The aim of this study was to investigate the acute changes in glucose metabolism induced by fornix DBS. First, the Morris water maze test and novel object recognition memory test were used to confirm declined memory in aged mice (C57BL/6, 20-22 months old). Then, four groups of mice were used as follows: aged mice with stimulation (n = 12), aged mice with sham-stimulation (n = 8), adult mice (3-4 months old) with stimulation (n = 12), and adult mice with sham-stimulation (n = 8). Ipsilateral hippocampal glucose metabolism and glutamate levels were measured in vivo by microdialysis before, during, and after fornix DBS treatment. Histological staining was used to verify the localization of electrodes and mice with inaccurate placement were excluded from subsequent analyses. The effects of fornix DBS on extracellular glucose, lactate, pyruvate, and glutamate levels over time were analyzed by repeated-measures analysis of variance followed by Fisher's least significant difference post hoc test. The aged mice had a higher basal lactate/pyruvate ratio (LPR) and lactate/glucose ratio (LGR) than the adult mice (LPR: 0.34 ± 0.04 vs. 0.13 ± 0.02, t = 4.626, P Fornix DBS decreased the ipsilateral hippocampal pyruvate and lactate levels (P fornix DBS treatment (P fornix DBS. In addition, fornix DBS significantly decreased the ipsilateral hippocampal extracellular levels of glutamate in aged mice (P fornix DBS could significantly improve hippocampal glucose metabolism in aged mice by promoting cellular aerobic respiration activity.

  20. 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.

  1. A sharp recovery condition for block sparse signals by block orthogonal multi-matching pursuit

    OpenAIRE

    Chen, Wengu; Ge, Huanmin

    2016-01-01

    We consider the block orthogonal multi-matching pursuit (BOMMP) algorithm for the recovery of block sparse signals. A sharp bound is obtained for the exact reconstruction of block $K$-sparse signals via the BOMMP algorithm in the noiseless case, based on the block restricted isometry constant (block-RIC). Moreover, we show that the sharp bound combining with an extra condition on the minimum $\\ell_2$ norm of nonzero blocks of block $K-$sparse signals is sufficient to recover the true support ...

  2. Efficient electrochemical etching method to fabricate sharp metallic tips for scanning probe microscopes

    International Nuclear Information System (INIS)

    Kim, Pilkyu; Kim, Jun Ho; Jeong, Mun Seok; Ko, Do-Kyeong; Lee, Jongmin; Jeong, Sungho

    2006-01-01

    A new technique based on electrochemical etching for the fabrication of sharp metallic tips for scanning probe microscopes is introduced. In the proposed method, a small Teflon mass is attached to the end of an immersed tungsten wire using an aluminum tape, which leads to a significant enhancement of yield rate of sharp tungsten tips with an apex size below 100 nm to over 60%. The functionality of the tungsten tips fabricated by the proposed method is verified by measuring the topography of a standard sample using a shear-force scanning probe microscope

  3. 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.

  4. Alcohol and adult hippocampal neurogenesis: Promiscuous drug, wanton effects

    Science.gov (United States)

    Geil, Chelsea R.; Hayes, Dayna M.; McClain, Justin A.; Liput, Daniel J.; Marshall, S. Alex; Chen, Kevin Y.; Nixon, Kimberly

    2014-01-01

    Adult neurogenesis is now widely accepted as an important contributor to hippocampal integrity and function but also dysfunction when adult neurogenesis is affected in neuropsychiatric diseases such as alcohol use disorders. Excessive alcohol consumption, the defining characteristic of alcohol use disorders, results in a variety of cognitive and behavioral impairments related wholly or in part to hippocampal structure and function. Recent preclinical work has shown that adult neurogenesis may be one route by which alcohol produces hippocampal neuropathology. Alcohol is a pharmacologically promiscuous drug capable of interfering with adult neurogenesis through multiple mechanisms. This review will discuss the primary mechanisms underlying alcohol-induced changes in adult hippocampal neurogenesis including alcohol's effects on neurotransmitters, CREB and its downstream effectors, and the neurogenic niche. PMID:24842804

  5. 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 ...

  6. Needlestick and Sharps Injuries in Dermatologic Surgery: A Review of Preventative Techniques and Post-exposure Protocols.

    Science.gov (United States)

    Rizk, Christopher; Monroe, Holly; Orengo, Ida; Rosen, Theodore

    2016-10-01

    Background: Needlestickand sharps injuries are the leading causes of morbidity in the dermatologicfield. Among medical specialties, surgeons and dermatologists have the highest rates of needlestickand sharps injuries.The high rates of needlestickand sharps injuries in dermatology not only apply to physicians, but also to nurses, physician assistants, and technicians in the demnatologic field. Needlestickand sharps injuries are of great concern due to the monetary, opportunity, social, and emotional costs associated with their occurrence. Objective: A review of preventative techniques and post-exposure protocols for the majortypes of sharps injuries encountered in dermatologic practice. Design: The terms "needle-stick injuryT'sharps injuryTdermatologic surgery? "post-exposure prophylaxis,"and "health-care associated injury" were used in combinations to search the PubMed database. Relevant studies were reviewed for validity and included. Results The authors discuss the major types of sharps injuries that occur in the dermatologic surgery setting and summarize preventative techniques with respect to each type of sharps injury.The authors also summarize and discuss relevant post-exposure protocols in the event of a sharps injury. Conclusion: The adoption of the discussed methods, techniques, practices, and attire can result in the elimination of the vast majority of dermatologic sharps injuries.

  7. Sharp Morphological Transitions from Nanoscale Mixed-Anchoring Patterns in Confined Nematic Liquid Crystals.

    Science.gov (United States)

    Armas-Pérez, Julio C; Li, Xiao; Martínez-González, José A; Smith, Coleman; Hernández-Ortiz, J P; Nealey, Paul F; de Pablo, Juan J

    2017-10-31

    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 liquid-crystal-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.

  8. 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.

  9. The impact of sleep loss on hippocampal function

    OpenAIRE

    Prince, Toni-Moi; Abel, Ted

    2013-01-01

    Hippocampal cellular and molecular processes critical for memory consolidation are affected by the amount and quality of sleep attained. Questions remain with regard to how sleep enhances memory, what parameters of sleep after learning are optimal for memory consolidation, and what underlying hippocampal molecular players are targeted by sleep deprivation to impair memory consolidation and plasticity. In this review, we address these topics with a focus on the detrimental effects of post-lear...

  10. Le Projet hippocampe devient un important protagoniste de la ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Le Projet hippocampe devient un important protagoniste de la conservation de la faune marine. 29 octobre 2012. Image. Stephen Dale. Des effets durables. Pour certains, le Projet hippocampe est un organisme qui a mobilisé des collectivités de pêcheurs pauvres des Philippines pour créer des dizaines d'aires protégées ...

  11. Automated hippocampal segmentation in patients with epilepsy: Available free online

    Science.gov (United States)

    Winston, Gavin P; Cardoso, M Jorge; Williams, Elaine J; Burdett, Jane L; Bartlett, Philippa A; Espak, Miklos; Behr, Charles; Duncan, John S; Ourselin, Sebastien

    2013-01-01

    Purpose Hippocampal sclerosis, a common cause of refractory focal epilepsy, requires hippocampal volumetry for accurate diagnosis and surgical planning. Manual segmentation is time-consuming and subject to interrater/intrarater variability. Automated algorithms perform poorly in patients with temporal lobe epilepsy. We validate and make freely available online a novel automated method. Methods Manual hippocampal segmentation was performed on 876, 3T MRI scans and 202, 1.5T scans. A template database of 400 high-quality manual segmentations was used to perform automated segmentation of all scans with a multi-atlas–based segmentation propagation method adapted to perform label fusion based on local similarity to ensure accurate segmentation regardless of pathology. Agreement between manual and automated segmentations was assessed by degree of overlap (Dice coefficient) and comparison of hippocampal volumes. Key Findings The automated segmentation algorithm provided robust delineation of the hippocampi on 3T scans with no more variability than that seen between different human raters (Dice coefficients: interrater 0.832, manual vs. automated 0.847). In addition, the algorithm provided excellent results with the 1.5T scans (Dice coefficient 0.827), and automated segmentation remained accurate even in small sclerotic hippocampi. There was a strong correlation between manual and automated hippocampal volumes (Pearson correlation coefficient 0.929 on the left and 0.941 on the right in 3T scans). Significance We demonstrate reliable identification of hippocampal atrophy in patients with hippocampal sclerosis, which is crucial for clinical management of epilepsy, particularly if surgical treatment is being contemplated. We provide a free online Web-based service to enable hippocampal volumetry to be available globally, with consequent greatly improved evaluation of those with epilepsy. PMID:24151901

  12. Sparse encoding of automatic visual association in hippocampal networks

    DEFF Research Database (Denmark)

    Hulme, Oliver J; Skov, Martin; Chadwick, Martin J

    2014-01-01

    by these stimuli. Using multivariate Bayesian decoding, we show that human hippocampal and temporal neocortical structures host sparse associative representations that are automatically triggered by visual input. Furthermore, as predicted theoretically, there was a significant increase in sparsity in the Cornu...... for the sparse encoding of associative density. In the absence of reportability or attentional confounds, this charts a distribution of visual associative representations within hippocampal populations and their temporal lobe afferent fields, and demonstrates the viability of retrospective associative sampling...

  13. 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.

  14. Rates of hippocampal atrophy and presence of post-mortem TDP-43 in patients with Alzheimer's disease: a longitudinal retrospective study.

    Science.gov (United States)

    Josephs, Keith A; Dickson, Dennis W; Tosakulwong, Nirubol; Weigand, Stephen D; Murray, Melissa E; Petrucelli, Leonard; Liesinger, Amanda M; Senjem, Matthew L; Spychalla, Anthony J; Knopman, David S; Parisi, Joseph E; Petersen, Ronald C; Jack, Clifford R; Whitwell, Jennifer L

    2017-11-01

    Post-mortem studies have not identified an association between β-amyloid or tau and rates of hippocampal atrophy in patients with Alzheimer's disease. TAR DNA binding protein 43 (TDP-43) is another protein linked to Alzheimer's disease. We aimed to investigate whether hippocampal TDP-43 is associated with increased rates of hippocampal atrophy. In this longitudinal retrospective study, we analysed post-mortem brain tissue of all individuals with an Alzheimer's disease spectrum pathological diagnosis who had antemortem head MRI scans between Jan 1, 1999, and Dec 31, 2012, and who had been recruited into the Mayo Clinic Alzheimer's Disease Research Center, Mayo Clinic Alzheimer's Disease Patient Registry, or the Mayo Clinic Study of Aging. We did TDP-43 immunohistochemistry and classified individuals as follows: no TDP-43 in the amygdala or hippocampus; TDP-43 restricted to the amygdala; and TDP-43 spreading into the hippocampus. Each individual was also assigned a neurofibrillary tangle stage (B1-B3), relating to the likelihood of having Alzheimer's disease. We used longitudinal FreeSurfer software and tensor-based morphometry with symmetric normalisation to calculate hippocampal volume on all serial MRI scans and used linear mixed-effects regression models to estimate associations between TDP-43 and rate of hippocampal atrophy and to assess the trajectory of TDP-43-associated atrophy. We identified 298 individuals meeting the inclusion criteria, with 816 usable MRI scans (spanning 1·0-11·2 years of the disease) available for analysis. 141 individuals showed no TDP-43 in the amygdala or hippocampus, 33 had TDP-43 restricted to the amygdala, and 124 had TDP-43 in the hippocampus. Among individuals with a high likelihood of having Alzheimer's disease (neurofibrillary tangle stage B3; n=205), those with hippocampal TDP-43 had faster rates of hippocampal atrophy (n=103, annual volume change -4·39%, 95% CI -4·82 to -3·95; patrophy (n=17, annual volume change -4·05

  15. 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

  16. Lesions affecting the right hippocampal formation differentially impair short-term memory of spatial and nonspatial associations.

    Science.gov (United States)

    Braun, Mischa; Weinrich, Christiane; Finke, Carsten; Ostendorf, Florian; Lehmann, Thomas-Nicolas; Ploner, Christoph J

    2011-03-01

    Converging evidence from behavioral and imaging studies suggests that within the human medial temporal lobe (MTL) the hippocampal formation may be particularly involved in recognition memory of associative information. However, it is unclear whether the hippocampal formation processes all types of associations or whether there is a specialization for processing of associations involving spatial information. Here, we investigated this issue in six patients with postsurgical lesions of the right MTL affecting the hippocampal formation and in ten healthy controls. Subjects performed a battery of delayed match-to-sample tasks with two delays (900/5,000 ms) and three set sizes. Subjects were requested to remember either single features (colors, locations, shapes, letters) or feature associations (color-location, color-shape, color-letter). In the single-feature conditions, performance of patients did not differ from controls. In the association conditions, a significant delay-dependent deficit in memory of color-location associations was found. This deficit was largely independent of set size. By contrast, performance in the color-shape and color-letter conditions was normal. These findings support the hypothesis that a region within the right MTL, presumably the hippocampal formation, does not equally support all kinds of visual memory but rather has a bias for processing of associations involving spatial information. Recruitment of this region during memory tasks appears to depend both on processing type (associative/nonassociative) and to-be-remembered material (spatial/nonspatial). Copyright © 2010 Wiley-Liss, Inc.

  17. 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.

  18. Hippocampal serotonin-1A receptor function in a mouse model of anxiety induced by long-term voluntary wheel running.

    Science.gov (United States)

    Fuss, Johannes; Vogt, Miriam A; Weber, Klaus-Josef; Burke, Teresa F; Gass, Peter; Hensler, Julie G

    2013-10-01

    We have recently demonstrated that, in C57/Bl6 mice, long-term voluntary wheel running is anxiogenic, and focal hippocampal irradiation prevents the increase in anxiety-like behaviors and neurobiological changes in the hippocampus induced by wheel running. Evidence supports a role of hippocampal 5-HT1A receptors in anxiety. Therefore, we investigated hippocampal binding and function of 5-HT1A receptors in this mouse model of anxiety. Four weeks of voluntary wheel running resulted in hippocampal subregion-specific changes in 5-HT1A receptor binding sites and function, as measured by autoradiography of [(3) H] 8-hydroxy-2-(di-n-propylamino)tetralin binding and agonist-stimulated binding of [(35) S]GTPγS to G proteins, respectively. In the dorsal CA1 region, 5-HT1A receptor binding and function were not altered by wheel running or irradiation. In the dorsal dentate gyrus and CA2/3 region, 5-HT1A receptor function was decreased by not only running but also irradiation. In the ventral pyramidal layer, wheel running resulted in a decrease of 5-HT1A receptor function, which was prevented by irradiation. Neither irradiation nor wheel running affected 5-HT1A receptors in medial prefrontal cortex or in the dorsal or median raphe nuclei. Our data indicate that downregulation of 5-HT1A receptor function in ventral pyramidal layer may play a role in anxiety-like behavior induced by wheel running. Copyright © 2013 Wiley Periodicals, Inc.

  19. Cloning and characterization of canine SHARP1 and its evaluation as a positional candidate for canine early retinal degeneration (erd).

    Science.gov (United States)

    Kukekova, Anna V; Aguirre, Gustavo D; Acland, Gregory M

    2003-07-17

    Canine early retinal degeneration (erd) is an early onset form of canine progressive retinal atrophy phenotypically similar to human retinitis pigmentosa. In a previous study, the locus responsible for erd was mapped to canine chromosome 27 in the region corresponding to HSA12p, a region where no human retinal degeneration loci have been mapped. Canine SHARP1 gene has been localized on CFA27 in the erd interval by RH mapping, and considered as a positional candidate gene for erd. SHARP1 was cloned and sequenced from normal and erd affected dogs, and no disease-causing mutations were identified. Genotyping of 117 dogs from informative pedigrees did not reveal any recombinants between SHARP1 and erd. To date SHARP1 gene is the closest gene-specific marker to erd; genotyping additional informative pedigrees, and sequencing SHARP1 upstream regions from normal and affected dogs will be necessary to establish if SHARP1 is involved in this canine retinal disease.

  20. A cognitive prosthesis for memory facilitation by closed-loop functional ensemble stimulation of hippocampal neurons in primate brain

    OpenAIRE

    Deadwyler, Sam A.; Hampson, Robert E.; Song, Dong; Opris, Ioan; Gerhardt, Greg A.; Marmarelis, Vasilis Z.; Berger, Theodore W.

    2016-01-01

    Very productive collaborative investigations characterized how multineuron hippocampal ensembles recorded in nonhuman primates (NHPs) encode short-term memory necessary for successful performance in a delayed match to sample (DMS) task and utilized that information to devise a unique nonlinear multi-input multi-output (MIMO) memory prosthesis device to enhance short-term memory in real-time during task performance. Investigations have characterized how the hippocampus in primate brain encodes...

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

    Indian Academy of Sciences (India)

    This paper is concerned with the Nagumo equation with nonlinear degenerate diffusion and convection which arises in several problems of population dynamics, chemical reactions and others. A sharp front-type solution with a minimum speed to this model equation is analysed using different methods. One of the methods ...

  2. Parameter Estimation of a Ground Moving Target Using Image Sharpness Optimization

    Directory of Open Access Journals (Sweden)

    Jing Yu

    2016-06-01

    Full Text Available Motion parameter estimation of a ground moving target is an important issue in synthetic aperture radar ground moving target indication (SAR-GMTI which has significant applications for civilian and military. The SAR image of a moving target may be displaced and defocused due to the radial and along-track velocity components, respectively. The sharpness cost function presents a measure of the degree of focus of the image. In this work, a new ground moving target parameter estimation algorithm based on the sharpness optimization criterion is proposed. The relationships between the quadratic phase errors and the target’s velocity components are derived. Using two-dimensional searching of the sharpness cost function, we can obtain the velocity components of the target and the focused target image simultaneously. The proposed moving target parameter estimation method and image sharpness metrics are analyzed in detail. Finally, numerical results illustrate the effective and superior velocity estimation performance of the proposed method when compared to existing algorithms.

  3. 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.

  4. 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).

  5. A sharp Rogers–Shephard type inequality for Orlicz-difference body ...

    Indian Academy of Sciences (India)

    (Math. Sci.) Vol. 124, No. 4, November 2014, pp. 573–580. c Indian Academy of Sciences. A sharp Rogers–Shephard type inequality for Orlicz-difference body of planar convex bodies. HAILIN JIN1 and SHUFENG YUAN2. 1Department of Mathematics, Suzhou University of Science and Technology,. Suzhou, 215009, China.

  6. 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.

  7. The Pattern of Sharps Injury to Health Care Workers at Witbank ...

    African Journals Online (AJOL)

    A total of 76.9% of all needlestick/sharps injuries were inflicted by injection needles. 3. Taking blood ... at Witbank Hospital. The areas of activity, procedures and occupational groups that result in a high risk of transmission of bloodborne infections to HCWs were identified, and will be used to design the preventive strategies.

  8. 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 ...

  9. Current status of sharps waste management in the lower-level ...

    African Journals Online (AJOL)

    Department of Chemical & Mining Engineering, College of Engineering and Technology, University of Dar es Salaam, P.O. Box 35131, Dar es Salaam, Tanzania .... Though sharps waste constitutes a small fraction of the solid medical waste, the potential environmental and health hazards could be deleterious if not properly ...

  10. 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 ...

  11. Thermoresponsive poly(N-vinyl caprolactam)-coated gold nanoparticles: sharp reversible response and easy tunability.

    Science.gov (United States)

    Beija, Mariana; Marty, Jean-Daniel; Destarac, Mathias

    2011-03-14

    Narrowly distributed poly(N-vinyl caprolactam) obtained by the MADIX/RAFT process was used for the preparation of novel thermoresponsive gold nanoparticles presenting a sharp reversible response to temperature, which can be easily modulated near the physiological temperature by simply changing the polymer molecular weight or concentration.

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

    Indian Academy of Sciences (India)

    A sharp front-type solution with a minimum speed to this model equation is analysed using different methods. One of the methods .... Dirichlet boundary condition u = 1. At the moving right-hand boundary, there is the boundary condition u = 0. The equation of moving boundary can be derived to take the following form: dx∗ dt.

  13. Effect of different levels of sharpness processing filter on the measurement accuracy of endodontic file length

    Directory of Open Access Journals (Sweden)

    Nastaran Farhadi

    2016-01-01

    Full Text Available Introduction: The present study was undertaken to evaluate the effect of different levels of sharpness processing filter on the accuracy of endodontic file length determination using digital periapical radiography. Materials and Methods: Forty human single-rooted permanent teeth were selected and International Organization for Standardization (ISO #08 K-files were inserted into the root canals of the teeth. The file lengths were measured with a digital caliper as the gold standard. Digital periapical images were obtained using a phosphor storage plate as a detector. Three levels of sharpness tool of Scanora software program version 5.1 was used to produce enhanced images: Sharpen 1 (mild level, Sharpen 2 (moderate level, and Sharpen 3 (high level. Two radiologists and two endodontists measured file lengths on the original and enhanced images. The measurements were compared using repeated measures ANOVA and Bonferroni tests (α = 0.05. Results: There were no significant differences between the measurement accuracy of original images and that of the Sharpen 1 and Sharpen 2 enhanced images (P > 0.05. However, significant differences were found between the measurement accuracy of original and that of the Sharpen 3 enhanced images (P 0.05. Conclusion: The application of mild and moderate levels of sharpness processing filter did not influence the accuracy of endodontic file length determination. However, high-level sharpness processing filter is not recommended due to its unfavorable effects on measurement accuracy.

  14. 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...

  15. 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

  16. Sharp force fatalities at the Pretoria Medico-Legal Laboratory, 2012 ...

    African Journals Online (AJOL)

    Background: South Africa's crude death rate was recorded as the highest in the world in 2014. In 2013, 47 murders occurred daily nationwide, and it was confirmed that sharp force fatalities were frequent events. The aim of our study was to review the fatalities of persons admitted to the Pretoria Medico-Legal Laboratory ...

  17. Sharpness of the percolation transition in the two-dimensional contact process

    NARCIS (Netherlands)

    van den Berg, J.

    2011-01-01

    For ordinary (independent) percolation on a large class of lattices it is well known that below the critical percolation parameter pc the cluster size distribution has exponential decay and that power-law behavior of this distribution can only occur at pc. This behavior is often called "sharpness of

  18. 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...

  19. 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...

  20. Change in hippocampal theta oscillation associated with multiple lever presses in a bimanual two-lever choice task for robot control in rats.

    Science.gov (United States)

    Tanaka, Norifumi; Sano, Katsunari; Rahman, Md Ashrafur; Miyata, Ryota; Capi, Genci; Kawahara, Shigenori

    2018-01-01

    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.

  1. 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.

  2. [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.

  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. 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

  5. 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

  6. Ketamine Protects Gamma Oscillations by Inhibiting Hippocampal LTD.

    Directory of Open Access Journals (Sweden)

    Lanting Huang

    Full Text Available 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.

  7. 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.

  8. Hippocampal volume predicts fluid intelligence in musically trained people.

    Science.gov (United States)

    Oechslin, Mathias S; Descloux, Céline; Croquelois, Alexandre; Chanal, Julien; Van De Ville, Dimitri; Lazeyras, François; James, Clara E

    2013-07-01

    Recently, age-related hippocampal (HP) volume loss could be associated with a decrease in general fluid intelligence (gF). In the present study we investigated whether and how extensive musical training modulates human HP volume and gF performance. Previously, some studies demonstrated positive effects of musical training on higher cognitive functions such as learning and memory, associated with neural adaptations beyond the auditory domain. In order to detect possible associations between musical training and gF, we bilaterally segmented the HP formation and assessed the individual gF performance of people with different levels of musical expertise. Multiple regression analyses revealed that HP volume predicts gF in musicians but not in nonmusicians; in particular, bilaterally enhanced HP volume is associated with increased gF exclusively in musically trained people (amateurs and experts). This result suggests that musical training facilitates the recruitment of cognitive resources, which are essential for gF and linked to HP functioning. Musical training, even at a moderate level of intensity, can thus be considered as a potential strategy to decelerate age-related effects of cognitive decline. Copyright © 2013 Wiley Periodicals, Inc.

  9. Hippocampal Hyperactivation in Presymptomatic Familial Alzheimer’s Disease

    Science.gov (United States)

    Quiroz, Yakeel T.; Budson, Andrew E.; Celone, Kim; Ruiz, Adriana; Newmark, Randall; Castrillón, Gabriel; Lopera, Francisco; Stern, Chantal E.

    2011-01-01

    Objective The examination of individuals who carry fully penetrant genetic alterations that result in familial Alzheimer’s disease (FAD) provides a unique model for studying the early presymptomatic disease stages. In AD, deficits in episodic and associative memory have been linked to structural and functional changes within the hippocampal system. This study used functional MRI (fMRI) to examine hippocampal function in a group of healthy, young, cognitively-intact presymptomatic individuals (average age 33.7 years) who carry the E280A presenilin-1 (PS1) genetic mutation for FAD. These PS1 subjects will go on to develop the first symptoms of the disease around the age of 45 years. Our objective was to examine hippocampal function years before the onset of clinical symptoms. Methods Twenty carriers of the Alzheimer’s-associated E280A PS1 mutation and 19 PS1-negative control subjects participated. Both groups were matched for age, sex, education level, and neuropsychological test performance. All participants performed a face-name associative encoding task while in a Philips 1.5T fMRI scanner. Analysis focused on the hippocampal system. Results Despite identical behavioral performance, presymptomatic PS1 mutation carriers exhibited increased activation of the right anterior hippocampus during encoding of novel face-name associations compared to matched controls. Interpretation Our results demonstrate that functional changes within the hippocampal memory system occur years before cognitive decline in FAD. These presymptomatic changes in hippocampal physiology in FAD suggest that hippocampal fMRI patterns during associative encoding may also provide a preclinical biomarker in sporadic AD. PMID:21194156

  10. Quantifying the margin sharpness of lesions on radiological images for content-based image retrieval

    International Nuclear Information System (INIS)

    Xu Jiajing; Napel, Sandy; Greenspan, Hayit; Beaulieu, Christopher F.; Agrawal, Neeraj; Rubin, Daniel

    2012-01-01

    Purpose: To develop a method to quantify the margin sharpness of lesions on CT and to evaluate it in simulations and CT scans of liver and lung lesions. Methods: The authors computed two attributes of margin sharpness: the intensity difference between a lesion and its surroundings, and the sharpness of the intensity transition across the lesion boundary. These two attributes were extracted from sigmoid curves fitted along lines automatically drawn orthogonal to the lesion margin. The authors then represented the margin characteristics for each lesion by a feature vector containing histograms of these parameters. The authors created 100 simulated CT scans of lesions over a range of intensity difference and margin sharpness, and used the concordance correlation between the known parameter and the corresponding computed feature as a measure of performance. The authors also evaluated their method in 79 liver lesions (44 patients: 23 M, 21 F, mean age 61) and 58 lung nodules (57 patients: 24 M, 33 F, mean age 66). The methodology presented takes into consideration the boundary of the liver and lung during feature extraction in clinical images to ensure that the margin feature do not get contaminated by anatomy other than the normal organ surrounding the lesions. For evaluation in these clinical images, the authors created subjective independent reference standards for pairwise margin sharpness similarity in the liver and lung cohorts, and compared rank orderings of similarity used using our sharpness feature to that expected from the reference standards using mean normalized discounted cumulative gain (NDCG) over all query images. In addition, the authors compared their proposed feature with two existing techniques for lesion margin characterization using the simulated and clinical datasets. The authors also evaluated the robustness of their features against variations in delineation of the lesion margin by simulating five types of deformations of the lesion margin

  11. Regulation of hippocampal cGMP levels as a candidate to treat cognitive deficits in Huntington's disease.

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    Ana Saavedra

    Full Text Available Huntington's disease (HD patients and mouse models show learning and memory impairment associated with hippocampal dysfunction. The neuronal nitric oxide synthase/3',5'-cyclic guanosine monophosphate (nNOS/cGMP pathway is implicated in synaptic plasticity, and in learning and memory processes. Here, we examined the nNOS/cGMP pathway in the hippocampus of HD mice to determine whether it can be a good therapeutic target for cognitive improvement in HD. We analyzed hippocampal nNOS and phosphodiesterase (PDE 5 and 9 levels in R6/1 mice, and cGMP levels in the hippocampus of R6/1, R6/2 and Hdh(Q7/Q111 mice, and of HD patients. We also investigated whether sildenafil, a PDE5 inhibitor, could improve cognitive deficits in R6/1 mice. We found that hippocampal cGMP levels were 3-fold lower in 12-week-old R6/1 mice, when they show deficits in object recognition memory and in passive avoidance learning. Consistent with hippocampal cGMP levels, nNOS levels were down-regulated, while there were no changes in the levels of PDE5 and PDE9 in R6/1 mice. A single intraperitoneal injection of sildenafil (3 mg/Kg immediately after training increased cGMP levels, and improved memory in R6/1 mice, as assessed by using the novel object recognition and the passive avoidance test. Importantly, cGMP levels were also reduced in R6/2 mouse and human HD hippocampus. Therefore, the regulation of hippocampal cGMP levels can be a suitable treatment for cognitive impairment in HD.

  12. Ipsilateral hippocampal atrophy is associated with long-term memory dysfunction after ischemic stroke in young adults.

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    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.

  13. Retinoic acid modulates intrahippocampal levels of corticosterone in middle-aged mice: consequences on hippocampal plasticity and contextual memory.

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    Damien eBonhomme

    2014-02-01

    Full Text Available It is now established that vitamin A and its derivatives, retinoic acid (RA, are required for cognitive functions in adulthood. RA hyposignaling and hyperactivity of glucocorticoid (GC pathway appear concomitantly during ageing and would contribute to the deterioration of hippocampal synaptic plasticity and functions. Furthermore, recent data have evidenced counteracting effects of retinoids on GC signaling pathway. In the present study, we addressed the following issue: whether the stimulation of RA pathway could modulate intrahippocampal corticosterone (CORT levels in middle-aged mice and thereby impact on hippocampal plasticity and cognitive functions. We firstly investigated the effects of vitamin A supplementation and RA treatment in middle-aged mice, on contextual serial discrimination task (CSD, a paradigm which allows the detection of early signs of age-related hippocampal-dependent memory dysfunction. We then measured intrahippocampal CORT concentrations by microdialysis before and after a novelty-induced stress. Our results show that both RA treatment and vitamin A supplementation improve episodic-like memory in middle-aged mice but RA treatment appears to be more efficient. Moreover, we show that the beneficial effect of RA on memory is associated to an increase in hippocampal PSD-95 expression. In addition, intrahippocampal CORT levels are reduced after novelty-induced stress in RA treated animals. This effect cannot be related to a modulation of hippocampal 11β-HSD1 expression. In addition, RA treatment induces a modulation of retinoic acid receptors RARα and RARβ expression in middle-aged mice, a finding which has been correlated with the amplitude of intrahippocampal CORT levels after novelty-induced stress. Taken together, our results suggest that the preventive action of RA treatment on age-related memory deficits in middle-aged mice could be, at least in part, due to an inhibitory effect of retinoids on glucocorticoid

  14. Role of hippocampal β-adrenergic and glucocorticoid receptors in the novelty-induced enhancement of fear extinction.

    Science.gov (United States)

    Liu, Jian-Feng; Yang, Chang; Deng, Jia-Hui; Yan, Wei; Wang, Hui-Min; Luo, Yi-Xiao; Shi, Hai-Shui; Meng, Shi-Qiu; Chai, Bai-Sheng; Fang, Qin; Chai, Ning; Xue, Yan-Xue; Sun, Jia; Chen, Chen; Wang, Xue-Yi; Wang, Ji-Shi; Lu, Lin

    2015-05-27

    Fear extinction forms a new memory but does not erase the original fear memory. Exposure to novelty facilitates transfer of short-term extinction memory to long-lasting memory. However, the underlying cellular and molecular mechanisms are still unclear. Using a classical contextual fear-conditioning model, we investigated the effect of novelty on long-lasting extinction memory in rats. We found that exposure to a novel environment but not familiar environment 1 h before or after extinction enhanced extinction long-term memory (LTM) and reduced fear reinstatement. However, exploring novelty 6 h before or after extinction had no such effect. Infusion of the β-adrenergic receptor (βAR) inhibitor propranolol and glucocorticoid receptor (GR) inhibitor RU486 into the CA1 area of the dorsal hippocampus before novelty exposure blocked the effect of novelty on extinction memory. Propranolol prevented activation of the hippocampal PKA-CREB pathway, and RU486 prevented activation of the hippocampal extracellular signal-regulated kinase 1/2 (Erk1/2)-CREB pathway induced by novelty exposure. These results indicate that the hippocampal βAR-PKA-CREB and GR-Erk1/2-CREB pathways mediate the extinction-enhancing effect of novelty exposure. Infusion of RU486 or the Erk1/2 inhibitor U0126, but not propranolol or the PKA inhibitor Rp-cAMPS, into the CA1 before extinction disrupted the formation of extinction LTM, suggesting that hippocampal GR and Erk1/2 but not βAR or PKA play critical roles in this process. These results indicate that novelty promotes extinction memory via hippocampal βAR- and GR-dependent pathways, and Erk1/2 may serve as a behavioral tag of extinction. Copyright © 2015 the authors 0270-6474/15/358308-14$15.00/0.

  15. Microelectrode array analysis of hippocampal network dynamics following theta-burst stimulation via current source density reconstruction by Gaussian interpolation.

    Science.gov (United States)

    Kim, Hyun-Bum; Oh, Tong-In; Swanberg, Kelley M; Lee, Mun-Bae; Kim, Tae-Woo; Woo, Eung-Je; Park, Ji-Ho; Kwon, Oh-In

    2016-05-01

    Multielectrode arrays (MEAs) have been used to understand electrophysiological network dynamics by recording real-time activity in groups of cells. The extent to which the collection of such data enables hypothesis testing on the level of circuits and networks depends largely on the sophistication of the analyses applied. We studied the systemic temporal variations of endogenous signaling within an organotypic hippocampal network following theta-burst stimulation (TBS) to the Schaffer collateral-commissural pathways. The recovered current source density (CSD) information from the raw grid of extracellular potentials by using a Gaussian interpolation method increases spatial resolution and avoids border artifacts by numerical differentials. We compared total sink and source currents in DG, CA3, and CA1; calculated accumulated correlation coefficients to compare pre- with post-stimulation CSD dynamics in each region; and reconstructed functional connectivity maps for regional cross-correlations with respect to temporal CSD variations. The functional connectivity maps for potential correlations pre- and post-TBS were compared to investigate the neural network as a whole, revealing differences post-TBS. Previous MEA work on plasticity in hippocampal evoked potentials has focused on synchronicity across the hippocampus within isolated subregions. Such analyses ignore the complex relationships among diverse components of the hippocampal circuitry, thus failing to capture network-level behaviors integral to understanding hippocampal function. The proposed method of recovering current source density to examine whole-hippocampal function is sensitive to experimental manipulation and is worth further examination in the context of network-level analyses of neural signaling. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Effect of Opioid on Adult Hippocampal Neurogenesis

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    Yue Zhang

    2016-01-01

    Full Text Available During the past decade, the study of the mechanisms and functional implications of adult neurogenesis has significantly progressed. Many studies focus on the factors that regulate proliferation and fate determination of adult neural stem/progenitor cells, including addictive drugs such as opioid. Here, we review the most recent works on opiate drugs’ effect on different developmental stages of adult hippocampal neurogenesis, as well as the possible underlying mechanisms. We conclude that opiate drugs in general cause a loss of newly born neural progenitors in the subgranular zone of dentate gyrus, by either modulating proliferation or interfering with differentiation and maturation. We also discuss the consequent impact of regulation of adult neurogenesis in animal’s opioid addiction behavior. We further look into the future directions in studying the convergence between the adult neurogenesis field and opioid addiction field, since the adult-born granular cells were shown to play a role in neuroplasticity and may help to reduce the vulnerability to drug craving and relapse.

  17. D-serine increases adult hippocampal neurogenesis

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    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.

  18. 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.

  19. Cortico-hippocampal interaction and adaptive stimulus representation: A neurocomputational theory of associative learning and memory.

    NARCIS (Netherlands)

    Gluck, M.A.; Myers, C.E; Meeter, M.

    2005-01-01

    Computational models of the hippocampal region link psychological theories of associative learning with their underlying physiological and anatomical substrates. Our approach to theory development began with a broad description of the computations that depend on the hippocampal region in classical

  20. [H2 receptor mediates the protective effect of histamine against the cellular edema and viability reduction induced by oxygen-glucose deprivation in rat hippocampal slices].

    Science.gov (United States)

    Ye, Yi-lu; Wang, Meng-ling; Chen, Li-ping; Liu, Lu-ying; Zhang, Li-hui; Chen, Zhong; Wei, Er-qing

    2006-04-01

    To determine the effect of histamine on ischemia-induced cellular edema and viability reduction in rat hippocampal slices, and the involved subtypes of histamine receptor in this effect. In vitro ischemic injury of hippocampal slices was induced by oxygen-glucose deprivation (OGD). The slice injury was determined by real-timely measuring the changes of light transmittance (LT) for the cellular edema in CA1 region of the hippocampal slice, and by detecting the product of 2, 3, 5-triphenyltetrazolium chloride (TTC), formazan, for the slice viability. The effect of histamine at various concentrations on the slice injury was observed, and the blockage by antagonists of histamine receptors was also investigated. Histamine (0.01-10 micromol x L(-1)) inhibited the peak value of LT during OGD in hippocampal slices and improved the reduced viability after OGD. Diphenhydramine (0.1-10 micromol x L(-1)), an H1 receptor antagonist, did not affect the effect of histamine, while cimetidine (0.1-10 micromol x L(-1)), an H2 receptor antagonist, partly abolished the protective effect of histamine. Histamine protects hippocampal slices against ischemia-induced cellular edema and viability reduction; this effect might be mediated via, at least partly, H2 receptor.

  1. Orexin-A aggravates the impairment of hippocampal neurons caused by intermittent hypoxemia by the OXR-PLCβ1-ERK1/2 pathway.

    Science.gov (United States)

    Li, Guohua; Tang, Shi; Chi, Heng; Huang, Weiwei; Lu, Shanshan; Lv, Xin; Liu, Xiaomin; Li, Yan; Wang, Yanpeng; Tang, Jiyou

    2017-04-12

    Obstructive sleep apnea is a highly prevalent but under-recognized disorder that causes neurocognitive deficits such as spatial memory and learning deficits. These deficits are frequently accompanied by an increase in orexin-A, which has been shown to be involved in learning and memory as well as in neuronal apoptosis in brain areas involved in cognition, such as the hippocampus. The aim of this work was to study the possible harmful effects of orexin-A on intermittent hypoxemia-induced hippocampal neuronal damage and to investigate the potential underlying molecular mechanisms and signaling pathways in vitro. We established a hypoxia model in cultured rat hippocampal neurons and evaluated the effects of orexin-A by testing the apoptosis rate of the hippocampal neurons. Further studies using the extracellular signal-regulated kinase 1/2 inhibitor U0126, siRNA-PLCβ1, and siRNA-PLCβ4 were carried out to evaluate the mechanisms by which orexin-A contributes toward impairment of hippocampal neurons. The results showed that orexin-A increases intermittent hypoxemia-induced hippocampal neurons damage by overphosphorylating extracellular signal-regulated kinase 1/2 through the OXR-PLCβ1 pathway.

  2. Qualitative and Quantitative Hippocampal MRI Assessments in Intractable Epilepsy

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    Paramdeep Singh

    2013-01-01

    Full Text Available Aims. To acquire normative data of hippocampal volumes and T2 relaxation times, to evaluate and compare qualitative and quantitative assessments in evaluating hippocampi in patients with different durations of intractable epilepsy, and to propose an imaging protocol based on performance of these techniques. Methods. MRI analysis was done in 50 nonepileptic controls and 30 patients with intractable epilepsy on 1.5T scanner. Visual assessment and hippocampal volumetry were done on oblique coronal IR/T2W and T1W MP-RAGE images, respectively. T2 relaxation times were measured using 16-echo Carr-Purcell-Meiboom-Gill sequence. Volumetric data was normalized for variation in head size between individuals. Patients were divided into temporal ( and extratemporal ( groups based on clinical and EEG localization. Results. In controls, right hippocampal volume was slightly more than the left with no effect of age or gender. In TLE patients, hippocampal volumetry provided maximum concordance with EEG. Visual assessment of unilateral pathology concurred well with measured quantitative values but poorly in cases with bilateral pathologies. There were no significant differences of mean values between extratemporal group and controls group. Quantitative techniques detected mild abnormalities, undetected on visual assessment. Conclusions. Quantitative techniques are more sensitive to diagnose bilateral and mild unilateral hippocampal abnormalities.

  3. Hippocampal and Amygdalar Volumes in Dissociative Identity Disorder

    Science.gov (United States)

    Vermetten, Eric; Schmahl, Christian; Lindner, Sanneke; Loewenstein, Richard J.; Bremner, J. Douglas

    2011-01-01

    Objective Smaller hippocampal volume has been reported in several stress-related psychiatric disorders, including posttraumatic stress disorder (PTSD), borderline personality disorder with early abuse, and depression with early abuse. Patients with borderline personality disorder and early abuse have also been found to have smaller amygdalar volume. The authors examined hippocampal and amygdalar volumes in patients with dissociative identity disorder, a disorder that has been associated with a history of severe childhood trauma. Method The authors used magnetic resonance imaging to measure the volumes of the hippocampus and amygdala in 15 female patients with dissociative identity disorder and 23 female subjects without dissociative identity disorder or any other psychiatric disorder. The volumetric measurements for the two groups were compared. Results Hippocampal volume was 19.2% smaller and amygdalar volume was 31.6% smaller in the patients with dissociative identity disorder, compared to the healthy subjects. The ratio of hippocampal volume to amygdalar volume was significantly different between groups. Conclusions The findings are consistent with the presence of smaller hippocampal and amygdalar volumes in patients with dissociative identity disorder, compared with healthy subjects. PMID:16585437

  4. Remote semantic memory is impoverished in hippocampal amnesia.

    Science.gov (United States)

    Klooster, Nathaniel B; Duff, Melissa C

    2015-12-01

    The necessity of the hippocampus for acquiring new semantic concepts is a topic of considerable debate. However, it is generally accepted that any role the hippocampus plays in semantic memory is time limited and that previously acquired information becomes independent of the hippocampus over time. This view, along with intact naming and word-definition matching performance in amnesia, has led to the notion that remote semantic memory is intact in patients with hippocampal amnesia. Motivated by perspectives of word learning as a protracted process where additional features and senses of a word are added over time, and by recent discoveries about the time course of hippocampal contributions to on-line relational processing, reconsolidation, and the flexible integration of information, we revisit the notion that remote semantic memory is intact in amnesia. Using measures of semantic richness and vocabulary depth from psycholinguistics and first and second language-learning studies, we examined how much information is associated with previously acquired, highly familiar words in a group of patients with bilateral hippocampal damage and amnesia. Relative to healthy demographically matched comparison participants and a group of brain-damaged comparison participants, the patients with hippocampal amnesia performed significantly worse on both productive and receptive measures of vocabulary depth and semantic richness. These findings suggest that remote semantic memory is impoverished in patients with hippocampal amnesia and that the hippocampus may play a role in the maintenance and updating of semantic memory beyond its initial acquisition. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Amyloid Beta Peptide Slows Down Sensory-Induced Hippocampal Oscillations

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    Fernando Peña-Ortega

    2012-01-01

    Full Text Available Alzheimer’s disease (AD progresses with a deterioration of hippocampal function that is likely induced by amyloid beta (Aβ oligomers. Hippocampal function is strongly dependent on theta rhythm, and disruptions in this rhythm have been related to the reduction of cognitive performance in AD. Accordingly, both AD patients and AD-transgenic mice show an increase in theta rhythm at rest but a reduction in cognitive-induced theta rhythm. We have previously found that monomers of the short sequence of Aβ (peptide 25–35 reduce sensory-induced theta oscillations. However, considering on the one hand that different Aβ sequences differentially affect hippocampal oscillations and on the other hand that Aβ oligomers seem to be responsible for the cognitive decline observed in AD, here we aimed to explore the effect of Aβ oligomers on sensory-induced theta rhythm. Our results show that intracisternal injection of Aβ1–42 oligomers, which has no significant effect on spontaneous hippocampal activity, disrupts the induction of theta rhythm upon sensory stimulation. Instead of increasing the power in the theta band, the hippocampus of Aβ-treated animals responds to sensory stimulation (tail pinch with an increase in lower frequencies. These findings demonstrate that Aβ alters induced theta rhythm, providing an in vivo model to test for therapeutic approaches to overcome Aβ-induced hippocampal and cognitive dysfunctions.

  6. Hippocampal-neocortical functional reorganization underlies children's cognitive development.

    Science.gov (United States)

    Qin, Shaozheng; Cho, Soohyun; Chen, Tianwen; Rosenberg-Lee, Miriam; Geary, David C; Menon, Vinod

    2014-09-01

    The importance of the hippocampal system for rapid learning and memory is well recognized, but its contributions to a cardinal feature of children's cognitive development-the transition from procedure-based to memory-based problem-solving strategies-are unknown. Here we show that the hippocampal system is pivotal to this strategic transition. Longitudinal functional magnetic resonance imaging (fMRI) in 7-9-year-old children revealed that the transition from use of counting to memory-based retrieval parallels increased hippocampal and decreased prefrontal-parietal engagement during arithmetic problem solving. Longitudinal improvements in retrieval-strategy use were predicted by increased hippocampal-neocortical functional connectivity. Beyond childhood, retrieval-strategy use continued to improve through adolescence into adulthood and was associated with decreased activation but more stable interproblem representations in the hippocampus. Our findings provide insights into the dynamic role of the hippocampus in the maturation of memory-based problem solving and establish a critical link between hippocampal-neocortical reorganization and children's cognitive development.

  7. Hippocampal functional connectivity and episodic memory in early childhood.

    Science.gov (United States)

    Riggins, Tracy; Geng, Fengji; Blankenship, Sarah L; Redcay, Elizabeth

    2016-06-01

    Episodic memory relies on a distributed network of brain regions, with the hippocampus playing a critical and irreplaceable role. Few studies have examined how changes in this network contribute to episodic memory development early in life. The present addressed this gap by examining relations between hippocampal functional connectivity and episodic memory in 4- and 6-year-old children (n=40). Results revealed similar hippocampal functional connectivity between age groups, which included lateral temporal regions, precuneus, and multiple parietal and prefrontal regions, and functional specialization along the longitudinal axis. Despite these similarities, developmental differences were also observed. Specifically, 3 (of 4) regions within the hippocampal memory network were positively associated with episodic memory in 6-year-old children, but negatively associated with episodic memory in 4-year-old children. In contrast, all 3 regions outside the hippocampal memory network were negatively associated with episodic memory in older children, but positively associated with episodic memory in younger children. These interactions are interpreted within an interactive specialization framework and suggest the hippocampus becomes functionally integrated with cortical regions that are part of the hippocampal memory network in adults and functionally segregated from regions unrelated to memory in adults, both of which are associated with age-related improvements in episodic memory ability. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  8. Altered Hippocampal Morphology in Unmedicated Patients with Major Depressive Illness

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    Carrie E Bearden

    2009-10-01

    Full Text Available Despite converging evidence that major depressive illness is associated with both memory impairment and hippocampal pathology, findings vary widely across studies and it is not known whether these changes are regionally specific. In the present study we acquired brain MRIs (magnetic resonance images from 31 unmedicated patients with MDD (major depressive disorder; mean age 39.2±11.9 years; 77% female and 31 demographically comparable controls. Three-dimensional parametric mesh models were created to examine localized alterations of hippocampal morphology. Although global volumes did not differ between groups, statistical mapping results revealed that in MDD patients, more severe depressive symptoms were associated with greater left hippocampal atrophy, particularly in CA1 (cornu ammonis 1 subfields and the subiculum. However, previous treatment with atypical antipsychotics was associated with a trend towards larger left hippocampal volume. Our findings suggest effects of illness severity on hippocampal size, as well as a possible effect of past history of atypical antipsychotic treatment, which may reflect prolonged neuroprotective effects. This possibility awaits confirmation in longitudinal studies.

  9. Hippocampal and amygdalar volumes in dissociative identity disorder.

    Science.gov (United States)

    Vermetten, Eric; Schmahl, Christian; Lindner, Sanneke; Loewenstein, Richard J; Bremner, J Douglas

    2006-04-01

    Smaller hippocampal volume has been reported in several stress-related psychiatric disorders, including posttraumatic stress disorder (PTSD), borderline personality disorder with early abuse, and depression with early abuse. Patients with borderline personality disorder and early abuse have also been found to have smaller amygdalar volume. The authors examined hippocampal and amygdalar volumes in patients with dissociative identity disorder, a disorder that has been associated with a history of severe childhood trauma. The authors used magnetic resonance imaging to measure the volumes of the hippocampus and amygdala in 15 female patients with dissociative identity disorder and 23 female subjects without dissociative identity disorder or any other psychiatric disorder. The volumetric measurements for the two groups were compared. Hippocampal volume was 19.2% smaller and amygdalar volume was 31.6% smaller in the patients with dissociative identity disorder, compared to the healthy subjects. The ratio of hippocampal volume to amygdalar volume was significantly different between groups. The findings are consistent with the presence of smaller hippocampal and amygdalar volumes in patients with dissociative identity disorder, compared with healthy subjects.

  10. SHARP hypofractionated stereotactic radiotherapy is well tolerated in prostate cancer. Toxicity and quality of life assessment

    International Nuclear Information System (INIS)

    Rucinska, Monika; Kieszkowska-Grudny, Anna; Nawrocki, Sergiusz

    2016-01-01

    Quality of life (QoL) is one of the most significant issues in prostate cancer treatment decisions. This study aimed to investigate the toxicity of hypofractionated stereotactic radiotherapy (SBRT) and QoL after treatment in localized prostate cancer patients. A prospective single-center clinical study was performed in low- and intermediate-risk prostate cancer patients. Patients received 33.5 Gy in 5 fractions (SHARP regimen). Acute and late toxicity was assessed according to RTOG/EORTC score. Patients filled out EORTC QLQ-C30 and prostate cancer-specific QLQ-PR25 questionnaires. The analysis included 68 prostate cancer patients (55-83 years, median 73) with clinical stage T1c-T2cN0M0, median combined Gleason score of 6 (3-8), and median prostate-specific antigen (PSA) level of 10 ng/mL (4-20 ng/mL). Neoadjuvant androgen deprivation therapy was given to 52 patients (76.5 %), and stopped in 31 patients (45.5 %) after 6 months; in 21 patients (31 %) after 2-3 years. Average and median follow-up was 24 months (18-45). Median nadir PSA level was 0.03 ng/mL for all patients and 0.6 ng/mL for patients without hormone treatment. No patients had PSA failure. There were no acute grade IV toxicities. One patient (1.5 %) developed grade III and 24 patients (35.3 %) grade II acute bladder toxicity. No one developed grade III and 7 patients (10.3 %) grade II acute rectal toxicity. No grade III or IV late gastrointestinal or genitourinary toxicities were reported. Grade II late urinary symptoms were observed in 8 patients (11.8 %) and gastrointestinal symptoms in 3 patients (4.4 %). Global health status/QoL was good and improved during the observational period. SBRT for prostate cancer patients is a well-tolerated treatment in terms of toxicity and QoL, has no negative impact on functioning and everyday life, with the important benefit of a short treatment period. However, long-term follow-up data are needed. (orig.) [de

  11. Effects of 900 MHz electromagnetic radiation on ultrastructure of rats’ hippocampal neural stem cells in vitro

    OpenAIRE

    Hai-shui LUO; Wei-hua CHU; Zi-bing WAN; Sheng-li HU; Rong HU; Nan WU; Bo HU; Hua FENG; Gang ZHU

    2012-01-01

    Objective To investigate the effect of 900MHz electromagnetic radiation on the ultrastructure of rat hippocampal neural stem cells (NSCs) in vitro in order to provide basic materials for studying the biological effects of electromagnetic wave on the central nervous system. Methods Rat NSCs were divided into sham group, Radi1 group and Radi2 group, and they were respectively exposed to 900 MHz electromagnetic wave at power density of 0, 1, and 3mW/cm2 in vitro. Cells in Radi1 group and Radi2 g...

  12. Do the ball-ended probe cause less damage than sharp explorers?—An ultrastructural analysis

    OpenAIRE

    Mattos-Silveira, Juliana; Oliveira, Marina Monreal; Matos, Ronilza; Moura-Netto, Cacio; Mendes, Fausto Medeiros; Fraga, Mariana Minatel Braga

    2016-01-01

    Abstract Background No evidence about damage caused by ball-ended probes on tooth is available. No study compared probing defects caused by ball-ended probes with sharp explorers during tactile examinations of primary teeth. This exploratory study aimed to compare ultrastructural defects caused by ball-ended probes with sharp explorers during tactile examinations of primary teeth. Me...

  13. Multi-Physics Demonstration Problem with the SHARP Reactor Simulation Toolkit

    Energy Technology Data Exchange (ETDEWEB)

    Merzari, E. [Argonne National Lab. (ANL), Argonne, IL (United States); Shemon, E. R. [Argonne National Lab. (ANL), Argonne, IL (United States); Yu, Y. Q. [Argonne National Lab. (ANL), Argonne, IL (United States); Thomas, J. W. [Argonne National Lab. (ANL), Argonne, IL (United States); Obabko, A. [Argonne National Lab. (ANL), Argonne, IL (United States); Jain, Rajeev [Argonne National Lab. (ANL), Argonne, IL (United States); Mahadevan, Vijay [Argonne National Lab. (ANL), Argonne, IL (United States); Tautges, Timothy [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Solberg, Jerome [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ferencz, Robert Mark [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Whitesides, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-12-21

    This report describes to employ SHARP to perform a first-of-a-kind analysis of the core radial expansion phenomenon in an SFR. This effort required significant advances in the framework Multi-Physics Demonstration Problem with the SHARP Reactor Simulation Toolkit used to drive the coupled simulations, manipulate the mesh in response to the deformation of the geometry, and generate the necessary modified mesh files. Furthermore, the model geometry is fairly complex, and consistent mesh generation for the three physics modules required significant effort. Fully-integrated simulations of a 7-assembly mini-core test problem have been performed, and the results are presented here. Physics models of a full-core model of the Advanced Burner Test Reactor have also been developed for each of the three physics modules. Standalone results of each of the three physics modules for the ABTR are presented here, which provides a demonstration of the feasibility of the fully-integrated simulation.

  14. Study of hydrodynamic characteristics of a Sharp Eagle wave energy converter

    Science.gov (United States)

    Zhang, Ya-qun; Sheng, Song-wei; You, Ya-ge; Huang, Zhen-xin; Wang, Wen-sheng

    2017-06-01

    According to Newton's Second Law and the microwave theory, mechanical analysis of multiple buoys which form Sharp Eagle wave energy converter (WEC) is carried out. The movements of every buoy in three modes couple each other when they are affected with incident waves. Based on the above, mechanical models of the WEC are established, which are concerned with fluid forces, damping forces, hinge forces, and so on. Hydrodynamic parameters of one buoy are obtained by taking the other moving buoy as boundary conditions. Then, by taking those hydrodynamic parameters into the mechanical models, the optimum external damping and optimal capture width ratio are calculated out. Under the condition of the optimum external damping, a plenty of data are obtained, such as the displacements amplitude of each buoy in three modes (sway, heave, pitch), damping forces, hinge forces, and speed of the hydraulic cylinder. Research results provide theoretical references and basis for Sharp Eagle WECs in the design and manufacture.

  15. "Secrets of the female sex": Jane Sharp, the reproductive female body, and early modern midwifery manuals.

    Science.gov (United States)

    Hobby, E

    2001-01-01

    Early modern midwifery manuals in Britain were usually the work of men. These books were a significant source of information about the body to the wider reading public: many sold well, and their prefatory materials include injunctions to readers not to make improper use of them. What is particularly interesting about Jane Sharp's Midwives Book (1671) is that it both provides a compendium of current beliefs concerning reproduction, and indicates the author's ironic perception of the misogyny that underpinned accepted ideas about the female reproductive body. This article gives key examples of Sharp's interventions, and also refers to Thomas Bartholin, Bartholinus Anatomy (1688); Richard Bunworth, The Doctresse (1656); Hugh Chamberlen, The Accomplisht Midwife (1673); The Compleat Midwifes Practice (1656); Helkiah Crooke, Microcosmographia (1615); Nicholas Culpeper, A Directory for Midwives (1651); Jacques Guillemeau, Childbirth (1612); Jean Riolan, A Sure Guide (1657); Daniel Sennert, Practical Physick (1664); William Sermon, The Ladies Companion (1671); and Percival Willughby, Observations in Midwifery (c. 1675).

  16. The 1985 National Aeronautics and Space Administration's Summer High School Apprenticeship Research Program (SHARP)

    Science.gov (United States)

    1985-01-01

    In 1985, a total of 126 talented high school students gained first hand knowledge about science and engineering careers by working directly with a NASA scientist or engineer during the summer. This marked the sixth year of operation for NASA's Summer High School Apprenticeship Research Program (SHARP). The major priority of maintaining the high standards and success of prior years was satisfied. The following eight sites participated in the Program: Ames Research Center, Ames' Dryden Flight Research Facility, Goddard Space Flight Center, Goddard's Wallop Flight Facility, Kennedy Space Center, Langley Research Center, Lewis Research Center, and Marshall Space Flight Center. Tresp Associates served as the SHARP contractor and worked closely with NASA staff at headquarters and the sites just mentioned to plan, implement, and evaluate the program.

  17. Sex steroid hormones matter for learning and memory: estrogenic regulation of hippocampal function in male and female rodents

    Science.gov (United States)

    Kim, Jaekyoon; Tuscher, Jennifer J.; Fortress, Ashley M.

    2015-01-01

    Ample evidence has demonstrated that sex steroid hormones, such as the potent estrogen 17β-estradiol (E2), 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 the effects of E2 on hippocampal spinogenesis, neurogenesis, physiology, and memory, with particular attention paid to the effects of E2 in male rodents. The estrogen receptors, cell-signaling pathways, and epigenetic processes necessary for E2 to enhance memory in female rodents are also discussed in detail. Finally, practical considerations for working with female rodents are described for those investigators thinking of adding females to their experimental designs. PMID:26286657

  18. Aggression Using a Knife or Other Sharp Instruments and Oral-Maxillofacial Traumas: Incidence, Risk Factors, and Epidemiologic Trends.

    Science.gov (United States)

    Santos, Luzia Michelle; Bernardino, Italo M; Ferreira Porto, Alysson Vinicius; Nórbrega Barbosa, Kevan Guilherme; Marques da Nóbrega, Lorena; d'Avila, Sérgio

    2018-01-31

    The aim of the present study was to characterize the profile of victims of interpersonal physical violence (IPV) caused by a knife or other sharp instrument, identify the factors associated with maxillofacial trauma, and examine the incidence of maxillofacial trauma over time. In a retrospective cohort study, we evaluated 569 medicolegal and social records of IPV victims by knife or other sharp instruments treated at a forensic medicine and dentistry center in Brazil during a 4-year consecutive period. The variables investigated were related to the sociodemographic characteristics of the victims, circumstances of the aggression, and trauma patterns. Descriptive and multivariate statistics through Poisson regression and trend analysis with the creation of polynomial regression models were used. The cumulative incidence of oral-maxillofacial trauma was 19.3%. The mean age of the victims was 31.29 ± 13.82 years. Cases of trauma affecting more than one region of the face prevailed (45.5%). Based on the final Poisson regression model, unemployed people were more likely to exhibit maxillofacial trauma (relative risk [RR] 1.86; 95% confidence interval [CI] 1.03-3.35; P = .039). In addition, individuals were more likely to experience maxillofacial trauma on Wednesdays (RR 1.85; 95% CI 1.01-3.37; P = .045). The trend analysis revealed a significant increase in oral-maxillofacial injuries over time (P maxillofacial trauma was high, and the main factors associated with trauma were the victim's employment status and day of occurrence. Future studies will focus on assessing the effect of maxillofacial trauma on the quality of life and well-being of violence victims. Copyright © 2018. Published by Elsevier Inc.

  19. Analysis of image sharpness reproducibility on a novel engineered micro-CT scanner with variable geometry and embedded recalibration software.

    Science.gov (United States)

    Panetta, D; Belcari, N; Del Guerra, A; Bartolomei, A; Salvadori, P A

    2012-04-01

    This study investigates the reproducibility of the reconstructed image sharpness, after modifications of the geometry setup, for a variable magnification micro-CT (μCT) scanner. All the measurements were performed on a novel engineered μCT scanner for in vivo imaging of small animals (Xalt), which has been recently built at the Institute of Clinical Physiology of the National Research Council (IFC-CNR, Pisa, Italy), in partnership with the University of Pisa. The Xalt scanner is equipped with an integrated software for on-line geometric recalibration, which will be used throughout the experiments. In order to evaluate the losses of image quality due to modifications of the geometry setup, we have made 22 consecutive acquisitions by changing alternatively the system geometry between two different setups (Large FoV - LF, and High Resolution - HR). For each acquisition, the tomographic images have been reconstructed before and after the on-line geometric recalibration. For each reconstruction, the image sharpness was evaluated using two different figures of merit: (i) the percentage contrast on a small bar pattern of fixed frequency (f = 5.5 lp/mm for the LF setup and f = 10 lp/mm for the HR setup) and (ii) the image entropy. We have found that, due to the small-scale mechanical uncertainty (in the order of the voxel size), a recalibration is necessary for each geometric setup after repositioning of the system's components; the resolution losses due to the lack of recalibration are worse for the HR setup (voxel size = 18.4 μm). The integrated on-line recalibration algorithm of the Xalt scanner allowed to perform the recalibration quickly, by restoring the spatial resolution of the system to the reference resolution obtained after the initial (off-line) calibration. Copyright © 2011 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  20. Do ward and department managers know their responsibilities in relation to the management of sharps, and is this reflected in the way that they practise sharps management?

    Science.gov (United States)

    Powell, Sheena

    2014-05-01

    Needlestick injuries (NSIs) involving hollowbore needles are the most commonly reported occupational exposure within the healthcare sector in the United Kingdom (HPA, 2012). It is estimated that at least 100,000 NSIs occur each year but due to under-reporting the figure may be much higher (RCN, 2008). Many strategies aimed at preventing NSIs have been implemented in the healthcare environment, including administrative controls, safer work practices and engineering controls, but despite these measures NSIs remain a serious health and safety threat (EU, 2010). New legislation has now been introduced as part of EU Directive 2010/32/EU, which requires UK and all EU member states to bring into force regulations, laws and administrative provisions to further protect healthcare workers from sustaining NSIs (EU Directive, 2010). The aim of this study was to determine the degree of responsibility that NHS ward/department managers felt they have in relation to the prevention and management of NSIs and if this was reflected in the way that they carry out relevant practices in their clinical environment. The study also aimed to identify factors which might impact on the ward/department managers' ability to manage sharps effectively. The study found that although ward/department managers did acknowledge a high degree of responsibility overall for the prevention and management of NSIs, there were some concerns highlighted in relation to certain practices. These included not ensuring that all staff had received up to date training on the safe use and disposal of sharps and not disseminating information on NSI incidences and outcomes to staff in their clinical areas. The findings of this study have the potential to inform and enhance future training and education schedules that relate to NSI prevention and management and to improve the corporate strategic commitment to reducing NSIs across healthcare organisations.