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Sample records for volumes neuronal densities

  1. Cortical cell and neuron density estimates in one chimpanzee hemisphere.

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    Collins, Christine E; Turner, Emily C; Sawyer, Eva Kille; Reed, Jamie L; Young, Nicole A; Flaherty, David K; Kaas, Jon H

    2016-01-19

    The density of cells and neurons in the neocortex of many mammals varies across cortical areas and regions. This variability is, perhaps, most pronounced in primates. Nonuniformity in the composition of cortex suggests regions of the cortex have different specializations. Specifically, regions with densely packed neurons contain smaller neurons that are activated by relatively few inputs, thereby preserving information, whereas regions that are less densely packed have larger neurons that have more integrative functions. Here we present the numbers of cells and neurons for 742 discrete locations across the neocortex in a chimpanzee. Using isotropic fractionation and flow fractionation methods for cell and neuron counts, we estimate that neocortex of one hemisphere contains 9.5 billion cells and 3.7 billion neurons. Primary visual cortex occupies 35 cm(2) of surface, 10% of the total, and contains 737 million densely packed neurons, 20% of the total neurons contained within the hemisphere. Other areas of high neuron packing include secondary visual areas, somatosensory cortex, and prefrontal granular cortex. Areas of low levels of neuron packing density include motor and premotor cortex. These values reflect those obtained from more limited samples of cortex in humans and other primates.

  2. Current Source Density Estimation for Single Neurons

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    Dorottya Cserpán

    2014-03-01

    Full Text Available Recent developments of multielectrode technology made it possible to measure the extracellular potential generated in the neural tissue with spatial precision on the order of tens of micrometers and on submillisecond time scale. Combining such measurements with imaging of single neurons within the studied tissue opens up new experimental possibilities for estimating distribution of current sources along a dendritic tree. In this work we show that if we are able to relate part of the recording of extracellular potential to a specific cell of known morphology we can estimate the spatiotemporal distribution of transmembrane currents along it. We present here an extension of the kernel CSD method (Potworowski et al., 2012 applicable in such case. We test it on several model neurons of progressively complicated morphologies from ball-and-stick to realistic, up to analysis of simulated neuron activity embedded in a substantial working network (Traub et al, 2005. We discuss the caveats and possibilities of this new approach.

  3. Protocol for culturing low density pure rat hippocampal neurons supported by mature mixed neuron cultures.

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    Yang, Qian; Ke, Yini; Luo, Jianhong; Tang, Yang

    2017-02-01

    primary hippocampal neuron cultures allow for subcellular morphological dissection, easy access to drug treatment and electrophysiology analysis of individual neurons, and is therefore an ideal model for the study of neuron physiology. While neuron and glia mixed cultures are relatively easy to prepare, pure neurons are particular hard to culture at low densities which are suitable for morphology studies. This may be due to a lack of neurotrophic factors such as brain derived neurotrophic factor (BDNF), neurotrophin-3 (NT3) and Glial cell line-derived neurotrophic factor (GDNF). In this study we used a two step protocol in which neuron-glia mixed cultures were initially prepared for maturation to support the growth of young neurons plated at very low densities. Our protocol showed that neurotrophic support resulted in physiologically functional hippocampal neurons with larger cell body, increased neurite length and decreased branching and complexity compared to cultures prepared using a conventional method. Our protocol provides a novel way to culture highly uniformed hippocampal neurons for acquiring high quality, neuron based data. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Inhibitory neurons modulate spontaneous signaling in cultured cortical neurons: density-dependent regulation of excitatory neuronal signaling

    International Nuclear Information System (INIS)

    Serra, Michael; Guaraldi, Mary; Shea, Thomas B

    2010-01-01

    Cortical neuronal activity depends on a balance between excitatory and inhibitory influences. Culturing of neurons on multi-electrode arrays (MEAs) has provided insight into the development and maintenance of neuronal networks. Herein, we seeded MEAs with murine embryonic cortical/hippocampal neurons at different densities ( 1000 cells mm −2 ) and monitored resultant spontaneous signaling. Sparsely seeded cultures displayed a large number of bipolar, rapid, high-amplitude individual signals with no apparent temporal regularity. By contrast, densely seeded cultures instead displayed clusters of signals at regular intervals. These patterns were observed even within thinner and thicker areas of the same culture. GABAergic neurons (25% of total neurons in our cultures) mediated the differential signal patterns observed above, since addition of the inhibitory antagonist bicuculline to dense cultures and hippocampal slice cultures induced the signal pattern characteristic of sparse cultures. Sparsely seeded cultures likely lacked sufficient inhibitory neurons to modulate excitatory activity. Differential seeding of MEAs can provide a unique model for analyses of pertubation in the interaction between excitatory and inhibitory function during aging and neuropathological conditions where dysregulation of GABAergic neurons is a significant component

  5. The infant mirror neuron system studied with high density EEG.

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    Nyström, Pär

    2008-01-01

    The mirror neuron system has been suggested to play a role in many social capabilities such as action understanding, imitation, language and empathy. These are all capabilities that develop during infancy and childhood, but the human mirror neuron system has been poorly studied using neurophysiological measures. This study measured the brain activity of 6-month-old infants and adults using a high-density EEG net with the aim of identifying mirror neuron activity. The subjects viewed both goal-directed movements and non-goal-directed movements. An independent component analysis was used to extract the sources of cognitive processes. The desynchronization of the mu rhythm in adults has been shown to be a marker for activation of the mirror neuron system and was used as a criterion to categorize independent components between subjects. The results showed significant mu desynchronization in the adult group and significantly higher ERP activation in both adults and 6-month-olds for the goal-directed action observation condition. This study demonstrate that infants as young as 6 months display mirror neuron activity and is the first to present a direct ERP measure of the mirror neuron system in infants.

  6. A low-density culture method of cerebellar granule neurons with paracrine support applicable for the study of neuronal morphogenesis.

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    Kubota, Kenta; Seno, Takeshi; Konishi, Yoshiyuki

    2013-11-20

    Cerebellar granule neuronal cultures have been used to study the molecular mechanisms underlying neuronal functions, including neuronal morphogenesis. However, a limitation of this system is the difficulty to analyze isolated neurons because these are required to be maintained at a high density. Therefore, in the present study, we aimed to develop a simple and cost-effective method for culturing low-density cerebellar granule neurons. Cerebellar granule cells at two different densities (low- and high-density) were co-cultivated in order for the low-density culture to be supported by the paracrine signals from the high-density culture. This method enabled morphology analysis of isolated cerebellar granule neurons without astrocytic feeder cultures or supplements such as B27. Using this method, we investigated the function of a polarity factor. Studies using hippocampal neurons suggested that glycogen synthase kinase-3 (GSK-3) is an essential regulator of neuronal polarity, and inhibition of GSK-3 results in the formation of multiple axons. Pharmacological inhibitors for GSK-3 (6-bromoindirubin-3'-oxime and lithium chloride) did not cause the formation of multiple axons of cerebellar granule neurons but significantly reduced their length. Consistent results were obtained by introducing kinase-dead form of GSK-3 beta (K85A). These results indicated that GSK-3 is not directly involved in the control of neuronal polarity in cerebellar granule neurons. Overall, this study provides a simple method for culturing low-density cerebellar granule neurons and insights in to the neuronal-type dependent function of GSK-3 in neuronal morphogenesis. © 2013 Elsevier B.V. All rights reserved.

  7. Design-based estimation of neuronal number and individual neuronal volume in the rat hippocampus

    DEFF Research Database (Denmark)

    Hosseini-Sharifabad, Mohammad; Nyengaard, Jens Randel

    2007-01-01

    Tools recently developed in stereology were employed for unbiased estimation of the neuronal number and volume in three major subdivisions of rat hippocampus (dentate granular, CA1 and CA3 pyramidal layers). The optical fractionator is used extensively in quantitative studies of the hippocampus; ...

  8. Osmosensation in vasopressin neurons: changing actin density to optimize function.

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    Prager-Khoutorsky, Masha; Bourque, Charles W

    2010-02-01

    The proportional relation between circulating vasopressin concentration and plasma osmolality is fundamental for body fluid homeostasis. Although changes in the sensitivity of this relation are associated with pathophysiological conditions, central mechanisms modulating osmoregulatory gain are unknown. Here, we review recent data that sheds important light on this process. The cell autonomous osmosensitivity of vasopressin neurons depends on cation channels comprising a variant of the transient receptor potential vanilloid 1 (TRPV1) channel. Hyperosmotic activation is mediated by a mechanical process where sensitivity increases in proportion with actin filament density. Moreover, angiotensin II amplifies osmotic activation by a rapid stimulation of actin polymerization, suggesting that neurotransmitter-induced changes in cytoskeletal organization in osmosensory neurons can mediate central changes in osmoregulatory gain. (c) 2009 Elsevier Ltd. All rights reserved.

  9. Automated computation of arbor densities: a step toward identifying neuronal cell types

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    Uygar eSümbül

    2014-11-01

    Full Text Available The shape and position of a neuron convey information regarding its molecular and functional identity. The identification of cell types from structure, a classic method, relies on the time-consuming step of arbor tracing. However, as genetic tools and imaging methods make data-driven approaches to neuronal circuit analysis feasible, the need for automated processing increases. Here, we first establish that mouse retinal ganglion cell types can be as precise about distributing their arbor volumes across the inner plexiform layer as they are about distributing the skeletons of the arbors. Then, we describe an automated approach to computing the spatial distribution of the dendritic arbors, or arbor density, with respect to a global depth coordinate based on this observation. Our method involves three-dimensional reconstruction of neuronal arbors by a supervised machine learning algorithm, post-processing of the enhanced stacks to remove somata and isolate the neuron of interest, and registration of neurons to each other using automatically detected arbors of the starburst amacrine interneurons as fiducial markers. In principle, this method could be generalizable to other structures of the CNS, provided that they allow sparse labeling of the cells and contain a reliable axis of spatial reference.

  10. Effect of different densities of silver nanoparticles on neuronal growth

    Energy Technology Data Exchange (ETDEWEB)

    Nissan, Ifat [Bar-Ilan University, Department of Chemistry (Israel); Schori, Hadas [Bar-Ilan University, Faculty of Engineering (Israel); Lipovsky, Anat [Bar-Ilan University, Department of Chemistry (Israel); Alon, Noa [Bar-Ilan University, Faculty of Engineering (Israel); Gedanken, Aharon, E-mail: gedanken@biu.ac.il [Bar-Ilan University, Department of Chemistry (Israel); Shefi, Orit, E-mail: orit.shefi@biu.ac.il [Bar-Ilan University, Faculty of Engineering (Israel)

    2016-08-15

    Nerve regeneration has become a subject of great interest, and much effort is devoted to the design and manufacturing of effective biomaterials. In this paper, we report the capability of surfaces coated with silver nanoparticles (AgNPs) to serve as platforms for nerve regeneration. We fabricated substrates coated with silver nanoparticles at different densities using sonochemistry, and grew neuroblastoma cells on the AgNPs. The effect of the different densities on the development of the neurites during the initiation and elongation growth phases was studied. We found that the AgNPs function as favorable anchoring sites for the neuroblastoma cells, significantly enhancing neurite outgrowth. One of the main goals of this study is to test whether the enhanced growth of the neurites is due to the mere presence of AgNPs or whether their topography also plays a vital role. We found that this phenomenon was repeated for all the tested densities, with a maximal effect for the substrates that are coated with 45 NPs/μm{sup 2}. We also studied the amount of reactive oxygen spices (ROS) in the presence of AgNPs as indicator of cell activation. Our results, combined with the well-known antibacterial effects of AgNPs, suggest that substrates coated with AgNP are attractive nanomaterials—with dual activity—for neuronal repair studies and therapeutics.Graphical Abstract.

  11. Higher gamma-aminobutyric acid neuron density in the white matter of orbital frontal cortex in schizophrenia.

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    Joshi, Dipesh; Fung, Samantha J; Rothwell, Alice; Weickert, Cynthia Shannon

    2012-11-01

    In the orbitofrontal cortex (OFC), reduced gray matter volume and reduced glutamic acid decarboxylase 67kDa isoform (GAD67) messenger (m)RNA are found in schizophrenia; however, how these alterations relate to developmental pathology of interneurons is unclear. The present study therefore aimed to determine if increased interstitial white matter neuron (IWMN) density exists in the OFC; whether gamma-aminobutyric acid (GABA)ergic neuron density in OFC white matter was altered; and how IWMN density may be related to an early-expressed inhibitory neuron marker, Dlx1, in OFC gray matter in schizophrenia. IWMN densities were determined (38 schizophrenia and 38 control subjects) for neuronal nuclear antigen (NeuN+) and 65/67 kDa isoform of glutamic acid decarboxylase immunopositive (GAD65/67+) neurons. In situ hybridization was performed to determine Dlx1 and GAD67 mRNA expression in the OFC gray matter. NeuN and GAD65/67 immunopositive cell density was significantly increased in the superficial white matter in schizophrenia. Gray matter Dlx1 and GAD67 mRNA expression were reduced in schizophrenia. Dlx1 mRNA levels were negatively correlated with GAD65/67 IWMN density. Our study provides evidence that pathology of IWMNs in schizophrenia includes GABAergic interneurons and that increased IWMN density may be related to GABAergic deficits in the overlying gray matter. These findings provide evidence at the cellular level that the OFC is a site of pathology in schizophrenia and support the hypothesis that inappropriate migration of cortical inhibitory interneurons occurs in schizophrenia. Copyright © 2012 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  12. Comparative analyses of the neuron numbers and volumes of the amygdaloid complex in old and new world primates.

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    Carlo, C N; Stefanacci, L; Semendeferi, K; Stevens, C F

    2010-04-15

    The amygdaloid complex (AC), a key component of the limbic system, is a brain region critical for the detection and interpretation of emotionally salient information. Therefore, changes in its structure and function are likely to provide correlates of mood and emotion disorders, diseases that afflict a large portion of the human population. Previous gross comparisons of the AC in control and diseased individuals have, however, mainly failed to discover these expected correlations with diseases. We have characterized AC nuclei in different nonhuman primate species to establish a baseline for more refined comparisons between the normal and the diseased amygdala. AC nuclei volume and neuron number in 19 subdivisions are reported from 13 Old and New World primate brains, spanning five primate species, and compared with corresponding data from humans. Analysis of the four largest AC nuclei revealed that volume and neuron number of one component, the central nucleus, has a negative allometric relationship with total amygdala volume and neuron number, which is in contrast with the isometric relationship found in the other AC nuclei (for both neuron number and volume). Neuron density decreases across all four nuclei according to a single power law with an exponent of about minus one-half. Because we have included quantitative comparisons with great apes and humans, our conclusions apply to human brains, and our scaling laws can potentially be used to study the anatomical correlates of the amygdala in disorders involving pathological emotion processing. (c) 2009 Wiley-Liss, Inc.

  13. Correction volumes and densities in Vitrea Program

    International Nuclear Information System (INIS)

    Abrantes, Marcos E.S.; Oliveira, A.H. de

    2014-01-01

    Introduction: with the increased use of 3D reconstruction techniques to assist in diagnosis, Vitrea® program is widely used. To use this program you need to know the correction values to generate the volumes and number of real CT human tissues. Objective: provide correction values for volumes and number of CT, read the Vitrea program, of the tissues generated by DICOM images from CT. Methodology: this study used a PMMA chest phantom to generate the DICOM images on a scanner. To check the calibration of the scanner was used Catphan phantom and compared the manufacturer of the values associated with its straight linearity. Results: the volume of PMMA phantom was of 11166.58 cm³ and CT number (123.5 ± 33.4) UH. For the volume found in Vitrea program, according to the structures of interest, were 11897.29 cm 3 , 10901.65 cm³, 16906.49 cm 3 and 11848.34 cm³ and corrections values are -6.14%, + 2.43% -6.94% -5.75% respectively for the tissues: lung, bone, soft and full. For the CT numbers found in this program were (97.60 ± 58.9) UH, (72.00 ± 176.00) UH, (143.20 ± 19.50) UH and (31.90 ± 239,10) UH and corrections of + 26.54%, + 71.53%, -13.64% and 387.15% respectively for tissues: lung, bone, soft and full. Conclusion: the procedure performed can be used in other 3D reconstruction programs and where there are tools to reading CT number, observing the necessary corrections

  14. Magmatic densities control erupted volumes in Icelandic volcanic systems

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    Hartley, Margaret; Maclennan, John

    2018-04-01

    Magmatic density and viscosity exert fundamental controls on the eruptibility of magmas. In this study, we investigate the extent to which magmatic physical properties control the eruptibility of magmas from Iceland's Northern Volcanic Zone (NVZ). By studying subaerial flows of known age and volume, we are able to directly relate erupted volumes to magmatic physical properties, a task that has been near-impossible when dealing with submarine samples dredged from mid-ocean ridges. We find a strong correlation between magmatic density and observed erupted volumes on the NVZ. Over 85% of the total volume of erupted material lies close to a density and viscosity minimum that corresponds to the composition of basalts at the arrival of plagioclase on the liquidus. These magmas are buoyant with respect to the Icelandic upper crust. However, a number of small-volume eruptions with densities greater than typical Icelandic upper crust are also found in Iceland's neovolcanic zones. We use a simple numerical model to demonstrate that the eruption of magmas with higher densities and viscosities is facilitated by the generation of overpressure in magma chambers in the lower crust and uppermost mantle. This conclusion is in agreement with petrological constraints on the depths of crystallisation under Iceland.

  15. Magmatic Densities Control Erupted Volumes in Icelandic Volcanic Systems

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    Margaret Hartley

    2018-04-01

    Full Text Available Magmatic density and viscosity exert fundamental controls on the eruptibility of magmas. In this study, we investigate the extent to which magmatic physical properties control the eruptibility of magmas from Iceland's Northern Volcanic Zone (NVZ. By studying subaerial flows of known age and volume, we are able to directly relate erupted volumes to magmatic physical properties, a task that has been near-impossible when dealing with submarine samples dredged from mid-ocean ridges. We find a strong correlation between magmatic density and observed erupted volumes on the NVZ. Over 85% of the total volume of erupted material lies close to a density and viscosity minimum that corresponds to the composition of basalts at the arrival of plagioclase on the liquidus. These magmas are buoyant with respect to the Icelandic upper crust. However, a number of small-volume eruptions with densities greater than typical Icelandic upper crust are also found in Iceland's neovolcanic zones. We use a simple numerical model to demonstrate that the eruption of magmas with higher densities and viscosities is facilitated by the generation of overpressure in magma chambers in the lower crust and uppermost mantle. This conclusion is in agreement with petrological constraints on the depths of crystallization under Iceland.

  16. MR Imaging-based Estimation of Upper Motor Neuron Density in Patients with Amyotrophic Lateral Sclerosis: A Feasibility Study.

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    Chen, Jacqueline; Kostenko, Volodymyr; Pioro, Erik P; Trapp, Bruce D

    2018-01-23

    Purpose To determine if magnetic resonance (MR) imaging metrics can estimate primary motor cortex (PMC) motor neuron (MN) density in patients with amyotrophic lateral sclerosis (ALS). Materials and Methods Between 2012 and 2014, in situ brain MR imaging was performed in 11 patients with ALS (age range, 35-81 years; seven women and four men) soon after death (mean, 5.5 hours after death; range, 3.2-9.6 hours). The brain was removed, right PMC (RPMC) was excised, and MN density was quantified. RPMC metrics (thickness, volume, and magnetization transfer ratio) were calculated from MR images. Regression modeling was used to estimate MN density by using RPMC and global MR imaging metrics (brain and tissue volumes); clinical variables were subsequently evaluated as additional estimators. Models were tested at in vivo MR imaging by using the same imaging protocol (six patients with ALS; age range, 54-66 years; three women and three men). Results RPMC mean MN density varied over a greater than threefold range across patients and was estimated by a linear function of normalized gray matter volume (adjusted R 2 = 0.51; P = .008; <10% error in most patients). When considering only sporadic ALS, a linear function of normalized RPMC and white matter volumes estimated MN density (adjusted R 2 = 0.98; P = .01; <10% error in all patients). In vivo data analyses detected decreases in MN density over time. Conclusion PMC mean MN density varies widely in end-stage ALS possibly because of disease heterogeneity. MN density can potentially be estimated by MR imaging metrics. © RSNA, 2018 Online supplemental material is available for this article.

  17. Effect of reinforcement volume fraction on the density & elastic ...

    African Journals Online (AJOL)

    Effect of reinforcement volume fraction on the density & elastic parameters of BMG's matrix composites. Wahiba Metiri 1, Fatiha Hadjoub1, 2 and Leila Touati Tliba 1. 1 Laboratoire des Semi-Conducteurs, Département de Physique, Faculté des Sciences, Université Badji-. Mokhtar, BP 12, Annaba -23000, Algeria.

  18. CREB regulates spine density of lateral amygdala neurons: implications for memory allocation

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    Derya eSargin

    2013-12-01

    Full Text Available Neurons may compete against one another for integration into a memory trace. Specifically, neurons in the lateral nucleus of the amygdala with relatively higher levels of CREB seem to be preferentially allocated to a fear memory trace, while neurons with relatively decreased CREB function seem to be excluded from a fear memory trace. CREB is a ubiquitous transcription factor that modulates many diverse cellular processes, raising the question as to which of these CREB-mediated processes underlie memory allocation. CREB is implicated in modulating dendritic spine number and morphology. As dendritic spines are intimately involved in memory formation, we investigated whether manipulations of CREB function alter spine number or morphology of neurons at the time of fear conditioning. We used viral vectors to manipulate CREB function in the lateral amygdala principal neurons in mice maintained in their homecages. At the time that fear conditioning normally occurs, we observed that neurons with high levels of CREB had more dendritic spines, while neurons with low CREB function had relatively fewer spines compared to control neurons. These results suggest that the modulation of spine density provides a potential mechanism for preferential allocation of a subset of neurons to the memory trace.

  19. Wiring economy and volume exclusion determine neuronal placement in the Drosophila brain.

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    Rivera-Alba, Marta; Vitaladevuni, Shiv N; Mishchenko, Yuriy; Mischenko, Yuriy; Lu, Zhiyuan; Takemura, Shin-Ya; Scheffer, Lou; Meinertzhagen, Ian A; Chklovskii, Dmitri B; de Polavieja, Gonzalo G

    2011-12-06

    Wiring economy has successfully explained the individual placement of neurons in simple nervous systems like that of Caenorhabditis elegans [1-3] and the locations of coarser structures like cortical areas in complex vertebrate brains [4]. However, it remains unclear whether wiring economy can explain the placement of individual neurons in brains larger than that of C. elegans. Indeed, given the greater number of neuronal interconnections in larger brains, simply minimizing the length of connections results in unrealistic configurations, with multiple neurons occupying the same position in space. Avoiding such configurations, or volume exclusion, repels neurons from each other, thus counteracting wiring economy. Here we test whether wiring economy together with volume exclusion can explain the placement of neurons in a module of the Drosophila melanogaster brain known as lamina cartridge [5-13]. We used newly developed techniques for semiautomated reconstruction from serial electron microscopy (EM) [14] to obtain the shapes of neurons, the location of synapses, and the resultant synaptic connectivity. We show that wiring length minimization and volume exclusion together can explain the structure of the lamina microcircuit. Therefore, even in brains larger than that of C. elegans, at least for some circuits, optimization can play an important role in individual neuron placement. Copyright © 2011 Elsevier Ltd. All rights reserved.

  20. Mean expression of the X chromosome is associated with neuronal density

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    James Thomas Swingland

    2012-11-01

    Full Text Available Neurodegenerative diseases are characterised by neuronal loss. Neuronal loss causes a varying density of neurons across samples which confounds results from gene expression studies. Chromosome X is known to be specifically important in brain. We hypothesised the existence of a chromosomal signature of gene expression associated with the X-chromosome for neurological conditions not normally associated with that chromosome. The hypothesis was investigated using microarray datasets from studies on Parkinson's disease, Alzheimer's disease and Huntington's disease. Data were analysed using Chromowave, an analytical tool for detecting spatially extended expression changes across chromosomes. To examine associations with neuronal density, expressions from a set of neuron specific genes were extracted. The association between these genes and the expression patterns extracted by Chromowave was then analyzed. We observed an extended pattern of low expression of ChrX consistent in all the neurodegenerative disease brain datasets. There was a strong correlation between mean ChrX expression and the pattern extracted from the autosomal neuronal specific genes, but no correlation with mean autosomal expression. No chromosomal patterns associated with the neuron specific genes were found on other chromosomes. The chromosomal expression pattern was not present in datasets from blood cells. The ChrX:Autosome expression ratio was also higher in neuronal cells than in tissues with a mix of cell types.The results suggest that a loss of neurons manifests in gene expression experiments primarily as a reduction in mean expression of genes along ChrX. The most likely explanation for this finding relates to the documented general up-regulation of ChrX in brain tissue which, this work suggests, occurs primarily in neurons. The purpose and mechanisms behind this cell specific higher expression warrant further research, which may also help elucidate connectio

  1. Cdk5 Is Essential for Amphetamine to Increase Dendritic Spine Density in Hippocampal Pyramidal Neurons

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    Soledad Ferreras

    2017-11-01

    Full Text Available Psychostimulant drugs of abuse increase dendritic spine density in reward centers of the brain. However, little is known about their effects in the hippocampus, where activity-dependent changes in the density of dendritic spine are associated with learning and memory. Recent reports suggest that Cdk5 plays an important role in drug addiction, but its role in psychostimulant’s effects on dendritic spines in hippocampus remain unknown. We used in vivo and in vitro approaches to demonstrate that amphetamine increases dendritic spine density in pyramidal neurons of the hippocampus. Primary cultures and organotypic slice cultures were used for cellular, molecular, pharmacological and biochemical analyses of the role of Cdk5/p25 in amphetamine-induced dendritic spine formation. Amphetamine (two-injection protocol increased dendritic spine density in hippocampal neurons of thy1-green fluorescent protein (GFP mice, as well as in hippocampal cultured neurons and organotypic slice cultures. Either genetic or pharmacological inhibition of Cdk5 activity prevented the amphetamine–induced increase in dendritic spine density. Amphetamine also increased spine density in neurons overexpressing the strong Cdk5 activator p25. Finally, inhibition of calpain, the protease necessary for the conversion of p35 to p25, prevented amphetamine’s effect on dendritic spine density. We demonstrate, for the first time, that amphetamine increases the density of dendritic spine in hippocampal pyramidal neurons in vivo and in vitro. Moreover, we show that the Cdk5/p25 signaling and calpain activity are both necessary for the effect of amphetamine on dendritic spine density. The identification of molecular mechanisms underlying psychostimulant effects provides novel and promising therapeutic approaches for the treatment of drug addiction.

  2. Developmental Patterns of Doublecortin Expression and White Matter Neuron Density in the Postnatal Primate Prefrontal Cortex and Schizophrenia

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    Fung, Samantha J.; Joshi, Dipesh; Allen, Katherine M.; Sivagnanasundaram, Sinthuja; Rothmond, Debora A.; Saunders, Richard; Noble, Pamela L.; Webster, Maree J.; Shannon Weickert, Cynthia

    2011-01-01

    Postnatal neurogenesis occurs in the subventricular zone and dentate gyrus, and evidence suggests that new neurons may be present in additional regions of the mature primate brain, including the prefrontal cortex (PFC). Addition of new neurons to the PFC implies local generation of neurons or migration from areas such as the subventricular zone. We examined the putative contribution of new, migrating neurons to postnatal cortical development by determining the density of neurons in white matter subjacent to the cortex and measuring expression of doublecortin (DCX), a microtubule-associated protein involved in neuronal migration, in humans and rhesus macaques. We found a striking decline in DCX expression (human and macaque) and density of white matter neurons (humans) during infancy, consistent with the arrival of new neurons in the early postnatal cortex. Considering the expansion of the brain during this time, the decline in white matter neuron density does not necessarily indicate reduced total numbers of white matter neurons in early postnatal life. Furthermore, numerous cells in the white matter and deep grey matter were positive for the migration-associated glycoprotein polysialiated-neuronal cell adhesion molecule and GAD65/67, suggesting that immature migrating neurons in the adult may be GABAergic. We also examined DCX mRNA in the PFC of adult schizophrenia patients (n = 37) and matched controls (n = 37) and did not find any difference in DCX mRNA expression. However, we report a negative correlation between DCX mRNA expression and white matter neuron density in adult schizophrenia patients, in contrast to a positive correlation in human development where DCX mRNA and white matter neuron density are higher earlier in life. Accumulation of neurons in the white matter in schizophrenia would be congruent with a negative correlation between DCX mRNA and white matter neuron density and support the hypothesis of a migration deficit in schizophrenia. PMID

  3. Developmental patterns of doublecortin expression and white matter neuron density in the postnatal primate prefrontal cortex and schizophrenia.

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    Samantha J Fung

    Full Text Available Postnatal neurogenesis occurs in the subventricular zone and dentate gyrus, and evidence suggests that new neurons may be present in additional regions of the mature primate brain, including the prefrontal cortex (PFC. Addition of new neurons to the PFC implies local generation of neurons or migration from areas such as the subventricular zone. We examined the putative contribution of new, migrating neurons to postnatal cortical development by determining the density of neurons in white matter subjacent to the cortex and measuring expression of doublecortin (DCX, a microtubule-associated protein involved in neuronal migration, in humans and rhesus macaques. We found a striking decline in DCX expression (human and macaque and density of white matter neurons (humans during infancy, consistent with the arrival of new neurons in the early postnatal cortex. Considering the expansion of the brain during this time, the decline in white matter neuron density does not necessarily indicate reduced total numbers of white matter neurons in early postnatal life. Furthermore, numerous cells in the white matter and deep grey matter were positive for the migration-associated glycoprotein polysialiated-neuronal cell adhesion molecule and GAD65/67, suggesting that immature migrating neurons in the adult may be GABAergic. We also examined DCX mRNA in the PFC of adult schizophrenia patients (n = 37 and matched controls (n = 37 and did not find any difference in DCX mRNA expression. However, we report a negative correlation between DCX mRNA expression and white matter neuron density in adult schizophrenia patients, in contrast to a positive correlation in human development where DCX mRNA and white matter neuron density are higher earlier in life. Accumulation of neurons in the white matter in schizophrenia would be congruent with a negative correlation between DCX mRNA and white matter neuron density and support the hypothesis of a migration deficit in

  4. Density and volume measurements of reprocessing plant feed

    International Nuclear Information System (INIS)

    Platzer, R.; Carrier, M.; Neuilly, M.; Dedaldechamp, P.

    1985-05-01

    A theoretical study of the phenomenon of gas bubbles formation within a liquid led to an adaptation of the differential pressure bubbling technique for the measurement of liquid levels and densities in tanks. Experiments, carried out on a 800 liters tank with water and uranyl nitrate solutions had the double aim to study the precision attainable on volume and density measurements and to design a method for corrections of influencing factors. In parallel, procedures for transfer of known volumes through the use of siphons and for tank calibration by liquid level measurement are also investigated. The paper presents the first results obtained so far and the conclusions to be drawn for the elaboration of calibration and exploitation procedures suitables for use in reprocessing plants. The demonstration to transfer mass of solution with an accuracy of 0.1% is made [fr

  5. Population density models of integrate-and-fire neurons with jumps: well-posedness.

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    Dumont, Grégory; Henry, Jacques

    2013-09-01

    In this paper we study the well-posedness of different models of population of leaky integrate-and-fire neurons with a population density approach. The synaptic interaction between neurons is modeled by a potential jump at the reception of a spike. We study populations that are self excitatory or self inhibitory. We distinguish the cases where this interaction is instantaneous from the one where there is a repartition of conduction delays. In the case of a bounded density of delays both excitatory and inhibitory population models are shown to be well-posed. But without conduction delay the solution of the model of self excitatory neurons may blow up. We analyze the different behaviours of the model with jumps compared to its diffusion approximation.

  6. Mineral density volume gradients in normal and diseased human tissues.

    Directory of Open Access Journals (Sweden)

    Sabra I Djomehri

    Full Text Available Clinical computed tomography provides a single mineral density (MD value for heterogeneous calcified tissues containing early and late stage pathologic formations. The novel aspect of this study is that, it extends current quantitative methods of mapping mineral density gradients to three dimensions, discretizes early and late mineralized stages, identifies elemental distribution in discretized volumes, and correlates measured MD with respective calcium (Ca to phosphorus (P and Ca to zinc (Zn elemental ratios. To accomplish this, MD variations identified using polychromatic radiation from a high resolution micro-computed tomography (micro-CT benchtop unit were correlated with elemental mapping obtained from a microprobe X-ray fluorescence (XRF using synchrotron monochromatic radiation. Digital segmentation of tomograms from normal and diseased tissues (N=5 per group; 40-60 year old males contained significant mineral density variations (enamel: 2820-3095 mg/cc, bone: 570-1415 mg/cc, cementum: 1240-1340 mg/cc, dentin: 1480-1590 mg/cc, cementum affected by periodontitis: 1100-1220 mg/cc, hypomineralized carious dentin: 345-1450 mg/cc, hypermineralized carious dentin: 1815-2740 mg/cc, and dental calculus: 1290-1770 mg/cc. A plausible linear correlation between segmented MD volumes and elemental ratios within these volumes was established, and Ca/P ratios for dentin (1.49, hypomineralized dentin (0.32-0.46, cementum (1.51, and bone (1.68 were observed. Furthermore, varying Ca/Zn ratios were distinguished in adapted compared to normal tissues, such as in bone (855-2765 and in cementum (595-990, highlighting Zn as an influential element in prompting observed adaptive properties. Hence, results provide insights on mineral density gradients with elemental concentrations and elemental footprints that in turn could aid in elucidating mechanistic processes for pathologic formations.

  7. Mineral Density Volume Gradients in Normal and Diseased Human Tissues

    Science.gov (United States)

    Djomehri, Sabra I.; Candell, Susan; Case, Thomas; Browning, Alyssa; Marshall, Grayson W.; Yun, Wenbing; Lau, S. H.; Webb, Samuel; Ho, Sunita P.

    2015-01-01

    Clinical computed tomography provides a single mineral density (MD) value for heterogeneous calcified tissues containing early and late stage pathologic formations. The novel aspect of this study is that, it extends current quantitative methods of mapping mineral density gradients to three dimensions, discretizes early and late mineralized stages, identifies elemental distribution in discretized volumes, and correlates measured MD with respective calcium (Ca) to phosphorus (P) and Ca to zinc (Zn) elemental ratios. To accomplish this, MD variations identified using polychromatic radiation from a high resolution micro-computed tomography (micro-CT) benchtop unit were correlated with elemental mapping obtained from a microprobe X-ray fluorescence (XRF) using synchrotron monochromatic radiation. Digital segmentation of tomograms from normal and diseased tissues (N=5 per group; 40-60 year old males) contained significant mineral density variations (enamel: 2820-3095mg/cc, bone: 570-1415mg/cc, cementum: 1240-1340mg/cc, dentin: 1480-1590mg/cc, cementum affected by periodontitis: 1100-1220mg/cc, hypomineralized carious dentin: 345-1450mg/cc, hypermineralized carious dentin: 1815-2740mg/cc, and dental calculus: 1290-1770mg/cc). A plausible linear correlation between segmented MD volumes and elemental ratios within these volumes was established, and Ca/P ratios for dentin (1.49), hypomineralized dentin (0.32-0.46), cementum (1.51), and bone (1.68) were observed. Furthermore, varying Ca/Zn ratios were distinguished in adapted compared to normal tissues, such as in bone (855-2765) and in cementum (595-990), highlighting Zn as an influential element in prompting observed adaptive properties. Hence, results provide insights on mineral density gradients with elemental concentrations and elemental footprints that in turn could aid in elucidating mechanistic processes for pathologic formations. PMID:25856386

  8. A unit density method of grain analysis used to identify GABEergic neurons for electron microscopic autoradiographs

    International Nuclear Information System (INIS)

    Burry, R.W.

    1982-01-01

    The distribution of electron microscopic autoradiographic grains over neurons in cerebellar cultures incubated with [ 3 H]gamma-aminobutyric acid ([ 3 H]GABA) was examined. With the unit density method of grain analysis, the number of grains over each structure was tested against the total grain density for the entire section. If an individual structure has a grain density higher than the expected grain density, it is considered one of the group of heavily labeled structures. The expected grain density for each structure is calculated based on the area for that structure, the total grain density and the Poisson distribution. A different expected grain density can be calculated for any P value required. The method provides an adequate population of structures for morphological analysis but excludes weakly labeled structures and thus may underestimate the number of labeled structures. The unit density method of grain analysis showed, as expected, a group of cell bodies and synapses that was labeled heavily. Cultures incubated with other [ 3 H]amino acids did not have any heavily labeled synaptic elements. In addition, serial section analysis of sections showed that synapses heavily labeled with [ 3 H]GABA are seen in adjacent sections. The advantage of the unit density method of grain analysis is that it can be used to separate two groups of metabolically different neurons even when no morphological differences are present. (Auth.)

  9. Information in a Network of Neuronal Cells: Effect of Cell Density and Short-Term Depression

    KAUST Repository

    Onesto, Valentina

    2016-05-10

    Neurons are specialized, electrically excitable cells which use electrical to chemical signals to transmit and elaborate information. Understanding how the cooperation of a great many of neurons in a grid may modify and perhaps improve the information quality, in contrast to few neurons in isolation, is critical for the rational design of cell-materials interfaces for applications in regenerative medicine, tissue engineering, and personalized lab-on-a-chips. In the present paper, we couple an integrate-and-fire model with information theory variables to analyse the extent of information in a network of nerve cells. We provide an estimate of the information in the network in bits as a function of cell density and short-term depression time. In the model, neurons are connected through a Delaunay triangulation of not-intersecting edges; in doing so, the number of connecting synapses per neuron is approximately constant to reproduce the early time of network development in planar neural cell cultures. In simulations where the number of nodes is varied, we observe an optimal value of cell density for which information in the grid is maximized. In simulations in which the posttransmission latency time is varied, we observe that information increases as the latency time decreases and, for specific configurations of the grid, it is largely enhanced in a resonance effect.

  10. Information in a Network of Neuronal Cells: Effect of Cell Density and Short-Term Depression

    Directory of Open Access Journals (Sweden)

    Valentina Onesto

    2016-01-01

    Full Text Available Neurons are specialized, electrically excitable cells which use electrical to chemical signals to transmit and elaborate information. Understanding how the cooperation of a great many of neurons in a grid may modify and perhaps improve the information quality, in contrast to few neurons in isolation, is critical for the rational design of cell-materials interfaces for applications in regenerative medicine, tissue engineering, and personalized lab-on-a-chips. In the present paper, we couple an integrate-and-fire model with information theory variables to analyse the extent of information in a network of nerve cells. We provide an estimate of the information in the network in bits as a function of cell density and short-term depression time. In the model, neurons are connected through a Delaunay triangulation of not-intersecting edges; in doing so, the number of connecting synapses per neuron is approximately constant to reproduce the early time of network development in planar neural cell cultures. In simulations where the number of nodes is varied, we observe an optimal value of cell density for which information in the grid is maximized. In simulations in which the posttransmission latency time is varied, we observe that information increases as the latency time decreases and, for specific configurations of the grid, it is largely enhanced in a resonance effect.

  11. Information in a Network of Neuronal Cells: Effect of Cell Density and Short-Term Depression

    KAUST Repository

    Onesto, Valentina; Cosentino, Carlo; Di Fabrizio, Enzo M.; Cesarelli, Mario; Amato, Francesco; Gentile, Francesco

    2016-01-01

    Neurons are specialized, electrically excitable cells which use electrical to chemical signals to transmit and elaborate information. Understanding how the cooperation of a great many of neurons in a grid may modify and perhaps improve the information quality, in contrast to few neurons in isolation, is critical for the rational design of cell-materials interfaces for applications in regenerative medicine, tissue engineering, and personalized lab-on-a-chips. In the present paper, we couple an integrate-and-fire model with information theory variables to analyse the extent of information in a network of nerve cells. We provide an estimate of the information in the network in bits as a function of cell density and short-term depression time. In the model, neurons are connected through a Delaunay triangulation of not-intersecting edges; in doing so, the number of connecting synapses per neuron is approximately constant to reproduce the early time of network development in planar neural cell cultures. In simulations where the number of nodes is varied, we observe an optimal value of cell density for which information in the grid is maximized. In simulations in which the posttransmission latency time is varied, we observe that information increases as the latency time decreases and, for specific configurations of the grid, it is largely enhanced in a resonance effect.

  12. Transgenic miR132 alters neuronal spine density and impairs novel object recognition memory.

    Directory of Open Access Journals (Sweden)

    Katelin F Hansen

    2010-11-01

    Full Text Available Inducible gene expression plays a central role in neuronal plasticity, learning, and memory, and dysfunction of the underlying molecular events can lead to severe neuronal disorders. In addition to coding transcripts (mRNAs, non-coding microRNAs (miRNAs appear to play a role in these processes. For instance, the CREB-regulated miRNA miR132 has been shown to affect neuronal structure in an activity-dependent manner, yet the details of its physiological effects and the behavioral consequences in vivo remain unclear. To examine these questions, we employed a transgenic mouse strain that expresses miR132 in forebrain neurons. Morphometric analysis of hippocampal neurons revealed that transgenic miR132 triggers a marked increase in dendritic spine density. Additionally, miR132 transgenic mice exhibited a decrease in the expression of MeCP2, a protein implicated in Rett Syndrome and other disorders of mental retardation. Consistent with these findings, miR132 transgenic mice displayed significant deficits in novel object recognition. Together, these data support a role for miR132 as a regulator of neuronal structure and function, and raise the possibility that dysregulation of miR132 could contribute to an array of cognitive disorders.

  13. Neuron density is decreased in the prefrontal cortex in Williams syndrome.

    Science.gov (United States)

    Lew, Caroline Horton; Brown, Chelsea; Bellugi, Ursula; Semendeferi, Katerina

    2017-01-01

    Williams Syndrome (WS) is a rare neurodevelopmental disorder associated with a hemideletion in chromosome 7, which manifests a distinct behavioral phenotype characterized by a hyperaffiliative social drive, in striking contrast to the social avoidance behaviors that are common in Autism Spectrum Disorder (ASD). MRI studies have observed structural and functional abnormalities in WS cortex, including the prefrontal cortex (PFC), a region implicated in social cognition. This study utilizes the Bellugi Williams Syndrome Brain Collection, a unique resource that comprises the largest WS postmortem brain collection in existence, and is the first to quantitatively examine WS PFC cytoarchitecture. We measured neuron density in layers II/III and V/VI of five cortical areas: PFC areas BA 10 and BA 11, primary motor BA 4, primary somatosensory BA 3, and visual area BA 18 in six matched pairs of WS and typically developing (TD) controls. Neuron density in PFC was lower in WS relative to TD, with layers V/VI demonstrating the largest decrease in density, reaching statistical significance in BA 10. In contrast, BA 3 and BA 18 demonstrated a higher density in WS compared to TD, although this difference was not statistically significant. Neuron density in BA 4 was similar in WS and TD. While other cortical areas were altered in WS, prefrontal areas appeared to be most affected. Neuron density is also altered in the PFC of individuals with ASD. Together these findings suggest that the PFC is targeted in neurodevelopmental disorders associated with sociobehavioral alterations. Autism Res 2017, 10: 99-112. © 2016 International Society for Autism Research, Wiley Periodicals, Inc. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.

  14. A NEW RECIPE FOR OBTAINING CENTRAL VOLUME DENSITIES OF PRESTELLAR CORES FROM SIZE MEASUREMENTS

    International Nuclear Information System (INIS)

    Tassis, Konstantinos; Yorke, Harold W.

    2011-01-01

    We propose a simple analytical method for estimating the central volume density of prestellar molecular cloud cores from their column density profiles. Prestellar cores feature a flat central part of the column density and volume density profiles of the same size indicating the existence of a uniform-density inner region. The size of this region is set by the thermal pressure force which depends only on the central volume density and temperature of the core, and can provide a direct measurement of the central volume density. Thus, a simple length measurement can immediately yield a central density estimate independent of any dynamical model for the core and without the need for fitting. Using the radius at which the column density is 90% of the central value as an estimate of the size of the flat inner part of the column density profile yields an estimate of the central volume density within a factor of two for well-resolved cores.

  15. The influence of increased rearing density on medial protocerebral neurosecretory neurons of Lymantria dispar L. caterpillars

    Directory of Open Access Journals (Sweden)

    Ilijin Larisa

    2010-01-01

    Full Text Available Morphometric changes of A1, A1' and A2 protocerebral dorsomedial neurosecretory neurons, total brain protein content and brain protein profiles were analyzed in 4th instar Lymantria dispar larvae under elevated rearing density, i.e. under intense stress when 5 larvae were kept in a petri dish (V = 80 ml, less intense stress when 5 larvae were kept in a plastic cup (V = 300 ml. In the control samples the larvae were reared in isolated conditions. Protein pattern changes in the brain were observed. Proteins with the following molecular masses: 30, 14, 10 and 3.4-2.5 kD were detected in the experimental groups. The size and cytological characteristics of protocerebral dorsomedial neurosecretory neurons were changed under elevated rearing density.

  16. A High Density Electrophysiological Data Analysis System for a Peripheral Nerve Interface Communicating with Individual Neurons in the Brain

    Science.gov (United States)

    2016-11-14

    of-the-art instrumentation to communicate with individual neurons in the brain and the peripheral nervous system. The major theme of the research is...Nerve Interface Communicating with Individual Neurons in the Brain The views, opinions and/or findings contained in this report are those of the author... Communicating with Individual Neurons in the Brain Report Title The high density electrophysiological data acquisition system obtained through this

  17. Porosity, Bulk Density, and Volume Reduction During Drying: Review of Measurement Methods and Coefficient Determinations

    NARCIS (Netherlands)

    Qiu, J.; Khalloufi, S.; Martynenko, A.; Dalen, van G.; Schutyser, M.A.I.; Almeida-Rivera, C.

    2015-01-01

    Several experimental methods for measuring porosity, bulk density and volume reduction during drying of foodstuff are available. These methods include among others geometric dimension, volume displacement, mercury porosimeter, micro-CT, and NMR. However, data on their accuracy, sensitivity, and

  18. Activity of gypsy moth dorsolateral neurosecretory neurons under increased rearing density

    Directory of Open Access Journals (Sweden)

    Mrdaković Marija

    2012-01-01

    Full Text Available Lymantria dispar caterpillars were reared under two different rearing densities for the first three days of the 4th larval instar: 5 larvae that were kept in a Petri dish (V = 80 ml belonged to the intense stress (D1 group; 5 larvae that were kept in a plastic cup (V = 300ml belonged to the group exposed to less intense stress (D2 group. In the control group, single larvae were reared in a Petri dish. Morphometric changes in L1, L2 and L2’ dorsolateral neurosecretory neurons (nsn were analyzed. After keeping 5 larvae in a Petri dish, the size of L2 neurosecretory neurons (nsn significantly increased. Rearing 5 larvae in a plastic cup significantly increased the size of L1 nsn nuclei and the number of L2’nsn. A decrease in relative band densities in the region of molecular masses (11-15 kD that correspond to prothoracicotropic hormones in the gypsy moth was observed in the electrophoretic profiles that were obtained after both treatments in comparison to the control group. [Acknowledgments. This study was supported by the Serbian Ministry of Education and Science (Grant No. 173027.

  19. Discontinuous Galerkin finite element method for solving population density functions of cortical pyramidal and thalamic neuronal populations.

    Science.gov (United States)

    Huang, Chih-Hsu; Lin, Chou-Ching K; Ju, Ming-Shaung

    2015-02-01

    Compared with the Monte Carlo method, the population density method is efficient for modeling collective dynamics of neuronal populations in human brain. In this method, a population density function describes the probabilistic distribution of states of all neurons in the population and it is governed by a hyperbolic partial differential equation. In the past, the problem was mainly solved by using the finite difference method. In a previous study, a continuous Galerkin finite element method was found better than the finite difference method for solving the hyperbolic partial differential equation; however, the population density function often has discontinuity and both methods suffer from a numerical stability problem. The goal of this study is to improve the numerical stability of the solution using discontinuous Galerkin finite element method. To test the performance of the new approach, interaction of a population of cortical pyramidal neurons and a population of thalamic neurons was simulated. The numerical results showed good agreement between results of discontinuous Galerkin finite element and Monte Carlo methods. The convergence and accuracy of the solutions are excellent. The numerical stability problem could be resolved using the discontinuous Galerkin finite element method which has total-variation-diminishing property. The efficient approach will be employed to simulate the electroencephalogram or dynamics of thalamocortical network which involves three populations, namely, thalamic reticular neurons, thalamocortical neurons and cortical pyramidal neurons. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Volume generation of negative ions in high density hydrogen discharges

    International Nuclear Information System (INIS)

    Hiskes, J.R.; Karo, A.M.

    1983-01-01

    A parametric survey is made of a high-density tandem two-chamber hydrogen negative ion system. The optimum extracted negative ion current densities are sensitive to the atom concentration in the discharge and to the system scale length. For scale lengths ranging from 10 cm to 0.1 cm optimum current densities range from of order 1 to 100 mA cm -2 , respectively

  1. Volume regulated anion channel currents of rat hippocampal neurons and their contribution to oxygen-and-glucose deprivation induced neuronal death.

    Directory of Open Access Journals (Sweden)

    Huaqiu Zhang

    2011-02-01

    Full Text Available Volume-regulated anion channels (VRAC are widely expressed chloride channels that are critical for the cell volume regulation. In the mammalian central nervous system, the physiological expression of neuronal VRAC and its role in cerebral ischemia are issues largely unknown. We show that hypoosmotic medium induce an outwardly rectifying chloride conductance in CA1 pyramidal neurons in rat hippocampal slices. The induced chloride conductance was sensitive to some of the VRAC inhibitors, namely, IAA-94 (300 µM and NPPB (100 µM, but not to tamoxifen (10 µM. Using oxygen-and-glucose deprivation (OGD to simulate ischemic conditions in slices, VRAC activation appeared after OGD induced anoxic depolarization (AD that showed a progressive increase in current amplitude over the period of post-OGD reperfusion. The OGD induced VRAC currents were significantly inhibited by inhibitors for glutamate AMPA (30 µM NBQX and NMDA (40 µM AP-5 receptors in the OGD solution, supporting the view that induction of AD requires an excessive Na(+-loading via these receptors that in turn to activate neuronal VRAC. In the presence of NPPB and DCPIB in the post-OGD reperfusion solution, the OGD induced CA1 pyramidal neuron death, as measured by TO-PRO-3-I staining, was significantly reduced, although DCPIB did not appear to be an effective neuronal VRAC blocker. Altogether, we show that rat hippocampal pyramidal neurons express functional VRAC, and ischemic conditions can initial neuronal VRAC activation that may contribute to ischemic neuronal damage.

  2. Neuronal density, size and shape in the human anterior cingulate cortex: a comparison of Nissl and NeuN staining.

    Science.gov (United States)

    Gittins, Rebecca; Harrison, Paul J

    2004-03-15

    There are an increasing number of quantitative morphometric studies of the human cerebral cortex, especially as part of comparative investigations of major psychiatric disorders. In this context, the present study had two aims. First, to provide quantitative data regarding key neuronal morphometric parameters in the anterior cingulate cortex. Second, to compare the results of conventional Nissl staining with those observed after immunostaining with NeuN, an antibody becoming widely used as a selective neuronal marker. We stained adjacent sections of area 24b from 16 adult brains with cresyl violet or NeuN. We measured the density of pyramidal and non-pyramidal neurons, and the size and shape of pyramidal neurons, in laminae II, III, Va, Vb and VI, using two-dimensional counting methods. Strong correlations between the two modes of staining were seen for all variables. However, NeuN gave slightly higher estimates of neuronal density and size, and a more circular perikaryal shape. Brain pH was correlated with neuronal size, measured with both methods, and with neuronal shape. Age and post-mortem interval showed no correlations with any parameter. These data confirm the value of NeuN as a tool for quantitative neuronal morphometric studies in routinely processed human brain tissue. Absolute values are highly correlated between NeuN and cresyl violet stains, but cannot be interchanged. NeuN may be particularly useful when it is important to distinguish small neurons from glia, such as in cytoarchitectural studies of the cerebral cortex in depression and schizophrenia.

  3. Densities and Excess Molar Volume for the Ternary Systems (1 ...

    African Journals Online (AJOL)

    NICO

    2012-09-10

    Sep 10, 2012 ... studied as 'green solvents' for organic reactions, combined with a catalyst to ... The physical properties of ILs such as density, viscosity, melting point, polarity and ... wide electrochemical window, high recyclability, good ionic.

  4. Generator localization by current source density (CSD): Implications of volume conduction and field closure at intracranial and scalp resolutions

    Science.gov (United States)

    Tenke, Craig E.; Kayser, Jürgen

    2012-01-01

    The topographic ambiguity and reference-dependency that has plagued EEG/ERP research throughout its history are largely attributable to volume conduction, which may be concisely described by a vector form of Ohm’s Law. This biophysical relationship is common to popular algorithms that infer neuronal generators via inverse solutions. It may be further simplified as Poisson’s source equation, which identifies underlying current generators from estimates of the second spatial derivative of the field potential (Laplacian transformation). Intracranial current source density (CSD) studies have dissected the “cortical dipole” into intracortical sources and sinks, corresponding to physiologically-meaningful patterns of neuronal activity at a sublaminar resolution, much of which is locally cancelled (i.e., closed field). By virtue of the macroscopic scale of the scalp-recorded EEG, a surface Laplacian reflects the radial projections of these underlying currents, representing a unique, unambiguous measure of neuronal activity at scalp. Although the surface Laplacian requires minimal assumptions compared to complex, model-sensitive inverses, the resulting waveform topographies faithfully summarize and simplify essential constraints that must be placed on putative generators of a scalp potential topography, even if they arise from deep or partially-closed fields. CSD methods thereby provide a global empirical and biophysical context for generator localization, spanning scales from intracortical to scalp recordings. PMID:22796039

  5. Plasma volume methodology: Evans blue, hemoglobin-hematocrit, and mass density transformations

    Science.gov (United States)

    Greenleaf, J. E.; Hinghofer-Szalkay, H.

    1985-01-01

    Methods for measuring absolute levels and changes in plasma volume are presented along with derivations of pertinent equations. Reduction in variability of the Evans blue dye dilution technique using chromatographic column purification suggests that the day-to-day variability in the plasma volume in humans is less than + or - 20 m1. Mass density determination using the mechanical-oscillator technique provides a method for measuring vascular fluid shifts continuously for assessing the density of the filtrate, and for quantifying movements of protein across microvascular walls. Equations for the calculation of volume and density of shifted fluid are presented.

  6. Volume and density changes of biological fluids with temperature

    Science.gov (United States)

    Hinghofer-Szalkay, H.

    1985-01-01

    The thermal expansion of human blood, plasma, ultrafiltrate, and erythrocycte concentration at temperatures in the range of 4-48 C is studied. The mechanical oscillator technique which has an accuracy of 1 x 10 to the -5 th g/ml is utilized to measure fluid density. The relationship between thermal expansion, density, and temperature is analyzed. The study reveals that: (1) thermal expansion increases with increasing temperature; (2) the magnitude of the increase declines with increasing temperature; (3) thermal expansion increases with density at temperatures below 40 C; and (4) the thermal expansion of intracellular fluid is greater than that of extracellular fluid in the temperature range of 4-10 C, but it is equal at temperatures greater than or equal to 40 C.

  7. Molar Volume Analysis of Molten Ni-Al-Co Alloy by Measuring the Density

    Institute of Scientific and Technical Information of China (English)

    XIAO Feng; FANG Liang; FU Yuechao; YANG Lingchuan

    2004-01-01

    The density of molten Ni-Al-Co alloys was measured in the temperature range of 1714~1873K using a modified pycnometric method, and the molar volume of molten alloys was analyzed. The density of molten Ni-Al-Co alloys was found to decrease with increasing temperature and Co concentration in alloys. The molar volume of molten Ni-Al-Co alloys increases with increasing Co concentration in alloys. The molar volume of molten Ni-Al-Co alloys shows a negative deviation from the linear molar volume.

  8. ERK1/2 Activation Is Necessary for BDNF to Increase Dendritic Spine Density in Hippocampal CA1 Pyramidal Neurons

    Science.gov (United States)

    Alonso, Mariana; Medina, Jorge H.; Pozzo-Miller, Lucas

    2004-01-01

    Brain-derived neurotrophic factor (BDNF) is a potent modulator of synaptic transmission and plasticity in the CNS, acting both pre- and postsynaptically. We demonstrated recently that BDNF/TrkB signaling increases dendritic spine density in hippocampal CA1 pyramidal neurons. Here, we tested whether activation of the prominent ERK (MAPK) signaling…

  9. Volume Transmission in Central Dopamine and Noradrenaline Neurons and Its Astroglial Targets.

    Science.gov (United States)

    Fuxe, Kjell; Agnati, Luigi F; Marcoli, Manuela; Borroto-Escuela, Dasiel O

    2015-12-01

    Already in the 1960s the architecture and pharmacology of the brainstem dopamine (DA) and noradrenaline (NA) neurons with formation of vast numbers of DA and NA terminal plexa of the central nervous system (CNS) indicated that they may not only communicate via synaptic transmission. In the 1980s the theory of volume transmission (VT) was introduced as a major communication together with synaptic transmission in the CNS. VT is an extracellular and cerebrospinal fluid transmission of chemical signals like transmitters, modulators etc. moving along energy gradients making diffusion and flow of VT signals possible. VT interacts with synaptic transmission mainly through direct receptor-receptor interactions in synaptic and extrasynaptic heteroreceptor complexes and their signaling cascades. The DA and NA neurons are specialized for extrasynaptic VT at the soma-dendrtitic and terminal level. The catecholamines released target multiple DA and adrenergic subtypes on nerve cells, astroglia and microglia which are the major cell components of the trophic units building up the neural-glial networks of the CNS. DA and NA VT can modulate not only the strength of synaptic transmission but also the VT signaling of the astroglia and microglia of high relevance for neuron-glia interactions. The catecholamine VT targeting astroglia can modulate the fundamental functions of astroglia observed in neuroenergetics, in the Glymphatic system, in the central renin-angiotensin system and in the production of long-distance calcium waves. Also the astrocytic and microglial DA and adrenergic receptor subtypes mediating DA and NA VT can be significant drug targets in neurological and psychiatric disease.

  10. Oligodendrocyte- and Neuron-Specific Nogo-A Restrict Dendritic Branching and Spine Density in the Adult Mouse Motor Cortex.

    Science.gov (United States)

    Zemmar, Ajmal; Chen, Chia-Chien; Weinmann, Oliver; Kast, Brigitt; Vajda, Flora; Bozeman, James; Isaad, Noel; Zuo, Yi; Schwab, Martin E

    2018-06-01

    Nogo-A has been well described as a myelin-associated inhibitor of neurite outgrowth and functional neuroregeneration after central nervous system (CNS) injury. Recently, a new role of Nogo-A has been identified as a negative regulator of synaptic plasticity in the uninjured adult CNS. Nogo-A is present in neurons and oligodendrocytes. However, it is yet unclear which of these two pools regulate synaptic plasticity. To address this question we used newly generated mouse lines in which Nogo-A is specifically knocked out in (1) oligodendrocytes (oligoNogo-A KO) or (2) neurons (neuroNogo-A KO). We show that both oligodendrocyte- and neuron-specific Nogo-A KO mice have enhanced dendritic branching and spine densities in layer 2/3 cortical pyramidal neurons. These effects are compartmentalized: neuronal Nogo-A affects proximal dendrites whereas oligodendrocytic Nogo-A affects distal regions. Finally, we used two-photon laser scanning microscopy to measure the spine turnover rate of adult mouse motor cortex layer 5 cells and find that both Nogo-A KO mouse lines show enhanced spine remodeling after 4 days. Our results suggest relevant control functions of glial as well as neuronal Nogo-A for synaptic plasticity and open new possibilities for more selective and targeted plasticity enhancing strategies.

  11. Neuronal low-density lipoprotein receptor-related protein 1 binds and endocytoses prion fibrils via receptor cluster 4

    DEFF Research Database (Denmark)

    Jen, Angela; Parkyn, Celia J; Mootoosamy, Roy C

    2010-01-01

    For infectious prion protein (designated PrP(Sc)) to act as a template to convert normal cellular protein (PrP(C)) to its distinctive pathogenic conformation, the two forms of prion protein (PrP) must interact closely. The neuronal receptor that rapidly endocytoses PrP(C) is the low......-density lipoprotein receptor-related protein 1 (LRP1). We show here that on sensory neurons LRP1 is also the receptor that binds and rapidly endocytoses smaller oligomeric forms of infectious prion fibrils, and recombinant PrP fibrils. Although LRP1 binds two molecules of most ligands independently to its receptor...... both prion and LRP1 biology....

  12. Millimeter-wave Line Ratios and Sub-beam Volume Density Distributions

    Energy Technology Data Exchange (ETDEWEB)

    Leroy, Adam K.; Gallagher, Molly [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Usero, Antonio [Observatorio Astronmico Nacional (IGN), C/Alfonso XII, 3, E-28014 Madrid (Spain); Schruba, Andreas [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße 1, D-85748 Garching (Germany); Bigiel, Frank [Institute für theoretische Astrophysik, Zentrum für Astronomie der Universität Heidelberg, Albert-Ueberle Str. 2, D-69120 Heidelberg (Germany); Kruijssen, J. M. Diederik; Schinnerer, Eva [Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, Mönchhofstraße 12-14, D-69120 Heidelberg (Germany); Kepley, Amanda [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Blanc, Guillermo A. [Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago (Chile); Bolatto, Alberto D. [Department of Astronomy, Laboratory for Millimeter-wave Astronomy, and Joint Space Institute, University of Maryland, College Park, MD 20742 (United States); Cormier, Diane; Jiménez-Donaire, Maria J. [Max Planck Institute für Astronomie, Königstuhl 17, D-69117, Heidelberg (Germany); Hughes, Annie [CNRS, IRAP, 9 av. du Colonel Roche, BP 44346, F-31028 Toulouse cedex 4 (France); Rosolowsky, Erik [Department of Physics, University of Alberta, Edmonton, AB (Canada)

    2017-02-01

    We explore the use of mm-wave emission line ratios to trace molecular gas density when observations integrate over a wide range of volume densities within a single telescope beam. For observations targeting external galaxies, this case is unavoidable. Using a framework similar to that of Krumholz and Thompson, we model emission for a set of common extragalactic lines from lognormal and power law density distributions. We consider the median density of gas that produces emission and the ability to predict density variations from observed line ratios. We emphasize line ratio variations because these do not require us to know the absolute abundance of our tracers. Patterns of line ratio variations have the potential to illuminate the high-end shape of the density distribution, and to capture changes in the dense gas fraction and median volume density. Our results with and without a high-density power law tail differ appreciably; we highlight better knowledge of the probability density function (PDF) shape as an important area. We also show the implications of sub-beam density distributions for isotopologue studies targeting dense gas tracers. Differential excitation often implies a significant correction to the naive case. We provide tabulated versions of many of our results, which can be used to interpret changes in mm-wave line ratios in terms of adjustments to the underlying density distributions.

  13. Fear extinction deficits following acute stress associate with increased spine density and dendritic retraction in basolateral amygdala neurons.

    Science.gov (United States)

    Maroun, Mouna; Ioannides, Pericles J; Bergman, Krista L; Kavushansky, Alexandra; Holmes, Andrew; Wellman, Cara L

    2013-08-01

    Stress-sensitive psychopathologies such as post-traumatic stress disorder are characterized by deficits in fear extinction and dysfunction of corticolimbic circuits mediating extinction. Chronic stress facilitates fear conditioning, impairs extinction, and produces dendritic proliferation in the basolateral amygdala (BLA), a critical site of plasticity for extinction. Acute stress impairs extinction, alters plasticity in the medial prefrontal cortex-to-BLA circuit, and causes dendritic retraction in the medial prefrontal cortex. Here, we examined extinction learning and basolateral amygdala pyramidal neuron morphology in adult male rats following a single elevated platform stress. Acute stress impaired extinction acquisition and memory, and produced dendritic retraction and increased mushroom spine density in basolateral amygdala neurons in the right hemisphere. Unexpectedly, irrespective of stress, rats that underwent fear and extinction testing showed basolateral amygdala dendritic retraction and altered spine density relative to non-conditioned rats, particularly in the left hemisphere. Thus, extinction deficits produced by acute stress are associated with increased spine density and dendritic retraction in basolateral amygdala pyramidal neurons. Furthermore, the finding that conditioning and extinction as such was sufficient to alter basolateral amygdala morphology and spine density illustrates the sensitivity of basolateral amygdala morphology to behavioral manipulation. These findings may have implications for elucidating the role of the amygdala in the pathophysiology of stress-related disorders. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

  14. Fear extinction deficits following acute stress associate with increased spine density and dendritic retraction in basolateral amygdala neurons

    Science.gov (United States)

    Maroun, Mouna; Ioannides, Pericles J.; Bergman, Krista L.; Kavushansky, Alexandra; Holmes, Andrew; Wellman, Cara L.

    2013-01-01

    Stress-sensitive psychopathologies such as post-traumatic stress disorder are characterized by deficits in fear extinction and dysfunction of corticolimbic circuits mediating extinction. Chronic stress facilitates fear conditioning, impairs extinction, and produces dendritic proliferation in the basolateral amygdala (BLA), a critical site of plasticity for extinction. Acute stress impairs extinction, alters plasticity in the medial prefrontal cortex-to-BLA circuit, and causes dendritic retraction in the medial prefrontal cortex. Here, we examined extinction learning and basolateral amygdala pyramidal neuron morphology in adult male rats following a single elevated platform stress. Acute stress impaired extinction acquisition and memory, and produced dendritic retraction and increased mushroom spine density in basolateral amygdala neurons in the right hemisphere. Unexpectedly, irrespective of stress, rats that underwent fear and extinction testing showed basolateral amygdala dendritic retraction and altered spine density relative to non-conditioned rats, particularly in the left hemisphere. Thus, extinction deficits produced by acute stress are associated with increased spine density and dendritic retraction in basolateral amygdala pyramidal neurons. Furthermore, the finding that conditioning and extinction as such was sufficient to alter basolateral amygdala morphology and spine density illustrates the sensitivity of basolateral amygdala morphology to behavioral manipulation. These findings may have implications for elucidating the role of the amygdala in the pathophysiology of stress-related disorders. PMID:23714419

  15. A principled dimension-reduction method for the population density approach to modeling networks of neurons with synaptic dynamics.

    Science.gov (United States)

    Ly, Cheng

    2013-10-01

    The population density approach to neural network modeling has been utilized in a variety of contexts. The idea is to group many similar noisy neurons into populations and track the probability density function for each population that encompasses the proportion of neurons with a particular state rather than simulating individual neurons (i.e., Monte Carlo). It is commonly used for both analytic insight and as a time-saving computational tool. The main shortcoming of this method is that when realistic attributes are incorporated in the underlying neuron model, the dimension of the probability density function increases, leading to intractable equations or, at best, computationally intensive simulations. Thus, developing principled dimension-reduction methods is essential for the robustness of these powerful methods. As a more pragmatic tool, it would be of great value for the larger theoretical neuroscience community. For exposition of this method, we consider a single uncoupled population of leaky integrate-and-fire neurons receiving external excitatory synaptic input only. We present a dimension-reduction method that reduces a two-dimensional partial differential-integral equation to a computationally efficient one-dimensional system and gives qualitatively accurate results in both the steady-state and nonequilibrium regimes. The method, termed modified mean-field method, is based entirely on the governing equations and not on any auxiliary variables or parameters, and it does not require fine-tuning. The principles of the modified mean-field method have potential applicability to more realistic (i.e., higher-dimensional) neural networks.

  16. The effect of alcoholic extract of Panicum miliaceum L. seed on hippocampus neuronal density in male mouse

    Directory of Open Access Journals (Sweden)

    Arezoo Bornarodi

    2017-08-01

    Full Text Available Background: Hippocampus organization is a part of temporal lobe, which consists of several sections including hippocampal body, dentate gyrus and subiculum. Panicum miliaceum L. contains proteins, vitamins and antioxidants for human health. This study was conducted to examine the effect of the alcoholic extract of the seed of Panicum miliaceum L. plant on hippocampus neuronal density. Materials and Methods: In this experimental study, 24 male mice were divided into 4 groups (n=6, each group. The alcoholic extract of the seed of the Panicum miliaceum L. plant was prepared by soxhlet extraction. Three doses of the extract 25, 50, 75 mg/kg were intraperitoneally injected to 3 treatment groups for 21 days and the control group received normal saline injection. At the end of the experiment, the animals were anesthetized and after perfusion, their brains were removed from the skull. After tissue processing, slices of the brain were prepared and stained. Then, different regions of the hippocampus were photographed and neuronal densities were evaluated. Results: Results showed that the neuronal density in the CA1, CA3 regions of the group treated with 50 mg/kg of the alcoholic extract and in all regions of hippocampus (CA1,CA2,CA3 in groups treated with dose of 75 mg/kg of the alcoholic extract had a significant increase compared to the control group (P<0.05. Conclusion: The present study shows that the alcoholic extract of the seed of Panicum miliaceum L. plant increases neuronal density and induces neurogenesis in the mouse hippocampus.

  17. Stable Density and Dynamics of Dendritic Spines of Cortical Neurons Across the Estrous Cycle While Expressing Differential Levels of Sensory-Evoked Plasticity

    Directory of Open Access Journals (Sweden)

    Bailin H. Alexander

    2018-03-01

    Full Text Available Periodic oscillations of gonadal hormone levels during the estrous cycle exert effects on the female brain, impacting cognition and behavior. While previous research suggests that changes in hormone levels across the cycle affect dendritic spine dynamics in the hippocampus, little is known about the effects on cortical dendritic spines and previous studies showed contradictory results. In this in vivo imaging study, we investigated the impact of the estrous cycle on the density and dynamics of dendritic spines of pyramidal neurons in the primary somatosensory cortex of mice. We also examined if the induction of synaptic plasticity during proestrus, estrus, and metestrus/diestrus had differential effects on the degree of remodeling of synapses in this brain area. We used chronic two-photon excitation (2PE microscopy during steady-state conditions and after evoking synaptic plasticity by whisker stimulation at the different stages of the cycle. We imaged apical dendritic tufts of layer 5 pyramidal neurons of naturally cycling virgin young female mice. Spine density, turnover rate (TOR, survival fraction, morphology, and volume of mushroom spines remained unaltered across the estrous cycle, and the values of these parameters were comparable with those of young male mice. However, while whisker stimulation of female mice during proestrus and estrus resulted in increases in the TOR of spines (74.2 ± 14.9% and 75.1 ± 12.7% vs. baseline, respectively, sensory-evoked plasticity was significantly lower during metestrus/diestrus (32.3 ± 12.8%. In males, whisker stimulation produced 46.5 ± 20% increase in TOR compared with baseline—not significantly different from female mice at any stage of the cycle. These results indicate that, while steady-state density and dynamics of dendritic spines of layer 5 pyramidal neurons in the primary somatosensory cortex of female mice are constant during the estrous cycle, the susceptibility of these neurons to

  18. Density and atomic volume in liquid Al-Fe and Al-Ni binary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Plevachuk, Yu. [Ivan Franko National Univ., Lviv (Ukraine). Dept. of Metal Physics; Egry, I.; Brillo, J.; Holland-Moritz, D. [Deutsches Zentrum fuer Luft- und Raumfahrt, Koeln (Germany). Inst. fuer Raumsimulation; Kaban, I. [Chemnitz Univ. of Technolgy (Germany). Inst. of Physics

    2007-02-15

    The density of liquid Al-Fe and Al-Ni binary alloys have been determined over a wide temperature range by a noncontact technique combining electromagnetic levitation and optical dilatometry. The temperature and composition dependences of the density are analysed. A negative excess volume correlates with the negative enthalpy of mixing, compound forming ability and chemical short-range ordering in liquid Al-Fe and Al-Ni alloys. (orig.)

  19. Reduced astrocyte density underlying brain volume reduction in activity-based anorexia rats

    Science.gov (United States)

    Frintrop, Linda; Liesbrock, Johanna; Paulukat, Lisa; Johann, Sonja; Kas, Martien J; Tolba, Rene; Heussen, Nicole; Neulen, Joseph; Konrad, Kerstin; Herpertz-Dahlmann, Beate; Beyer, Cordian; Seitz, Jochen

    2018-04-01

    Severe grey and white matter volume reductions were found in patients with anorexia nervosa (AN) that were linked to neuropsychological deficits while their underlying pathophysiology remains unclear. For the first time, we analysed the cellular basis of brain volume changes in an animal model (activity-based anorexia, ABA). Female rats had 24 h/day running wheel access and received reduced food intake until a 25% weight reduction was reached and maintained for 2 weeks. In ABA rats, the volumes of the cerebral cortex and corpus callosum were significantly reduced compared to controls by 6% and 9%, respectively. The number of GFAP-positive astrocytes in these regions decreased by 39% and 23%, total astrocyte-covered area by 83% and 63%. In neurons no changes were observed. The findings were complemented by a 60% and 49% reduction in astrocyte (GFAP) mRNA expression. Volumetric brain changes in ABA animals mirror those in human AN patients. These alterations are associated with a reduction of GFAP-positive astrocytes as well as GFAP expression. Reduced astrocyte functioning could help explain neuronal dysfunctions leading to symptoms of rigidity and impaired learning. Astrocyte loss could constitute a new research target for understanding and treating semi-starvation and AN.

  20. Cadherin-13 Deficiency Increases Dorsal Raphe 5-HT Neuron Density and Prefrontal Cortex Innervation in the Mouse Brain

    Directory of Open Access Journals (Sweden)

    Andrea Forero

    2017-09-01

    Full Text Available Background: During early prenatal stages of brain development, serotonin (5-HT-specific neurons migrate through somal translocation to form the raphe nuclei and subsequently begin to project to their target regions. The rostral cluster of cells, comprising the median and dorsal raphe (DR, innervates anterior regions of the brain, including the prefrontal cortex. Differential analysis of the mouse 5-HT system transcriptome identified enrichment of cell adhesion molecules in 5-HT neurons of the DR. One of these molecules, cadherin-13 (Cdh13 has been shown to play a role in cell migration, axon pathfinding, and synaptogenesis. This study aimed to investigate the contribution of Cdh13 to the development of the murine brain 5-HT system.Methods: For detection of Cdh13 and components of the 5-HT system at different embryonic developmental stages of the mouse brain, we employed immunofluorescence protocols and imaging techniques, including epifluorescence, confocal and structured illumination microscopy. The consequence of CDH13 loss-of-function mutations on brain 5-HT system development was explored in a mouse model of Cdh13 deficiency.Results: Our data show that in murine embryonic brain Cdh13 is strongly expressed on 5-HT specific neurons of the DR and in radial glial cells (RGCs, which are critically involved in regulation of neuronal migration. We observed that 5-HT neurons are intertwined with these RGCs, suggesting that these neurons undergo RGC-guided migration. Cdh13 is present at points of intersection between these two cell types. Compared to wildtype controls, Cdh13-deficient mice display increased cell densities in the DR at embryonic stages E13.5, E17.5, and adulthood, and higher serotonergic innervation of the prefrontal cortex at E17.5.Conclusion: Our findings provide evidence for a role of CDH13 in the development of the serotonergic system in early embryonic stages. Specifically, we indicate that Cdh13 deficiency affects the cell

  1. Morphometric analysis of the neuronal numbers and densities of the inferior olivary complex in the donkey (Equus asinus).

    Science.gov (United States)

    Alkafafy, Mohamed; Rashed, Reda; Attia, Hossam

    2011-07-01

    The morphometric interrelations between the compartments of the inferior olivary complex (IOC) in the donkey (Equus asinus) were ascertained by examining serial sections throughout the entire length of the IOC for both sides. Nissl-stained celloidin sections of four brainstems of donkeys were used. The IOC consisted of three major nuclei and four small cell groups. The total neuronal count in both sides of the IOC was 202,040±8480 cells. The medial accessory olivary nucleus (MAO) had the largest relative area (46%) and the highest number of neurons (90,800±7600). The dorsal accessory olivary nucleus (DAO) had the second largest relative area (33%), while the principal olivary nucleus (PO) had the lowest relative area (21%). However, the total neuron count in the PO was larger (60,840±1840) than DAO (50,360±4040). The average neuronal density was 2700±400 cells/mm(3). The numerical values of the current study of the IOC in the donkey were similar to those of other mammals. Copyright © 2010 Elsevier GmbH. All rights reserved.

  2. Impact of particle density and initial volume on mathematical compression models

    DEFF Research Database (Denmark)

    Sonnergaard, Jørn

    2000-01-01

    In the calculation of the coefficients of compression models for powders either the initial volume or the particle density is introduced as a normalising factor. The influence of these normalising factors is, however, widely different on coefficients derived from the Kawakita, Walker and Heckel...... equations. The problems are illustrated by investigations on compaction profiles of 17 materials with different molecular structures and particle densities. It is shown that the particle density of materials with covalent bonds in the Heckel model acts as a key parameter with a dominating influence...

  3. Excess Molar Volumes of (Propiophenone + Toluene) and Estimated Density of Liquid Propiophenone below Its Melting Temperature

    Czech Academy of Sciences Publication Activity Database

    Morávková, Lenka; Linek, Jan

    2006-01-01

    Roč. 38, č. 10 (2006), s. 1240-1244 ISSN 0021-9614 R&D Projects: GA ČR(CZ) GA203/02/1098 Institutional research plan: CEZ:AV0Z40720504 Keywords : density * excess volume * temperature dependence Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.842, year: 2006

  4. Measurement of regional extravascular lung density and of pulmonary blood volume with positron emitting isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Larock, M.P.; Quaglia, L.; Lamotte, D.; De Landsheere, C.; Del Fiore, G.; Chevigne, M.; Peters, J.M.; Rigo, P. (Universite de Liege (Belgium))

    1982-01-01

    Studies of pulmonary blood volume changes with exercise can be performed after labelling of the blood pool by /sup 11/CO inhalation. Positron transaxial tomography permits the quantitative study of density distribution of the chest and of the pulmonary blood volume. This paper represents our preliminary experience with these techniques on models and control patients. We have first verified the linearity of transmission for density distribution below one. The tomographic examination first records a transmission image, then an emission image on the same section. We next normalize emission and transmission values on a region of unit density corresponding to blood: then we substract the emission from the transmission values to measure the extravascular pulmonary density. With crystal probes we record pulmonary blood volume variations before, during and after exercise. Peripheral hemodynamic variations explain the change recorded at the begining and at the end of exercise. Combination of these two techniques should help us to better study the importance of the acute changes in the ''formation'' of pulmonary oedema and its influence on regional pulmonary blood volume.

  5. Volume adjustment of lung density by computed tomography scans in patients with emphysema

    DEFF Research Database (Denmark)

    Shaker, S B; Dirksen, A; Laursen, Lars Christian

    2004-01-01

    of pulmonary emphysema derived from CT scans. These parameters are markedly influenced by changes in the level of inspiration. The variability of lung density due to within-subject variation in TLV was explored by plotting TLV against PD and RA. RESULTS: The coefficients for volume adjustment for PD were...... relatively stable over a wide range from the 10th to the 80th percentile, whereas for RA the coefficients showed large variability especially in the lower range, which is the most relevant for quantitation of pulmonary emphysema. CONCLUSION: Volume adjustment is mandatory in repeated CT densitometry......PURPOSE: To determine how to adjust lung density measurements for the volume of the lung calculated from computed tomography (CT) scans in patients with emphysema. MATERIAL AND METHODS: Fifty patients with emphysema underwent 3 CT scans at 2-week intervals. The scans were analyzed with a software...

  6. Densities, molar volumes, and isobaric expansivities of (d-xylose+hydrochloric acid+water) systems

    International Nuclear Information System (INIS)

    Zhang Qiufen; Yan Zhenning; Wang Jianji; Zhang Hucheng

    2006-01-01

    Densities of (d-xylose+HCl+water) have been measured at temperature in the range (278.15 to 318.15) K as a function of concentration of both d-xylose and hydrochloric acid. The densities have been used to estimate the molar volumes and isobaric expansivity of the ternary solutions. The molar volumes of the ternary solutions vary linearly with mole fraction of d-xylose. The standard partial molar volumes V 2,φ - bar for d-xylose in aqueous solutions of molality (0.2, 0.4, 0.7, 1.1, 1.6, and 2.1) mol.kg -1 HCl have been determined. In the investigated temperature range, the relation: V 2,φ - bar =c 1 +c 2 {(T/K)-273.15} 1/2 , can be used to describe the temperature dependence of the standard partial molar volumes. These results have, in conjunction with the results obtained in water, been used to deduce the standard volumes of transfer, Δ t V - bar , of d-xylose from water to aqueous HCl solutions. An increase in the transfer volume of d-xylose with increasing HCl concentrations has been explained by the stronger interactions of H + with the hydrophilic groups of d-xylose

  7. Volume Adjustment of Lung Density by Computed Tomography Scans in Patients with Emphysema

    International Nuclear Information System (INIS)

    Shaker, S.B.; Dirksen, A.; Laursen, L.C.; Skovgaard, L.T.; Holstein-Rathlou, N.H.

    2004-01-01

    Purpose: To determine how to adjust lung density measurements for the volume of the lung calculated from computed tomography (CT) scans in patients with emphysema. Material and Methods: Fifty patients with emphysema underwent 3 CT scans at 2-week intervals. The scans were analyzed with a software package that detected the lung in contiguous images and subsequently generated a histogram of the pixel attenuation values. The total lung volume (TLV), lung weight, percentile density (PD), and relative area of emphysema (RA) were calculated from this histogram. RA and PD are commonly applied measures of pulmonary emphysema derived from CT scans. These parameters are markedly influenced by changes in the level of inspiration. The variability of lung density due to within-subject variation in TLV was explored by plotting TLV against PD and RA. Results: The coefficients for volume adjustment for PD were relatively stable over a wide range from the 10th to the 80th percentile, whereas for RA the coefficients showed large variability especially in the lower range, which is the most relevant for quantitation of pulmonary emphysema. Conclusion: Volume adjustment is mandatory in repeated CT densitometry and is more robust for PD than for RA. Therefore, PD seems more suitable for monitoring the progression of emphysema

  8. Variations of comoving volume and their effects on the star formation rate density

    Science.gov (United States)

    Kim, Sungeun; Physics and Astronomy, Sejong University, Seoul, Korea (the Republic of).

    2018-01-01

    To build a comprehensive picture of star formation in the universe, we havedeveloped an application to calculate the comoving volume at a specific redshift and visualize the changes of spaceand time. The application is based on the star formation rates of about a few thousands of galaxies and their redshiftvalues. Three dimensional modeling of these galaxies using the redshift, comoving volume, and star formation ratesas input data allows calculation of the star formation rate density corresponding to the redshift. This work issupported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP)(no. 2017037333).

  9. Indirect measurement of lung density and air volume from electrical impedance tomography (EIT) data.

    Science.gov (United States)

    Nebuya, Satoru; Mills, Gary H; Milnes, Peter; Brown, Brian H

    2011-12-01

    This paper describes a method for estimating lung density, air volume and changes in fluid content from a non-invasive measurement of the electrical resistivity of the lungs. Resistivity in Ω m was found by fitting measured electrical impedance tomography (EIT) data to a finite difference model of the thorax. Lung density was determined by comparing the resistivity of the lungs, measured at a relatively high frequency, with values predicted from a published model of lung structure. Lung air volume can then be calculated if total lung weight is also known. Temporal changes in lung fluid content will produce proportional changes in lung density. The method was implemented on EIT data, collected using eight electrodes placed in a single plane around the thorax, from 46 adult male subjects and 36 adult female subjects. Mean lung densities (±SD) of 246 ± 67 and 239 ± 64 kg m(-3), respectively, were obtained. In seven adult male subjects estimates of 1.68 ± 0.30, 3.42 ± 0.49 and 4.40 ± 0.53 l in residual volume, functional residual capacity and vital capacity, respectively, were obtained. Sources of error are discussed. It is concluded that absolute differences in lung density of about 30% and changes over time of less than 30% should be detected using the current technology in normal subjects. These changes would result from approximately 300 ml increase in lung fluid. The method proposed could be used for non-invasive monitoring of total lung air and fluid content in normal subjects but needs to be assessed in patients with lung disease.

  10. Prostate cancer volume associates with preoperative plasma levels of testosterone that independently predicts high grade tumours which show low densities (quotient testosterone/tumour volume

    Directory of Open Access Journals (Sweden)

    Antonio B. Porcaro

    2016-01-01

    Conclusion: The investigation shows that TT relates to volume and grade of PCa; moreover, the density of TT relative to TV inversely associates with rate of increase of cancer that depends on the grade of the tumour.

  11. Adipose tissue depot volume relationships with spinal trabecular bone mineral density in African Americans with diabetes.

    Directory of Open Access Journals (Sweden)

    Gary C Chan

    Full Text Available Changes in select adipose tissue volumes may differentially impact bone mineral density. This study was performed to assess cross-sectional and longitudinal relationships between computed tomography-determined visceral (VAT, subcutaneous (SAT, inter-muscular (IMAT, and pericardial adipose tissue (PAT volumes with respective changes in thoracic vertebral and lumbar vertebral volumetric trabecular bone mineral density (vBMD in African Americans with type 2 diabetes. Generalized linear models were fitted to test relationships between baseline and change in adipose volumes with change in vBMD in 300 African American-Diabetes Heart Study participants; adjustment was performed for age, sex, diabetes duration, study interval, smoking, hypertension, BMI, kidney function, and medications. Participants were 50% female with mean ± SD age 55.1±9.0 years, diabetes duration 10.2±7.2 years, and BMI 34.7±7.7 kg/m2. Over 5.3 ± 1.4 years, mean vBMD decreased in thoracic/lumbar spine, while mean adipose tissue volumes increased in SAT, IMAT, and PAT, but not VAT depots. In fully-adjusted models, changes in lumbar and thoracic vBMD were positively associated with change in SAT (β[SE] 0.045[0.011], p<0.0001; 0.40[0.013], p = 0.002, respectively. Change in thoracic vBMD was positively associated with change in IMAT (p = 0.029 and VAT (p = 0.016; and change in lumbar vBMD positively associated with baseline IMAT (p<0.0001. In contrast, vBMD was not associated with change in PAT. After adjusting for BMI, baseline and change in volumes of select adipose depots were associated with increases in thoracic and lumbar trabecular vBMD in African Americans. Effects of adiposity on trabecular bone appear to be site-specific and related to factors beyond mechanical load.

  12. Thermodynamic analysis of energy density in pressure retarded osmosis: The impact of solution volumes and costs

    International Nuclear Information System (INIS)

    Reimund, Kevin K.

    2015-01-01

    A general method was developed for estimating the volumetric energy efficiency of pressure retarded osmosis via pressure-volume analysis of a membrane process. The resulting model requires only the osmotic pressure, π, and mass fraction, w, of water in the concentrated and dilute feed solutions to estimate the maximum achievable specific energy density, uu, as a function of operating pressure. The model is independent of any membrane or module properties. This method utilizes equilibrium analysis to specify the volumetric mixing fraction of concentrated and dilute solution as a function of operating pressure, and provides results for the total volumetric energy density of similar order to more complex models for the mixing of seawater and riverwater. Within the framework of this analysis, the total volumetric energy density is maximized, for an idealized case, when the operating pressure is π(1+√w -1 ), which is lower than the maximum power density operating pressure, Δπ/2, derived elsewhere, and is a function of the solute osmotic pressure at a given mass fraction. It was also found that a minimum 1.45 kmol of ideal solute is required to produce 1 kWh of energy while a system operating at "maximum power density operating pressure" requires at least 2.9 kmol. Utilizing this methodology, it is possible to examine the effects of volumetric solution cost, operation of a module at various pressure, and operation of a constant pressure module with various feed.

  13. Thermodynamic analysis of energy density in pressure retarded osmosis: The impact of solution volumes and costs

    Energy Technology Data Exchange (ETDEWEB)

    Reimund, Kevin K. [Univ. of Connecticut, Storrs, CT (United States). Dept. of Chemical and Biomolecular Engineering; McCutcheon, Jeffrey R. [Univ. of Connecticut, Storrs, CT (United States). Dept. of Chemical and Biomolecular Engineering; Wilson, Aaron D. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-08-01

    A general method was developed for estimating the volumetric energy efficiency of pressure retarded osmosis via pressure-volume analysis of a membrane process. The resulting model requires only the osmotic pressure, π, and mass fraction, w, of water in the concentrated and dilute feed solutions to estimate the maximum achievable specific energy density, uu, as a function of operating pressure. The model is independent of any membrane or module properties. This method utilizes equilibrium analysis to specify the volumetric mixing fraction of concentrated and dilute solution as a function of operating pressure, and provides results for the total volumetric energy density of similar order to more complex models for the mixing of seawater and riverwater. Within the framework of this analysis, the total volumetric energy density is maximized, for an idealized case, when the operating pressure is π/(1+√w⁻¹), which is lower than the maximum power density operating pressure, Δπ/2, derived elsewhere, and is a function of the solute osmotic pressure at a given mass fraction. It was also found that a minimum 1.45 kmol of ideal solute is required to produce 1 kWh of energy while a system operating at “maximum power density operating pressure” requires at least 2.9 kmol. Utilizing this methodology, it is possible to examine the effects of volumetric solution cost, operation of a module at various pressure, and operation of a constant pressure module with various feed.

  14. Species richness, habitable volume, and species densities in freshwater, the sea, and on land

    Directory of Open Access Journals (Sweden)

    Michael N Dawson

    2012-09-01

    Full Text Available Approximately 0.5–2.0 million eukaryotic species inhabit the seas, whereas 2.0–10.0 million inhabit freshwater or the land. Much has been made of this several-fold difference in species richness but there is little consensus about the causes. Here, I ask a related question: what is the relative density of species in marine and non-marine realms? I use recent estimates of global eukaryotic species richness and published estimates of the areal coverage and depth of habitat for freshwater, marine, and terrestrial biomes. I find that the marine realm harbors ~99.83% of the habitable volume on this planet. Eukaryotic species density of the marine realm is ~3600-fold (i.e., 3-4 orders of magnitude less than that of non-marine environments. Species–volume relationships (SVRs help reconcile actinopterygian fish diversity with global primary productivity and emphasize the interacting roles of abiotic and biotic complexity in shaping patterns of biodiversity in freshwater, the sea, and on land. Comparing SVRs of habitats within and across realms may help resolve the factors and interactions that influence species density.

  15. Market Competition and Density in Liver Transplantation: Relationship to Volume and Outcomes.

    Science.gov (United States)

    Adler, Joel T; Yeh, Heidi; Markmann, James F; Nguyen, Louis L

    2015-08-01

    Liver transplantation centers are unevenly distributed within the Donor Service Areas (DSAs) of the United States. This study assessed how market competition and liver transplantation center density are associated with liver transplantation volume within individual DSAs. We conducted a retrospective cohort study of 53,156 adult liver transplants in 45 DSAs with 110 transplantation centers identified from the Scientific Registry of Transplant Recipients between 2003 and 2012. The following measures were derived annually for each DSA: market competition using the Herfindahl Hirschman Index, transplantation center density by the Average Nearest Neighbor method, liver quality by the Liver Donor Risk Index, and patient risk by the Model for End-Stage Liver Disease. A hierarchical mixed effects negative binomial regression model of the relationship between liver transplants and market factors was created annually. Patient and graft survival were investigated with a Cox proportional hazards model. Transplantation center density was associated with market competition (p market competition (IRR = 1.36; p = 0.02), increased listings (IRR = 1.14; p market variables were associated with increased mortality after transplantation. After controlling for demographic and market factors, a greater concentration of centers was associated with more liver transplants without impacting overall survival. These results warrant additional investigation into the relationship between geospatial factors and liver transplantation volume with consideration for the optimization of scarce resources. Copyright © 2015 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

  16. Cerebral volumes, neuronal integrity and brain inflammation measured by MRI in patients receiving PI monotherapy or triple therapy.

    Science.gov (United States)

    Valero, Ignacio Pérez; Baeza, Alicia Gonzalez; Hernandez-Tamames, Juan Antonio; Monge, Susana; Arnalich, Francisco; Arribas, Jose Ramon

    2014-01-01

    Penetration of protease inhibitors (PI) in the central nervous system (CNS) is limited. Therefore, there are concerns about the capacity of PI monotherapy (MT) to control HIV in CNS and preserve brain integrity. Exploratory case-control study designed to compare neuronal integrity and brain inflammation in HIV-suppressed patients (>2 years) with and without neurocognitive impairment (NI), treated with MT or triple therapy (TT), 3-Tesla cerebral magnetic resonance image (MRI) and spectroscopy (MRS) were used to evaluate neuronal integrity (volume of cerebral structures and MRS levels of N-acetyl-aspartate (NAA)) and brain inflammation (MRS levels of myo-inositol (MI) and choline (CHO)). MRS biomarkers were measured in 4 voxels located in basal ganglia, frontal (2) and parietal lobes. A comprehensive battery of tests (14 tests - 7 domains) was used to diagnose neurocognitive impairment (1). We included 18 neurocognitively impaired patients (MT: 10, TT: 8) and 21 without NI (MT: 9; TT: 12, Table 1). Subset of patients with NI: cerebral volumes and MRS biomarkers were mostly similar between MT and TT with exception of the right cingulate nucleolus volume (MT: 8854±1851 vs TT: 10482±1107 mm(3); p<0.04), CHO levels in basal ganglia (MT: 0.44±0.05 vs TT: 0.37±0.03 MMOL/L; p<0.01) and the NAA levels in parietal lobe (MT: 1.49±0.12 vs 1.70±0.13 MMOL/L; p<0.01). Subset of patients without NI: cerebral volumes and MRS biomarkers were mostly similar between MT and TT with exception of MI levels in frontal lobe (MT: 1.20±0.36 vs 0.81±0.25 MMOL/L; p=0.01). We did not find significant differences in cerebral volumes or MRS biomarkers in most areas of the brain. However, we found higher levels of inflammation and neuronal damage in some brain areas of patients who received MT. This observation has to be taken into caution while we could not adjust our results by potential confounders. Further investigation is needed to confirm these preliminary results.

  17. Neuronal loss, demyelination and volume change in the multiple sclerosis neocortex

    DEFF Research Database (Denmark)

    Carassiti, D; Altmann, D R; Petrova, N

    2017-01-01

    . METHODS: Nine MS and seven control hemispheres were dissected into coronal slices. On sections stained for Giemsa, the cortex was outlined and optical disectors applied using systematic uniform random sampling. Neurons were counted using an oil immersion objective (× 60) following stereological principles...

  18. Bone mineral density across a range of physical activity volumes: NHANES 2007-2010.

    Science.gov (United States)

    Whitfield, Geoffrey P; Kohrt, Wendy M; Pettee Gabriel, Kelley K; Rahbar, Mohammad H; Kohl, Harold W

    2015-02-01

    The association between aerobic physical activity volume and bone mineral density (BMD) is not completely understood. The purpose of this study was to clarify the association between BMD and aerobic activity across a broad range of activity volumes, particularly volumes between those recommended in the 2008 Physical Activity Guidelines for Americans and those of trained endurance athletes. Data from the 2007-2010 National Health and Nutrition Examination Survey were used to quantify the association between reported physical activity and BMD at the lumbar spine and proximal femur across the entire range of activity volumes reported by US adults. Participants were categorized into multiples of the minimum guideline-recommended volume based on reported moderate- and vigorous-intensity leisure activity. Lumbar and proximal femur BMD were assessed with dual-energy x-ray absorptiometry. Among women, multivariable-adjusted linear regression analyses revealed no significant differences in lumbar BMD across activity categories, whereas proximal femur BMD was significantly higher among those who exceeded the guidelines by 2-4 times than those who reported no activity. Among men, multivariable-adjusted BMD at both sites neared its highest values among those who exceeded the guidelines by at least 4 times and was not progressively higher with additional activity. Logistic regression estimating the odds of low BMD generally echoed the linear regression results. The association between physical activity volume and BMD is complex. Among women, exceeding guidelines by 2-4 times may be important for maximizing BMD at the proximal femur, whereas among men, exceeding guidelines by ≥4 times may be beneficial for lumbar and proximal femur BMD.

  19. Models for high cell density bioreactors must consider biomass volume fraction: Cell recycle example.

    Science.gov (United States)

    Monbouquette, H G

    1987-06-01

    Intrinsic models, which take into account biomass volume fraction, must be formulated for adequate simulation of high-biomass-density fermentations with cell recycle. Through comparison of corresponding intrinsic and non-intrinsic models in dimensionless form, constraints for non-intrinsic model usage in terms of biokinetic and fermenter operating parameters can be identified a priori. Analysis of a simple product-inhibition model indicates that the non-intrinsic approach is suitable only when the attainable biomass volume fraction in the fermentation broth is less than about 0.10. Inappropriate application of a non-intrinsic model can lead to gross errors in calculated substrate and product concentrations, substrate conversion, and volumetric productivity.

  20. Models for high cell density bioreactors must consider biomass volume fraction: cell recycle example

    Energy Technology Data Exchange (ETDEWEB)

    Monbouquette, H.G.

    1987-06-01

    Intrinsic models, which take into account biomass volume fraction, must be formulated for adequate simulation of high-biomass-density fermentations with cell recycle. Through comparison of corresponding intrinsic and non-intrinsic models in dimensionless form, constraints for non-intrinsic model usage in terms of biokinetic and fermenter operating parameters can be identified a priori. Analysis of a simple product-inhibition model indicates that the non-intrinsic approach is suitable only when the attainable biomass volume fraction in the fermentation broth is less than about 0.10. Inappropriate application of a non-intrinsic model can lead to gross errors in calculated substrate and product concentrations, substrate conversion, and volumetric productivity. (Refs. 14).

  1. Constraining the supersaturation density equation of state from core-collapse supernova simulations? Excluded volume extension of the baryons

    International Nuclear Information System (INIS)

    Fischer, Tobias

    2016-01-01

    In this article the role of the supersaturation density equation of state (EOS) is explored in simulations of failed core-collapse supernova explosions. Therefore the nuclear EOS is extended via a one-parameter excluded-volume description for baryons, taking into account their finite and increasing volume with increasing density in excess of saturation density. Parameters are selected such that the resulting supernova EOS represent extreme cases, with high pressure variations at supersaturation density which feature extreme stiff and soft EOS variants of the reference case, i.e. without excluded-volume corrections. Unlike in the interior of neutron stars with central densities in excess of several times saturation density, central densities of core-collapse supernovae reach only slightly above saturation density. Hence, the impact of the supersaturation density EOS on the supernova dynamics as well as the neutrino signal is found to be negligible. It is mainly determined from the low- and intermediate-density domain, which is left unmodified within this generalized excluded volume approach. (orig.)

  2. A finite volume method for density driven flows in porous media

    Directory of Open Access Journals (Sweden)

    Hilhorst Danielle

    2013-01-01

    Full Text Available In this paper, we apply a semi-implicit finite volume method for the numerical simulation of density driven flows in porous media; this amounts to solving a nonlinear convection-diffusion parabolic equation for the concentration coupled with an elliptic equation for the pressure. We compute the solutions for two specific problems: a problem involving a rotating interface between salt and fresh water and the classical but difficult Henry’s problem. All solutions are compared to results obtained by running FEflow, a commercial software package for the simulation of groundwater flow, mass and heat transfer in porous media.

  3. Measurement of average density and relative volumes in a dispersed two-phase fluid

    Science.gov (United States)

    Sreepada, Sastry R.; Rippel, Robert R.

    1992-01-01

    An apparatus and a method are disclosed for measuring the average density and relative volumes in an essentially transparent, dispersed two-phase fluid. A laser beam with a diameter no greater than 1% of the diameter of the bubbles, droplets, or particles of the dispersed phase is directed onto a diffraction grating. A single-order component of the diffracted beam is directed through the two-phase fluid and its refraction is measured. Preferably, the refracted beam exiting the fluid is incident upon a optical filter with linearly varing optical density and the intensity of the filtered beam is measured. The invention can be combined with other laser-based measurement systems, e.g., laser doppler anemometry.

  4. The relationships between breast volume, breast dense volume and volumetric breast density with body mass index, body fat mass and ethnicity

    Science.gov (United States)

    Zakariyah, N.; Pathy, N. B.; Taib, N. A. M.; Rahmat, K.; Judy, C. W.; Fadzil, F.; Lau, S.; Ng, K. H.

    2016-03-01

    It has been shown that breast density and obesity are related to breast cancer risk. The aim of this study is to investigate the relationships of breast volume, breast dense volume and volumetric breast density (VBD) with body mass index (BMI) and body fat mass (BFM) for the three ethnic groups (Chinese, Malay and Indian) in Malaysia. We collected raw digital mammograms from 2450 women acquired on three digital mammography systems. The mammograms were analysed using Volpara software to obtain breast volume, breast dense volume and VBD. Body weight, BMI and BFM of the women were measured using a body composition analyser. Multivariable logistic regression was used to determine the independent predictors of increased overall breast volume, breast dense volume and VBD. Indians have highest breast volume and breast dense volume followed by Malays and Chinese. While Chinese are highest in VBD, followed by Malay and Indian. Multivariable analysis showed that increasing BMI and BFM were independent predictors of increased overall breast volume and dense volume. Moreover, BMI and BFM were independently and inversely related to VBD.

  5. Density-viscosity product of small-volume ionic liquid samples using quartz crystal impedance analysis.

    Science.gov (United States)

    McHale, Glen; Hardacre, Chris; Ge, Rile; Doy, Nicola; Allen, Ray W K; MacInnes, Jordan M; Bown, Mark R; Newton, Michael I

    2008-08-01

    Quartz crystal impedance analysis has been developed as a technique to assess whether room-temperature ionic liquids are Newtonian fluids and as a small-volume method for determining the values of their viscosity-density product, rho eta. Changes in the impedance spectrum of a 5-MHz fundamental frequency quartz crystal induced by a water-miscible room-temperature ionic liquid, 1-butyl-3-methylimiclazolium trifluoromethylsulfonate ([C4mim][OTf]), were measured. From coupled frequency shift and bandwidth changes as the concentration was varied from 0 to 100% ionic liquid, it was determined that this liquid provided a Newtonian response. A second water-immiscible ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [C4mim][NTf2], with concentration varied using methanol, was tested and also found to provide a Newtonian response. In both cases, the values of the square root of the viscosity-density product deduced from the small-volume quartz crystal technique were consistent with those measured using a viscometer and density meter. The third harmonic of the crystal was found to provide the closest agreement between the two measurement methods; the pure ionic liquids had the largest difference of approximately 10%. In addition, 18 pure ionic liquids were tested, and for 11 of these, good-quality frequency shift and bandwidth data were obtained; these 12 all had a Newtonian response. The frequency shift of the third harmonic was found to vary linearly with square root of viscosity-density product of the pure ionic liquids up to a value of square root(rho eta) approximately 18 kg m(-2) s(-1/2), but with a slope 10% smaller than that predicted by the Kanazawa and Gordon equation. It is envisaged that the quartz crystal technique could be used in a high-throughput microfluidic system for characterizing ionic liquids.

  6. Layer 5 Pyramidal Neurons' Dendritic Remodeling and Increased Microglial Density in Primary Motor Cortex in a Murine Model of Facial Paralysis

    Science.gov (United States)

    Urrego, Diana; Troncoso, Julieta; Múnera, Alejandro

    2015-01-01

    This work was aimed at characterizing structural changes in primary motor cortex layer 5 pyramidal neurons and their relationship with microglial density induced by facial nerve lesion using a murine facial paralysis model. Adult transgenic mice, expressing green fluorescent protein in microglia and yellow fluorescent protein in projecting neurons, were submitted to either unilateral section of the facial nerve or sham surgery. Injured animals were sacrificed either 1 or 3weeks after surgery. Two-photon excitation microscopy was then used for evaluating both layer 5 pyramidal neurons and microglia in vibrissal primary motor cortex (vM1). It was found that facial nerve lesion induced long-lasting changes in the dendritic morphology of vM1 layer 5 pyramidal neurons and in their surrounding microglia. Dendritic arborization of the pyramidal cells underwent overall shrinkage. Apical dendrites suffered transient shortening while basal dendrites displayed sustained shortening. Moreover, dendrites suffered transient spine pruning. Significantly higher microglial cell density was found surrounding vM1 layer 5 pyramidal neurons after facial nerve lesion with morphological bias towards the activated phenotype. These results suggest that facial nerve lesions elicit active dendrite remodeling due to pyramidal neuron and microglia interaction, which could be the pathophysiological underpinning of some neuropathic motor sequelae in humans. PMID:26064916

  7. Whole-lung volume and density in spirometrically-gated inspiratory and expiratory CT in systemic sclerosis: correlation with static volumes at pulmonary function tests.

    Science.gov (United States)

    Camiciottoli, G; Diciotti, S; Bartolucci, M; Orlandi, I; Bigazzi, F; Matucci-Cerinic, M; Pistolesi, M; Mascalchi, M

    2013-03-01

    Spiral low-dose computed tomography (LDCT) permits to measure whole-lung volume and density in a single breath-hold. To evaluate the agreement between static lung volumes measured with LDCT and pulmonary function test (PFT) and the correlation between the LDCT volumes and lung density in restrictive lung disease. Patients with Systemic Sclerosis (SSc) with (n = 24) and without (n = 16) pulmonary involvement on sequential thin-section CT and patients with chronic obstructive pulmonary disease (COPD)(n = 29) underwent spirometrically-gated LDCT at 90% and 10% of vital capacity to measure inspiratory and expiratory lung volumes and mean lung attenuation (MLA). Total lung capacity and residual volume were measured the same day of CT. Inspiratory [95% limits of agreement (95% LoA)--43.8% and 39.2%] and expiratory (95% LoA -45.8% and 37.1%) lung volumes measured on LDCT and PFT showed poor agreement in SSc patients with pulmonary involvement, whereas they were in substantial agreement (inspiratory 95% LoA -14.1% and 16.1%; expiratory 95% LoA -13.5% and 23%) in SSc patients without pulmonary involvement and in inspiratory scans only (95% LoA -23.1% and 20.9%) of COPD patients. Inspiratory and expiratory LDCT volumes, MLA and their deltas differentiated both SSc patients with or without pulmonary involvement from COPD patients. LDCT lung volumes and density were not correlated in SSc patients with pulmonary involvement, whereas they did correlate in SSc without pulmonary involvement and in COPD patients. In restrictive lung disease due to SSc there is poor agreement between static lung volumes measured using LDCT and PFT and the relationship between volume and density values on CT is altered.

  8. Effect of explant density and medium culture volumes on cassava micropropagation in Temporal Immersion System

    Directory of Open Access Journals (Sweden)

    Milagros Basail

    2003-04-01

    Full Text Available Due to the need of producing high quality planting material available to cassava growers, it has been necessary to look for alternatives in order to increase the efficiancy of in vitro propagation methods and their automation, such as the use of the Temporal Immersion Systems (RITA®. This work was carried out to increase the multiplication coefficient for cassava mass propagation through out Temporal Immersion Systems. The clone ‘CMC-40’ was used. Different medium volumes per explant, and material density per unit at a given Immersion frequency were tested. The highest results were obtained in the 2.8 multiplication coefficient with 20 ml culture medium volume and 3.2 using a density of 40 explants/flask. When the Temporal Immersion System is used with these results, a more efficient method for cassava micropropagation is established and also higher quality vitroplants for the rooting stage and further acclimatization in field conditions are produced. Key Words: Tissue Culture, liquid culture medium, Manihot esculenta Crantz

  9. Density overwrites of internal tumor volumes in intensity modulated proton therapy plans for mobile lung tumors

    Science.gov (United States)

    Botas, Pablo; Grassberger, Clemens; Sharp, Gregory; Paganetti, Harald

    2018-02-01

    The purpose of this study was to investigate internal tumor volume density overwrite strategies to minimize intensity modulated proton therapy (IMPT) plan degradation of mobile lung tumors. Four planning paradigms were compared for nine lung cancer patients. Internal gross tumor volume (IGTV) and internal clinical target volume (ICTV) structures were defined encompassing their respective volumes in every 4DCT phase. The paradigms use different planning CT (pCT) created from the average intensity projection (AIP) of the 4DCT, overwriting the density within the IGTV to account for movement. The density overwrites were: (a) constant filling with 100 HU (C100) or (b) 50 HU (C50), (c) maximum intensity projection (MIP) across phases, and (d) water equivalent path length (WEPL) consideration from beam’s-eye-view. Plans were created optimizing dose-influence matrices calculated with fast GPU Monte Carlo (MC) simulations in each pCT. Plans were evaluated with MC on the 4DCTs using a model of the beam delivery time structure. Dose accumulation was performed using deformable image registration. Interplay effect was addressed applying 10 times rescanning. Significantly less DVH metrics degradation occurred when using MIP and WEPL approaches. Target coverage (D99≥slant 70 Gy(RBE)) was fulfilled in most cases with MIP and WEPL (D{{99}WEPL}=69.2+/- 4.0 Gy (RBE)), keeping dose heterogeneity low (D5-D{{95}WEPL}=3.9+/- 2.0 Gy(RBE)). The mean lung dose was kept lowest by the WEPL strategy, as well as the maximum dose to organs at risk (OARs). The impact on dose levels in the heart, spinal cord and esophagus were patient specific. Overall, the WEPL strategy gives the best performance and should be preferred when using a 3D static geometry for lung cancer IMPT treatment planning. Newly available fast MC methods make it possible to handle long simulations based on 4D data sets to perform studies with high accuracy and efficiency, even prior to individual treatment planning.

  10. Hydrogen bonding interactions between ethylene glycol and water: density, excess molar volume, and spectral study

    Institute of Scientific and Technical Information of China (English)

    ZHANG JianBin; ZHANG PengYan; MA Kai; HAN Fang; CHEN GuoHua; WEI XiongHui

    2008-01-01

    Studies of the density and the excess molar volume of ethylene glycol (EG)-water mixtures were carried out to illustrate the hydrogen bonding interactions of EG with water at different temperatures, The re-sults suggest that a likely complex of 3 ethylene glycol molecules bonding with 4 water molecules in an ethylene glycol-water mixture (EGW) is formed at the maximal excess molar volume, which displays stronger absorption capabilities for SO2 when the concentration of SO2 reaches 400×106 (volume ratio) in the gas phase. Meanwhile, FTIR and UV spectra of EGWs were recorded at various EG concentra-tions to display the hydrogen bonding interactions of EG with water. The FTIR spectra show that the stretching vibrational band of hydroxyl in the EGWs shifts to a lower frequency and the bending vibra-tional band of water shifts to a higher frequency with increasing the EG concentration, respectively. Furthermore, the UV spectra show that the electron transferring band of the hydroxyl oxygen in EG shows red shift with increasing the EG concentration. The frequency shifts in FTIR spectra and the shifts of absorption bands in UV absorption spectra of EGWs are interpreted as the strong hydrogen bonding interactions of the hydrogen atoms in water with the hydroxyl oxygen atoms of EG.

  11. A New Approach to Determine the Density of Liquids and Solids without Measuring Mass and Volume: Introducing the "Solidensimeter"

    Science.gov (United States)

    Kiriktas, Halit; Sahin, Mehmet; Eslek, Sinan; Kiriktas, Irem

    2018-01-01

    This study aims to design a mechanism with which the density of any solid or liquid can be determined without measuring its mass and volume in order to help students comprehend the concept of density more easily. The "solidensimeter" comprises of two scaled and nested glass containers (graduated cylinder or beaker) and sufficient water.…

  12. An autoradiographic method of mapping the distribution and density of monoamine neurons in mouse brain

    International Nuclear Information System (INIS)

    Masuoka, D.T.; Alcaraz, A.F.

    1975-01-01

    A combined in vitro uptake and autoradiographic procedure as an important complement to the histochemical fluorescence method is described. Slabs of fresh mouse brain were incubated with 14 C-NE, 14 C-DA or 14 C-5-HT, freeze-dried, and placed against X-ray film for autoradiography. Catecholamine nerve terminals were labeled by in vitro incubation with 14 C-NE or 14 C-DA. Dopaminergic terminals were labeled by 14 C-NE incubation preceded by desipramine (to block uptake into NE terminals). With 14 C-5-HT incubation, the uptake pattern indicated the possibility that 5-HT nerve terminals were being labeled. Advantages of this method are that it allows the visualization of overall density and distribution of selected monoamine nerve terminals or uptake sites of other putative neurotransmitters in whole coronal or sagittal sections, so that data are obtained from many areas of brain or spinal cord rather than in only those areas preselected for microscopic viewing

  13. VOLUME STUDY WITH HIGH DENSITY OF PARTICLES BASED ON CONTOUR AND CORRELATION IMAGE ANALYSIS

    Directory of Open Access Journals (Sweden)

    Tatyana Yu. Nikolaeva

    2014-11-01

    Full Text Available The subject of study is the techniques of particle statistics evaluation, in particular, processing methods of particle images obtained by coherent illumination. This paper considers the problem of recognition and statistical accounting for individual images of small scattering particles in an arbitrary section of the volume in case of high concentrations. For automatic recognition of focused particles images, a special algorithm for statistical analysis based on contouring and thresholding was used. By means of the mathematical formalism of the scalar diffraction theory, coherent images of the particles formed by the optical system with high numerical aperture were simulated. Numerical testing of the method proposed for the cases of different concentrations and distributions of particles in the volume was performed. As a result, distributions of density and mass fraction of the particles were obtained, and the efficiency of the method in case of different concentrations of particles was evaluated. At high concentrations, the effect of coherent superposition of the particles from the adjacent planes strengthens, which makes it difficult to recognize images of particles using the algorithm considered in the paper. In this case, we propose to supplement the method with calculating the cross-correlation function of particle images from adjacent segments of the volume, and evaluating the ratio between the height of the correlation peak and the height of the function pedestal in the case of different distribution characters. The method of statistical accounting of particles considered in this paper is of practical importance in the study of volume with particles of different nature, for example, in problems of biology and oceanography. Effective work in the regime of high concentrations expands the limits of applicability of these methods for practically important cases and helps to optimize determination time of the distribution character and

  14. Changes in hippocampal volume and neuron number co-occur with memory decline in old homing pigeons (Columba livia).

    Science.gov (United States)

    Coppola, Vincent J; Kanyok, Nate; Schreiber, Austin J; Flaim, Mary E; Bingman, Verner P

    2016-05-01

    The mammalian hippocampus is particularly susceptible to age-related structural changes, which have been used to explain, in part, age-related memory decline. These changes are generally characterized by atrophy (e.g., a decrease in volume and number of synaptic contacts). Recent studies have reported age-related spatial memory deficits in older pigeons similar to those seen in older mammals. However, to date, little is known about any co-occurring changes in the aging avian hippocampal formation (HF). In the current study, it was found that the HF of older pigeons was actually larger and contained more neurons than the HF of younger pigeons, a finding that suggests that the pattern of structural changes during aging in the avian HF is different from that seen in the mammalian hippocampus. A working hypothesis for relating the observed structural changes with spatial-cognitive decline is offered. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. Mitogen-activated protein kinase signaling pathways promote low-density lipoprotein receptor-related protein 1-mediated internalization of beta-amyloid protein in primary cortical neurons.

    Science.gov (United States)

    Yang, Wei-Na; Ma, Kai-Ge; Qian, Yi-Hua; Zhang, Jian-Shui; Feng, Gai-Feng; Shi, Li-Li; Zhang, Zhi-Chao; Liu, Zhao-Hui

    2015-07-01

    Mounting evidence suggests that the pathological hallmarks of Alzheimer's disease (AD) are caused by the intraneuronal accumulation of beta-amyloid protein (Aβ). Reuptake of extracellular Aβ is believed to contribute significantly to the intraneuronal Aβ pool in the early stages of AD. Published reports have claimed that the low-density lipoprotein receptor-related protein 1 (LRP1) mediates Aβ1-42 uptake and lysosomal trafficking in GT1-7 neuronal cells and mouse embryonic fibroblast non-neuronal cells. However, there is no direct evidence supporting the role of LRP1 in Aβ internalization in primary neurons. Our recent study indicated that p38 MAPK and ERK1/2 signaling pathways are involved in regulating α7 nicotinic acetylcholine receptor (α7nAChR)-mediated Aβ1-42 uptake in SH-SY5Y cells. This study was designed to explore the regulation of MAPK signaling pathways on LRP1-mediated Aβ internalization in neurons. We found that extracellular Aβ1-42 oligomers could be internalized into endosomes/lysosomes and mitochondria in cortical neurons. Aβ1-42 and LRP1 were also found co-localized in neurons during Aβ1-42 internalization, and they could form Aβ1-42-LRP1 complex. Knockdown of LRP1 expression significantly decreased neuronal Aβ1-42 internalization. Finally, we identified that p38 MAPK and ERK1/2 signaling pathways regulated the internalization of Aβ1-42 via LRP1. Therefore, these results demonstrated that LRP1, p38 MAPK and ERK1/2 mediated the internalization of Aβ1-42 in neurons and provided evidence that blockade of LRP1 or inhibitions of MAPK signaling pathways might be a potential approach to lowering brain Aβ levels and served a potential therapeutic target for AD. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Accurate polynomial expressions for the density and specific volume of seawater using the TEOS-10 standard

    Science.gov (United States)

    Roquet, F.; Madec, G.; McDougall, Trevor J.; Barker, Paul M.

    2015-06-01

    A new set of approximations to the standard TEOS-10 equation of state are presented. These follow a polynomial form, making it computationally efficient for use in numerical ocean models. Two versions are provided, the first being a fit of density for Boussinesq ocean models, and the second fitting specific volume which is more suitable for compressible models. Both versions are given as the sum of a vertical reference profile (6th-order polynomial) and an anomaly (52-term polynomial, cubic in pressure), with relative errors of ∼0.1% on the thermal expansion coefficients. A 75-term polynomial expression is also presented for computing specific volume, with a better accuracy than the existing TEOS-10 48-term rational approximation, especially regarding the sound speed, and it is suggested that this expression represents a valuable approximation of the TEOS-10 equation of state for hydrographic data analysis. In the last section, practical aspects about the implementation of TEOS-10 in ocean models are discussed.

  17. Implication of volume changes in uranium oxides: A density functional study

    International Nuclear Information System (INIS)

    Szpunar, B.; Szpunar, J.A.; Milman, V.; Goldberg, A.

    2013-01-01

    In severe nuclear accident scenarios (in air environments and high temperatures) UO 2 fuel pellets oxidise to produce uranium oxides with higher oxygen content, e.g., U 4 O 9 or U 3 O 8 . As a first step in investigating the microstructural changes following UO 2 oxidation to hexagonal high temperature phase of U 3 O 8 , density functional quantum mechanical calculations of the structure, elastic properties and electronic structure of U 3 O 8 have been performed. The calculated properties of hexagonal phase of U 3 O 8 are compared to those of the orthorhombic pseudo-hexagonal phase which is stable at room temperature. The total energy technique based on the local density approximation plus Hubbard U as implemented in the CASTEP code is used to investigate changes in the lattice constants. The first-principles calculations predict a 35-42% increase in volume per uranium atom as a result of the transformation from UO 2 to U 3 O 8 , in agreement with experimental data. The implications of this prediction on the linear expansion and fragmentation of fuel are discussed. (authors)

  18. A Mouse Model of Visual Perceptual Learning Reveals Alterations in Neuronal Coding and Dendritic Spine Density in the Visual Cortex.

    Science.gov (United States)

    Wang, Yan; Wu, Wei; Zhang, Xian; Hu, Xu; Li, Yue; Lou, Shihao; Ma, Xiao; An, Xu; Liu, Hui; Peng, Jing; Ma, Danyi; Zhou, Yifeng; Yang, Yupeng

    2016-01-01

    Visual perceptual learning (VPL) can improve spatial vision in normally sighted and visually impaired individuals. Although previous studies of humans and large animals have explored the neural basis of VPL, elucidation of the underlying cellular and molecular mechanisms remains a challenge. Owing to the advantages of molecular genetic and optogenetic manipulations, the mouse is a promising model for providing a mechanistic understanding of VPL. Here, we thoroughly evaluated the effects and properties of VPL on spatial vision in C57BL/6J mice using a two-alternative, forced-choice visual water task. Briefly, the mice underwent prolonged training at near the individual threshold of contrast or spatial frequency (SF) for pattern discrimination or visual detection for 35 consecutive days. Following training, the contrast-threshold trained mice showed an 87% improvement in contrast sensitivity (CS) and a 55% gain in visual acuity (VA). Similarly, the SF-threshold trained mice exhibited comparable and long-lasting improvements in VA and significant gains in CS over a wide range of SFs. Furthermore, learning largely transferred across eyes and stimulus orientations. Interestingly, learning could transfer from a pattern discrimination task to a visual detection task, but not vice versa. We validated that this VPL fully restored VA in adult amblyopic mice and old mice. Taken together, these data indicate that mice, as a species, exhibit reliable VPL. Intrinsic signal optical imaging revealed that mice with perceptual training had higher cut-off SFs in primary visual cortex (V1) than those without perceptual training. Moreover, perceptual training induced an increase in the dendritic spine density in layer 2/3 pyramidal neurons of V1. These results indicated functional and structural alterations in V1 during VPL. Overall, our VPL mouse model will provide a platform for investigating the neurobiological basis of VPL.

  19. A mouse model of visual perceptual learning reveals alterations in neuronal coding and dendritic spine density in the visual cortex

    Directory of Open Access Journals (Sweden)

    Yan eWang

    2016-03-01

    Full Text Available Visual perceptual learning (VPL can improve spatial vision in normally sighted and visually impaired individuals. Although previous studies of humans and large animals have explored the neural basis of VPL, elucidation of the underlying cellular and molecular mechanisms remains a challenge. Owing to the advantages of molecular genetic and optogenetic manipulations, the mouse is a promising model for providing a mechanistic understanding of VPL. Here, we thoroughly evaluated the effects and properties of VPL on spatial vision in C57BL/6J mice using a two-alternative, forced-choice visual water task. Briefly, the mice underwent prolonged training at near the individual threshold of contrast or spatial frequency (SF for pattern discrimination or visual detection for 35 consecutive days. Following training, the contrast-threshold trained mice showed an 87% improvement in contrast sensitivity (CS and a 55% gain in visual acuity (VA. Similarly, the SF-threshold trained mice exhibited comparable and long-lasting improvements in VA and significant gains in CS over a wide range of SFs. Furthermore, learning largely transferred across eyes and stimulus orientations. Interestingly, learning could transfer from a pattern discrimination task to a visual detection task, but not vice versa. We validated that this VPL fully restored VA in adult amblyopic mice and old mice. Taken together, these data indicate that mice, as a species, exhibit reliable VPL. Intrinsic signal optical imaging revealed that mice with perceptual training had higher cut-off SFs in primary visual cortex (V1 than those without perceptual training. Moreover, perceptual training induced an increase in the dendritic spine density in layer 2/3 pyramidal neurons of V1. These results indicated functional and structural alterations in V1 during VPL. Overall, our VPL mouse model will provide a platform for investigating the neurobiological basis of VPL.

  20. A new approach to determine the density of liquids and solids without measuring mass and volume: introducing the solidensimeter

    Science.gov (United States)

    Kiriktaş, Halit; Şahin, Mehmet; Eslek, Sinan; Kiriktaş, İrem

    2018-05-01

    This study aims to design a mechanism with which the density of any solid or liquid can be determined without measuring its mass and volume in order to help students comprehend the concept of density more easily. The solidensimeter comprises of two scaled and nested glass containers (graduated cylinder or beaker) and sufficient water. In this method, the density measurement was made using the Archimedes’ principle stating that an object fully submerged in a liquid displaces the same amount of liquid as its volume, while an object partially submerged or floating displaces the same amount of liquid as its mass. Using this method, the density of any solids or liquids can be determined using a simple mathematical ratio. At the end of the process a mechanism that helps students to comprehend the density topic more easily was designed. The system is easy-to-design, uses low-cost equipment and enables one to determine the density of any solid or liquid without measuring its mass and volume.

  1. Early changes of parotid density and volume predict modifications at the end of therapy and intensity of acute xerostomia

    International Nuclear Information System (INIS)

    Belli, Maria Luisa; Broggi, Sara; Scalco, Elisa; Rizzo, Giovanna; Sanguineti, Giuseppe; Fiorino, Claudio; Cattaneo, Giovanni Mauro; Dinapoli, Nicola; Valentini, Vincenzo; Ricchetti, Francesco

    2014-01-01

    To quantitatively assess the predictive power of early variations of parotid gland volume and density on final changes at the end of therapy and, possibly, on acute xerostomia during IMRT for head-neck cancer. Data of 92 parotids (46 patients) were available. Kinetics of the changes during treatment were described by the daily rate of density (rΔρ) and volume (rΔvol) variation based on weekly diagnostic kVCT images. Correlation between early and final changes was investigated as well as the correlation with prospective toxicity data (CTCAEv3.0) collected weekly during treatment for 24/46 patients. A higher rΔρ was observed during the first compared to last week of treatment (-0,50 vs -0,05HU, p-value = 0.0001). Based on early variations, a good estimation of the final changes may be obtained (Δρ: AUC = 0.82, p = 0.0001; Δvol: AUC = 0.77, p = 0.0001). Both early rΔρ and rΔvol predict a higher ''mean'' acute xerostomia score (≥ median value, 1.57; p-value = 0.01). Median early density rate changes for patients with mean xerostomia score ≥ / 3 /day for rΔρ and rΔvol respectively. Further studies are necessary to definitively assess the potential of early density/volume changes in identifying more sensitive patients at higher risk of experiencing xerostomia. (orig.) [de

  2. Risk Factors for Chronic Subdural Hematoma Recurrence Identified Using Quantitative Computed Tomography Analysis of Hematoma Volume and Density.

    Science.gov (United States)

    Stavrinou, Pantelis; Katsigiannis, Sotirios; Lee, Jong Hun; Hamisch, Christina; Krischek, Boris; Mpotsaris, Anastasios; Timmer, Marco; Goldbrunner, Roland

    2017-03-01

    Chronic subdural hematoma (CSDH), a common condition in elderly patients, presents a therapeutic challenge with recurrence rates of 33%. We aimed to identify specific prognostic factors for recurrence using quantitative analysis of hematoma volume and density. We retrospectively reviewed radiographic and clinical data of 227 CSDHs in 195 consecutive patients who underwent evacuation of the hematoma through a single burr hole, 2 burr holes, or a mini-craniotomy. To examine the relationship between hematoma recurrence and various clinical, radiologic, and surgical factors, we used quantitative image-based analysis to measure the hematoma and trapped air volumes and the hematoma densities. Recurrence of CSDH occurred in 35 patients (17.9%). Multivariate logistic regression analysis revealed that the percentage of hematoma drained and postoperative CSDH density were independent risk factors for recurrence. All 3 evacuation methods were equally effective in draining the hematoma (71.7% vs. 73.7% vs. 71.9%) without observable differences in postoperative air volume captured in the subdural space. Quantitative image analysis provided evidence that percentage of hematoma drained and postoperative CSDH density are independent prognostic factors for subdural hematoma recurrence. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Effects of current density and electrolyte temperature on the volume expansion factor of anodic alumina formed in oxalic acid

    International Nuclear Information System (INIS)

    Zhou, F.; Baron-Wiecheć, A.; Garcia-Vergara, S.J.; Curioni, M.; Habazaki, H.; Skeldon, P.; Thompson, G.E.

    2012-01-01

    The formation of porous anodic alumina in 0.4 M oxalic acid is investigated over a range of current density and electrolyte temperature using sputtering-deposited substrates containing tungsten tracer layers. The findings reveal volume expansion factors and efficiencies of film growth that increase with the increase of the current density and decrease of the temperature. Pore generation by the flow of the anodic alumina in the barrier layer toward the pore walls is proposed to dominate at relatively high current densities (above ∼2 mA cm −2 ), with tungsten tracer species being retained within films. Conversely, losses of tungsten species occur at lower current densities, possibly due to increased field-assisted ejection of Al 3+ ions and/or field-assisted dissolution of the anodic alumina.

  4. Reduced astrocyte density underlying brain volume reduction in activity-based anorexia rats

    NARCIS (Netherlands)

    Frintrop, Linda; Liesbrock, Johanna; Paulukat, Lisa; Johann, Sonja; Kas, Martien J; Tolba, Rene; Heussen, Nicole; Neulen, Joseph; Konrad, Kerstin; Herpertz-Dahlmann, Beate; Beyer, Cordian; Seitz, Jochen

    2017-01-01

    OBJECTIVES: Severe grey and white matter volume reductions were found in patients with anorexia nervosa (AN) that were linked to neuropsychological deficits while their underlying pathophysiology remains unclear. For the first time, we analysed the cellular basis of brain volume changes in an animal

  5. Electrical method for the measurements of volume averaged electron density and effective coupled power to the plasma bulk

    Science.gov (United States)

    Henault, M.; Wattieaux, G.; Lecas, T.; Renouard, J. P.; Boufendi, L.

    2016-02-01

    Nanoparticles growing or injected in a low pressure cold plasma generated by a radiofrequency capacitively coupled capacitive discharge induce strong modifications in the electrical parameters of both plasma and discharge. In this paper, a non-intrusive method, based on the measurement of the plasma impedance, is used to determine the volume averaged electron density and effective coupled power to the plasma bulk. Good agreements are found when the results are compared to those given by other well-known and established methods.

  6. Neuronal factors determining high intelligence.

    Science.gov (United States)

    Dicke, Ursula; Roth, Gerhard

    2016-01-05

    Many attempts have been made to correlate degrees of both animal and human intelligence with brain properties. With respect to mammals, a much-discussed trait concerns absolute and relative brain size, either uncorrected or corrected for body size. However, the correlation of both with degrees of intelligence yields large inconsistencies, because although they are regarded as the most intelligent mammals, monkeys and apes, including humans, have neither the absolutely nor the relatively largest brains. The best fit between brain traits and degrees of intelligence among mammals is reached by a combination of the number of cortical neurons, neuron packing density, interneuronal distance and axonal conduction velocity--factors that determine general information processing capacity (IPC), as reflected by general intelligence. The highest IPC is found in humans, followed by the great apes, Old World and New World monkeys. The IPC of cetaceans and elephants is much lower because of a thin cortex, low neuron packing density and low axonal conduction velocity. By contrast, corvid and psittacid birds have very small and densely packed pallial neurons and relatively many neurons, which, despite very small brain volumes, might explain their high intelligence. The evolution of a syntactical and grammatical language in humans most probably has served as an additional intelligence amplifier, which may have happened in songbirds and psittacids in a convergent manner. © 2015 The Author(s).

  7. Densities, excess molar volumes, and refractive indices of 1,1,2,2-tetrabromoethane and 1-alkanols binary mixtures

    International Nuclear Information System (INIS)

    Al-Hayan, M.N.M.; Al-Bader, Maher A.M.

    2006-01-01

    Densities, excess molar volumes, refractive indices, and changes in refractive index on mixing for (1,1,2,2-tetrabromoethane + 1-pentanol, or 1-hexanol, or 1-heptanol, or 1-octanol, or 1-decanol) have been determined at T = 293.15 K and at T = 303.15 K. The excess molar volumes and changes in refractive index have been fitted to Redlich-Kister polynomials. The effect of the chain length of the 1-alkanol on the excess molar volume and the change in the refractive index of its mixtures with 1,1,2,2-tetrabromoethane are discussed. In addition, the refractive indices are compared with calculated values using mixing rules proposed by several authors, and a good agreement is obtained

  8. Densities, excess molar volumes, and refractive indices of 1,1,2,2-tetrachloroethane and 1-alkanols binary mixtures

    International Nuclear Information System (INIS)

    Al-Hayan, M.N.M.

    2006-01-01

    Densities, excess molar volumes, refractive indices, and changes in refractive index on mixing for 1,1,2,2-tetrachloroethane + 1-pentanol, or 1-hexanol, or 1-heptanol, or 1-octanol, or 1-decanol have been determined at T = (293.15 and 303.15) K. The excess molar volumes and changes in refractive index have been fitted to Redlich-Kister polynomials. The effect of the chain length of the 1-alkanol on the excess molar volume and the change in the refractive index of its mixtures with 1,1,2,2-tetrachloroethane was discussed. In addition, the refractive indices were compared with calculated values using mixing rules proposed by several authors, and a very good agreement was obtained

  9. Volume and density of microglomeruli in the honey bee mushroom bodies do not predict performance on a foraging task.

    Science.gov (United States)

    Van Nest, Byron N; Wagner, Ashley E; Marrs, Glen S; Fahrbach, Susan E

    2017-09-01

    The mushroom bodies (MBs) are insect brain regions important for sensory integration, learning, and memory. In adult worker honey bees (Apis mellifera), the volume of neuropil associated with the MBs is larger in experienced foragers compared with hive bees and less experienced foragers. In addition, the characteristic synaptic structures of the calycal neuropils, the microglomeruli, are larger but present at lower density in 35-day-old foragers relative to 1-day-old workers. Age- and experience-based changes in plasticity of the MBs are assumed to support performance of challenging tasks, but the behavioral consequences of brain plasticity in insects are rarely examined. In this study, foragers were recruited from a field hive to a patch comprising two colors of otherwise identical artificial flowers. Flowers of one color contained a sucrose reward mimicking nectar; flowers of the second were empty. Task difficulty was adjusted by changing flower colors according to the principle of honey bee color vision space. Microglomerular volume and density in the lip (olfactory inputs) and collar (visual inputs) compartments of the MB calyces were analyzed using anti-synapsin I immunolabeling and laser scanning confocal microscopy. Foragers displayed significant variation in microglomerular volume and density, but no correlation was found between these synaptic attributes and foraging performance. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 1057-1071, 2017. © 2017 Wiley Periodicals, Inc.

  10. Low volume undiluted Btk application against heavy gypsy moth population densities in southern Corsica

    Science.gov (United States)

    Robert A. Fusco; Jean-Claude Martin

    2003-01-01

    Low volume undiluted applications of Bacillus thuringiensis are common and efficacious against coniferous forest pests such as pine processionary moth and spruce budworm, but have not been common practice against deciduous forest pests due to coverage issues.

  11. Early changes of parotid density and volume predict modifications at the end of therapy and intensity of acute xerostomia.

    Science.gov (United States)

    Belli, Maria Luisa; Scalco, Elisa; Sanguineti, Giuseppe; Fiorino, Claudio; Broggi, Sara; Dinapoli, Nicola; Ricchetti, Francesco; Valentini, Vincenzo; Rizzo, Giovanna; Cattaneo, Giovanni Mauro

    2014-10-01

    To quantitatively assess the predictive power of early variations of parotid gland volume and density on final changes at the end of therapy and, possibly, on acute xerostomia during IMRT for head-neck cancer. Data of 92 parotids (46 patients) were available. Kinetics of the changes during treatment were described by the daily rate of density (rΔρ) and volume (rΔvol) variation based on weekly diagnostic kVCT images. Correlation between early and final changes was investigated as well as the correlation with prospective toxicity data (CTCAEv3.0) collected weekly during treatment for 24/46 patients. A higher rΔρ was observed during the first compared to last week of treatment (-0,50 vs -0,05HU, p-value = 0.0001). Based on early variations, a good estimation of the final changes may be obtained (Δρ: AUC = 0.82, p = 0.0001; Δvol: AUC = 0.77, p = 0.0001). Both early rΔρ and rΔvol predict a higher "mean" acute xerostomia score (≥ median value, 1.57; p-value = 0.01). Median early density rate changes for patients with mean xerostomia score ≥ / xerostomia is well predicted by higher rΔρ and rΔvol in the first two weeks of treatment: best cut-off values were -0.50 HU/day and -380 mm(3)/day for rΔρ and rΔvol respectively. Further studies are necessary to definitively assess the potential of early density/volume changes in identifying more sensitive patients at higher risk of experiencing xerostomia.

  12. Technical Note: Stored grain volume measurement using a low density point cloud

    Science.gov (United States)

    The mass of stored grain is often determined from volume measurements by crop insurers, government auditors, and stored grain managers conducting inventories. Recent increases in bin size have accentuated the difficulty of accounting for irregularities and variations in surface conditions in calcula...

  13. Low density lipoprotein for oxidation and metabolic studies. Isolation from small volumes of plasma using a tabletop ultracentrifuge.

    Science.gov (United States)

    Himber, J; Bühler, E; Moll, D; Moser, U K

    1995-01-01

    A rapid method is described for the isolation of small volumes of plasma low density lipoprotein (LDL) free of plasma protein contaminants using the TL-100 Tabletop Ultracentrifuge (Beckman). The isolation of LDL was achieved by a 25 min discontinuous gradient density centrifugation between the density range of 1.006 and 1.21 g/ml, recovery of LDL by tube slicing followed by a 90 min flotation step (d = 1.12 g/ml). The purity of LDL and apolipoprotein B100 (apo B100) were monitored by agarose electrophoresis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), radial immunodiffusion and micropreparative fast protein liquid chromatography (FPLC). The ability of LDL oxidation was assessed by following absorbance at 234 nm after addition of copper ions. The functional integrity of the isolated LDL was checked by clearance kinetics after injection of [125I]-labelled LDL in estrogen-treated rats. The additional purification step led to LDL fractions free of protein contamination and left apo B100, alpha-tocopherol and beta-carotene intact. The LDL prepared in this way was free of albumin, as evident from analytic tests and from its enhanced oxidative modification by copper ions. Used for analytical purposes, this method allows LDL preparations from plasma volumes up to 570 microliters. This method is also convenient for metabolic studies in small animals, especially those relating to the determination of kinetic parameters of LDL in which LDL-apo B100 has to be specifically radiolabelled.

  14. Vorinostat positively regulates synaptic plasticity genes expression and spine density in HIV infected neurons: role of nicotine in progression of HIV-associated neurocognitive disorder

    Science.gov (United States)

    2014-01-01

    Background HIV-associated neurocognitive disorder (HAND) is characterized by development of cognitive, behavioral and motor abnormalities, and occurs in approximately 50% of HIV infected individuals. In the United States, the prevalence of cigarette smoking ranges from 35-70% in HIV-infected individuals compared to 20% in general population. Cognitive impairment in heavy cigarette smokers has been well reported. However, the synergistic effects of nicotine and HIV infection and the underlying mechanisms in the development of HAND are unknown. Results In this study, we explored the role of nicotine in the progression of HAND using SK-N-MC, a neuronal cell line. SK-N-MC cells were infected with HIV-1 in the presence or absence of nicotine for 7 days. We observed significant increase in HIV infectivity in SK-N-MC treated with nicotine compared to untreated HIV-infected neuronal cells. HIV and nicotine synergize to significantly dysregulate the expression of synaptic plasticity genes and spine density; with a concomitant increase of HDAC2 levels in SK-N-MC cells. In addition, inhibition of HDAC2 up-regulation with the use of vorinostat resulted in HIV latency breakdown and recovery of synaptic plasticity genes expression and spine density in nicotine/HIV alone and in co-treated SK-N-MC cells. Furthermore, increased eIF2 alpha phosphorylation, which negatively regulates eukaryotic translational process, was observed in HIV alone and in co-treatment with nicotine compared to untreated control and nicotine alone treated SK-N-MC cells. Conclusions These results suggest that nicotine and HIV synergize to negatively regulate the synaptic plasticity gene expression and spine density and this may contribute to the increased risk of HAND in HIV infected smokers. Apart from disrupting latency, vorinostat may be a useful therapeutic to inhibit the negative regulatory effects on synaptic plasticity in HIV infected nicotine abusers. PMID:24886748

  15. Smaller amygdala volume and reduced anterior cingulate gray matter density associated with history of post-traumatic stress disorder.

    Science.gov (United States)

    Rogers, Mark A; Yamasue, Hidenori; Abe, Osamu; Yamada, Haruyasu; Ohtani, Toshiyuki; Iwanami, Akira; Aoki, Shigeki; Kato, Nobumasa; Kasai, Kiyoto

    2009-12-30

    Although post-traumatic stress disorder (PTSD) may be seen to represent a failure to extinguish learned fear, significant aspects of the pathophysiology relevant to this hypothesis remain unknown. Both the amygdala and hippocampus are necessary for fear extinction occur, and thus both regions may be abnormal in PTSD. Twenty-five people who experienced the Tokyo subway sarin attack in 1995, nine who later developed PTSD and 16 who did not, underwent magnetic resonance imaging (MRI) with manual tracing to determine bilateral amygdala and hippocampus volumes. At the time of scanning, one had PTSD and eight had a history of PTSD. Results indicated that the group with a history of PTSD had significantly smaller mean bilateral amygdala volume than did the group that did not develop PTSD. Furthermore, left amygdala volume showed a significant negative correlation with severity of PTSD symptomatology as well as reduced gray matter density in the left anterior cingulate cortex. To our knowledge, this is the first observation of an association between PTSD and amygdala volume. Furthermore the apparent interplay between amygdala and anterior cingulate cortex represents support at the level of gross brain morphology for the theory of PTSD as a failure of fear extinction.

  16. Fast Computation of Solvation Free Energies with Molecular Density Functional Theory: Thermodynamic-Ensemble Partial Molar Volume Corrections.

    Science.gov (United States)

    Sergiievskyi, Volodymyr P; Jeanmairet, Guillaume; Levesque, Maximilien; Borgis, Daniel

    2014-06-05

    Molecular density functional theory (MDFT) offers an efficient implicit-solvent method to estimate molecule solvation free-energies, whereas conserving a fully molecular representation of the solvent. Even within a second-order approximation for the free-energy functional, the so-called homogeneous reference fluid approximation, we show that the hydration free-energies computed for a data set of 500 organic compounds are of similar quality as those obtained from molecular dynamics free-energy perturbation simulations, with a computer cost reduced by 2-3 orders of magnitude. This requires to introduce the proper partial volume correction to transform the results from the grand canonical to the isobaric-isotherm ensemble that is pertinent to experiments. We show that this correction can be extended to 3D-RISM calculations, giving a sound theoretical justification to empirical partial molar volume corrections that have been proposed recently.

  17. Comparison of the Volume Charge Density of Nanofiltration Membranes Obtained from Retention and Conductivity Experiments

    DEFF Research Database (Denmark)

    Benavente, J.; Silva, V.; Pradanos, P.

    2010-01-01

    A version of the Donnan steric-partitioning pore model with dielectrical exclusion (DSPM-DE) has been used to get information on the pore size and charge density of a commercial membrane, NF45 from FilmTec, from its retention of KCl solutions. The conductivity inside the pores has been measured b...

  18. Propellant Improvement Program. Volume 2. Iron Contamination Effect in HDA (High Density Acid)

    Science.gov (United States)

    Density Acid ( HDA ) and the effect of iron impurity level up to 100 parts per million as Fe2O3 on HDA heat transfer. Thirty tests were conducted using...resistance heated, circular, 6061T6 aluminum tubes. Results showed that normal nucleate boiling did not occur with either of the HDA compositions. The

  19. Real-time viscosity and mass density sensors requiring microliter sample volume based on nanomechanical resonators.

    Science.gov (United States)

    Bircher, Benjamin A; Duempelmann, Luc; Renggli, Kasper; Lang, Hans Peter; Gerber, Christoph; Bruns, Nico; Braun, Thomas

    2013-09-17

    A microcantilever based method for fluid viscosity and mass density measurements with high temporal resolution and microliter sample consumption is presented. Nanomechanical cantilever vibration is driven by photothermal excitation and detected by an optical beam deflection system using two laser beams of different wavelengths. The theoretical framework relating cantilever response to the viscosity and mass density of the surrounding fluid was extended to consider higher flexural modes vibrating at high Reynolds numbers. The performance of the developed sensor and extended theory was validated over a viscosity range of 1-20 mPa·s and a corresponding mass density range of 998-1176 kg/m(3) using reference fluids. Separating sample plugs from the carrier fluid by a two-phase configuration in combination with a microfluidic flow cell, allowed samples of 5 μL to be sequentially measured under continuous flow, opening the method to fast and reliable screening applications. To demonstrate the study of dynamic processes, the viscosity and mass density changes occurring during the free radical polymerization of acrylamide were monitored and compared to published data. Shear-thinning was observed in the viscosity data at higher flexural modes, which vibrate at elevated frequencies. Rheokinetic models allowed the monomer-to-polymer conversion to be tracked in spite of the shear-thinning behavior, and could be applied to study the kinetics of unknown processes.

  20. Densities and excess volumes of binary mixtures of N,N-dimethylformamide with aromatic hydrocarbon at different temperature

    International Nuclear Information System (INIS)

    Peng Sanjun; Hou Haiyun; Zhou Congshan; Yang Tao

    2007-01-01

    Density of three binary mixtures formed by N,N-dimethylformamide (DMF) with aromatic hydrocarbon (one of benzene, toluene, and ethylbenzene) has been determined over the full range of compositions at the temperatures range (293.15 to 353.15)K and atmospheric pressure using a vibrating-tube densimeter. From these experiments, excess molar volumes (V m E ) could be calculated and fitted by the fourth-order Redlich-Kister equation, so the coefficients and the standard error (σ) could be got. Our result shows V m E decreases when temperature increases in the studied systems

  1. Theoretical Model for Volume Fraction of UC, 235U Enrichment, and Effective Density of Final U 10Mo Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Devaraj, Arun [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); Prabhakaran, Ramprashad [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); Joshi, Vineet V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); Hu, Shenyang Y. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); McGarrah, Eric J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); Lavender, Curt A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)

    2016-04-12

    The purpose of this document is to provide a theoretical framework for (1) estimating uranium carbide (UC) volume fraction in a final alloy of uranium with 10 weight percent molybdenum (U-10Mo) as a function of final alloy carbon concentration, and (2) estimating effective 235U enrichment in the U-10Mo matrix after accounting for loss of 235U in forming UC. This report will also serve as a theoretical baseline for effective density of as-cast low-enriched U-10Mo alloy. Therefore, this report will serve as the baseline for quality control of final alloy carbon content

  2. Influence of Zinc on the Surface Tension, Density and Molar Volume of (Ag-Sneut +Zn Liquid Alloys

    Directory of Open Access Journals (Sweden)

    Gąsior W.

    2016-03-01

    Full Text Available The dilatometric and maximum bubble pressure methods were applied for the measurements of the density and surface tension of liquid (Ag-Sneut +Zn lead-free solders. The experiments were carried out in the temperature range from 515 to 1223 K for the alloys of the zinc concentration equaling 0.01, 0.02, 0.04, 0.05, 0.1 and 0.2 of the mole fraction. It was found that the temperature dependence of both the density and the surface tension could be thought as linear, so they were interpreted by straight line equations. The experimental data of the molar volume of the investigated alloys were described by the polynomial dependent on the composition and temperature.

  3. Capillary ultrastructure and mitochondrial volume density in skeletal muscle in relation to reduced exercise capacity of patients with intermittent claudication

    DEFF Research Database (Denmark)

    Baum, Oliver; Torchetti, Eleonora; Malik, Corinna

    2016-01-01

    power output (PPO) was determined for all participants using an incremental single-leg knee-extension protocol. Capillary density was lower (411±90 mm(-2)versus 506±95 mm(-2); P≤0.05) in the biopsies of the IC patients than in those of the controls. The basement membrane (BM) around capillaries...... was thicker (543±82 nm versus 423±97 nm; P≤0.01) and the volume density of mitochondria was lower (3.51±0.56% versus 4.60±0.74; P≤0.01) in the IC-patients than the controls. In the IC-patients, a higher proportion of capillaries appeared with collapsed slit-like lumen and/or swollen endothelium. PPO was lower...

  4. Placed in a steady magnetic field, the flux density inside a permalloy-shielded volume decreases over hours and days

    Science.gov (United States)

    Feinberg, Benedict; Gould, Harvey

    2018-03-01

    Following the application of an external magnetic field to a thin-walled demagnetized Permalloy cylinder, the magnetic flux density at the center of the shielded volume decreases by roughly 20% over periods of hours to days. We measured this effect for applied magnetic fields from 0.48 A/m to 16 A/m, the latter being comparable to the Earths magnetic field at its weakest point. Delayed changes in magnetic flux density are also observed following alternating current demagnetization. We attribute these effects to delayed changes in magnetization, which have previously been observed in thin Permalloy films and small bulk samples of ferromagnetic materials. Phenomenological models of thermal activation are discussed. Some possible effects on experiments that rely on static shielding are noted.

  5. Long-term culture of rat hippocampal neurons at low density in serum-free medium: combination of the sandwich culture technique with the three-dimensional nanofibrous hydrogel PuraMatrix.

    Science.gov (United States)

    Kaneko, Ai; Sankai, Yoshiyuki

    2014-01-01

    The primary culture of neuronal cells plays an important role in neuroscience. There has long been a need for methods enabling the long-term culture of primary neurons at low density, in defined serum-free medium. However, the lower the cell density, the more difficult it is to maintain the cells in culture. Therefore, we aimed to develop a method for long-term culture of neurons at low density, in serum-free medium, without the need for a glial feeder layer. Here, we describe the work leading to our determination of a protocol for long-term (>2 months) primary culture of rat hippocampal neurons in serum-free medium at the low density of 3×10(4) cells/mL (8.9×10(3) cells/cm2) without a glial feeder layer. Neurons were cultured on a three-dimensional nanofibrous hydrogel, PuraMatrix, and sandwiched under a coverslip to reproduce the in vivo environment, including the three-dimensional extracellular matrix, low-oxygen conditions, and exposure to concentrated paracrine factors. We examined the effects of varying PuraMatrix concentrations, the timing and presence or absence of a coverslip, the timing of neuronal isolation from embryos, cell density at plating, medium components, and changing the medium or not on parameters such as developmental pattern, cell viability, neuronal ratio, and neurite length. Using our method of combining the sandwich culture technique with PuraMatrix in Neurobasal medium/B27/L-glutamine for primary neuron culture, we achieved longer neurites (≥3,000 µm), greater cell viability (≥30%) for 2 months, and uniform culture across the wells. We also achieved an average neuronal ratio of 97%, showing a nearly pure culture of neurons without astrocytes. Our method is considerably better than techniques for the primary culture of neurons, and eliminates the need for a glial feeder layer. It also exhibits continued support for axonal elongation and synaptic activity for long periods (>6 weeks).

  6. Long-term culture of rat hippocampal neurons at low density in serum-free medium: combination of the sandwich culture technique with the three-dimensional nanofibrous hydrogel PuraMatrix.

    Directory of Open Access Journals (Sweden)

    Ai Kaneko

    Full Text Available The primary culture of neuronal cells plays an important role in neuroscience. There has long been a need for methods enabling the long-term culture of primary neurons at low density, in defined serum-free medium. However, the lower the cell density, the more difficult it is to maintain the cells in culture. Therefore, we aimed to develop a method for long-term culture of neurons at low density, in serum-free medium, without the need for a glial feeder layer. Here, we describe the work leading to our determination of a protocol for long-term (>2 months primary culture of rat hippocampal neurons in serum-free medium at the low density of 3×10(4 cells/mL (8.9×10(3 cells/cm2 without a glial feeder layer. Neurons were cultured on a three-dimensional nanofibrous hydrogel, PuraMatrix, and sandwiched under a coverslip to reproduce the in vivo environment, including the three-dimensional extracellular matrix, low-oxygen conditions, and exposure to concentrated paracrine factors. We examined the effects of varying PuraMatrix concentrations, the timing and presence or absence of a coverslip, the timing of neuronal isolation from embryos, cell density at plating, medium components, and changing the medium or not on parameters such as developmental pattern, cell viability, neuronal ratio, and neurite length. Using our method of combining the sandwich culture technique with PuraMatrix in Neurobasal medium/B27/L-glutamine for primary neuron culture, we achieved longer neurites (≥3,000 µm, greater cell viability (≥30% for 2 months, and uniform culture across the wells. We also achieved an average neuronal ratio of 97%, showing a nearly pure culture of neurons without astrocytes. Our method is considerably better than techniques for the primary culture of neurons, and eliminates the need for a glial feeder layer. It also exhibits continued support for axonal elongation and synaptic activity for long periods (>6 weeks.

  7. Hypothyroidism in the adult rat causes incremental changes in brain-derived neurotrophic factor, neuronal and astrocyte apoptosis, gliosis, and deterioration of postsynaptic density.

    Science.gov (United States)

    Cortés, Claudia; Eugenin, Eliseo; Aliaga, Esteban; Carreño, Leandro J; Bueno, Susan M; Gonzalez, Pablo A; Gayol, Silvina; Naranjo, David; Noches, Verónica; Marassi, Michelle P; Rosenthal, Doris; Jadue, Cindy; Ibarra, Paula; Keitel, Cecilia; Wohllk, Nelson; Court, Felipe; Kalergis, Alexis M; Riedel, Claudia A

    2012-09-01

    Adult hypothyroidism is a highly prevalent condition that impairs processes, such as learning and memory. Even though tetra-iodothyronine (T(4)) treatment can overcome the hypothyroidism in the majority of cases, it cannot fully recover the patient's learning capacity and memory. In this work, we analyzed the cellular and molecular changes in the adult brain occurring with the development of experimental hypothyroidism. Adult male Sprague-Dawley rats were treated with 6-propyl-2-thiouracil (PTU) for 20 days to induce hypothyroidism. Neuronal and astrocyte apoptosis were analyzed in the hippocampus of control and hypothyroid adult rats by confocal microscopy. The content of brain-derived neurotrophic factor (BDNF) was analyzed using enzyme-linked immunosorbent assay (ELISA) and in situ hybridization. The glutamatergic synapse and the postsynaptic density (PSD) were analyzed by electron microscopy. The content of PSD proteins like tyrosine receptor kinase B (TrkB), p75, and N-methyl-D-aspartate receptor (NMDAr) were analyzed by immunoblot. We observed that the hippocampus of hypothyroid adult rats displayed increased apoptosis levels in neurons and astrocyte and reactive gliosis compared with controls. Moreover, we found that the amount of BDNF mRNA was higher in the hippocampus of hypothyroid rats and the content of TrkB, the receptor for BDNF, was reduced at the PSD of the CA3 region of hypothyroid rats, compared with controls. We also observed that the glutamatergic synapses from the stratum radiatum of CA3 from hypothyroid rats, contained thinner PSDs than control rats. This observation was in agreement with a reduced content of NMDAr subunits at the PSD in hypothyroid animals. Our data suggest that adult hypothyroidism affects the hippocampus by a mechanism that alters the composition of PSD, reduces neuronal and astrocyte survival, and alters the content of the signaling neurotrophic factors, such as BDNF.

  8. Association of the AMPA receptor-related postsynaptic density proteins GRIP and ABP with subsets of glutamate-sensitive neurons in the rat retina.

    Science.gov (United States)

    Gábriel, Robert; de Souza, Sunita; Ziff, Edward B; Witkovsky, Paul

    2002-07-22

    We used specific antibodies against two postsynaptic density proteins, GRIP (glutamate receptor interacting protein) and ABP (AMPA receptor-binding protein), to study their distribution in the rat retina. In the central nervous system, it has been shown that both proteins bind strongly to the AMPA glutamate receptor (GluR) 2/3 subunits, but not other GluRs, through a set of three PDZ domains. Western blots detected a single GRIP protein that was virtually identical in retina and brain, whereas retinal ABP corresponded to only one of three ABP peptides found in brain. The retinal distributions of GluR2/3, GRIP, and ABP immunoreactivity (IR) were similar but not identical. GluR2/3 immunoreactivity (IR) was abundant in both plexiform layers and in large perikarya. ABP IR was concentrated in large perikarya but was sparse in the plexiform layers, whereas GRIP IR was relatively more abundant in the plexiform layers than in perikarya. Immunolabel for these three antibodies consisted of puncta ABP IR was examined by double labeling subclasses of retinal neuron with characteristic marker proteins, e.g., calbindin. GRIP, ABP, and GluR2/3 IR were detected in horizontal cells, dopaminergic and glycinergic AII amacrine cells and large ganglion cells. Immunolabel was absent in rod bipolar and weak or absent in cholinergic amacrine cells. By using the tyramide method of signal amplification, a colocalization of GluR2/3 was found with either GRIP or ABP in horizontal cell terminals, and perikarya of amacrine and ganglion cells. Our results show that ABP and GRIP colocalize with GluR2/3 in particular subsets of retinal neuron, as was previously established for certain neurons in the brain. Copyright 2002 Wiley-Liss, Inc.

  9. The StreamCat Dataset: Accumulated Attributes for NHDPlusV2 (Version 2.1) Catchments for the Conterminous United States: Dam Density and Storage Volume

    Data.gov (United States)

    U.S. Environmental Protection Agency — This dataset represents the dam density and storage volumes within individual, local NHDPlusV2 catchments and upstream, contributing watersheds based on National...

  10. High density matter in AGS, SPS and RHIC collisions: Proceedings. Volume 9

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-12-01

    This 1-day workshop focused on phenomenological models regarding the specific question of the maximum energy density achievable in collisions at AGS, SPS and RHIC. The idea was to have 30-minute (or less) presentations of each model--but not the model as a whole, rather then that strongly narrowed to the above physics question. The key topics addressed were: (1) to estimate the energy density in heavy-ion collisions within a model, and to discuss its physical implications; (2) to suggest experimental observables that may confirm the correctness of a model approach--with respect to the energy density estimate; (3) to compare with existing data from AGS and SPS heavy-ion collisions, and to give predictions for the future RHIC experiments. G. Ogilvie started up the workshop with a critical summary of experimental manifestations of high-density matter at the AGS, and gave a personal outlook on RHIC physics. R. Mattiello talked about his newly developed hadron cascade model for applications to AGS and SPS collisions. Next, D. Kharzeev gave a nice introduction of the Glauber approach to high-energy collisions and illustrated the predictive power of this approach in nucleus-nucleus collisions at the SPS. It followed S. Vance with a presentation of the baryon-junction model to explain the observed baryon stopping phenomenon in collisions of heavy nuclei. S. Bass continued with a broad perspective of the UrQMD model, and provided insight into the details of the microscopic dynamical features of nuclear collisions at high energy. J. Sandweiss and J. Kapusta addressed the interesting aspect of photon production in peripherical nuclear collisions due to intense electromagnetic bremstrahlung by the highly charged, fast moving ions. Finally, H. Sorge closed up the one-day workshop with a presentation of his recent work with the RQMD model. This report consists of a summary and vugraphs of the presentations.

  11. High density matter in AGS, SPS and RHIC collisions. Proceedings. Volume 9

    International Nuclear Information System (INIS)

    1998-01-01

    This 1-day workshop focused on phenomenological models regarding the specific question of the maximum energy density achievable in collisions at AGS, SPS and RHIC. The idea was to have 30-minute (or less) presentations of each model--but not the model as a whole, rather then that strongly narrowed to the above physics question. The key topics addressed were: (1) to estimate the energy density in heavy-ion collisions within a model, and to discuss its physical implications; (2) to suggest experimental observables that may confirm the correctness of a model approach--with respect to the energy density estimate; (3) to compare with existing data from AGS and SPS heavy-ion collisions, and to give predictions for the future RHIC experiments. G. Ogilvie started up the workshop with a critical summary of experimental manifestations of high-density matter at the AGS, and gave a personal outlook on RHIC physics. R. Mattiello talked about his newly developed hadron cascade model for applications to AGS and SPS collisions. Next, D. Kharzeev gave a nice introduction of the Glauber approach to high-energy collisions and illustrated the predictive power of this approach in nucleus-nucleus collisions at the SPS. It followed S. Vance with a presentation of the baryon-junction model to explain the observed baryon stopping phenomenon in collisions of heavy nuclei. S. Bass continued with a broad perspective of the UrQMD model, and provided insight into the details of the microscopic dynamical features of nuclear collisions at high energy. J. Sandweiss and J. Kapusta addressed the interesting aspect of photon production in peripherical nuclear collisions due to intense electromagnetic bremstrahlung by the highly charged, fast moving ions. Finally, H. Sorge closed up the one-day workshop with a presentation of his recent work with the RQMD model. This report consists of a summary and vugraphs of the presentations

  12. Simultaneous viscosity and density measurement of small volumes of liquids using a vibrating microcantilever.

    Science.gov (United States)

    Payam, A F; Trewby, W; Voïtchovsky, K

    2017-05-02

    Many industrial and technological applications require precise determination of the viscosity and density of liquids. Such measurements can be time consuming and often require sampling substantial amounts of the liquid. These problems can partly be overcome with the use of microcantilevers but most existing methods depend on the specific geometry and properties of the cantilever, which renders simple, accurate measurement difficult. Here we present a new approach able to simultaneously quantify both the density and the viscosity of microliters of liquids. The method, based solely on the measurement of two characteristic frequencies of an immersed microcantilever, is completely independent of the choice of a cantilever. We derive analytical expressions for the liquid's density and viscosity and validate our approach with several simple liquids and different cantilevers. Application of our model to non-Newtonian fluids shows that the calculated viscosities are remarkably robust when compared to measurements obtained from a standard rheometer. However, the results become increasingly dependent on the cantilever geometry as the frequency-dependent nature of the liquid's viscosity becomes more significant.

  13. Neuronal apoptosis and synaptic density in the dentate gyrus of ischemic rats' response to chronic mild stress and the effects of Notch signaling.

    Directory of Open Access Journals (Sweden)

    Shaohua Wang

    Full Text Available Our previous research highlighted an inconsistency with Notch1 signaling-related compensatory neurogenesis after chronic mild stress (CMS in rodents suffering from cerebral ischemia, which continue to display post-stroke depressive symptoms. Here, we hypothesize that CMS aggrandized ischemia-related apoptosis injury and worsened synaptic integrity via gamma secretase-meditated Notch1 signaling. Adult rats were exposed to a CMS paradigm after left middle cerebral artery occlusion (MCAO. Open-field and sucrose consumption testing were employed to assess depression-like behavior. Gene expression of pro-apoptotic Bax, anti-apoptotic Bcl-2, and synaptic density-related synaptophysin were measured by western blotting and real-time PCR on Day 28 after MCAO surgery. CMS induced depressive behaviors in ischemic rats, which was accompanied by an elevation in Bax/bcl-2 ratio, TUNEL staining in neurons and reduced synaptophysin expression in the dentate gyrus. These collective effects were reversed by the gamma-secretase inhibitor DAPT (N-[N-(3,5-difluorophenacetyl-L-alanyl]-S-phenyl-glycine t-butyl ester. We found that post-stroke stressors made neurons in the dentate gyrus vulnerable to apoptosis, which supports a putative role for Notch signaling in neural integrity, potentially in newborn cells' synaptic deficit with regard to preexisting cells. These findings suggest that post-stroke depression therapeutically benefits from blocking gamma secretase mediated Notch signaling, and whether this signaling pathway could be a therapeutic target needs to be further investigated.

  14. Tap density equations of granular powders based on the rate process theory and the free volume concept.

    Science.gov (United States)

    Hao, Tian

    2015-02-28

    The tap density of a granular powder is often linked to the flowability via the Carr index that measures how tight a powder can be packed, under an assumption that more easily packed powders usually flow poorly. Understanding how particles are packed is important for revealing why a powder flows better than others. There are two types of empirical equations that were proposed to fit the experimental data of packing fractions vs. numbers of taps in the literature: the inverse logarithmic and the stretched exponential. Using the rate process theory and the free volume concept under the assumption that particles will obey similar thermodynamic laws during the tapping process if the "granular temperature" is defined in a different way, we obtain the tap density equations, and they are reducible to the two empirical equations currently widely used in literature. Our equations could potentially fit experimental data better with an additional adjustable parameter. The tapping amplitude and frequency, the weight of the granular materials, and the environmental temperature are grouped into this parameter that weighs the pace of the packing process. The current results, in conjunction with our previous findings, may imply that both "dry" (granular) and "wet" (colloidal and polymeric) particle systems are governed by the same physical mechanisms in term of the role of the free volume and how particles behave (a rate controlled process).

  15. Apparent molal volumes of HMT and TATD in aqueous solutions around the temperature of maximum density of water

    International Nuclear Information System (INIS)

    Clavijo Penagos, J.A.; Blanco, L.H.

    2012-01-01

    Highlights: ►V φ for HMT and TATD in aqueous solutions around the temperature of maximum density of water are reported. ► V φ is linear in m form m = 0.025 for all the aqueous solutions investigated. ► Variation of V ¯ 2 ∞ with T obeys a second grade polynomial trend. ► The solutes are classified as structure breakers according to Hepler’s criterion. - Abstract: Apparent molal volumes V φ have been determined from density measurements for several aqueous solutions of 1,3,5,7-tetraazatricyclo[3.3.1.1(3,7)]decane (HMT) and 1,3,6,8-tetraazatricyclo[4.4.1.1(3,8)]dodecane (TATD) at T = (275.15, 275.65, 276.15, 276.65, 277.15, 277.65 and 278.15) K as function of composition. The infinite dilution partial molar volumes of solutes in aqueous solution are evaluated through extrapolation. Interactions of the solutes with water are discussed in terms of the effect of the temperature on the volumetric properties and the structure of the solutes. The results are interpreted in terms of water structure-breaking or structure forming character of the solutes.

  16. Hydrogen bonding interactions between ethylene glycol and water:density,excess molar volume,and spectral study

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Studies of the density and the excess molar volume of ethylene glycol (EG)-water mixtures were carried out to illustrate the hydrogen bonding interactions of EG with water at different temperatures. The re-sults suggest that a likely complex of 3 ethylene glycol molecules bonding with 4 water molecules in an ethylene glycol-water mixture (EGW) is formed at the maximal excess molar volume,which displays stronger absorption capabilities for SO2 when the concentration of SO2 reaches 400×10?6 (volume ratio) in the gas phase. Meanwhile,FTIR and UV spectra of EGWs were recorded at various EG concentra-tions to display the hydrogen bonding interactions of EG with water. The FTIR spectra show that the stretching vibrational band of hydroxyl in the EGWs shifts to a lower frequency and the bending vibra-tional band of water shifts to a higher frequency with increasing the EG concentration,respectively. Furthermore,the UV spectra show that the electron transferring band of the hydroxyl oxygen in EG shows red shift with increasing the EG concentration. The frequency shifts in FTIR spectra and the shifts of absorption bands in UV absorption spectra of EGWs are interpreted as the strong hydrogen bonding interactions of the hydrogen atoms in water with the hydroxyl oxygen atoms of EG.

  17. Optical Quantification of Cellular Mass, Volume, and Density of Circulating Tumor Cells Identified in an Ovarian Cancer Patient

    International Nuclear Information System (INIS)

    Phillips, Kevin G.; Velasco, Carmen Ruiz; Li, Julia; Kolatkar, Anand; Luttgen, Madelyn; Bethel, Kelly; Duggan, Bridgette; Kuhn, Peter; McCarty, Owen J. T.

    2012-01-01

    Clinical studies have demonstrated that circulating tumor cells (CTCs) are present in the blood of cancer patients with known metastatic disease across the major types of epithelial malignancies. Recent studies have shown that the concentration of CTCs in the blood is prognostic of overall survival in breast, prostate, colorectal, and non-small cell lung cancer. This study characterizes CTCs identified using the high-definition (HD)-CTC assay in an ovarian cancer patient with stage IIIC disease. We characterized the physical properties of 31 HD-CTCs and 50 normal leukocytes from a single blood draw taken just prior to the initial debulking surgery. We utilized a non-interferometric quantitative phase microscopy technique using brightfield imagery to measure cellular dry mass. Next we used a quantitative differential interference contrast microscopy technique to measure cellular volume. These techniques were combined to determine cellular dry mass density. We found that HD-CTCs were more massive than leukocytes: 33.6 ± 3.2 pg (HD-CTC) compared to 18.7 ± 0.6 pg (leukocytes), p < 0.001; had greater volumes: 518.3 ± 24.5 fL (HD-CTC) compared to 230.9 ± 78.5 fL (leukocyte), p < 0.001; and possessed a decreased dry mass density with respect to leukocytes: 0.065 ± 0.006 pg/fL (HD-CTC) compared to 0.085 ± 0.004 pg/fL (leukocyte), p < 0.006. Quantification of HD-CTC dry mass content and volume provide key insights into the fluid dynamics of cancer, and may provide the rationale for strategies to isolate, monitor or target CTCs based on their physical properties. The parameters reported here can also be incorporated into blood cell flow models to better understand metastasis.

  18. Sequential estimation of intrinsic activity and synaptic input in single neurons by particle filtering with optimal importance density

    Science.gov (United States)

    Closas, Pau; Guillamon, Antoni

    2017-12-01

    This paper deals with the problem of inferring the signals and parameters that cause neural activity to occur. The ultimate challenge being to unveil brain's connectivity, here we focus on a microscopic vision of the problem, where single neurons (potentially connected to a network of peers) are at the core of our study. The sole observation available are noisy, sampled voltage traces obtained from intracellular recordings. We design algorithms and inference methods using the tools provided by stochastic filtering that allow a probabilistic interpretation and treatment of the problem. Using particle filtering, we are able to reconstruct traces of voltages and estimate the time course of auxiliary variables. By extending the algorithm, through PMCMC methodology, we are able to estimate hidden physiological parameters as well, like intrinsic conductances or reversal potentials. Last, but not least, the method is applied to estimate synaptic conductances arriving at a target cell, thus reconstructing the synaptic excitatory/inhibitory input traces. Notably, the performance of these estimations achieve the theoretical lower bounds even in spiking regimes.

  19. Restoration of Thickness, Density, and Volume for Highly Blurred Thin Cortical Bones in Clinical CT Images.

    Science.gov (United States)

    Pakdel, Amirreza; Hardisty, Michael; Fialkov, Jeffrey; Whyne, Cari

    2016-11-01

    In clinical CT images containing thin osseous structures, accurate definition of the geometry and density is limited by the scanner's resolution and radiation dose. This study presents and validates a practical methodology for restoring information about thin bone structure by volumetric deblurring of images. The methodology involves 2 steps: a phantom-free, post-reconstruction estimation of the 3D point spread function (PSF) from CT data sets, followed by iterative deconvolution using the PSF estimate. Performance of 5 iterative deconvolution algorithms, blind, Richardson-Lucy (standard, plus Total Variation versions), modified residual norm steepest descent (MRNSD), and Conjugate Gradient Least-Squares were evaluated using CT scans of synthetic cortical bone phantoms. The MRNSD algorithm resulted in the highest relative deblurring performance as assessed by a cortical bone thickness error (0.18 mm) and intensity error (150 HU), and was subsequently applied on a CT image of a cadaveric skull. Performance was compared against micro-CT images of the excised thin cortical bone samples from the skull (average thickness 1.08 ± 0.77 mm). Error in quantitative measurements made from the deblurred images was reduced 82% (p < 0.01) for cortical thickness and 55% (p < 0.01) for bone mineral mass. These results demonstrate a significant restoration of geometrical and radiological density information derived for thin osseous features.

  20. Effect of explant density and volume of cultivation medium on in-vitro multiplication of blueberry (Vaccinium corymbosum L. varieties "Brigitta" and "Legacy"

    Directory of Open Access Journals (Sweden)

    Mario Rodríguez Beraud

    2015-03-01

    Full Text Available The objective of the investigation was to evaluate the in-vitro multiplication of two varieties of blueberry (Vaccinium corymbosum L., “Brigitta” and “Legacy” in response to five explants densities (5, 10, 15, 20 and 25 and four flask volumes (10, 20, 30 and 40 mL for cultivation. For both varieties the cultivation medium WPM (Woody Plant Medium was used. The experiment was completely randomized with 20 treatments and 12 repetitions per treatment. After 45 days of cultivation we evaluated the height of shoots, number of shoots/explant, number of nodes/shoot and number of shoots/flask. Variety “Brigitta” had highest shoots at higher densities and flask volumes, while variety “Legacy” had the highest average shoot height with intermediate densities and high volumes. Regarding the number of shoots/explant, the volume of the medium had no influence on “Brigitta”, however, higher plant densities affected this parameter. With variety “Legacy” the maximum number of shoots was achieved with lower plant densities and intermediate culture volumes per flask. In relation to the number of nodes per explant "Brigitta had lower numbers as compared to “Legacy”, but with both varieties the number of nodes decresed with smaller volumes of medium in the flasks. For the number of shoots per flask, “Brigitta” responsed best at higher densities exceeding 40 shoots per flask. In contrast, “Legacy” produced maximum results at density of 25 explants in 30 mL of medium. It is concluded that for the optimum multiplication of both varieties the correct selection of both, the planting density and the volume of multiplication medium are important.

  1. Premature ovarian insufficiency in young girls: repercussions on uterine volume and bone mineral density.

    Science.gov (United States)

    Bakhsh, Hanadi; Dei, Metella; Bucciantini, Sandra; Balzi, Daniela; Bruni, Vincenzina

    2015-01-01

    To evaluate biological differences among young subjects with premature ovarian insufficiency (POI) commencing at different stages of life. Retrospective observational study. Careggi University Hospital Participants: One hundred sixty-two females aged between 15 and 29 years with premature ovarian insufficiency. Data were collected as a retrospective chart review of baseline evaluation at diagnosis of premature ovarian insufficiency (POI). About 162 participants were divided into four groups based on gynecological age. Two primary outcome variables (uterine development and bone mineral density (BMD)) were analyzed in terms of differences among groups and in a multivariate logistic regression analysis. Uterine development was clearly jeopardized when estrogen insufficiency started at a very young age. Total body BMD showed significant differences among the four groups studied, clearly corresponding to the duration of ovarian function. Data were discussed in relation to the choice of hormone replacement therapy regimens.

  2. Study of short haul high-density V/STOL transportation systems, volume 1

    Science.gov (United States)

    Solomon, H. L.

    1972-01-01

    The relative advantages of STOL aircraft concepts were examined by simulating the operations of a short haul high-density intercity STOL system set in two arenas, the California corridor and the Chicago-Detroit-Cleveland triangle, during the 1980 time period. The study was constrained to the use of three aircraft concepts designated as the deflected slipstream turboprop, externally blown flap, and augmentor wing turbofan configurations. The projected demographic, economic, travel demand, and travel characteristics of the representative arenas were identified. The STOL airline operating scenarios were then formulated and through the use of the aerospace modal split simulation program, the traveler modal choices involving alternative STOL concepts were estimated in the context of the total transportation environment for 1980. System combinations that presented the best potential for economic return and traveler acceptance were then identified for each STOL concept.

  3. SynPAnal: software for rapid quantification of the density and intensity of protein puncta from fluorescence microscopy images of neurons.

    Directory of Open Access Journals (Sweden)

    Eric Danielson

    Full Text Available Continuous modification of the protein composition at synapses is a driving force for the plastic changes of synaptic strength, and provides the fundamental molecular mechanism of synaptic plasticity and information storage in the brain. Studying synaptic protein turnover is not only important for understanding learning and memory, but also has direct implication for understanding pathological conditions like aging, neurodegenerative diseases, and psychiatric disorders. Proteins involved in synaptic transmission and synaptic plasticity are typically concentrated at synapses of neurons and thus appear as puncta (clusters in immunofluorescence microscopy images. Quantitative measurement of the changes in puncta density, intensity, and sizes of specific proteins provide valuable information on their function in synaptic transmission, circuit development, synaptic plasticity, and synaptopathy. Unfortunately, puncta quantification is very labor intensive and time consuming. In this article, we describe a software tool designed for the rapid semi-automatic detection and quantification of synaptic protein puncta from 2D immunofluorescence images generated by confocal laser scanning microscopy. The software, dubbed as SynPAnal (for Synaptic Puncta Analysis, streamlines data quantification for puncta density and average intensity, thereby increases data analysis throughput compared to a manual method. SynPAnal is stand-alone software written using the JAVA programming language, and thus is portable and platform-free.

  4. Densities and apparent molar volumes of aqueous LiI solutions at temperatures from (296 to 600) K and at pressures up to 30 MPa

    International Nuclear Information System (INIS)

    Abdulagatov, I.M.; Azizov, N.D.

    2004-01-01

    Densities of five aqueous LiI solutions (0.0906, 0.2832, 0.6621, 1.6046, and 3.0886) mol . kg -1 H 2 O were measured in the liquid phase with a constant-volume piezometer immersed in a precision liquid thermostat. Measurements were made along various isotherms between (296.95 and 600.25) K. The range of pressure was (0.1 to 30) MPa. The total uncertainty of density, pressure, temperature, and concentration measurements was estimated to be less than 0.06%, 0.05%, 15 mK, and 0.014%, respectively. To check and confirm the accuracy of the measurements, (p,V m ,T,x) data were taken for pure water at selected temperatures and pressures. Experimental and calculated (IAPWS formulation) densities for pure water show excellent agreement within their experimental uncertainties (average absolute deviation is 0.02%). Values of saturated densities were determined by extrapolating experimental p - ρ data to the vapour pressure at fixed temperature and composition using a linear interpolating equation. Apparent molar volumes were derived using measured values of density for solutions and pure water. The apparent molar volumes were extrapolated to zero concentration (m → 0) to yield partial molar volumes of electrolyte (LiI) at infinite dilution. The temperature, pressure, and concentration dependence of apparent and partial molar volumes was studied. The measured values of density, apparent and partial molar volume were compared with data reported in the literature by other authors. A polynomial type of equation of state for specific volume was obtained as a function of temperature, pressure, and composition by a least-squares method using the experimental data. The average absolute deviation (AAD) between measured and calculated values from this polynomial equation for density was 0.065%

  5. Measuring treatment response to systemic therapy and predicting outcome in biliary tract cancer: comparing tumor size, volume, density, and metabolism.

    Science.gov (United States)

    Sahani, Dushyant V; Hayano, Koichi; Galluzzo, Anna; Zhu, Andrew X

    2015-04-01

    The purpose of this study was to evaluate the response of biliary tract cancer treated with multidrug chemotherapy using FDG PET in comparison with morphologic and density changes. In this phase II clinical trial, 28 patients with unresectable or metastatic biliary tract cancers treated with gemcitabine and oxaliplatin combined with bevacizumab (GEMOX-B) underwent FDG PET and contrast-enhanced CT at baseline and after the second cycle of the therapy (8 weeks). A single reviewer recorded tumor maximum standardized uptake value (SUVmax) along with size, volume (3D-sphere), and density. The percentage changes of the parameters were compared with progression-free survival at 7 months. Overall survival was compared with the percentage change of SUVmax. After 8 weeks, measurable reductions (±SD) in size (7.05±4.19 to 5.52±3.28 cm, -21.70%), volume (411.38±540.08 to 212.41±293.45 cm3, -48.36%), and density (60.76±20.65 to 50.68±16.89 HU, -15.59%) were noted along with a substantial drop in SUVmax (5.95±1.95 to 3.36±1.28, -43.52%). The SUVmax change showed positive correlations with tumor size change (R2=0.39, p=0.0004) and volumetric change (R2=0.34, p=0.001). Patients who showed a larger drop in SUVmax at 8 weeks correlated with favorable progression-free survival (p=0.02). ROC analysis showed that a 45% reduction in SUVmax was the best cutoff value to detect favorable progression-free survival patients. When we used this cutoff value, Kaplan-Meier analysis showed that patients with tumors showing greater reduction in SUVmax had favorable progression-free survival and overall survival (p=0.0009, p=0.03). In biliary tract cancers treated with GEMOX-B, the reduction of SUVmax after therapy is a better predictor for survival than morphologic and density changes.

  6. Densities and apparent molar volumes of HClO4(aq) and Yb(ClO4)3(aq) at elevated temperatures and pressures

    International Nuclear Information System (INIS)

    Hakin, Andrew W.; Lukacs, Michael J.; Jin Lianliu

    2004-01-01

    Relative densities have been measured for acidified aqueous solutions of ytterbium perchlorate {Yb(ClO 4 ) 3 } at approximately T=(348.15, 373.15, 398.15, and 423.15) K and p=(10.0, 20.0, and 30.0) MPa over the concentration range 0.01624≤m 2 /(mol · kg -1 ) ≤ 0.2531 using an optically coupled vibrating tube densimeter (OCVTD). Experimental apparent molar volumes have been calculated from the density measurements, and apparent molar volumes for the aqueous perchlorate salt have been calculated using Young's rule. The application of Young's rule requires apparent molar volumes for aqueous perchloric acid (HClO 4 ) solutions over extended temperature and pressure ranges. These values were calculated from densities for aqueous HClO 4 solutions that were measured using the OCVTD at the same temperatures and pressures as those used to investigate the density surface of the acidified aqueous Yb(ClO 4 ) 3 solutions. The temperature, pressure, and composition surfaces of the apparent molar volumes for Yb(ClO 4 ) 3 (aq) and HClO 4 (aq) have been modelled using Pitzer ion-interaction equations. Apparent molar volumes at infinite dilution obtained from these models have been compared to those which can be calculated using the semi-empirical Helgeson, Kirkham, and Flowers equations of state. Values for the apparent molar volume at infinite dilution of the ytterbium trivalent cation have also been calculated using simple additivity principles

  7. Coronary Artery Calcium Volume and Density: Potential Interactions and Overall Predictive Value: The Multi-Ethnic Study of Atherosclerosis.

    Science.gov (United States)

    Criqui, Michael H; Knox, Jessica B; Denenberg, Julie O; Forbang, Nketi I; McClelland, Robyn L; Novotny, Thomas E; Sandfort, Veit; Waalen, Jill; Blaha, Michael J; Allison, Matthew A

    2017-08-01

    This study sought to determine the possibility of interactions between coronary artery calcium (CAC) volume or CAC density with each other, and with age, sex, ethnicity, the new atherosclerotic cardiovascular disease (ASCVD) risk score, diabetes status, and renal function by estimated glomerular filtration rate, and, using differing CAC scores, to determine the improvement over the ASCVD risk score in risk prediction and reclassification. In MESA (Multi-Ethnic Study of Atherosclerosis), CAC volume was positively and CAC density inversely associated with cardiovascular disease (CVD) events. A total of 3,398 MESA participants free of clinical CVD but with prevalent CAC at baseline were followed for incident CVD events. During a median 11.0 years of follow-up, there were 390 CVD events, 264 of which were coronary heart disease (CHD). With each SD increase of ln CAC volume (1.62), risk of CHD increased 73% (p present). In multivariable Cox models, significant interactions were present for CAC volume with age and ASCVD risk score for both CHD and CVD, and CAC density with ASCVD risk score for CVD. Hazard ratios were generally stronger in the lower risk groups. Receiver-operating characteristic area under the curve and Net Reclassification Index analyses showed better prediction by CAC volume than by Agatston, and the addition of CAC density to CAC volume further significantly improved prediction. The inverse association between CAC density and incident CHD and CVD events is robust across strata of other CVD risk factors. Added to the ASCVD risk score, CAC volume and density provided the strongest prediction for CHD and CVD events, and the highest correct reclassification. Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  8. Kajian Pemilihan Sumber Mikroorganisme Solid Phase Microbial Fuel Cell (SMFC Berdasarkan Jenis dan Volume Sampah, Power Density dan Efisiensi Penurunan COD

    Directory of Open Access Journals (Sweden)

    Ganjar Samudro

    2017-06-01

    Full Text Available Mikroorganisme merupakan salah satu komponen penting dalam proses Solid Phase Microbial Fuel Cell (SMFC untuk degradasi bahan organik dan transfer elektron. Pemilihan sumber mikroorganisme menjadi metode yang paling sederhana untuk dikaji sebagai informasi awal ketersediaan dan identifikasi jenis mikroorganisme yang mendukung proses SMFC. Tujuan kajian ini adalah untuk memilih sumber mikroorganisme tanah, septic tank dan sedimen sungai yang tepat digunakan dalam proses SMFC berdasarkan jenis dan volume sampah, power density, dan efisiensi penurunan COD. Kajian ini didasarkan pada hasil penelitian menggunakan reaktor SMFC tipe single chamber microbial fuel cell dengan variabel jenis dan volume sampah , serta sumber mikroorganisme. Metode perbandingan secara kuantitatif dilakukan berdasarkan kecenderungan nilai power density dan efisiensi penurunan COD tertinggi di antara jenis dan volume sampah kantin, dedaunan dan komposit kantin-dedaunan. Hasil yang didapatkan adalah sumber mikroorganisme tanah dan sedimen sungai tepat digunakan untuk volume sampah 1/3 dan 2/3 dari volume reaktor, sedangkan sumber mikroorganisme septic tank tepat digunakan untuk volume sampah 1/3 dan 1/2 dari volume reaktor. Sumber mikroorganisme dari septic tank menunjukkan kinerja power density dan efisiensi penurunan COD yang lebih rendah dibandingkan sumber mikroorganisme tanah dan sedimen sungai.

  9. Early changes of parotid density and volume predict modifications at the end of therapy and intensity of acute xerostomia

    Energy Technology Data Exchange (ETDEWEB)

    Belli, Maria Luisa; Broggi, Sara [Ospedale San Raffaele Scientific Institute, Medical Physics, Milano (Italy); Scalco, Elisa; Rizzo, Giovanna [CNR, Istituto di Bioimmagini e Fisiologia Molecolare, Milano (Italy); Sanguineti, Giuseppe [Regina Elena National Cancer Institute, Department of Radiation Oncology, Rome (Italy); Fiorino, Claudio; Cattaneo, Giovanni Mauro [Ospedale San Raffaele Scientific Institute, Medical Physics, Milano (Italy); CNR, Istituto di Bioimmagini e Fisiologia Molecolare, Milano (Italy); Dinapoli, Nicola; Valentini, Vincenzo [Universita Cattolica del Sacro Cuore, Radiotherapy, Rome (Italy); Ricchetti, Francesco [Ospedale Sacro Cuore, Radiotherapy, Negrar (Italy)

    2014-11-15

    To quantitatively assess the predictive power of early variations of parotid gland volume and density on final changes at the end of therapy and, possibly, on acute xerostomia during IMRT for head-neck cancer. Data of 92 parotids (46 patients) were available. Kinetics of the changes during treatment were described by the daily rate of density (rΔρ) and volume (rΔvol) variation based on weekly diagnostic kVCT images. Correlation between early and final changes was investigated as well as the correlation with prospective toxicity data (CTCAEv3.0) collected weekly during treatment for 24/46 patients. A higher rΔρ was observed during the first compared to last week of treatment (-0,50 vs -0,05HU, p-value = 0.0001). Based on early variations, a good estimation of the final changes may be obtained (Δρ: AUC = 0.82, p = 0.0001; Δvol: AUC = 0.77, p = 0.0001). Both early rΔρ and rΔvol predict a higher ''mean'' acute xerostomia score (≥ median value, 1.57; p-value = 0.01). Median early density rate changes for patients with mean xerostomia score ≥ / < 1.57 were -0.98 vs -0.22 HU/day respectively (p = 0.05). Early density and volume variations accurately predict final changes of parotid glands. A higher longitudinally assessed score of acute xerostomia is well predicted by higher rΔρ and rΔvol in the first two weeks of treatment: best cut-off values were -0.50 HU/day and -380 mm{sup 3}/day for rΔρ and rΔvol respectively. Further studies are necessary to definitively assess the potential of early density/volume changes in identifying more sensitive patients at higher risk of experiencing xerostomia. (orig.) [German] Ziel der Studie ist die Untersuchung der praediktiven Aussagekraft von fruehen Veraenderungen in Volumen und Dichte der Ohrspeicheldruese in Bezug auf die finale Verformung zum Ende der Therapie sowie das Risiko von Xerostomie waehrend der intesitaetsmodulierten Strahlentherapie (IMRT) bei Kopf und Hals Tumoren. Die Studie

  10. THE Hα LUMINOSITY FUNCTION AND STAR FORMATION RATE VOLUME DENSITY AT z = 0.8 FROM THE NEWFIRM Hα SURVEY

    International Nuclear Information System (INIS)

    Ly Chun; Lee, Janice C.; Momcheva, Ivelina; Dale, Daniel A.; Staudaher, Shawn; Moore, Carolynn A.; Salim, Samir; Finn, Rose

    2011-01-01

    We present new measurements of the Hα luminosity function (LF) and star formation rate (SFR) volume density for galaxies at z ∼ 0.8. Our analysis is based on 1.18 μm narrowband data from the NEWFIRM Hα (NewHα) Survey, a comprehensive program designed to capture deep samples of intermediate redshift emission-line galaxies using narrowband imaging in the near-infrared. The combination of depth (∼1.9 x 10 -17 erg s -1 cm -2 in Hα at 3σ) and areal coverage (0.82 deg 2 ) of the 1.18 μm observations complements other recent Hα studies at similar redshifts, and enables us to minimize the impact of cosmic variance and place robust constraints on the shape of the LF. The present sample contains 818 NB118 excess objects, 394 of which are selected as Hα emitters. Optical spectroscopy has been obtained for 62% of the NB118 excess objects. Empirical optical broadband color classification is used to sort the remainder of the sample. A comparison of the LFs constructed for the four individual fields covered by the observations reveals significant cosmic variance, emphasizing that multiple, widely separated observations are required for such analyses. The dust-corrected LF is well described by a Schechter function with L * = 10 43.00±0.52 erg s -1 , Φ * = 10 -3.20±0.54 Mpc -3 , and α = -1.6 ± 0.19. We compare our Hα LF and SFR density to those at z ∼ 3.4 , which we attribute to significant L * evolution. Our Hα SFR density of 10 -1.00±0.18 M sun yr -1 Mpc -3 is consistent with UV and [O II] measurements at z ∼ 1. We discuss how these results compare to other Hα surveys at z ∼ 0.8, and find that the different methods used to determine survey completeness can lead to inconsistent results. This suggests that future surveys probing fainter luminosities are needed, and more rigorous methods of estimating the completeness should be adopted as standard procedure (for example, with simulations which try to simultaneously reproduce the observed Hα LF and

  11. Liquid densities and excess molar volumes for (ionic liquids + methanol + water) ternary system at atmospheric pressure and at various temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Deenadayalu, Nirmala [Department of Chemistry, Durban University of Technology, Steve Biko Campus, P.O. Box 1334, Durban, KwaZulu-Natal 4001 (South Africa)], E-mail: NirmalaD@dut.ac.za; Kumar, Satish; Bhujrajh, Pravena [Department of Chemistry, Durban University of Technology, Steve Biko Campus, P.O. Box 1334, Durban, KwaZulu-Natal 4001 (South Africa)

    2007-09-15

    Excess molar volumes, V{sub m}{sup E} have been evaluated from density measurements over the entire composition range for ternary liquid system of ionic liquid (1-ethyl-3-methyl-imidazolium diethylenglycol monomethylether sulphate {l_brace}[EMIM][CH{sub 3}(OCH{sub 2}CH{sub 2}){sub 2}OSO{sub 3}]) (1) + methanol (2) + water (3){r_brace} at T = (298.15, 303.15, and 313.15) K. A vibrating tube densimeter was used for these measurements at atmospheric pressure. The V{sub m}{sup E} values were found to be negative at T = (298.15 and 303.15) K. For {l_brace}[EMIM][CH{sub 3}(OCH{sub 2}CH{sub 2}){sub 2}OSO{sub 3}] (1) + methanol (2) + water (3){r_brace} at T = 313.15 K the V{sub m}{sup E} values become positive at higher mole fraction of ionic liquid and at a corresponding decrease in mole fraction of water. All the experimental data were fitted with the Redlich-Kister equation. The results have also been analysed in term of graph theoretical approach.

  12. Linear and curvilinear correlations of brain gray matter volume and density with age using voxel-based morphometry with the Akaike information criterion in 291 healthy children.

    Science.gov (United States)

    Taki, Yasuyuki; Hashizume, Hiroshi; Thyreau, Benjamin; Sassa, Yuko; Takeuchi, Hikaru; Wu, Kai; Kotozaki, Yuka; Nouchi, Rui; Asano, Michiko; Asano, Kohei; Fukuda, Hiroshi; Kawashima, Ryuta

    2013-08-01

    We examined linear and curvilinear correlations of gray matter volume and density in cortical and subcortical gray matter with age using magnetic resonance images (MRI) in a large number of healthy children. We applied voxel-based morphometry (VBM) and region-of-interest (ROI) analyses with the Akaike information criterion (AIC), which was used to determine the best-fit model by selecting which predictor terms should be included. We collected data on brain structural MRI in 291 healthy children aged 5-18 years. Structural MRI data were segmented and normalized using a custom template by applying the diffeomorphic anatomical registration using exponentiated lie algebra (DARTEL) procedure. Next, we analyzed the correlations of gray matter volume and density with age in VBM with AIC by estimating linear, quadratic, and cubic polynomial functions. Several regions such as the prefrontal cortex, the precentral gyrus, and cerebellum showed significant linear or curvilinear correlations between gray matter volume and age on an increasing trajectory, and between gray matter density and age on a decreasing trajectory in VBM and ROI analyses with AIC. Because the trajectory of gray matter volume and density with age suggests the progress of brain maturation, our results may contribute to clarifying brain maturation in healthy children from the viewpoint of brain structure. Copyright © 2012 Wiley Periodicals, Inc.

  13. Compressed liquid densities and excess molar volumes for (CO2 + 1-pentanol) binary system at temperatures from 313 to 363 K and pressures up to 25 MPa

    International Nuclear Information System (INIS)

    Zuniga-Moreno, Abel; Galicia-Luna, Luis A.; Sandler, Stanley I.

    2008-01-01

    Measurements of compressed liquid densities for 1-pentanol and for {CO 2 (1) + 1-pentanol (2)} system were carried out at temperatures from 313 K to 363 K and pressures up to 25 MPa. Densities were measured for binary mixtures at 10 different compositions, x 1 = 0.0816, 0.1347, 0.3624, 0.4651, 0.6054, 0.7274, 0.8067, 0.8573, 0.9216, and 0.9757. A vibrating tube densimeter was used to perform density measurements using two reference calibration fluids. The uncertainty is estimated to be better than ±0.2 kg . m -3 for the experimental density measurements. For each mixture and for 1-pentanol, the experimental densities were correlated using an explicit volume equation of six parameters and an 11-parameter equation of state (EoS). Excess molar volumes were determined for the (CO 2 + 1-pentanol) system using 1-pentanol densities calculated from the 11-parameter EoS and CO 2 densities calculated from a multiparameter reference EoS

  14. It's what's inside that counts: egg contaminant concentrations are influenced by estimates of egg density, egg volume, and fresh egg mass.

    Science.gov (United States)

    Herzog, Mark P; Ackerman, Joshua T; Eagles-Smith, Collin A; Hartman, C Alex

    2016-05-01

    In egg contaminant studies, it is necessary to calculate egg contaminant concentrations on a fresh wet weight basis and this requires accurate estimates of egg density and egg volume. We show that the inclusion or exclusion of the eggshell can influence egg contaminant concentrations, and we provide estimates of egg density (both with and without the eggshell) and egg-shape coefficients (used to estimate egg volume from egg morphometrics) for American avocet (Recurvirostra americana), black-necked stilt (Himantopus mexicanus), and Forster's tern (Sterna forsteri). Egg densities (g/cm(3)) estimated for whole eggs (1.056 ± 0.003) were higher than egg densities estimated for egg contents (1.024 ± 0.001), and were 1.059 ± 0.001 and 1.025 ± 0.001 for avocets, 1.056 ± 0.001 and 1.023 ± 0.001 for stilts, and 1.053 ± 0.002 and 1.025 ± 0.002 for terns. The egg-shape coefficients for egg volume (K v ) and egg mass (K w ) also differed depending on whether the eggshell was included (K v  = 0.491 ± 0.001; K w  = 0.518 ± 0.001) or excluded (K v  = 0.493 ± 0.001; K w  = 0.505 ± 0.001), and varied among species. Although egg contaminant concentrations are rarely meant to include the eggshell, we show that the typical inclusion of the eggshell in egg density and egg volume estimates results in egg contaminant concentrations being underestimated by 6-13 %. Our results demonstrate that the inclusion of the eggshell significantly influences estimates of egg density, egg volume, and fresh egg mass, which leads to egg contaminant concentrations that are biased low. We suggest that egg contaminant concentrations be calculated on a fresh wet weight basis using only internal egg-content densities, volumes, and masses appropriate for the species. For the three waterbirds in our study, these corrected coefficients are 1.024 ± 0.001 for egg density, 0.493 ± 0.001 for K v , and 0.505 ± 0.001 for K w .

  15. Differences in Number of Midbrain Dopamine Neurons Associated with Summer and Winter Photoperiods in Humans.

    Directory of Open Access Journals (Sweden)

    Tim D Aumann

    Full Text Available Recent evidence indicates the number of dopaminergic neurons in the adult rodent hypothalamus and midbrain is regulated by environmental cues, including photoperiod, and that this occurs via up- or down-regulation of expression of genes and proteins that are important for dopamine (DA synthesis in extant neurons ('DA neurotransmitter switching'. If the same occurs in humans, it may have implications for neurological symptoms associated with DA imbalances. Here we tested whether there are differences in the number of tyrosine hydroxylase (TH, the rate-limiting enzyme in DA synthesis and DA transporter (DAT immunoreactive neurons in the midbrain of people who died in summer (long-day photoperiod, n = 5 versus winter (short-day photoperiod, n = 5. TH and DAT immunoreactivity in neurons and their processes was qualitatively higher in summer compared with winter. The density of TH immunopositive (TH+ neurons was significantly (~6-fold higher whereas the density of TH immunonegative (TH- neurons was significantly (~2.5-fold lower in summer compared with winter. The density of total neurons (TH+ and TH- combined was not different. The density of DAT+ neurons was ~2-fold higher whereas the density of DAT- neurons was ~2-fold lower in summer compared with winter, although these differences were not statistically significant. In contrast, midbrain nuclear volume, the density of supposed glia (small TH- cells, and the amount of TUNEL staining were the same in summer compared with winter. This study provides the first evidence of an association between environmental stimuli (photoperiod and the number of midbrain DA neurons in humans, and suggests DA neurotransmitter switching underlies this association.

  16. Densities and apparent molar volumes of HClO{sub 4}(aq) and Yb(ClO{sub 4}){sub 3}(aq) at elevated temperatures and pressures

    Energy Technology Data Exchange (ETDEWEB)

    Hakin, Andrew W. E-mail: hakin@uleth.ca; Lukacs, Michael J.; Jin Lianliu

    2004-09-01

    Relative densities have been measured for acidified aqueous solutions of ytterbium perchlorate {l_brace}Yb(ClO{sub 4}){sub 3}{r_brace} at approximately T=(348.15, 373.15, 398.15, and 423.15) K and p=(10.0, 20.0, and 30.0) MPa over the concentration range 0.01624{<=}m{sub 2}/(mol {center_dot} kg{sup -1}) {<=} 0.2531 using an optically coupled vibrating tube densimeter (OCVTD). Experimental apparent molar volumes have been calculated from the density measurements, and apparent molar volumes for the aqueous perchlorate salt have been calculated using Young's rule. The application of Young's rule requires apparent molar volumes for aqueous perchloric acid (HClO{sub 4}) solutions over extended temperature and pressure ranges. These values were calculated from densities for aqueous HClO{sub 4} solutions that were measured using the OCVTD at the same temperatures and pressures as those used to investigate the density surface of the acidified aqueous Yb(ClO{sub 4}){sub 3} solutions. The temperature, pressure, and composition surfaces of the apparent molar volumes for Yb(ClO{sub 4}){sub 3}(aq) and HClO{sub 4}(aq) have been modelled using Pitzer ion-interaction equations. Apparent molar volumes at infinite dilution obtained from these models have been compared to those which can be calculated using the semi-empirical Helgeson, Kirkham, and Flowers equations of state. Values for the apparent molar volume at infinite dilution of the ytterbium trivalent cation have also been calculated using simple additivity principles.

  17. Ab initio full charge-density study of the atomic volume of α-phase Fr, Ra, Ac, Th, Pa, U, Np, and Pu

    DEFF Research Database (Denmark)

    Vitos, Levente; Kollár, J.; Skriver, Hans Lomholt

    1997-01-01

    We have used a full charge-density technique based on the linear muffin-tin orbitals method in first-principles calculations of the atomic volumes of the light actinides including Fr, Ra, and Ac in their low-temperature crystallographic phases. The good agreement between the theoretical and exper......We have used a full charge-density technique based on the linear muffin-tin orbitals method in first-principles calculations of the atomic volumes of the light actinides including Fr, Ra, and Ac in their low-temperature crystallographic phases. The good agreement between the theoretical...... and experimental values along the series support the picture of itinerant 5f electronic states in Th to Pu. The increased deviation between theory and experiment found in Np and Pu may be an indication of correlation effects not included in the local density approximation....

  18. Densidade global de solos medida com anel volumétrico e por cachimbagem de terra fina seca ao ar Bulk density of soil samples measured in the field and through volume measurement of sieved soil

    Directory of Open Access Journals (Sweden)

    Bernardo Van Raij

    1989-01-01

    Full Text Available Em laboratórios de rotina de fertilidade do solo, a medida de quantidade de terra para análise é feita em volume, mediante utensílios chamados "cachimbos", que permitem medir volumes de terra. Admite-se que essas medidas reflitam a quantidade de terra existente em volume de solo similar em condições de campo. Essa hipótese foi avaliada neste trabalho, por doze amostras dos horizontes A e B de seis perfis de solos. A densidade em condições de campo foi avaliada por anel volumétrico e, no laboratório, por meio de cachimbos de diversos tamanhos. A cachimbagem revelou-se bastante precisa. Os valores de densidade global calculada variaram de 0,63 a 1,46g/cm³ para medidas de campo e de 0,91 a 1,33g/cm³ para medidas com cachimbos. Portanto, a medida de laboratório subestimou valores altos de densidade e deu resultados mais elevados para valores de campo mais baixos.In soil testing laboratories, soil samples for chemical analysis are usually measured by volume, using appropriate measuring spoons. It is tacitly assumed that such measurements would reflect amounts of soil existing in the same volume under field conditions. This hypothesis was tested, using 12 soil samples of the A and B horizons of six soil profiles. Bulk density in the field was evaluated through a cylindrical metal sampler of 50cm³ and in the laboratory using spoons of different sizes. Measurements of soil volumes by spoons were quite precise. Values of bulk density varied between 0.63 and 1.46g/cm³ for field measurements and between 0.91 and 1.33g/cm³ for laboratory measurements with spoons. Thus, laboratory measurements overestimated lower values of bulk densities and underestimated the higher ones.

  19. Gestational Exposure to Air Pollution Alters Cortical Volume, Microglial Morphology, and Microglia-Neuron Interactions in a Sex-Specific Manner

    Directory of Open Access Journals (Sweden)

    Jessica L. Bolton

    2017-05-01

    Full Text Available Microglia are the resident immune cells of the brain, important for normal neural development in addition to host defense in response to inflammatory stimuli. Air pollution is one of the most pervasive and harmful environmental toxicants in the modern world, and several large scale epidemiological studies have recently linked prenatal air pollution exposure with an increased risk of neurodevelopmental disorders such as autism spectrum disorder (ASD. Diesel exhaust particles (DEP are a primary toxic component of air pollution, and markedly activate microglia in vitro and in vivo in adult rodents. We have demonstrated that prenatal exposure to DEP in mice, i.e., to the pregnant dams throughout gestation, results in a persistent vulnerability to behavioral deficits in adult offspring, especially in males, which is intriguing given the greater incidence of ASD in males to females (∼4:1. Moreover, there is a striking upregulation of toll-like receptor (TLR 4 gene expression within the brains of the same mice, and this expression is primarily in microglia. Here we explored the impact of gestational exposure to DEP or vehicle on microglial morphology in the developing brains of male and female mice. DEP exposure increased inflammatory cytokine protein and altered the morphology of microglia, consistent with activation or a delay in maturation, only within the embryonic brains of male mice; and these effects were dependent on TLR4. DEP exposure also increased cortical volume at embryonic day (E18, which switched to decreased volume by post-natal day (P30 in males, suggesting an impact on the developing neural stem cell niche. Consistent with this hypothesis, we found increased microglial-neuronal interactions in male offspring that received DEP compared to all other groups. Taken together, these data suggest a mechanism by which prenatal exposure to environmental toxins may affect microglial development and long-term function, and thereby contribute

  20. Densities and apparent molar volumes for aqueous solutions of HNO3-UO2(NO3)2 at 298.15 K

    International Nuclear Information System (INIS)

    Yang-Xin Yu; Tie-Zhu Bao; Guang-Hua Gao; Yi-Gui Li

    1999-01-01

    In order to obtain the exact information of atomic number density in the ternary system of HNO 3 -UO 2 (NO 3 ) 2 -H 2 O, the densities were measured with an Anton-Paar DMA60/602 digital density meter thermostated at 298.15±0.01 K. The apparent molal volumes for the systems were calculated from the experimental data. The present measured apparent molar volumes have been fitted to the Pitzer ion-interaction model, which provides an adequate representation of the experimental data for mixed aqueous electrolyte solutions up to 6.2 mol/kg ionic strength. This fit yields θ V , and Ψ V , which are the first derivatives with respect to pressure of the mixing interaction parameters for the excess free energy. With the mixing parameters θ V , and ψ V , the densities and apparent molar volumes of the ternary system studied in this work can be calculated with good accuracy, as shown by the standard deviations. (author)

  1. Breast fat volume measurement using wide-bore 3 T MRI: comparison of traditional mammographic density evaluation with MRI density measurements using automatic segmentation.

    Science.gov (United States)

    Petridou, E; Kibiro, M; Gladwell, C; Malcolm, P; Toms, A; Juette, A; Borga, M; Dahlqvist Leinhard, O; Romu, T; Kasmai, B; Denton, E

    2017-07-01

    To compare magnetic resonance imaging (MRI)-derived breast density measurements using automatic segmentation algorithms with radiologist estimations using the Breast Imaging Reporting and Data Systems (BI-RADS) density classification. Forty women undergoing mammography and dynamic breast MRI as part of their clinical management were recruited. Fat-water separated MRI images derived from a two-point Dixon technique, phase-sensitive reconstruction, and atlas-based segmentation were obtained before and after intravenous contrast medium administration. Breast density was assessed using software from Advanced MR Analytics (AMRA), Linköping, Sweden, with results compared to the widely used four-quartile quantitative BI-RADS scale. The proportion of glandular tissue in the breast on MRI was derived from the AMRA sequence. The mean unenhanced breast density was 0.31±0.22 (mean±SD; left) and 0.29±0.21 (right). Mean breast density on post-contrast images was 0.32±0.19 (left) and 0.32±0.2 (right). There was "almost perfect" correlation between pre- and post-contrast breast density quantification: Spearman's correlation rho=0.98 (95% confidence intervals [CI]: 0.97-0.99; left) and rho=0.99 (95% CI: 0.98-0.99; right). The 95% limits of agreement were -0.11-0.08 (left) and -0.08-0.03 (right). Interobserver reliability for BI-RADS was "substantial": weighted Kappa k=0.8 (95% CI: 0.74-0.87). The Spearman correlation coefficient between BI-RADS and MRI breast density was rho=0.73 (95% CI: 0.60-0.82; left) and rho=0.75 (95% CI: 0.63-0.83; right) which was also "substantial". The AMRA sequence provides a fully automated, reproducible, objective assessment of fibroglandular breast tissue proportion that correlates well with mammographic assessment of breast density with the added advantage of avoidance of ionising radiation. Copyright © 2017 The Royal College of Radiologists. All rights reserved.

  2. Effect of culture medium volume and embryo density on early mouse embryonic development: tracking the development of the individual embryo.

    Science.gov (United States)

    Dai, Shan-Jun; Xu, Chang-Long; Wang, Jeffrey; Sun, Ying-Pu; Chian, Ri-Cheng

    2012-07-01

    To determine the optimal volume or density of embryos for the well-of-the-well (WOW) system in order to track the development of individual embryos and to determine whether the WOW system can reverse the negative impact of culturing embryos singly. (1) Mouse embryos (groups of nine at the 2-cell stage) were cultured in 6.25 μl, 12.50 μl, 25.00 μl and 50.00 μl of droplets of culture medium under paraffin oil; (2) Groups of three, six, nine and twelve embryos at the 2-cell stage were cultured in 50 μl of droplet of culture medium under paraffin oil; (3) Groups of nine embryos at the 2-cell stage were cultured in 50 μl of droplet under paraffin oil with or without nine micro-wells made on the bottom of the Petri dish into each of which were placed one of the nine embryos (WOW system). Also single 2-cell stage embryos was cultured individually in 5.5 μl of droplet of culture medium under paraffin oil with or without a single micro-well made on the bottom of the Petri dish (WOW system for single culture). At the end of culture, the percentages of blastocyst development, hatching and hatched blastocysts were compared in each group. The blastocysts were fixed for differential staining. The blastocyst development was significantly higher (P WOW system. The blastocyst development was not improved when single embryo cultured individually in a micro-well was compared to single embryo cultured individually without micro-well. The total cell numbers of blastocysts were significantly higher in group embryo culture than single embryo culture regardless of whether the WOW system was used. In addition, the total cell numbers of blastocysts were significantly higher (P WOW system than without. Group embryo culture is superior to single embryo culture for blastocyst development. The WOW system with 50 μl of droplet of culture medium can be used to track the individual development of embryo cultured in groups while preserving good embryonic development. The reduced

  3. The alterations of cortical volume, thickness, surface and density in the intermediate sporadic Parkinson's disease from the Han population of Mainland China

    Directory of Open Access Journals (Sweden)

    Xia Deng

    2016-08-01

    Full Text Available Many symptoms of sporadic Parkinson's disease (sPD can’t be completely explained by the lesion of simple typical extrapyramidal circuit between striatum and substantia nigra. Therefore, we investigated the alteration of cortical volume, thickness, surface and density in the intermediate sPD from the Han population of Mainland China in order to find the new pathological brain regions associated with the complex clinical manifestations of sPD. The cortical volume, thickness, surface and density were examined using the voxel-based cortical morphometry and corticometry on magnetic resonance image (MRI in 67 intermediate sPD and 35 controls, the multiple adjusted comparisons analysis of all MRI data were employed to assess the relationships between the cortical morphometric alteration in the specific brain regions and sPD. Results showed that a significantly shrunk volume, thinned thickness and enlarged or reduced surface of cortex in some specific brain regions were closely associated with sPD, but all cortical densities were not different. The majority of morphometric alteration of hemisphere cortex was symmetric, but that in the left hemisphere was more significant. The cortical morphometric alterations in the frontal, temporal, parietal, occipital and limbic lobe, cerebellum, caudate and thalamus were closely related to the clinical neural dysfunction (Clinical manifestations of sPD. Our data indicated that the deficits of extensive brain regions involved in the development of sPD, resulted in a series of correspondent complex clinical manifestations in the disease.

  4. Stereological analysis of neuron, glial and endothelial cell numbers in the human amygdaloid complex.

    Directory of Open Access Journals (Sweden)

    María García-Amado

    Full Text Available Cell number alterations in the amygdaloid complex (AC might coincide with neurological and psychiatric pathologies with anxiety imbalances as well as with changes in brain functionality during aging. This stereological study focused on estimating, in samples from 7 control individuals aged 20 to 75 years old, the number and density of neurons, glia and endothelial cells in the entire AC and in its 5 nuclear groups (including the basolateral (BL, corticomedial and central groups, 5 nuclei and 13 nuclear subdivisions. The volume and total cell number in these territories were determined on Nissl-stained sections with the Cavalieri principle and the optical fractionator. The AC mean volume was 956 mm(3 and mean cell numbers (x10(6 were: 15.3 neurons, 60 glial cells and 16.8 endothelial cells. The numbers of endothelial cells and neurons were similar in each AC region and were one fourth the number of glial cells. Analysis of the influence of the individuals' age at death on volume, cell number and density in each of these 24 AC regions suggested that aging does not affect regional size or the amount of glial cells, but that neuron and endothelial cell numbers respectively tended to decrease and increase in territories such as AC or BL. These accurate stereological measures of volume and total cell numbers and densities in the AC of control individuals could serve as appropriate reference values to evaluate subtle alterations in this structure in pathological conditions.

  5. Stereological analysis of neuron, glial and endothelial cell numbers in the human amygdaloid complex.

    Science.gov (United States)

    García-Amado, María; Prensa, Lucía

    2012-01-01

    Cell number alterations in the amygdaloid complex (AC) might coincide with neurological and psychiatric pathologies with anxiety imbalances as well as with changes in brain functionality during aging. This stereological study focused on estimating, in samples from 7 control individuals aged 20 to 75 years old, the number and density of neurons, glia and endothelial cells in the entire AC and in its 5 nuclear groups (including the basolateral (BL), corticomedial and central groups), 5 nuclei and 13 nuclear subdivisions. The volume and total cell number in these territories were determined on Nissl-stained sections with the Cavalieri principle and the optical fractionator. The AC mean volume was 956 mm(3) and mean cell numbers (x10(6)) were: 15.3 neurons, 60 glial cells and 16.8 endothelial cells. The numbers of endothelial cells and neurons were similar in each AC region and were one fourth the number of glial cells. Analysis of the influence of the individuals' age at death on volume, cell number and density in each of these 24 AC regions suggested that aging does not affect regional size or the amount of glial cells, but that neuron and endothelial cell numbers respectively tended to decrease and increase in territories such as AC or BL. These accurate stereological measures of volume and total cell numbers and densities in the AC of control individuals could serve as appropriate reference values to evaluate subtle alterations in this structure in pathological conditions.

  6. Ventilatory protective strategies during thoracic surgery: effects of alveolar recruitment maneuver and low-tidal volume ventilation on lung density distribution.

    Science.gov (United States)

    Kozian, Alf; Schilling, Thomas; Schütze, Hartmut; Senturk, Mert; Hachenberg, Thomas; Hedenstierna, Göran

    2011-05-01

    The increased tidal volume (V(T)) applied to the ventilated lung during one-lung ventilation (OLV) enhances cyclic alveolar recruitment and mechanical stress. It is unknown whether alveolar recruitment maneuvers (ARMs) and reduced V(T) may influence tidal recruitment and lung density. Therefore, the effects of ARM and OLV with different V(T) on pulmonary gas/tissue distribution are examined. Eight anesthetized piglets were mechanically ventilated (V(T) = 10 ml/kg). A defined ARM was applied to the whole lung (40 cm H(2)O for 10 s). Spiral computed tomographic lung scans were acquired before and after ARM. Thereafter, the lungs were separated with an endobronchial blocker. The pigs were randomized to receive OLV in the dependent lung with a V(T) of either 5 or 10 ml/kg. Computed tomography was repeated during and after OLV. The voxels were categorized by density intervals (i.e., atelectasis, poorly aerated, normally aerated, or overaerated). Tidal recruitment was defined as the addition of gas to collapsed lung regions. The dependent lung contained atelectatic (56 ± 10 ml), poorly aerated (183 ± 10 ml), and normally aerated (187 ± 29 ml) regions before ARM. After ARM, lung volume and aeration increased (426 ± 35 vs. 526 ± 69 ml). Respiratory compliance enhanced, and tidal recruitment decreased (95% vs. 79% of the whole end-expiratory lung volume). OLV with 10 ml/kg further increased aeration (atelectasis, 15 ± 2 ml; poorly aerated, 94 ± 24 ml; normally aerated, 580 ± 98 ml) and tidal recruitment (81% of the dependent lung). OLV with 5 ml/kg did not affect tidal recruitment or lung density distribution. (Data are given as mean ± SD.) The ARM improves aeration and respiratory mechanics. In contrast to OLV with high V(T), OLV with reduced V(T) does not reinforce tidal recruitment, indicating decreased mechanical stress.

  7. Diagnosis of drowning using post-mortem computed tomography based on the volume and density of fluid accumulation in the maxillary and sphenoid sinuses.

    Science.gov (United States)

    Kawasumi, Yusuke; Kawabata, Tomoyoshi; Sugai, Yusuke; Usui, Akihito; Hosokai, Yoshiyuki; Sato, Miho; Saito, Haruo; Ishibashi, Tadashi; Hayashizaki, Yoshie; Funayama, Masato

    2013-10-01

    Recent studies have reported that drowning victims frequently have fluid accumulation in the paranasal sinuses, most notably the maxillary and sphenoid sinuses. However, in our previous study, many non-drowning victims also had fluid accumulation in the sinuses. Therefore, we evaluated the qualitative difference in fluid accumulation between drowning and non-drowning cases in the present study. Thirty-eight drowning and 73 non-drowning cases were investigated retrospectively. The fluid volume and density of each case were calculated using a DICOM workstation. The drowning cases were compared with the non-drowning cases using the Mann-Whitney U-test because the data showed non-normal distribution. The median fluid volume was 1.82 (range 0.02-11.7) ml in the drowning cases and 0.49 (0.03-8.7) ml in the non-drowning cases, and the median fluid density was 22 (-14 to 66) and 39 (-65 to 77) HU, respectively. Both volume and density differed significantly between the drowning and non-drowning cases (p=0.001, p=0.0007). Regarding cut-off levels in the ROC analysis, the points on the ROC curve closest (0, 1) were 1.03ml (sensitivity 68%, specificity 68%, PPV 53%, NPV 81%) and 27.5 HU (61%, 70%, 51%, 77%). The Youden indices were 1.03ml and 37.8 HU (84%, 51%, 47%, 86%). When the cut-off level was set at 1.03ml and 27.5HU, the sensitivity was 42%, specificity 45%, PPV 29% and NPV 60%. When the cut-off level was set at 1.03ml and 37.8HU, sensitivity was 58%, specificity 32%, PPV 31% and NPV 59%. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  8. Characterization of Mixtures. Part 2: QSPR Models for Prediction of Excess Molar Volume and Liquid Density Using Neural Networks.

    Science.gov (United States)

    Ajmani, Subhash; Rogers, Stephen C; Barley, Mark H; Burgess, Andrew N; Livingstone, David J

    2010-09-17

    In our earlier work, we have demonstrated that it is possible to characterize binary mixtures using single component descriptors by applying various mixing rules. We also showed that these methods were successful in building predictive QSPR models to study various mixture properties of interest. Here in, we developed a QSPR model of an excess thermodynamic property of binary mixtures i.e. excess molar volume (V(E) ). In the present study, we use a set of mixture descriptors which we earlier designed to specifically account for intermolecular interactions between the components of a mixture and applied successfully to the prediction of infinite-dilution activity coefficients using neural networks (part 1 of this series). We obtain a significant QSPR model for the prediction of excess molar volume (V(E) ) using consensus neural networks and five mixture descriptors. We find that hydrogen bond and thermodynamic descriptors are the most important in determining excess molar volume (V(E) ), which is in line with the theory of intermolecular forces governing excess mixture properties. The results also suggest that the mixture descriptors utilized herein may be sufficient to model a wide variety of properties of binary and possibly even more complex mixtures. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. BASIC program to compute uranium density and void volume fraction in laboratory-scale uranium silicide aluminum dispersion plate-type fuel

    International Nuclear Information System (INIS)

    Ugajin, Mitsuhiro

    1991-05-01

    BASIC program simple and easy to operate has been developed to compute uranium density and void volume fraction for laboratory-scale uranium silicide aluminum dispersion plate-type fuel, so called miniplate. An example of the result of calculation is given in order to demonstrate how the calculated void fraction correlates with the microstructural distribution of the void in a miniplate prepared in our laboratory. The program is also able to constitute data base on important parameters for miniplates from experimentally-determined values of density, weight of each constituent and dimensions of miniplates. Utility programs pertinent to the development of the BASIC program are also given which run in the popular MS-DOS environment. All the source lists are attached and brief description for each program is made. (author)

  10. Effect of phase behavior, density, and isothermal compressibility on the constant-volume heat capacity of ethane + n-pentane mixed fluids in different phase regions

    International Nuclear Information System (INIS)

    Mu, Tiancheng; Liu, Zhimin; Han, Buxing.; Li, Zhonghao; Zhang, Jianling; Zhang, Xiaogang

    2003-01-01

    The phase behavior, density, and constant-volume molar heat capacity (C v,m ) of ethane + n-pentane binary mixtures have been measured in the supercritical region and subcritical region at T=309.45 K. In addition, the isothermal compressibility (κ T ) has been calculated using the density data determined. For a mixed fluid with a composition close to the critical composition, C v,m and κ T increase sharply as the pressure approaches the critical point (CP), the dew point (DP), or the bubble point (BP). However, C v,m is not sensitive to pressure in the entire pressure range if the composition of the mixed fluid is far from the critical composition. To tune the properties of the binary mixtures effectively by pressure, both the composition and the pressure should be close to the critical point of the mixture. The intermolecular interactions in the mixture are also discussed on the basis of the experimental results

  11. ASRDI oxygen technology survey. Volume 5: Density and liquid level measurement instrumentation for the cryogenic fluids oxygen, hydrogen, and nitrogen

    Science.gov (United States)

    Roder, H. M.

    1974-01-01

    Information is presented on instrumentation for density measurement, liquid level measurement, quantity gauging, and phase measurement. Coverage of existing information directly concerned with oxygen was given primary emphasis. A description of the physical principle of measurement for each instrumentation type is included. The basic materials of construction are listed if available from the source document for each instrument discussed. Cleaning requirements, procedures, and verification techniques are included.

  12. On-line micro-volume introduction system developed for lower density than water extraction solvent and dispersive liquid–liquid microextraction coupled with flame atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Anthemidis, Aristidis N.; Mitani, Constantina; Balkatzopoulou, Paschalia; Tzanavaras, Paraskevas D.

    2012-01-01

    Highlights: ► A dispersive liquid–liquid micro extraction method for lead and copper determination. ► A micro-volume transportation system for extractant solvent lighter than water. ► Analysis of natural water samples. - Abstract: A simple and fast preconcentration/separation dispersive liquid–liquid micro extraction (DLLME) method for metal determination based on the use of extraction solvent with lower density than water has been developed. For this purpose a novel micro-volume introduction system was developed enabling the on-line injection of the organic solvent into flame atomic absorption spectrometry (FAAS). The effectiveness and efficiency of the proposed system were demonstrated for lead and copper preconcentration in environmental water samples using di-isobutyl ketone (DBIK) as extraction solvent. Under the optimum conditions the enhancement factor for lead and copper was 187 and 310 respectively. For a sample volume of 10 mL, the detection limit (3 s) and the relative standard deviation were 1.2 μg L −1 and 3.3% for lead and 0.12 μg L −1 and 2.9% for copper respectively. The developed method was evaluated by analyzing certified reference material and it was applied successfully to the analysis of environmental water samples.

  13. 3D CT cerebral angiography technique using a 320-detector machine with a time–density curve and low contrast medium volume: Comparison with fixed time delay technique

    International Nuclear Information System (INIS)

    Das, K.; Biswas, S.; Roughley, S.; Bhojak, M.; Niven, S.

    2014-01-01

    Aim: To describe a cerebral computed tomography angiography (CTA) technique using a 320-detector CT machine and a small contrast medium volume (35 ml, 15 ml for test bolus). Also, to compare the quality of these images with that of the images acquired using a larger contrast medium volume (90 or 120 ml) and a fixed time delay (FTD) of 18 s using a 16-detector CT machine. Materials and methods: Cerebral CTA images were acquired using a 320-detector machine by synchronizing the scanning time with the time of peak enhancement as determined from the time–density curve (TDC) using a test bolus dose. The quality of CTA images acquired using this technique was compared with that obtained using a FTD of 18 s (by 16-detector CT), retrospectively. Average densities in four different intracranial arteries, overall opacification of arteries, and the degree of venous contamination were graded and compared. Results: Thirty-eight patients were scanned using the TDC technique and 40 patients using the FTD technique. The arterial densities achieved by the TDC technique were higher (significant for supraclinoid and basilar arteries, p < 0.05). The proportion of images deemed as having “good” arterial opacification was 95% for TDC and 90% for FTD. The degree of venous contamination was significantly higher in images produced by the FTD technique (p < 0.001%). Conclusion: Good diagnostic quality CTA images with significant reduction of venous contamination can be achieved with a low contrast medium dose using a 320-detector machine by coupling the time of data acquisition with the time of peak enhancement

  14. Experimental study of the density and derived volumetric (excess, apparent, and partial molar volumes) properties of aqueous 1-propanol mixtures at temperatures from 298 K to 582 K and pressures up to 40 MPa

    International Nuclear Information System (INIS)

    Abdulagatov, I.M.; Azizov, N.D.

    2014-01-01

    Highlights: • Density of (water + 1-propanol) mixtures. • Excess molar volumes of (water + 1-propanol) mixtures. • Apparent molar volumes of (water + 1-propanol) mixtures. -- Abstract: Densities of (water + 1-propanol) mixtures have been measured over the temperature range from 298 K to 582 K and at pressures up to 40 MPa using the constant-volume piezometer immersed in a precision liquid thermostat. The measurements were made for six compositions of (0.869, 2.465, 2.531, 7.407, 14.377, and 56.348) mol · kg −1 of 1-propanol. The expanded uncertainty of the density, pressure, temperature, and concentration measurements at the 95% confidence level with a coverage factor of k = 2 is estimated to be 0.06%, 0.05%, 15 mK, and 0.015%, respectively. The derived volumetric properties such as excess (V m E ), apparent (V Φ ), and partial (V ¯ 2 ∞ ) molar volumes were calculated using the measured values of density for the mixture and for pure components (water and 1-propanol). The concentration dependences of the apparent molar volumes were extrapolated to zero concentration to yield the partial molar volumes of 1-propanol at infinite dilution (V ¯ 2 ∞ ). The temperature, pressure, and concentration dependence of density and derived properties of the mixture were studied. All experimental and derived properties (excess, apparent, and partial molar volumes) were compared with the reported data by other authors. The small and negative values of excess molar volume for the mixtures were found at all experimental temperatures, pressures, and over the entire concentration range. The excess molar volume minimum is found at concentration about 0.4 mole fraction of 1-propanol. The concentration minimum of the derived apparent molar volumes V Φ near the 2.5 mol · kg −1 (dilute mixture) was observed

  15. Beneficial effects of young coconut juice on preserving neuronal cell density, lipid, renal and liver profiles in ovariectomized rats. A preliminary study.

    Directory of Open Access Journals (Sweden)

    Kolip Payanglee

    2017-04-01

    Full Text Available Our previous study showed that young coconut juice (YCJ at a high dose of 100 mL/kgBW had many health benefits e.g. it delayed Alzheimer’s pathologies, preserved neuronal cells, accelerated wound healing and prevented osteoporosis. However, such a large dose of YCJ over a period of time started to have unfavourable side effects e.g. the deposition of glycogen in the liver. Therefore, our aim in the present study was to investigate the lowest neuroprotective dose of YCJ that would cause the least side effects for long-term consumption by postmenopausal women, using ovariectomized (ovx rats as a model for postmenopausal women. Three lower doses of YCJ (10, 20 and 40 mL/kg body weight were applied. The results clearly showed that the OY10 group was the best dose to help to preserve neuronal cells in both the hippocampus and the prefrontal cortex with cell numbers being higher than for the ovx group at various degrees of significance in each brain region. After 10 weeks of treatment, the circulating levels of BUN, creatinine, cholesterol, triglyceride, HDL, LDL, AST, ALT, ALP, total protein, albumin, calcium and phosphorus of the OY10 group were not significantly different from those of the sham and ovx groups. This study has confirmed that feeding YCJ had beneficial effects on the serum lipid profile, and maintained liver and renal functions for up to 10 weeks after administration. YCJ consumption at 10 mL/kgBW/day for 10 weeks, however, did increase body weight and serum glucose when compared with the control groups. Therefore, supplementation with YCJ in postmenopausal women with a diabetic condition should only be allowed under supervision by a physician.

  16. Protein malnutrition during gestation and early life decreases neuronal size in the medial prefrontal cortex of post-pubertal rats

    Directory of Open Access Journals (Sweden)

    Roelf J. Cruz-Rizzolo

    2017-12-01

    Full Text Available Retrospective studies in human populations indicate that protein deprivation during pregnancy and early life (early protein malnutrition, EPM is associated with cognitive impairments, learning disabilities and may represent a risk factor for the late onset of some psychiatric disorders, fundamentally schizophrenia, a condition where the prefrontal cortex plays an important role. The purpose of this study was to analyze whether EPM affects structural aspects of the rat medial prefrontal cortex (mPFC, such as cortical volume, neuronal density and neuronal soma size, which seem altered in patients with schizophrenia. For this, a rat model of EPM (5% casein from conception to postnatal day 60 was adopted and the rat mPFC volume, total number of neurons and average neuronal volume were evaluated on postnatal day 60 (post-pubertal animals by histo- and immunohistochemical techniques using unbiased stereological analysis. EPM did not alter the number of NeuN+ neurons in the rat mPFC. However, a very significant decrease in mPFC volume and average neuronal size was observed in malnourished rats. Although the present study does not establish causal relationships between malnutrition and schizophrenia, our results may indicate a similar structural phenomenon in these two situations.

  17. Prenatal exposure to an NMDA receptor antagonist, MK-801 reduces density of parvalbumin-immunoreactive GABAergic neurons in the medial prefrontal cortex and enhances phencyclidine-induced hyperlocomotion but not behavioral sensitization to methamphetamine in postpubertal rats.

    Science.gov (United States)

    Abekawa, Tomohiro; Ito, Koki; Nakagawa, Shin; Koyama, Tsukasa

    2007-06-01

    Neurodevelopmental deficits of parvalbumin-immunoreactive gamma-aminobutyric acid (GABA)ergic interneurons in prefrontal cortex have been reported in schizophrenia. Glutamate influences the proliferation of this type of interneuron by an N-methyl-D-aspartate (NMDA)-receptor-mediated mechanism. The present study hypothesized that prenatal blockade of NMDA receptors would disrupt GABAergic neurodevelopment, resulting in differences in effects on behavioral responses to a noncompetitive NMDA antagonist, phencyclidine (PCP), and a dopamine releaser, methamphetamine (METH). GABAergic neurons were immunohistochemically stained with parvalbumin antibody. Psychostimulant-induced hyperlocomotion was measured using an infrared sensor. Prenatal exposure (E15-E18) to the NMDA receptor antagonist MK-801 reduced the density of parvalbumin-immunoreactive neurons in rat medial prefrontal cortex on postnatal day 63 (P63) and enhanced PCP-induced hyperlocomotion but not the acute effects of METH on P63 or the development of behavioral sensitization. Prenatal exposure to MK-801 reduced the number of parvalbumin-immunoreactive neurons even on postnatal day 35 (P35) and did not enhance PCP-induced hyperlocomotion, the acute effects of METH on P35, or the development of behavioral sensitization to METH. These findings suggest that prenatal blockade of NMDA receptors disrupts GABAergic neurodevelopment in medial prefrontal cortex, and that this disruption of GABAergic development may be related to the enhancement of the locomotion-inducing effect of PCP in postpubertal but not juvenile offspring. GABAergic deficit is unrelated to the effects of METH. This GABAergic neurodevelopmental disruption and the enhanced PCP-induced hyperlocomotion in adult offspring prenatally exposed to MK-801 may prove useful as a new model of the neurodevelopmental process of pathogenesis of treatment-resistant schizophrenia via an NMDA-receptor-mediated hypoglutamatergic mechanism.

  18. Lung density

    DEFF Research Database (Denmark)

    Garnett, E S; Webber, C E; Coates, G

    1977-01-01

    The density of a defined volume of the human lung can be measured in vivo by a new noninvasive technique. A beam of gamma-rays is directed at the lung and, by measuring the scattered gamma-rays, lung density is calculated. The density in the lower lobe of the right lung in normal man during quiet...... breathing in the sitting position ranged from 0.25 to 0.37 g.cm-3. Subnormal values were found in patients with emphsema. In patients with pulmonary congestion and edema, lung density values ranged from 0.33 to 0.93 g.cm-3. The lung density measurement correlated well with the findings in chest radiographs...... but the lung density values were more sensitive indices. This was particularly evident in serial observations of individual patients....

  19. Unaltered Neuronal and Glial Counts in Animal Models of Magnetic Seizure Therapy and Electroconvulsive Therapy

    DEFF Research Database (Denmark)

    Dwork, A.J.; Christensen, J.R.; Larsen, K.B.

    2009-01-01

    report on its anatomical effects. We discerned no histological lesions in the brains of higher mammals subjected to electroconvulsive shock (ECS) or MST, under conditions that model closely those used in humans. We sought to extend these findings by determining whether these interventions affected...... the number of neurons or glia in the frontal cortex or hippocampus. Twenty-four animals received 6 weeks of ECS, MST, or anesthesia alone, 4 days per week. After perfusion fixation, numbers of neurons and glia in frontal cortex and hippocampus were determined by unbiased stereological methods. We found...... no effect of either intervention on volumes or total number or numerical density of neurons or glia in hippocampus, frontal cortex, or subregions of these structures. Induction of seizures in a rigorous model of human ECT and MST therapy does not cause a change in the number of neurons or glia...

  20. Density, viscosity, isothermal (vapour + liquid) equilibrium, excess molar volume, viscosity deviation, and their correlations for chloroform + methyl isobutyl ketone binary system

    International Nuclear Information System (INIS)

    Clara, Rene A.; Gomez Marigliano, Ana C.; Solimo, Horacio N.

    2007-01-01

    Density and viscosity measurements for pure chloroform and methyl isobutyl ketone at T = (283.15, 293.15, 303.15, and 313.15) K as well as for the binary system {x 1 chloroform + (1 - x 1 ) methyl isobutyl ketone} at the same temperatures were made over the whole concentration range. The experimental results were fitted to empirical equations, which permit the calculation of these properties over the whole concentration and temperature ranges studied. Data of the binary mixture were further used to calculate the excess molar volume and viscosity deviation. The (vapour + liquid) equilibrium (VLE) at T = 303.15 K for this binary system was also measured in order to calculate the activity coefficients and the excess molar Gibbs energy. This binary system shows no azeotrope and negative deviations from ideal behaviour. The excess or deviation properties were fitted to the Redlich-Kister polynomial relation to obtain their coefficients and standard deviations

  1. Densities and volume properties of (water + tert-butanol) over the temperature range of (274.15 to 348.15) K at pressure of 0.1 MPa

    International Nuclear Information System (INIS)

    Egorov, Gennadiy I.; Makarov, Dmitriy M.

    2011-01-01

    The densities of {water (1) + tert-butanol (2)} binary mixture were measured over the temperature range (274.15 to 348.15) K at atmospheric pressure using 'Anton Paar' digital vibrating-tube densimeter. Density measurements were carried out over the whole concentration range at (308.15 to 348.15) K. The following volume parameters were calculated: excess molar volumes and thermal isobaric expansivities of the mixture, partial molar volumes and partial molar thermal isobaric expansivities of the components. Concentration dependences of excess molar volumes were fitted with Redlich-Kister equation. The results of partial molar volume calculations using four equations were compared. It was established that for low alcohol concentrations at T ≤ 208 K the inflection points at x 2 ∼ 0.02 were observed at concentration dependences of specific volume. The concentration dependences of partial molar volumes of both water and tert-butanol had extremes at low alcohol content. The temperature dependence of partial molar volumes of water had some inversion at x 2 ∼ 0.65. The temperature dependence of partial molar volumes of tert-butanol at infinite dilution had minimum at ∼288 K. It was discovered that concentration dependences of thermal isobaric expansivities of the mixture at small alcohol content and low temperatures passed through minimum.

  2. Glial responses, neuron death and lesion resolution after intracerebral hemorrhage in young vs. aged rats.

    Science.gov (United States)

    Wasserman, Jason K; Yang, Helen; Schlichter, Lyanne C

    2008-10-01

    Intracerebral hemorrhage (ICH) usually affects older humans but almost no experimental studies have assessed aged animals. We address how aging alters inflammation, neuron death and lesion resolution after a hemorrhage in the rat striatum. In the normal aged brain, microglia displayed a 'dystrophic' phenotype, with shorter cellular processes and large gaps between adjacent cells, and there was more astrocyte reactivity. The ICH injury was monitored as hematoma volume and number of dying neurons at 1 and 3 days, and the volume of the residual lesion, ventricles and lost tissue at 28 days. Inflammation at 1 and 3 days was assessed from densities of microglia with resting vs. activated morphologies, or expressing the lysosomal marker ED1. Despite an initial delay in neuron death in aged animals, by 28 days, there was no difference in neuron density or volume of tissue lost. However, lesion resolution was impaired in aged animals and there was less compensatory ventricular expansion. At 1 day after ICH, there were fewer activated microglia/macrophages in the aged brain, but by 3 days there were more of these cells at the edge of the hematoma and in the surrounding parenchyma. In both age groups a glial limitans had developed by 3 days, but astrocyte reactivity and the spread of activated microglia/macrophages into the surrounding parenchyma was greater in the aged. These findings have important implications for efforts to reduce secondary injury after ICH and to develop anti-inflammatory therapies to treat ICH in aged humans.

  3. Mechanosensing in hypothalamic osmosensory neurons.

    Science.gov (United States)

    Prager-Khoutorsky, Masha

    2017-11-01

    Osmosensory neurons are specialized cells activated by increases in blood osmolality to trigger thirst, secretion of the antidiuretic hormone vasopressin, and elevated sympathetic tone during dehydration. In addition to multiple extrinsic factors modulating their activity, osmosensory neurons are intrinsically osmosensitive, as they are activated by increased osmolality in the absence of neighboring cells or synaptic contacts. This intrinsic osmosensitivity is a mechanical process associated with osmolality-induced changes in cell volume. This review summarises recent findings revealing molecular mechanisms underlying the mechanical activation of osmosensory neurons and highlighting important roles of microtubules, actin, and mechanosensitive ion channels in this process. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. The BDNF val-66-met Polymorphism Affects Neuronal Morphology and Synaptic Transmission in Cultured Hippocampal Neurons from Rett Syndrome Mice

    Directory of Open Access Journals (Sweden)

    Xin Xu

    2017-07-01

    Full Text Available Brain-derived neurotrophic factor (Bdnf has been implicated in several neurological disorders including Rett syndrome (RTT, an X-linked neurodevelopmental disorder caused by loss-of-function mutations in the transcriptional modulator methyl-CpG-binding protein 2 (MECP2. The human BDNF gene has a single nucleotide polymorphism (SNP—a methionine (met substitution for valine (val at codon 66—that affects BDNF’s trafficking and activity-dependent release and results in cognitive dysfunction. Humans that are carriers of the met-BDNF allele have subclinical memory deficits and reduced hippocampal volume and activation. It is still unclear whether this BDNF SNP affects the clinical outcome of RTT individuals. To evaluate whether this BDNF SNP contributes to RTT pathophysiology, we examined the consequences of expression of either val-BDNF or met-BDNF on dendrite and dendritic spine morphology, and synaptic function in cultured hippocampal neurons from wildtype (WT and Mecp2 knockout (KO mice. Our findings revealed that met-BDNF does not increase dendritic growth and branching, dendritic spine density and individual spine volume, and the number of excitatory synapses in WT neurons, as val-BDNF does. Furthermore, met-BDNF reduces dendritic complexity, dendritic spine volume and quantal excitatory synaptic transmission in Mecp2 KO neurons. These results suggest that the val-BDNF variant contributes to RTT pathophysiology, and that BDNF-based therapies should take into consideration the BDNF genotype of the RTT individuals.

  5. Motor Neurons

    DEFF Research Database (Denmark)

    Hounsgaard, Jorn

    2017-01-01

    Motor neurons translate synaptic input from widely distributed premotor networks into patterns of action potentials that orchestrate motor unit force and motor behavior. Intercalated between the CNS and muscles, motor neurons add to and adjust the final motor command. The identity and functional...... in in vitro preparations is far from complete. Nevertheless, a foundation has been provided for pursuing functional significance of intrinsic response properties in motoneurons in vivo during motor behavior at levels from molecules to systems....

  6. Chronic caffeine consumption prevents cognitive decline from young to middle age in rats, and is associated with increased length, branching, and spine density of basal dendrites in CA1 hippocampal neurons.

    Science.gov (United States)

    Vila-Luna, S; Cabrera-Isidoro, S; Vila-Luna, L; Juárez-Díaz, I; Bata-García, J L; Alvarez-Cervera, F J; Zapata-Vázquez, R E; Arankowsky-Sandoval, G; Heredia-López, F; Flores, G; Góngora-Alfaro, J L

    2012-01-27

    Chronic caffeine consumption has been inversely associated with the risk of developing dementia and Alzheimer's disease. Here we assessed whether chronic caffeine treatment prevents the behavioral and cognitive decline that male Wistar rats experience from young (≈3 months) to middle age (≈10 months). When animals were young they were evaluated at weekly intervals in three tests: motor activity habituation in the open field (30-min sessions at the same time on consecutive days), continuous spontaneous alternation in the Y-maze (8 min), and elevated plus-maze (5 min). Afterward, rats from the same litter were randomly assigned either to a caffeine-treated group (n=13) or a control group (n=11), which received only tap water. Caffeine treatment (5 mg/kg/day) began when animals were ≈4 months old, and lasted for 6 months. Behavioral tests were repeated from day 14 to day 28 after caffeine withdrawal, a time period that is far in excess for the full excretion of a caffeine dose in this species. Thirty days after caffeine discontinuation brains were processed for Golgi-Cox staining. Compared with controls, we found that middle-aged rats that had chronically consumed low doses of caffeine (1) maintained their locomotor habituation during the second consecutive day exposure to the open field (an index of non-associative learning), (2) maintained their exploratory drive to complete the conventional minimum of nine arm visits required to calculate the alternation performance in the Y-maze in a greater proportion, (3) maintained their alternation percentage above chance level (an index of working memory), and (4) did not increase the anxiety indexes assessed by measuring the time spent in the open arms of the elevated plus maze. In addition, morphometric analysis of hippocampal neurons revealed that dendritic branching (90-140 μm from the soma), length of 4th and 5th order branches, total dendritic length, and spine density in distal dendritic branches were greater in

  7. Storm/Quiet Ratio Comparisons Between TIMED/SABER NO (sup +)(v) Volume Emission Rates and Incoherent Scatter Radar Electron Densities at E-Region Altitudes

    Science.gov (United States)

    Fernandez, J. R.; Mertens, C. J.; Bilitza, D.; Xu, X.; Russell, J. M., III; Mlynczak, M. G.

    2009-01-01

    Broadband infrared limb emission at 4.3 microns is measured by the TIMED/SABER instrument. At night, these emission observations at E-region altitudes are used to derive the so called NO+(v) Volume Emission Rate (VER). NO+(v) VER can be derived by removing the background CO2(v3) 4.3 microns radiance contribution using SABER-based non-LTE radiation transfer models, and by performing a standard Abel inversion on the residual radiance. SABER observations show that NO+(v) VER is significantly enhanced during magnetic storms in accordance with increased ionization of the neutral atmosphere by auroral electron precipitation, followed by vibrational excitation of NO+ (i.e., NO+(v)) from fast exothermic ion-neutral reactions, and prompt infrared emission at 4.3 m. Due to charge neutrality, the NO+(v) VER enhancements are highly correlated with electron density enhancements, as observed for example by Incoherent Scatter Radar (ISR). In order to characterize the response of the storm-time E-region from both SABER and ISR measurements, a Storm/Quiet ratio (SQR) quantity is defined as a function of altitude. For SABER, the SQR is the ratio of the storm-to-quiet NO+(v) VER. SQR is the storm-to-quiet ratio of electron densities for ISR. In this work, we compare SABER and ISR SQR values between 100 to 120 km. Results indicate good agreement between these measurements. SQR values are intended to be used as a correction factor to be included in an empirical storm-time correction to the International Reference Ionosphere model at E-region altitudes.

  8. Constitutive mass balance relations between chemical composition, volume, density, porosity, and strain in metasomatic hydrochemical systems: Results on weathering and pedogenesis

    Science.gov (United States)

    Brimhall, George H.; Dietrich, William E.

    1987-03-01

    Relations characterizing the chemical, physical, and mechanical changes resulting from metasomatic hydrochemical processes are developed using mass balance models which formally link chemical composition to bulk density, mineral density, volumetric properties, porosity, and amount of deformation (strain). Rigorous analysis of aqueous solute transport effects is then made possible in a variety of porous media flow environments including chemical weathering, pedogenesis (soil formation), diagenesis, ore deposition and enrichment, and metamorphism. Application of these linear constitutive relations to chemical weathering profiles shows that immobile and locally mobile chemical elements, with masses conserved on the scale of soil profiles, can be accurately identified from analysis of appropriate data arrays and then used as natural geochemical tracers to infer the nature and extent of hydrochemical weathering processes and volume changes during pedogenesis. Assumptions commonly made in the past about the supposed immobility of certain elements, e.g., Ti and Zr, become unnecessary. Quantitative differentiation between the effects of residual and supergene fractionation is then easily made. These methods are applied to Ni-rich laterites developed by weathering of ultramafic rocks, showing that during ordinary residual enrichment, Ni is concentrated by as much as 4× protolith peridotite concentrations. This occurs simply by silicate mineral dissolution and removal of chemical elements other than Ni ( e.g., Mg) with a corresponding reduction in saprolite density and increase in bulk porosity without significant deformation. In contrast, laterites with mineable concentrations of Ni which are similarly undeformed (such as the Nickel Mountain Mine in Riddle, Oregon) have experienced, in addition to residual enrichment, strong supergene enrichment by fractionation of ore elements between a leached zone from which Ni is extracted and a complementary enriched zone positioned

  9. [Mirror neurons].

    Science.gov (United States)

    Rubia Vila, Francisco José

    2011-01-01

    Mirror neurons were recently discovered in frontal brain areas of the monkey. They are activated when the animal makes a specific movement, but also when the animal observes the same movement in another animal. Some of them also respond to the emotional expression of other animals of the same species. These mirror neurons have also been found in humans. They respond to or "reflect" actions of other individuals in the brain and are thought to represent the basis for imitation and empathy and hence the neurobiological substrate for "theory of mind", the potential origin of language and the so-called moral instinct.

  10. Liquid Densities and Excess Molar Volumes for Water + Diethylene Glycolamine, and Water, Methanol, Ethanol, 1-Propanol + Triethylene Glycol Binary Systems at Atmospheric Pressure and Temperatures in the Range of 283.15ů363.15 K

    Czech Academy of Sciences Publication Activity Database

    Valtz, A.; Teodorescu, M.; Wichterle, Ivan; Richon, D.

    2004-01-01

    Roč. 215, č. 2 (2004), s. 129-142 ISSN 0378-3812 R&D Projects: GA ČR GA104/03/1555 Institutional research plan: CEZ:AV0Z4072921 Keywords : excess molar volume * density * triethylene glycol Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.356, year: 2004

  11. Compressed liquid densities and excess molar volumes for (CO{sub 2} + 1-pentanol) binary system at temperatures from 313 to 363 K and pressures up to 25 MPa

    Energy Technology Data Exchange (ETDEWEB)

    Zuniga-Moreno, Abel [Instituto Politecnico Nacional, ESIQIE, Laboratorio de Termodinamica, Edif. Z, Secc. 6, 1er piso, UPALM Zacatenco, 07738, Lindavista, Mexico, D.F. (Mexico); Galicia-Luna, Luis A. [Instituto Politecnico Nacional, ESIQIE, Laboratorio de Termodinamica, Edif. Z, Secc. 6, 1er piso, UPALM Zacatenco, 07738, Lindavista, Mexico, D.F. (Mexico)], E-mail: lgalicial@ipn.mx; Sandler, Stanley I. [Department of Chemical Engineering, University of Delaware, Newark, DE 19716-3119 (United States)

    2008-02-15

    Measurements of compressed liquid densities for 1-pentanol and for {l_brace}CO{sub 2} (1) + 1-pentanol (2){r_brace} system were carried out at temperatures from 313 K to 363 K and pressures up to 25 MPa. Densities were measured for binary mixtures at 10 different compositions, x{sub 1} = 0.0816, 0.1347, 0.3624, 0.4651, 0.6054, 0.7274, 0.8067, 0.8573, 0.9216, and 0.9757. A vibrating tube densimeter was used to perform density measurements using two reference calibration fluids. The uncertainty is estimated to be better than {+-}0.2 kg . m{sup -3} for the experimental density measurements. For each mixture and for 1-pentanol, the experimental densities were correlated using an explicit volume equation of six parameters and an 11-parameter equation of state (EoS). Excess molar volumes were determined for the (CO{sub 2} + 1-pentanol) system using 1-pentanol densities calculated from the 11-parameter EoS and CO{sub 2} densities calculated from a multiparameter reference EoS.

  12. Density, excess volume, and excess coefficient of thermal expansion of the binary systems of dimethyl carbonate with butyl methacrylate, allyl methacrylate, styrene, and vinyl acetate at T = (293.15, 303.15, and 313.15) K

    International Nuclear Information System (INIS)

    Wisniak, Jaime; Cortez, Gladis; Peralta, Rene D.; Infante, Ramiro; Elizalde, Luis E.; Amaro, Tlaloc A.; Garcia, Omar; Soto, Homero

    2008-01-01

    Densities of the binary systems of dimethyl carbonate with butyl methacrylate, allyl methacrylate, styrene, and vinyl acetate have been measured as a function of the composition at (293.15, 303.15, and 313.15) K at atmospheric pressure, using an Anton Paar DMA 5000 oscillating U-tube densimeter. The excess molar volumes are negative for the (dimethyl carbonate + vinyl acetate) system and positive for the three other binaries, and become more so as the temperature increases from (293.15 to 313.15) K. The apparent volumes were used to calculate the values of the partial excess molar volumes at infinite dilution. The excess coefficient of thermal expansion is positive for the four binary systems. The calculated excess molar volumes were correlated with the Redlich-Kister equation and with a series of Legendre polynomials. An explanation of the results is offered based on the FT-IR (ATR) spectra of several mixtures of the different systems

  13. Density, excess volume, and excess coefficient of thermal expansion of the binary systems of dimethyl carbonate with butyl methacrylate, allyl methacrylate, styrene, and vinyl acetate at T = (293.15, 303.15, and 313.15) K

    Energy Technology Data Exchange (ETDEWEB)

    Wisniak, Jaime [Department of Chemical Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel)], E-mail: wisniak@bgumail.bgu.ac.il; Cortez, Gladis; Peralta, Rene D.; Infante, Ramiro; Elizalde, Luis E. [Centro de Investigacion en Quimica Aplicada, Saltillo 25253, Coahuila (Mexico); Amaro, Tlaloc A.; Garcia, Omar; Soto, Homero [Facultad de Ciencias Quimicas, Universidad Autonoma de Coahuila, Saltillo 25280, Coahuila (Mexico)

    2008-12-15

    Densities of the binary systems of dimethyl carbonate with butyl methacrylate, allyl methacrylate, styrene, and vinyl acetate have been measured as a function of the composition at (293.15, 303.15, and 313.15) K at atmospheric pressure, using an Anton Paar DMA 5000 oscillating U-tube densimeter. The excess molar volumes are negative for the (dimethyl carbonate + vinyl acetate) system and positive for the three other binaries, and become more so as the temperature increases from (293.15 to 313.15) K. The apparent volumes were used to calculate the values of the partial excess molar volumes at infinite dilution. The excess coefficient of thermal expansion is positive for the four binary systems. The calculated excess molar volumes were correlated with the Redlich-Kister equation and with a series of Legendre polynomials. An explanation of the results is offered based on the FT-IR (ATR) spectra of several mixtures of the different systems.

  14. A novel perspective on neuron study: damaging and promoting effects in different neurons induced by mechanical stress.

    Science.gov (United States)

    Wang, Yazhou; Wang, Wei; Li, Zong; Hao, Shilei; Wang, Bochu

    2016-10-01

    A growing volume of experimental evidence demonstrates that mechanical stress plays a significant role in growth, proliferation, apoptosis, gene expression, electrophysiological properties and many other aspects of neurons. In this review, first, the mechanical microenvironment and properties of neurons under in vivo conditions are introduced and analyzed. Second, research works in recent decades on the effects of different mechanical forces, especially compression and tension, on various neurons, including dorsal root ganglion neurons, retinal ganglion cells, cerebral cortex neurons, hippocampus neurons, neural stem cells, and other neurons, are summarized. Previous research results demonstrate that mechanical stress can not only injure neurons by damaging their morphology, impacting their electrophysiological characteristics and gene expression, but also promote neuron self-repair. Finally, some future perspectives in neuron research are discussed.

  15. Density, viscosity and excess molar volume of binary mixtures of tri-n-octylamine + diluents (n-heptane, n-octane, n-nonane, and n-decane) at various temperatures

    International Nuclear Information System (INIS)

    Fang, Sheng; Zuo, Xiao-Bo; Xu, Xue-Jiao; Ren, Da-Hai

    2014-01-01

    Highlights: • Densities and viscosities of tri-n-octylamine + n-heptane, +n-octane, +n-nonane, or +n-decane are determined. • The excess molar volume is calculated. • The Grunberg and Nissan equation and Fang and He equation are used to correlate the binary viscosities. -- Abstract: Densities (ρ) and viscosities (η) for binary mixtures of tri-n-octylamine (TOA) + n-heptane, TOA + n-octane, TOA + n-nonane, and TOA + n-decane are determined at T (283.15, 293.15, and 303.15) K and atmospheric pressure. The excess molar volume is calculated from the density data and is correlated by a Redlich–Kister type equation. The excess molar volume is negative for all the four systems. The results show that the volume accommodation effect is predominant in these systems. The Grunberg and Nissan equation and Fang and He equation for binary mixtures are used to correlate the experimental viscosity data. The Fang and He equation gives an average absolute deviation (AAD%) of 0.8% for TOA with alkane mixtures, better than that of 3.8% given by the Grunberg and Nissan equation

  16. Neurons other than motor neurons in motor neuron disease.

    Science.gov (United States)

    Ruffoli, Riccardo; Biagioni, Francesca; Busceti, Carla L; Gaglione, Anderson; Ryskalin, Larisa; Gambardella, Stefano; Frati, Alessandro; Fornai, Francesco

    2017-11-01

    Amyotrophic lateral sclerosis (ALS) is typically defined by a loss of motor neurons in the central nervous system. Accordingly, morphological analysis for decades considered motor neurons (in the cortex, brainstem and spinal cord) as the neuronal population selectively involved in ALS. Similarly, this was considered the pathological marker to score disease severity ex vivo both in patients and experimental models. However, the concept of non-autonomous motor neuron death was used recently to indicate the need for additional cell types to produce motor neuron death in ALS. This means that motor neuron loss occurs only when they are connected with other cell types. This concept originally emphasized the need for resident glia as well as non-resident inflammatory cells. Nowadays, the additional role of neurons other than motor neurons emerged in the scenario to induce non-autonomous motor neuron death. In fact, in ALS neurons diverse from motor neurons are involved. These cells play multiple roles in ALS: (i) they participate in the chain of events to produce motor neuron loss; (ii) they may even degenerate more than and before motor neurons. In the present manuscript evidence about multi-neuronal involvement in ALS patients and experimental models is discussed. Specific sub-classes of neurons in the whole spinal cord are reported either to degenerate or to trigger neuronal degeneration, thus portraying ALS as a whole spinal cord disorder rather than a disease affecting motor neurons solely. This is associated with a novel concept in motor neuron disease which recruits abnormal mechanisms of cell to cell communication.

  17. Imaging of intracranial neuronal and mixed neuronal-glial tumours

    International Nuclear Information System (INIS)

    Cui Shimin; Qin Jinxi; Zhang Leili; Liu Meili; Jin Song; Yan Shixin; Liu Li; Dai Weiying; Li Tao; Gao Man

    2001-01-01

    Objective: To investigate the characteristic clinical, imaging , and pathologic findings of intracranial neuronal and mixed neuronal-glial tumours. Methods: The imaging findings of surgery and pathobiology proved intracranial neuronal and mixed neuronal-glial tumours in 14 cases (7 male and 7 female, ranging in age from 6-56 years; mean age 33.8 years) were retrospectively analyzed. Results: Eight gangliogliomas were located in the frontal lobe (4 cases), temporal lobe (1 case), front- temporal lobe (2 cases), and pons (1 case). They appeared as iso-or low density on CT, iso-or low signal intensity on T 1 WI, and high signal intensity on T 2 WI on MR imaging. Two central neurocytomas were located in the supratentorial ventricles. Four desmoplastic gangliogliomas were seen as cystic masses, appearing as low signal intensity on T 1 WI and high signal intensity on T 2 WI. Conclusion: Intracranial neuronal and mixed neuronal-glial tumours had imaging characteristics. Combined with clinical history, it was possible to make a tendency preoperative diagnosis using CT or MR

  18. The Influence of Spatial Variation in Chromatin Density Determined by X-Ray Tomograms on the Time to Find DNA Binding Sites

    Science.gov (United States)

    Larabell, Carolyn A.; Le Gros, Mark A.; McQueen, David M.; Peskin, Charles S.

    2014-01-01

    In this work, we examine how volume exclusion caused by regions of high chromatin density might influence the time required for proteins to find specific DNA binding sites. The spatial variation of chromatin density within mouse olfactory sensory neurons is determined from soft X-ray tomography reconstructions of five nuclei. We show that there is a division of the nuclear space into regions of low-density euchromatin and high-density heterochromatin. Volume exclusion experienced by a diffusing protein caused by this varying density of chromatin is modeled by a repulsive potential. The value of the potential at a given point in space is chosen to be proportional to the density of chromatin at that location. The constant of proportionality, called the volume exclusivity, provides a model parameter that determines the strength of volume exclusion. Numerical simulations demonstrate that the mean time for a protein to locate a binding site localized in euchromatin is minimized for a finite, nonzero volume exclusivity. For binding sites in heterochromatin, the mean time is minimized when the volume exclusivity is zero (the protein experiences no volume exclusion). An analytical theory is developed to explain these results. The theory suggests that for binding sites in euchromatin there is an optimal level of volume exclusivity that balances a reduction in the volume searched in finding the binding site, with the height of effective potential barriers the protein must cross during the search process. PMID:23955281

  19. Sparse PDF Volumes for Consistent Multi-Resolution Volume Rendering

    KAUST Repository

    Sicat, Ronell Barrera; Kruger, Jens; Moller, Torsten; Hadwiger, Markus

    2014-01-01

    This paper presents a new multi-resolution volume representation called sparse pdf volumes, which enables consistent multi-resolution volume rendering based on probability density functions (pdfs) of voxel neighborhoods. These pdfs are defined

  20. Densities, excess molar volumes, speeds of sound and isothermal compressibilities for {2-(2-hexyloxyethoxy)ethanol + n-alkanol} systems at temperatures between (288.15 and 308.15) K

    International Nuclear Information System (INIS)

    Pal, Amalendu; Gaba, Rekha

    2008-01-01

    The densities, ρ and the speeds of sound, u, for {2-(2-hexyloxyethoxy)ethanol (C 6 E 2 ) + methanol, +1-propanol, +1-pentanol, and +1-heptanol} have been measured as a function of composition using an Anton-Paar DSA 5000 densimeter at temperatures (288.15, 293.15, 298.15, 303.15, and 308.15) K and atmospheric pressure over the whole concentration range. The ρ and u values were used to calculate excess molar volumes, V E , and excess molar isentropic compressibility, K S,m E , respectively. Also, thermal expansivity, α, partial molar volume, V-bar i , and partial molar volume of the components at infinite dilution, V-bar i 0 , have been calculated. The variation of these properties with composition and temperature of the mixtures are discussed in terms of molecular interactions

  1. Effects of concentration, temperature and solvent composition on density and apparent molar volume of the binary mixtures of cationic-anionic surfactants in methanol-water mixed solvent media.

    Science.gov (United States)

    Bhattarai, Ajaya; Chatterjee, Sujeet Kumar; Niraula, Tulasi Prasad

    2013-01-01

    The accurate measurements on density of the binary mixtures of cetyltrimethylammonium bromide and sodium dodecyl sulphate in pure water and in methanol(1) + water (2) mixed solvent media containing (0.10, 0.20, and 0.30) volume fractions of methanol at 308.15, 318.15, and 323.15 K are reported. The concentrations are varied from (0.03 to 0.12) mol.l(-1) of sodium dodecyl sulphate in presence of ~ 5.0×10(-4) mol.l(-1) cetyltrimethylammonium bromide. The results showed almost increase in the densities with increasing surfactant mixture concentration, also the densities are found to decrease with increasing temperature over the entire concentration range, investigated in a given mixed solvent medium and these values are found to decrease with increasing methanol content in the solvent composition. The concentration dependence of the apparent molar volumes appear to be negligible over the entire concentration range, investigated in a given mixed solvent medium and the apparent molar volumes increase with increasing temperature and are found to decrease with increasing methanol content in the solvent composition.

  2. Density, viscosity, surface tension, and molar volume of propylene glycol + water mixtures from 293 to 323 K and correlations by the Jouyban–Acree model

    Directory of Open Access Journals (Sweden)

    Ibrahim S. Khattab

    2017-02-01

    Full Text Available Density, viscosity, surface tension and molar volume of propylene glycol + water mixtures at 293, 298, 303, 308, 313, 318, and 323 K are reported, compared with the available literature data and the Jouyban–Acree model was used for mathematical correlation of the data. The mean relative deviation (MRD was used as an error criterion and the MRD values for data correlation of density, viscosity, surface tension and molar volume at different investigated temperatures are 0.1 ± 0.1%, 7.6 ± 6.4%, 3.4 ± 3.7%, and 0.4 ± 0.4%, respectively. The corresponding MRDs for the predicted properties after training the model using the experimental data at 298 K are 0.1 ± 0.2%, 12.8 ± 9.3%, 4.7 ± 4.1% and 0.6 ± 0.5%, respectively for density, viscosity, surface tension, and molar volume data.

  3. Physiological neuronal decline in healthy aging human brain - An in vivo study with MRI and short echo-time whole-brain (1)H MR spectroscopic imaging.

    Science.gov (United States)

    Ding, Xiao-Qi; Maudsley, Andrew A; Sabati, Mohammad; Sheriff, Sulaiman; Schmitz, Birte; Schütze, Martin; Bronzlik, Paul; Kahl, Kai G; Lanfermann, Heinrich

    2016-08-15

    Knowledge of physiological aging in healthy human brain is increasingly important for neuroscientific research and clinical diagnosis. To investigate neuronal decline in normal aging brain eighty-one healthy subjects aged between 20 and 70years were studied with MRI and whole-brain (1)H MR spectroscopic imaging. Concentrations of brain metabolites N-acetyl-aspartate (NAA), choline (Cho), total creatine (tCr), myo-inositol (mI), and glutamine+glutamate (Glx) in ratios to internal water, and the fractional volumes of brain tissue were estimated simultaneously in eight cerebral lobes and in cerebellum. Results demonstrated that an age-related decrease in gray matter volume was the largest contribution to changes in brain volume. Both lobar NAA and the fractional volume of gray matter (FVGM) decreased with age in all cerebral lobes, indicating that the decreased NAA was predominantly associated with decreased gray matter volume and neuronal density or metabolic activity. In cerebral white matter Cho, tCr, and mI increased with age in association with increased fractional volume, showing altered cellular membrane turn-over, energy metabolism, and glial activity in human aging white matter. In cerebellum tCr increased while brain tissue volume decreased with age, showing difference to cerebral aging. The observed age-related metabolic and microstructural variations suggest that physiological neuronal decline in aging human brain is associated with a reduction of gray matter volume and neuronal density, in combination with cellular aging in white matter indicated by microstructural alterations and altered energy metabolism in the cerebellum. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Shaping of the axial power density distribution in the core to minimize the vapor volume fraction at the outlet of the VVER-1200 fuel assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Savander, V. I.; Shumskiy, B. E., E-mail: borisshumskij@yandex.ru [National Research Nuclear University MEPhI (Russian Federation); Pinegin, A. A. [National Research Center Kurchatov Institute (Russian Federation)

    2016-12-15

    The possibility of decreasing the vapor fraction at the VVER-1200 fuel assembly outlet by shaping the axial power density field is considered. The power density field was shaped by axial redistribution of the concentration of the burnable gadolinium poison in the Gd-containing fuel rods. The mathematical modeling of the VVER-1200 core was performed using the NOSTRA computer code.

  5. Corneal and Retinal Neuronal Degeneration in Early Stages of Diabetic Retinopathy.

    Science.gov (United States)

    Srinivasan, Sangeetha; Dehghani, Cirous; Pritchard, Nicola; Edwards, Katie; Russell, Anthony W; Malik, Rayaz A; Efron, Nathan

    2017-12-01

    To examine the neuronal structural integrity of cornea and retina as markers for neuronal degeneration in nonproliferative diabetic retinopathy (NPDR). Participants were recruited from the broader Brisbane community, Queensland, Australia. Two hundred forty-one participants (187 with diabetes and 54 nondiabetic controls) were examined. Diabetic retinopathy (DR) was graded according to the Early Treatment Diabetic Retinopathy Study (ETDRS) scale. Corneal nerve fiber length (CNFL), corneal nerve branch density (CNBD), corneal nerve fiber tortuosity (CNFT), full retinal thickness, retinal nerve fiber layer (RNFL), ganglion cell complex (GCC), focal (FLV) and global loss volumes (GLV), hemoglobin A1c (HbA1c), nephropathy, neuropathy, and cardiovascular measures were examined. The central zone (P = 0.174), parafoveal thickness (P = 0.090), perifovea (P = 0.592), RNFL (P = 0.866), GCC (P = 0.798), and GCC GLV (P = 0.338) did not differ significantly between the groups. In comparison to the control group, those with very mild NPDR and those with mild NPDR had significantly higher focal loss in GCC volume (P = 0.036). CNFL was significantly lower in those with mild NPDR (P = 0.004) in comparison to the control group and those with no DR. The CNBD (P = 0.094) and CNFT (P = 0.458) did not differ between the groups. Both corneal and retinal neuronal degeneration may occur in early stages of diabetic retinopathy. Further studies are required to examine these potential markers for neuronal degeneration in the absence of clinical signs of DR.

  6. Role of neuronal activity in regulating the structure and function of auditory neurons

    International Nuclear Information System (INIS)

    Born, D.E.

    1986-01-01

    The role of afferent activity in maintaining neuronal structure and function was investigated in second order auditory neurons in nucleus magnocellularis (NM) of the chicken. The cochlea provides the major excitatory input to NM neurons via the eighth nerve. Removal of the cochlea causes dramatic changes in NM neurons. To determine if the elimination of neuronal activity is responsible for the changes in NM seen after cochlea removal, tetrodotoxin was used block action potentials in the cochlear ganglion cells. Tetrodotoxin injections into the perilymph reliably blocked neuronal activity in the cochlear nerve and NM. Far field recordings of sound-evoked potentials revealed that responses returned within 6 hours. Changes in amino acid incorporation in NM neurons were measured by giving intracardiac injections of 3 H-leucine and preparing tissue for autoradiographic demonstration of incorporated amino acid. Grain counts over individual neurons revealed that a single injection of tetrodotoxin produced a 40% decrease in grain density in ipsilateral NM neurons. It is concluded that neuronal activity plays an important contribution to the maintenance of the normal properties of NM neurons

  7. In-situ determination of electronic surface and volume defect density of amorphous silicon (a-Si:H) and silicon alloys

    International Nuclear Information System (INIS)

    Siebke, F.

    1992-07-01

    The density of localized gap states in the bulk and in the near-surface region of amorphous hydrogenated silicon (a-Si:H) was measured for non oxidized undoped, B-doped and P-doped samples as well as for films with low carbon (C) and germanium (Ge) content. Also the influence of light soaking on the bulk and surface density of states was investigated. The samples were prepared by rf glow discharge in an UHV-system at substrate temperatures between 100degC and 400degC and transferred to the analysis chamber by a vacuum lock. We combined the constant photocurrent method (CPM) and the total-yield photoelectron spectroscopy (TY) to obtain in-situ information about the defect densities. While the first method yields information about the density of states in the bulk, the other method obtains the density of occupied states in the near-surface region. The mean information depth of the TY-measurements is limited by the escape lenght of photoelectrons and can be estimated to 5 nm. In addition to the defect density the position of the Fermi energy was determined for the bulk by dark conductivity measurements and at the surface using a calibrated Kelvin probe. (orig.)

  8. Health and safety impacts of nuclear, geothermal, and fossil-fuel electric generation in California. Volume 5. Control of population densities surrounding nuclear power plants

    International Nuclear Information System (INIS)

    Nero, A.V.; Schroeder, C.H.; Yen, W.W.S.

    1977-01-01

    In view of the requirement that the California Energy Resources Conservation and Development Commission must specify land-use/population-density control measures to be used in the vicinity of nuclear power plants being granted land use, the possible forms of such measures are examined. Since these measures must maintain population densities below Nuclear Regulatory Commission criteria, if appropriate, NRC criteria for land use and population densities are given particular attention. In addition, a preliminary comparison of the cost of possible control measures with the reduced potential for damage to the public health and safety is made, yielding the result that control measures within approximately one mile of the plant site may be justified, in certain cases, on a strictly cost-benefit basis. However, it is not clear whether controls over such a limited region would satisfy the legal mandate

  9. Spike timing precision of neuronal circuits.

    Science.gov (United States)

    Kilinc, Deniz; Demir, Alper

    2018-04-17

    Spike timing is believed to be a key factor in sensory information encoding and computations performed by the neurons and neuronal circuits. However, the considerable noise and variability, arising from the inherently stochastic mechanisms that exist in the neurons and the synapses, degrade spike timing precision. Computational modeling can help decipher the mechanisms utilized by the neuronal circuits in order to regulate timing precision. In this paper, we utilize semi-analytical techniques, which were adapted from previously developed methods for electronic circuits, for the stochastic characterization of neuronal circuits. These techniques, which are orders of magnitude faster than traditional Monte Carlo type simulations, can be used to directly compute the spike timing jitter variance, power spectral densities, correlation functions, and other stochastic characterizations of neuronal circuit operation. We consider three distinct neuronal circuit motifs: Feedback inhibition, synaptic integration, and synaptic coupling. First, we show that both the spike timing precision and the energy efficiency of a spiking neuron are improved with feedback inhibition. We unveil the underlying mechanism through which this is achieved. Then, we demonstrate that a neuron can improve on the timing precision of its synaptic inputs, coming from multiple sources, via synaptic integration: The phase of the output spikes of the integrator neuron has the same variance as that of the sample average of the phases of its inputs. Finally, we reveal that weak synaptic coupling among neurons, in a fully connected network, enables them to behave like a single neuron with a larger membrane area, resulting in an improvement in the timing precision through cooperation.

  10. High-Degree Neurons Feed Cortical Computations.

    Directory of Open Access Journals (Sweden)

    Nicholas M Timme

    2016-05-01

    Full Text Available Recent work has shown that functional connectivity among cortical neurons is highly varied, with a small percentage of neurons having many more connections than others. Also, recent theoretical developments now make it possible to quantify how neurons modify information from the connections they receive. Therefore, it is now possible to investigate how information modification, or computation, depends on the number of connections a neuron receives (in-degree or sends out (out-degree. To do this, we recorded the simultaneous spiking activity of hundreds of neurons in cortico-hippocampal slice cultures using a high-density 512-electrode array. This preparation and recording method combination produced large numbers of neurons recorded at temporal and spatial resolutions that are not currently available in any in vivo recording system. We utilized transfer entropy (a well-established method for detecting linear and nonlinear interactions in time series and the partial information decomposition (a powerful, recently developed tool for dissecting multivariate information processing into distinct parts to quantify computation between neurons where information flows converged. We found that computations did not occur equally in all neurons throughout the networks. Surprisingly, neurons that computed large amounts of information tended to receive connections from high out-degree neurons. However, the in-degree of a neuron was not related to the amount of information it computed. To gain insight into these findings, we developed a simple feedforward network model. We found that a degree-modified Hebbian wiring rule best reproduced the pattern of computation and degree correlation results seen in the real data. Interestingly, this rule also maximized signal propagation in the presence of network-wide correlations, suggesting a mechanism by which cortex could deal with common random background input. These are the first results to show that the extent to

  11. Seasonal and spatial distribution of Bacterioplankton in a fluvial-lagunar system of a tropical region: density, biomass, cellular volume and morphologic variation

    Directory of Open Access Journals (Sweden)

    Magnólia Fernandes Florêncio de Araújo

    2008-02-01

    Full Text Available The temporal and spatial fluctuations of Bacterioplankton in a fluvial-lagunar system of a tropical region (Pitimbu River and Jiqui Lake, RN were studied during the dry and the rainy periods. The bacterial abundance varied from 2.67 to 5.1 Cells10(7mL-1 and did not show a typical temporal variation, presenting only small oscillations between the rainy and the dry periods. The bacterial biomass varied from 123 µgC L-1 to 269 µgC L-1 in the sampling sites and the average cellular volume varied from 0.12 to 0.54µm³, showing a predominance of the rods. The temperature showed a positive correlation with the cellular volume of the rods (R=0.55; p=0.02 and vibrio (R=0.53; p=0.03. Significant spatial differences of biomass (Mann Whitney: p=0.01 and cellular volume of the morphotypes (Mann Whitney: p=0.003 were found between the sampling sites. The strong positive correlations of the water temperature and oxygen with bacterioplankton showed a probable high bacterial activity in this system.A variação temporal e espacial do bacterioplâncton em um sistema fluvial-lagunar de região tropical foi estudada em períodos seco e chuvoso. As médias da abundância bacteriana variaram de 2,67 a 5,1 x 10(7 e não exibiram uma variação temporal marcante, tendo apresentado apenas pequenas oscilações entre os períodos chuvoso e seco. A biomassa bacteriana variou de 123 µg C L-1 a 269 µg C L-1 entre os locais de coleta e o volume celular médio de 0,12µm³ a 0,54µm³, ocorrendo predominância de bacilos. A temperatura mostrou correlação positiva com o volume celular de bacilos (R=0,55; p=0,02 e de vibriões (R=0,53; p=0,03. Foram encontradas diferenças espaciais significativas de biomassa (Mann Whitney: p=0,01 e volume celular dos morfotipos (Mann Whitney: p= 0,003, entre os locais de coleta. As fortes correlações positivas da temperatura da água e do oxigênio, com o bacterioplâncton, são sugestivas de uma provavelmente elevada atividade

  12. Nuclear fuel technology - Tank calibration and volume determination for nuclear materials accountancy - Part 6: Accurate in-tank determination of liquid density in accountancy tanks equipped with dip tubes

    International Nuclear Information System (INIS)

    2008-01-01

    ISO 18213 deals with the acquisition, standardization, analysis, and use of calibration data to determine liquid volumes in process tanks for accountability purposes. This part of ISO 18213 is complementary to the other parts, ISO 18213-1 (procedural overview), ISO 18213-2 (data standardization), ISO 18213-3 (statistical methods), ISO 18213-4 (slow bubbling rate), ISO 18213-5 (fast bubbling rate). The procedure described in this part of ISO 18213 is a two-step procedure. First, a liquid of known density is used to determine the vertical distance between the tips of the two probes (i.e. to calibrate their separation). The calibration step requires synchronous (or as nearly synchronous as possible) measurements of the pressure exerted at the tips of two probes by the calibration liquid in which they are submerged. The measurements obtained are used to make an accurate determination of probe separation. Second, the unknown density of the process liquid is determined with the aid of the probe separation calibration. The density-determination step also requires (nearly) synchronous measurements of the pressure exerted at the tips of two probes by the process liquid of unknown density. With careful technique, it is possible to make determinations of liquid density with in-tank measurements that approach the accuracy and precision of those made in the laboratory. Moreover, density determinations made with in-tank measurements are automatically made at the observed temperature of the tank liquid. Thus, no additional information about the liquid is required to infer its density at its tank temperature from determinations of its density at some other temperature. Except that the density of the process liquid is generally not well characterized, the steps involved in determining the height of process liquid in the tank are the same as those for determining the height of calibration liquid. Thus, the method of density determination given in this part of ISO 18213 is very

  13. Automatically tracking neurons in a moving and deforming brain.

    Directory of Open Access Journals (Sweden)

    Jeffrey P Nguyen

    2017-05-01

    Full Text Available Advances in optical neuroimaging techniques now allow neural activity to be recorded with cellular resolution in awake and behaving animals. Brain motion in these recordings pose a unique challenge. The location of individual neurons must be tracked in 3D over time to accurately extract single neuron activity traces. Recordings from small invertebrates like C. elegans are especially challenging because they undergo very large brain motion and deformation during animal movement. Here we present an automated computer vision pipeline to reliably track populations of neurons with single neuron resolution in the brain of a freely moving C. elegans undergoing large motion and deformation. 3D volumetric fluorescent images of the animal's brain are straightened, aligned and registered, and the locations of neurons in the images are found via segmentation. Each neuron is then assigned an identity using a new time-independent machine-learning approach we call Neuron Registration Vector Encoding. In this approach, non-rigid point-set registration is used to match each segmented neuron in each volume with a set of reference volumes taken from throughout the recording. The way each neuron matches with the references defines a feature vector which is clustered to assign an identity to each neuron in each volume. Finally, thin-plate spline interpolation is used to correct errors in segmentation and check consistency of assigned identities. The Neuron Registration Vector Encoding approach proposed here is uniquely well suited for tracking neurons in brains undergoing large deformations. When applied to whole-brain calcium imaging recordings in freely moving C. elegans, this analysis pipeline located 156 neurons for the duration of an 8 minute recording and consistently found more neurons more quickly than manual or semi-automated approaches.

  14. Spectrum of hydrodynamic volumes and sizes of macromolecules of linear polyelectrolytes versus their charge density in salt-free aqueous solutions.

    Science.gov (United States)

    Pavlov, Georges M; Dommes, Olga A; Okatova, Olga V; Gavrilova, Irina I; Panarin, Evgenii F

    2018-04-18

    Molecular characteristics of statistical copolymers based on hydrophilic poly(N-methyl-N-vinylacetamide) have been monitored throughout the entire possible range of charge density from 1.5 to 39 mol%. Different trends in the dependence of intrinsic viscosity on the average charge density of polymer chains at minimal ionic strength were revealed. A new parameter, lqq/Abare, describing this behavior was proposed (lqq is the average distance between the neighboring charges along the chain, and Abare is the statistical segment length of a non-charged homologue). For polyelectrolyte chains, this parameter allows the regions of charge density values where electrostatic long-range or short-range interactions dominate to be indicated. Two homologous series of copolymers were characterized by methods of molecular hydrodynamics under conditions of suppressed charge effects. Intrinsic viscosity in salt-free solutions characterizing an individual macromolecule was estimated by a method proposed earlier [Pavlov et al., Russ. J. Appl. Chem., 2006, 79, 1407-1412].

  15. Neuron Morphology Influences Axon Initial Segment Plasticity.

    Science.gov (United States)

    Gulledge, Allan T; Bravo, Jaime J

    2016-01-01

    In most vertebrate neurons, action potentials are initiated in the axon initial segment (AIS), a specialized region of the axon containing a high density of voltage-gated sodium and potassium channels. It has recently been proposed that neurons use plasticity of AIS length and/or location to regulate their intrinsic excitability. Here we quantify the impact of neuron morphology on AIS plasticity using computational models of simplified and realistic somatodendritic morphologies. In small neurons (e.g., dentate granule neurons), excitability was highest when the AIS was of intermediate length and located adjacent to the soma. Conversely, neurons having larger dendritic trees (e.g., pyramidal neurons) were most excitable when the AIS was longer and/or located away from the soma. For any given somatodendritic morphology, increasing dendritic membrane capacitance and/or conductance favored a longer and more distally located AIS. Overall, changes to AIS length, with corresponding changes in total sodium conductance, were far more effective in regulating neuron excitability than were changes in AIS location, while dendritic capacitance had a larger impact on AIS performance than did dendritic conductance. The somatodendritic influence on AIS performance reflects modest soma-to-AIS voltage attenuation combined with neuron size-dependent changes in AIS input resistance, effective membrane time constant, and isolation from somatodendritic capacitance. We conclude that the impact of AIS plasticity on neuron excitability will depend largely on somatodendritic morphology, and that, in some neurons, a shorter or more distally located AIS may promote, rather than limit, action potential generation.

  16. A single dose of a neuron-binding human monoclonal antibody improves brainstem NAA concentrations, a biomarker for density of spinal cord axons, in a model of progressive multiple sclerosis.

    Science.gov (United States)

    Wootla, Bharath; Denic, Aleksandar; Watzlawik, Jens O; Warrington, Arthur E; Rodriguez, Moses

    2015-04-29

    Intracerebral infection of susceptible mouse strains with Theiler's murine encephalomyelitis virus (TMEV) results in chronic demyelinating disease with progressive axonal loss and neurologic dysfunction similar to progressive forms of multiple sclerosis (MS). We previously showed that as the disease progresses, a marked decrease in brainstem N-acetyl aspartate (NAA; metabolite associated with neuronal integrity) concentrations, reflecting axon health, is measured. We also demonstrated stimulation of neurite outgrowth by a neuron-binding natural human antibody, IgM12. Treatment with either the serum-derived or recombinant human immunoglobulin M 12 (HIgM12) preserved functional motor activity in the TMEV model. In this study, we examined IgM-mediated changes in brainstem NAA concentrations and central nervous system (CNS) pathology. (1)H-magnetic resonance spectroscopy (MRS) showed that treatment with HIgM12 significantly increased brainstem NAA concentrations compared to controls in TMEV-infected mice. Pathologic analysis demonstrated a significant preservation of axons in the spinal cord of animals treated with HIgM12. This study links drug efficacy of slowing deficits with axon preservation and NAA concentrations in the brainstem in a model of progressive MS. HIgM12-mediated changes of NAA concentrations in the brainstem are a surrogate marker of axon injury/preservation throughout the spinal cord. This study provides proof-of-concept that a neuron-reactive human IgM can be therapeutic and provides a biomarker for clinical trials.

  17. Reconstruction of phrenic neuron identity in embryonic stem cell-derived motor neurons.

    Science.gov (United States)

    Machado, Carolina Barcellos; Kanning, Kevin C; Kreis, Patricia; Stevenson, Danielle; Crossley, Martin; Nowak, Magdalena; Iacovino, Michelina; Kyba, Michael; Chambers, David; Blanc, Eric; Lieberam, Ivo

    2014-02-01

    Air breathing is an essential motor function for vertebrates living on land. The rhythm that drives breathing is generated within the central nervous system and relayed via specialised subsets of spinal motor neurons to muscles that regulate lung volume. In mammals, a key respiratory muscle is the diaphragm, which is innervated by motor neurons in the phrenic nucleus. Remarkably, relatively little is known about how this crucial subtype of motor neuron is generated during embryogenesis. Here, we used direct differentiation of motor neurons from mouse embryonic stem cells as a tool to identify genes that direct phrenic neuron identity. We find that three determinants, Pou3f1, Hoxa5 and Notch, act in combination to promote a phrenic neuron molecular identity. We show that Notch signalling induces Pou3f1 in developing motor neurons in vitro and in vivo. This suggests that the phrenic neuron lineage is established through a local source of Notch ligand at mid-cervical levels. Furthermore, we find that the cadherins Pcdh10, which is regulated by Pou3f1 and Hoxa5, and Cdh10, which is controlled by Pou3f1, are both mediators of like-like clustering of motor neuron cell bodies. This specific Pcdh10/Cdh10 activity might provide the means by which phrenic neurons are assembled into a distinct nucleus. Our study provides a framework for understanding how phrenic neuron identity is conferred and will help to generate this rare and inaccessible yet vital neuronal subtype directly from pluripotent stem cells, thus facilitating subsequent functional investigations.

  18. Responses of neurons to extreme osmomechanical stress.

    Science.gov (United States)

    Wan, X; Harris, J A; Morris, C E

    1995-05-01

    Neurons are often regarded as fragile cells, easily destroyed by mechanical and osmotic insult. The results presented here demonstrate that this perception needs revision. Using extreme osmotic swelling, we show that molluscan neurons are astonishingly robust. In distilled water, a heterogeneous population of Lymnaea stagnalis CNS neurons swelled to several times their initial volume, yet had a ST50 (survival time for 50% of cells) > 60 min. Cells that were initially bigger survived longer. On return to normal medium, survivors were able, over the next 24 hr, to rearborize. Reversible membrane capacitance changes corresponding to about 0.7 muF/cm2 of apparent surface area accompanied neuronal swelling and shrinking in hypo- and hyperosmotic solutions; reversible changes in cell surface area evidently contributed to the neurons' ability to accommodate hydrostatic pressures then recover. The reversible membrane area/capacitance changes were not dependent on extracellular Ca2+. Neurons were monitored for potassium currents during direct mechanical inflation and during osmotically driven inflation. The latter but not the former stimulus routinely elicited small potassium currents, suggesting that tension increases activate the currents only if additional disruption of the cortex has occurred. Under stress in distilled water, a third of the neurons displayed a quite unexpected behavior: prolonged writhing of peripheral regions of the soma. This suggested that a plasma membrane-linked contractile machinery (presumably actomyosin) might contribute to the neurons' mechano-osmotic robustness by restricting water influx. Consistent with this possibility, 1 mM N-ethyl-maleimide, which inhibits myosin ATPase, decreased the ST50 to 18 min, rendered the survival time independent of initial size, and abolished writhing activity. For neurons, active mechanical resistance of the submembranous cortex, along with the mechanical compliance supplied by insertion or eversion of membrane

  19. Distribution and morphology of nitridergic neurons across functional domains of the rat primary somatosensory cortex

    Directory of Open Access Journals (Sweden)

    Anaelli A Nogueira-Campos

    2012-11-01

    Full Text Available The rat primary somatosensory cortex (S1 is remarkable for its conspicuous vertical compartmentalization in barrels and septal columns, which are additionally stratified in horizontal layers. Whereas excitatory neurons from each of these compartments perform different types of processing, the role of interneurons is much less clear. Among the numerous types of GABAergic interneurons, those producing nitric oxide (NO are especially puzzling, since this gaseous messenger can modulate neural activity, synaptic plasticity and neurovascular coupling. We used a quantitative morphological approach to investigate whether nitrergic interneurons, which might therefore be considered both as NO volume diffusers and as elements of local circuitry, display features that could relate to barrel cortex architecture. In fixed brain sections, nitrergic interneurons can be revealed by histochemical processing for NADPH-diaphorase (NADPHd. Here, the dendritic arbors of nitrergic neurons from different compartments of area S1 were 3D reconstructed from serial 200-μm thick sections, using 100x objective and the Neurolucida system. Standard morphological parameters were extracted for all individual arbors and compared across columns and layers. Wedge analysis was used to compute dendritic orientation indices. Supragranular layers displayed the highest density of nitrergic neurons, whereas layer IV contained nitrergic neurons with largest soma area. The highest nitrergic neuronal density was found in septa, where dendrites were previously characterized as more extense and ramified than in barrels. Dendritic arbors were not confined to the boundaries of the column nor layer of their respective soma, being mostly double-tufted and vertically oriented, except in supragranular layers. These data strongly suggest that nitrergic interneurons adapt their morphology to the dynamics of processing performed by cortical compartments.

  20. Neuronal Migration Disorders

    Science.gov (United States)

    ... Understanding Sleep The Life and Death of a Neuron Genes At Work In The Brain Order Publications ... birth defects caused by the abnormal migration of neurons in the developing brain and nervous system. In ...

  1. Motor Neuron Diseases

    Science.gov (United States)

    ... and other neurodegenerative diseases to better understand the function of neurons and other support cells and identify candidate therapeutic ... and other neurodegenerative diseases to better understand the function of neurons and other support cells and identify candidate therapeutic ...

  2. Ultrasonic velocities, densities, and excess molar volumes of binary mixtures of N,N-dimethyl formamide with methyl acrylate, or ethyl acrylate, or butyl acrylate, or 2-ethyl hexyl acrylate at T = 308.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Kondaiah, M. [Department of Physics, Acharya Nagarjuna University, Nagarjuna Nagar 522510, Andhra Pradesh (India); Sravana Kumar, D. [Dr. V.S. Krishna Govt. Degree College, Visakhapatnam, Andhra Pradesh (India); Sreekanth, K. [Department of Physics, Acharya Nagarjuna University, Nagarjuna Nagar 522510, Andhra Pradesh (India); Krishna Rao, D., E-mail: krdhanekula@yahoo.co.in [Department of Physics, Acharya Nagarjuna University, Nagarjuna Nagar 522510, Andhra Pradesh (India)

    2011-12-15

    Highlights: > Positive values of V{sub m}{sup E}, indicate dispersion forces between acrylic esters and DMF. > V{sub m}{sup E} values compared with Redlich-Kister polynomial. > Partial molar volumes data conclude that weak interactions exist in the systems. > Measured velocity values compared with theoretical values obtained by polynomials. - Abstract: Ultrasonic velocities, u, densities, {rho}, of binary mixtures of N,N-dimethyl formamide (DMF) with methyl acrylate (MA), ethyl acrylate (EA), butyl acrylate (BA), and 2-ethyl hexyl acrylate (EHA), including pure liquids, over the entire composition range have been measured at T = 308.15 K. Using the experimental results, the excess molar volume, V{sub m}{sup E}, partial molar volumes, V-bar {sub m,1}, V-bar{sub m,2}, and excess partial molar volumes, V-bar{sub m,1}{sup E}, V-bar{sub m,2}{sup E} have been calculated. Molecular interactions in the systems have been studied in the light of variation of excess values of calculated properties. The excess properties have been fitted to Redlich-Kister type polynomial and the corresponding standard deviations have been calculated. The positive values of V{sub m}{sup E} indicate the presence of dispersion forces between the DMF and acrylic ester molecules. Further theoretical values of sound velocity in the mixtures have been evaluated using various theories and have been compared with experimental sound velocities to verify the applicability of such theories to the systems studied. Theoretical ultrasonic velocity data have been used to study molecular interactions in the binary systems investigated.

  3. Hydrocephalus compacted cortex and hippocampus and altered their output neurons in association with spatial learning and memory deficits in rats.

    Science.gov (United States)

    Chen, Li-Jin; Wang, Yueh-Jan; Chen, Jeng-Rung; Tseng, Guo-Fang

    2017-07-01

    Hydrocephalus is a common neurological disorder in children characterized by abnormal dilation of cerebral ventricles as a result of the impairment of cerebrospinal fluid flow or absorption. Clinical presentation of hydrocephalus varies with chronicity and often shows cognitive dysfunction. Here we used a kaolin-induction method in rats and studied the effects of hydrocephalus on cerebral cortex and hippocampus, the two regions highly related to cognition. Hydrocephalus impaired rats' performance in Morris water maze task. Serial three-dimensional reconstruction from sections of the whole brain freshly froze in situ with skull shows that the volumes of both structures were reduced. Morphologically, pyramidal neurons of the somatosensory cortex and hippocampus appear to be distorted. Intracellular dye injection and subsequent three-dimensional reconstruction and analyses revealed that the dendritic arbors of layer III and V cortical pyramid neurons were reduced. The total dendritic length of CA1, but not CA3, pyramidal neurons was also reduced. Dendritic spine densities on both cortical and hippocampal pyramidal neurons were decreased, consistent with our concomitant findings that the expressions of both synaptophysin and postsynaptic density protein 95 were reduced. These cortical and hippocampal changes suggest reductions of excitatory connectivity, which could underlie the learning and memory deficits in hydrocephalus. © 2016 International Society of Neuropathology.

  4. The Nun study: clinically silent AD, neuronal hypertrophy, and linguistic skills in early life.

    Science.gov (United States)

    Iacono, D; Markesbery, W R; Gross, M; Pletnikova, O; Rudow, G; Zandi, P; Troncoso, J C

    2009-09-01

    It is common to find substantial Alzheimer disease (AD) lesions, i.e., neuritic beta-amyloid plaques and neurofibrillary tangles, in the autopsied brains of elderly subjects with normal cognition assessed shortly before death. We have termed this status asymptomatic AD (ASYMAD). We assessed the morphologic substrate of ASYMAD compared to mild cognitive impairment (MCI) in subjects from the Nun Study. In addition, possible correlations between linguistic abilities in early life and the presence of AD pathology with and without clinical manifestations in late life were considered. Design-based stereology was used to measure the volumes of neuronal cell bodies, nuclei, and nucleoli in the CA1 region of hippocampus (CA1). Four groups of subjects were compared: ASYMAD (n = 10), MCI (n = 5), AD (n = 10), and age-matched controls (n = 13). Linguistic ability assessed in early life was compared among all groups. A significant hypertrophy of the cell bodies (+44.9%), nuclei (+59.7%), and nucleoli (+80.2%) in the CA1 neurons was found in ASYMAD compared with MCI. Similar differences were observed with controls. Furthermore, significant higher idea density scores in early life were observed in controls and ASYMAD group compared to MCI and AD groups. 1) Neuronal hypertrophy may constitute an early cellular response to Alzheimer disease (AD) pathology or reflect compensatory mechanisms that prevent cognitive impairment despite substantial AD lesions; 2) higher idea density scores in early life are associated with intact cognition in late life despite the presence of AD lesions.

  5. Communication among neurons.

    Science.gov (United States)

    Marner, Lisbeth

    2012-04-01

    The communication among neurons is the prerequisite for the working brain. To understand the cellular, neurochemical, and structural basis of this communication, and the impacts of aging and disease on brain function, quantitative measures are necessary. This thesis evaluates several quantitative neurobiological methods with respect to possible bias and methodological issues. Stereological methods are suited for the unbiased estimation of number, length, and volumes of components of the nervous system. Stereological estimates of the total length of myelinated nerve fibers were made in white matter of post mortem brains, and the impact of aging and diseases as Schizophrenia and Alzheimer's disease were evaluated. Although stereological methods are in principle unbiased, shrinkage artifacts are difficult to account for. Positron emission tomography (PET) recordings, in conjunction with kinetic modeling, permit the quantitation of radioligand binding in brain. The novel serotonin 5-HT4 antagonist [11C]SB207145 was used as an example of the validation process for quantitative PET receptor imaging. Methods based on reference tissue as well as methods based on an arterial plasma input function were evaluated with respect to precision and accuracy. It was shown that [11C]SB207145 binding had high sensitivity to occupancy by unlabeled ligand, necessitating high specific activity in the radiosynthesis to avoid bias. The established serotonin 5-HT2A ligand [18F]altanersin was evaluated in a two-year follow-up study in elderly subjects. Application of partial volume correction of the PET data diminished the reliability of the measures, but allowed for the correct distinction between changes due to brain atrophy and receptor availability. Furthermore, a PET study of patients with Alzheimer's disease with the serotonin transporter ligand [11C]DASB showed relatively preserved serotonergic projections, despite a marked decrease in 5-HT2A receptor binding. Possible confounders are

  6. Neuron-specific caveolin-1 overexpression improves motor function and preserves memory in mice subjected to brain trauma.

    Science.gov (United States)

    Egawa, Junji; Schilling, Jan M; Cui, Weihua; Posadas, Edmund; Sawada, Atsushi; Alas, Basheer; Zemljic-Harpf, Alice E; Fannon-Pavlich, McKenzie J; Mandyam, Chitra D; Roth, David M; Patel, Hemal H; Patel, Piyush M; Head, Brian P

    2017-08-01

    Studies in vitro and in vivo demonstrate that membrane/lipid rafts and caveolin (Cav) organize progrowth receptors, and, when overexpressed specifically in neurons, Cav-1 augments neuronal signaling and growth and improves cognitive function in adult and aged mice; however, whether neuronal Cav-1 overexpression can preserve motor and cognitive function in the brain trauma setting is unknown. Here, we generated a neuron-targeted Cav-1-overexpressing transgenic (Tg) mouse [synapsin-driven Cav-1 (SynCav1 Tg)] and subjected it to a controlled cortical impact model of brain trauma and measured biochemical, anatomic, and behavioral changes. SynCav1 Tg mice exhibited increased hippocampal expression of Cav-1 and membrane/lipid raft localization of postsynaptic density protein 95, NMDA receptor, and tropomyosin receptor kinase B. When subjected to a controlled cortical impact, SynCav1 Tg mice demonstrated preserved hippocampus-dependent fear learning and memory, improved motor function recovery, and decreased brain lesion volume compared with wild-type controls. Neuron-targeted overexpression of Cav-1 in the adult brain prevents hippocampus-dependent learning and memory deficits, restores motor function after brain trauma, and decreases brain lesion size induced by trauma. Our findings demonstrate that neuron-targeted Cav-1 can be used as a novel therapeutic strategy to restore brain function and prevent trauma-associated maladaptive plasticity.-Egawa, J., Schilling, J. M., Cui, W., Posadas, E., Sawada, A., Alas, B., Zemljic-Harpf, A. E., Fannon-Pavlich, M. J., Mandyam, C. D., Roth, D. M., Patel, H. H., Patel, P. M., Head, B. P. Neuron-specific caveolin-1 overexpression improves motor function and preserves memory in mice subjected to brain trauma. © FASEB.

  7. GaAs optoelectronic neuron arrays

    Science.gov (United States)

    Lin, Steven; Grot, Annette; Luo, Jiafu; Psaltis, Demetri

    1993-01-01

    A simple optoelectronic circuit integrated monolithically in GaAs to implement sigmoidal neuron responses is presented. The circuit integrates a light-emitting diode with one or two transistors and one or two photodetectors. The design considerations for building arrays with densities of up to 10,000/sq cm are discussed.

  8. Intrinsic and integrative properties of substantia nigra pars reticulata neurons

    Science.gov (United States)

    Zhou, Fu-Ming; Lee, Christian R.

    2011-01-01

    The GABA projection neurons of the substantia nigra pars reticulata (SNr) are output neurons for the basal ganglia and thus critical for movement control. Their most striking neurophysiological feature is sustained, spontaneous high frequency spike firing. A fundamental question is: what are the key ion channels supporting the remarkable firing capability in these neurons? Recent studies indicate that these neurons express tonically active TRPC3 channels that conduct a Na-dependent inward current even at hyperpolarized membrane potentials. When the membrane potential reaches −60 mV, a voltage-gated persistent sodium current (INaP) starts to activate, further depolarizing the membrane potential. At or slightly below −50 mV, the large transient voltage-activated sodium current (INaT) starts to activate and eventually triggers the rapid rising phase of action potentials. SNr GABA neurons have a higher density of (INaT), contributing to the faster rise and larger amplitude of action potentials, compared with the slow-spiking dopamine neurons. INaT also recovers from inactivation more quickly in SNr GABA neurons than in nigral dopamine neurons. In SNr GABA neurons, the rising phase of the action potential triggers the activation of high-threshold, inactivation-resistant Kv3-like channels that can rapidly repolarize the membrane. These intrinsic ion channels provide SNr GABA neurons with the ability to fire spontaneous and sustained high frequency spikes. Additionally, robust GABA inputs from direct pathway medium spiny neurons in the striatum and GABA neurons in the globus pallidus may inhibit and silence SNr GABA neurons, whereas glutamate synaptic input from the subthalamic nucleus may induce burst firing in SNr GABA neurons. Thus, afferent GABA and glutamate synaptic inputs sculpt the tonic high frequency firing of SNr GABA neurons and the consequent inhibition of their targets into an integrated motor control signal that is further fine-tuned by neuromodulators

  9. Scaling of brain metabolism with a fixed energy budget per neuron: implications for neuronal activity, plasticity and evolution.

    Science.gov (United States)

    Herculano-Houzel, Suzana

    2011-03-01

    It is usually considered that larger brains have larger neurons, which consume more energy individually, and are therefore accompanied by a larger number of glial cells per neuron. These notions, however, have never been tested. Based on glucose and oxygen metabolic rates in awake animals and their recently determined numbers of neurons, here I show that, contrary to the expected, the estimated glucose use per neuron is remarkably constant, varying only by 40% across the six species of rodents and primates (including humans). The estimated average glucose use per neuron does not correlate with neuronal density in any structure. This suggests that the energy budget of the whole brain per neuron is fixed across species and brain sizes, such that total glucose use by the brain as a whole, by the cerebral cortex and also by the cerebellum alone are linear functions of the number of neurons in the structures across the species (although the average glucose consumption per neuron is at least 10× higher in the cerebral cortex than in the cerebellum). These results indicate that the apparently remarkable use in humans of 20% of the whole body energy budget by a brain that represents only 2% of body mass is explained simply by its large number of neurons. Because synaptic activity is considered the major determinant of metabolic cost, a conserved energy budget per neuron has several profound implications for synaptic homeostasis and the regulation of firing rates, synaptic plasticity, brain imaging, pathologies, and for brain scaling in evolution.

  10. Scaling of brain metabolism with a fixed energy budget per neuron: implications for neuronal activity, plasticity and evolution.

    Directory of Open Access Journals (Sweden)

    Suzana Herculano-Houzel

    Full Text Available It is usually considered that larger brains have larger neurons, which consume more energy individually, and are therefore accompanied by a larger number of glial cells per neuron. These notions, however, have never been tested. Based on glucose and oxygen metabolic rates in awake animals and their recently determined numbers of neurons, here I show that, contrary to the expected, the estimated glucose use per neuron is remarkably constant, varying only by 40% across the six species of rodents and primates (including humans. The estimated average glucose use per neuron does not correlate with neuronal density in any structure. This suggests that the energy budget of the whole brain per neuron is fixed across species and brain sizes, such that total glucose use by the brain as a whole, by the cerebral cortex and also by the cerebellum alone are linear functions of the number of neurons in the structures across the species (although the average glucose consumption per neuron is at least 10× higher in the cerebral cortex than in the cerebellum. These results indicate that the apparently remarkable use in humans of 20% of the whole body energy budget by a brain that represents only 2% of body mass is explained simply by its large number of neurons. Because synaptic activity is considered the major determinant of metabolic cost, a conserved energy budget per neuron has several profound implications for synaptic homeostasis and the regulation of firing rates, synaptic plasticity, brain imaging, pathologies, and for brain scaling in evolution.

  11. Scaling of Brain Metabolism with a Fixed Energy Budget per Neuron: Implications for Neuronal Activity, Plasticity and Evolution

    Science.gov (United States)

    Herculano-Houzel, Suzana

    2011-01-01

    It is usually considered that larger brains have larger neurons, which consume more energy individually, and are therefore accompanied by a larger number of glial cells per neuron. These notions, however, have never been tested. Based on glucose and oxygen metabolic rates in awake animals and their recently determined numbers of neurons, here I show that, contrary to the expected, the estimated glucose use per neuron is remarkably constant, varying only by 40% across the six species of rodents and primates (including humans). The estimated average glucose use per neuron does not correlate with neuronal density in any structure. This suggests that the energy budget of the whole brain per neuron is fixed across species and brain sizes, such that total glucose use by the brain as a whole, by the cerebral cortex and also by the cerebellum alone are linear functions of the number of neurons in the structures across the species (although the average glucose consumption per neuron is at least 10× higher in the cerebral cortex than in the cerebellum). These results indicate that the apparently remarkable use in humans of 20% of the whole body energy budget by a brain that represents only 2% of body mass is explained simply by its large number of neurons. Because synaptic activity is considered the major determinant of metabolic cost, a conserved energy budget per neuron has several profound implications for synaptic homeostasis and the regulation of firing rates, synaptic plasticity, brain imaging, pathologies, and for brain scaling in evolution. PMID:21390261

  12. Neuropeptide Y-immunoreactive neurons in the cerebral cortex of humans and other haplorrhine primates

    Science.gov (United States)

    Raghanti, Mary Ann; Conley, Tiffini; Sudduth, Jessica; Erwin, Joseph M.; Stimpson, Cheryl D.; Hof, Patrick R.; Sherwood, Chet C.

    2012-01-01

    We examined the distribution of neurons immunoreactive for neuropeptide Y (NPY) in the posterior part of the superior temporal cortex (Brodmann's area 22 or area Tpt) of humans and nonhuman haplorrhine primates. NPY has been implicated in learning and memory and the density of NPY-expressing cortical neurons and axons is reduced in depression, bipolar disorder, schizophrenia, and Alzheimer's disease. Due to the role that NPY plays in both cognition and neurodegenerative diseases, we tested the hypothesis that the density of cortical and interstitial neurons expressing NPY was increased in humans relative to other primate species. The study sample included great apes (chimpanzee and gorilla), Old World monkeys (pigtailed macaque, moor macaque, and baboon) and New World monkeys (squirrel monkey and capuchin). Stereologic methods were used to estimate the density of NPY-immunoreactive (-ir) neurons in layers I-VI of area Tpt and the subjacent white matter. Adjacent Nissl-stained sections were used to calculate local densities of all neurons. The ratio of NPY-ir neurons to total neurons within area Tpt and the total density of NPY-ir neurons within the white matter were compared among species. Overall, NPY-ir neurons represented only an average of 0.006% of the total neuron population. While there were significant differences among species, phylogenetic trends in NPY-ir neuron distributions were not observed and humans did not differ from other primates. However, variation among species warrants further investigation into the distribution of this neuromodulator system. PMID:23042407

  13. A hidden Markov model approach to neuron firing patterns.

    Science.gov (United States)

    Camproux, A C; Saunier, F; Chouvet, G; Thalabard, J C; Thomas, G

    1996-11-01

    Analysis and characterization of neuronal discharge patterns are of interest to neurophysiologists and neuropharmacologists. In this paper we present a hidden Markov model approach to modeling single neuron electrical activity. Basically the model assumes that each interspike interval corresponds to one of several possible states of the neuron. Fitting the model to experimental series of interspike intervals by maximum likelihood allows estimation of the number of possible underlying neuron states, the probability density functions of interspike intervals corresponding to each state, and the transition probabilities between states. We present an application to the analysis of recordings of a locus coeruleus neuron under three pharmacological conditions. The model distinguishes two states during halothane anesthesia and during recovery from halothane anesthesia, and four states after administration of clonidine. The transition probabilities yield additional insights into the mechanisms of neuron firing.

  14. A STEREOLOGICAL ANALYSIS OF THE EFFECT OF EARLY POSTNATAL ETHANOL EXPOSURE ON NEURONAL NUMBERS IN RAT DENTATE GYRUS

    Directory of Open Access Journals (Sweden)

    Takanori Miki

    2011-05-01

    Full Text Available Maternal ethanol ingestion during pregnancy can cause fetal alcohol syndrome (FAS in their offspring. Among the symptoms of FAS, damage to the central nervous system has emerged as one of the most serious problems. We have previously shown that a relatively high dose of ethanol exposure during early postnatal life can cause alterations in spatial learning ability. This ability is controlled, at least in part, by the hippocampal formation. The purpose of the present study was to determine whether exposure of rat pups to ethanol during early postnatal life had effects on the total number of the dentate gyrus neurons. Wistar rats were exposed to a relatively high daily dose of ethanol between postnatal days 10 to 15. Ethanol exposure was achieved by placing rat pups in a chamber containing ethanol vapour for 3 hours a day. The blood ethanol concentration was found to be about 430 mg/dL at the end of the exposure period. Groups of ethanol treated (ET, separation controls (SC and mother reared controls (MRC were anaesthetised and killed at 16-days-of-age by perfusion with phosphate-buffered 2.5% glutaraldehyde. The Cavalieri principle was used to determine the volume of subdivisions of the dentate gyrus, and the physical disector method was used to estimate the numerical densities of neurons within each subdivision. The total number of neurons was calculated by multiplying estimates of the numerical density with the volume. There was, on average, about 421,000 granule cells in all three treatment groups. In the hilus region, ET rats had about 27,000 neuronal cells. This value was significantly smaller than the average of 38,000 such neurons estimated to be present in both MRC and SC animals. It is concluded that neurons in the hilus region of the dentate gyrus may be particularly vulnerable to the effects of a high dose of ethanol exposure during PND 10-15. It is likely that this deficit was due to neuronal death induced by some mechanisms related to

  15. Morphometric characteristics of the neurons of the human subiculum proper

    Directory of Open Access Journals (Sweden)

    Živanović-Mačužić Ivana

    2012-01-01

    Full Text Available The human subiculum is a significant part of the hippocampal formation positioned between the hippocampus proper and the entorhinal and other cortices. It plays an important role in spatial navigation, memory processing and control of the response to stress. The aim of our study was identification of the morphometric characteristics of the neurons of the human subiculum proper: the maximum length and width of cell body and total dendritic length and volume of cell body. Comparing the measured parameters of different types of subicular neurons (bipolar, multipolar, pyramidal neurons with triangular-shaped soma and neurons with oval-shaped soma, we can conclude that bipolar neurons have the lowest values of the measured parameters: the maximum length of their cell body is 14.1 ± 0.2 µm, the maximum width is 13.9 ± 0.5 µm, and total dendritic length is 14597 ± 3.1 µm. The lowest volume value was observed in bipolar neurons; the polymorphic layer is 1152.99 ± 662.69 µm3. The pyramidal neurons of the pyramidal layer have the highest value for the maximal length of the cell body (44.43 ± 7.94 µm, maximum width (23.64 ± 1.89 µm, total dendritic length (1830 ± 466.3 µm and volume (11768.65±4004.9 µm3 These characteristics of the pyramidal neurons indicate their importance, because the axons of these neurons make up the greatest part of the fornix, along with the axons of neurons of the CA1 hippocampal field.

  16. Road density

    Data.gov (United States)

    U.S. Environmental Protection Agency — Road density is generally highly correlated with amount of developed land cover. High road densities usually indicate high levels of ecological disturbance. More...

  17. Kappe neurons, a novel population of olfactory sensory neurons

    OpenAIRE

    Ahuja, Gaurav; Nia, Shahrzad Bozorg; Zapilko, Veronika; Shiriagin, Vladimir; Kowatschew, Daniel; Oka, Yuichiro; Korsching, Sigrun I.

    2014-01-01

    Perception of olfactory stimuli is mediated by distinct populations of olfactory sensory neurons, each with a characteristic set of morphological as well as functional parameters. Beyond two large populations of ciliated and microvillous neurons, a third population, crypt neurons, has been identified in teleost and cartilaginous fishes. We report here a novel, fourth olfactory sensory neuron population in zebrafish, which we named kappe neurons for their characteristic shape. Kappe neurons ar...

  18. The roles of prostate-specific antigen (PSA) density, prostate volume, and their zone-adjusted derivatives in predicting prostate cancer in patients with PSA less than 20.0 ng/mL.

    Science.gov (United States)

    Shen, P; Zhao, J; Sun, G; Chen, N; Zhang, X; Gui, H; Yang, Y; Liu, J; Shu, K; Wang, Z; Zeng, H

    2017-05-01

    The aim of this study was to develop nomograms for predicting prostate cancer and its zonal location using prostate-specific antigen density, prostate volume, and their zone-adjusted derivatives. A total of 928 consecutive patients with prostate-specific antigen (PSA) less than 20.0 ng/mL, who underwent transrectal ultrasound-guided transperineal 12-core prostate biopsy at West China Hospital between 2011 and 2014, were retrospectively enrolled. The patients were randomly split into training cohort (70%, n = 650) and validation cohort (30%, n = 278). Predicting models and the associated nomograms were built using the training cohort, while the validations of the models were conducted using the validation cohort. Univariate and multivariate logistic regression was performed. Then, new nomograms were generated based on multivariate regression coefficients. The discrimination power and calibration of these nomograms were validated using the area under the ROC curve (AUC) and the calibration curve. The potential clinical effects of these models were also tested using decision curve analysis. In total, 285 (30.7%) patients were diagnosed with prostate cancer. Among them, 131 (14.1%) and 269 (29.0%) had transition zone prostate cancer and peripheral zone prostate cancer. Each of zone-adjusted derivatives-based nomogram had an AUC more than 0.75. All nomograms had higher calibration and much better net benefit than the scenarios in predicting patients with or without different zones prostate cancer. Prostate-specific antigen density, prostate volume, and their zone-adjusted derivatives have important roles in detecting prostate cancer and its zonal location for patients with PSA 2.5-20.0 ng/mL. To the best of our knowledge, this is the first nomogram using these parameters to predict outcomes of 12-core prostate biopsy. These instruments can help clinicians to increase the accuracy of prostate cancer screening and to avoid unnecessary prostate biopsy. © 2017

  19. Identification of neuronal network properties from the spectral analysis of calcium imaging signals in neuronal cultures.

    Science.gov (United States)

    Tibau, Elisenda; Valencia, Miguel; Soriano, Jordi

    2013-01-01

    Neuronal networks in vitro are prominent systems to study the development of connections in living neuronal networks and the interplay between connectivity, activity and function. These cultured networks show a rich spontaneous activity that evolves concurrently with the connectivity of the underlying network. In this work we monitor the development of neuronal cultures, and record their activity using calcium fluorescence imaging. We use spectral analysis to characterize global dynamical and structural traits of the neuronal cultures. We first observe that the power spectrum can be used as a signature of the state of the network, for instance when inhibition is active or silent, as well as a measure of the network's connectivity strength. Second, the power spectrum identifies prominent developmental changes in the network such as GABAA switch. And third, the analysis of the spatial distribution of the spectral density, in experiments with a controlled disintegration of the network through CNQX, an AMPA-glutamate receptor antagonist in excitatory neurons, reveals the existence of communities of strongly connected, highly active neurons that display synchronous oscillations. Our work illustrates the interest of spectral analysis for the study of in vitro networks, and its potential use as a network-state indicator, for instance to compare healthy and diseased neuronal networks.

  20. On thermodynamic limits of entropy densities

    NARCIS (Netherlands)

    Moriya, H; Van Enter, A

    We give some sufficient conditions which guarantee that the entropy density in the thermodynamic limit is equal to the thermodynamic limit of the entropy densities of finite-volume (local) Gibbs states.

  1. Measurement of loose powder density

    International Nuclear Information System (INIS)

    Akhtar, S.; Ali, A.; Haider, A.; Farooque, M.

    2011-01-01

    Powder metallurgy is a conventional technique for making engineering articles from powders. Main objective is to produce final products with the highest possible uniform density, which depends on the initial loose powder characteristics. Producing, handling, characterizing and compacting materials in loose powder form are part of the manufacturing processes. Density of loose metallic or ceramic powder is an important parameter for die design. Loose powder density is required for calculating the exact mass of powder to fill the die cavity for producing intended green density of the powder compact. To fulfill this requirement of powder metallurgical processing, a loose powder density meter as per ASTM standards is designed and fabricated for measurement of density. The density of free flowing metallic powders can be determined using Hall flow meter funnel and density cup of 25 cm/sup 3/ volume. Density of metal powders like cobalt, manganese, spherical bronze and pure iron is measured and results are obtained with 99.9% accuracy. (author)

  2. NEURON and Python.

    Science.gov (United States)

    Hines, Michael L; Davison, Andrew P; Muller, Eilif

    2009-01-01

    The NEURON simulation program now allows Python to be used, alone or in combination with NEURON's traditional Hoc interpreter. Adding Python to NEURON has the immediate benefit of making available a very extensive suite of analysis tools written for engineering and science. It also catalyzes NEURON software development by offering users a modern programming tool that is recognized for its flexibility and power to create and maintain complex programs. At the same time, nothing is lost because all existing models written in Hoc, including graphical user interface tools, continue to work without change and are also available within the Python context. An example of the benefits of Python availability is the use of the xml module in implementing NEURON's Import3D and CellBuild tools to read MorphML and NeuroML model specifications.

  3. Spinal cord: motor neuron diseases.

    Science.gov (United States)

    Rezania, Kourosh; Roos, Raymond P

    2013-02-01

    Spinal cord motor neuron diseases affect lower motor neurons in the ventral horn. This article focuses on the most common spinal cord motor neuron disease, amyotrophic lateral sclerosis, which also affects upper motor neurons. Also discussed are other motor neuron diseases that only affect the lower motor neurons. Despite the identification of several genes associated with familial amyotrophic lateral sclerosis, the pathogenesis of this complex disease remains elusive. Copyright © 2013 Elsevier Inc. All rights reserved.

  4. Neuronal-glial trafficking

    International Nuclear Information System (INIS)

    Bachelard, H.S.

    2001-01-01

    Full text: The name 'glia' originates from the Greek word for glue, because astro glia (or astrocytes) were thought only to provide an anatomical framework for the electrically-excitable neurones. However, awareness that astrocytes perform vital roles in protecting the neurones, which they surround, emerged from evidence that they act as neuroprotective K + -sinks, and that they remove potentially toxic extracellular glutamate from the vicinity of the neurones. The astrocytes convert the glutamate to non-toxic glutamine which is returned to the neurones and used to replenish transmitter glutamate. This 'glutamate-glutamine cycle' (established in the 1960s by Berl and his colleagues) also contributes to protecting the neurones against a build-up of toxic ammonia. Glial cells also supply the neurones with components for free-radical scavenging glutathione. Recent studies have revealed that glial cells play a more positive interactive role in furnishing the neurones with fuels. Studies using radioactive 14 C, 13 C-MRS and 15 N-GCMS have revealed that glia produce alanine, lactate and proline for consumption by neurones, with increased formation of neurotransmitter glutamate. On neuronal activation the release of NH 4 + and glutamate from the neurones stimulates glucose uptake and glycolysis in the glia to produce more alanine, which can be regarded as an 'alanine-glutamate cycle' Use of 14 C-labelled precursors provided early evidence that neurotransmitter GABA may be partly derived from glial glutamine, and this has been confirmed recently in vivo by MRS isotopomer analysis of the GABA and glutamine labelled from 13 C-acetate. Relative rates of intermediary metabolism in glia and neurones can be calculated using a combination of [1- 13 C] glucose and [1,2- 13 C] acetate. When glutamate is released by neurones there is a net neuronal loss of TCA intermediates which have to be replenished. Part of this is derived from carboxylation of pyruvate, (pyruvate carboxylase

  5. Nuclear Calcium Buffering Capacity Shapes Neuronal Architecture*

    Science.gov (United States)

    Mauceri, Daniela; Hagenston, Anna M.; Schramm, Kathrin; Weiss, Ursula; Bading, Hilmar

    2015-01-01

    Calcium-binding proteins (CaBPs) such as parvalbumin are part of the cellular calcium buffering system that determines intracellular calcium diffusion and influences the spatiotemporal dynamics of calcium signals. In neurons, CaBPs are primarily localized to the cytosol and function, for example, in nerve terminals in short-term synaptic plasticity. However, CaBPs are also expressed in the cell nucleus, suggesting that they modulate nuclear calcium signals, which are key regulators of neuronal gene expression. Here we show that the calcium buffering capacity of the cell nucleus in mouse hippocampal neurons regulates neuronal architecture by modulating the expression levels of VEGFD and the complement factor C1q-c, two nuclear calcium-regulated genes that control dendrite geometry and spine density, respectively. Increasing the levels of nuclear calcium buffers by means of expression of a nuclearly targeted form of parvalbumin fused to mCherry (PV.NLS-mC) led to a reduction in VEGFD expression and, as a result, to a decrease in total dendritic length and complexity. In contrast, mRNA levels of the synapse pruning factor C1q-c were increased in neurons expressing PV.NLS-mC, causing a reduction in the density and size of dendritic spines. Our results establish a close link between nuclear calcium buffering capacity and the transcription of genes that determine neuronal structure. They suggest that the development of cognitive deficits observed in neurological conditions associated with CaBP deregulation may reflect the loss of necessary structural features of dendrites and spines. PMID:26231212

  6. Nuclear Calcium Buffering Capacity Shapes Neuronal Architecture.

    Science.gov (United States)

    Mauceri, Daniela; Hagenston, Anna M; Schramm, Kathrin; Weiss, Ursula; Bading, Hilmar

    2015-09-18

    Calcium-binding proteins (CaBPs) such as parvalbumin are part of the cellular calcium buffering system that determines intracellular calcium diffusion and influences the spatiotemporal dynamics of calcium signals. In neurons, CaBPs are primarily localized to the cytosol and function, for example, in nerve terminals in short-term synaptic plasticity. However, CaBPs are also expressed in the cell nucleus, suggesting that they modulate nuclear calcium signals, which are key regulators of neuronal gene expression. Here we show that the calcium buffering capacity of the cell nucleus in mouse hippocampal neurons regulates neuronal architecture by modulating the expression levels of VEGFD and the complement factor C1q-c, two nuclear calcium-regulated genes that control dendrite geometry and spine density, respectively. Increasing the levels of nuclear calcium buffers by means of expression of a nuclearly targeted form of parvalbumin fused to mCherry (PV.NLS-mC) led to a reduction in VEGFD expression and, as a result, to a decrease in total dendritic length and complexity. In contrast, mRNA levels of the synapse pruning factor C1q-c were increased in neurons expressing PV.NLS-mC, causing a reduction in the density and size of dendritic spines. Our results establish a close link between nuclear calcium buffering capacity and the transcription of genes that determine neuronal structure. They suggest that the development of cognitive deficits observed in neurological conditions associated with CaBP deregulation may reflect the loss of necessary structural features of dendrites and spines. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  7. Single neuron computation

    CERN Document Server

    McKenna, Thomas M; Zornetzer, Steven F

    1992-01-01

    This book contains twenty-two original contributions that provide a comprehensive overview of computational approaches to understanding a single neuron structure. The focus on cellular-level processes is twofold. From a computational neuroscience perspective, a thorough understanding of the information processing performed by single neurons leads to an understanding of circuit- and systems-level activity. From the standpoint of artificial neural networks (ANNs), a single real neuron is as complex an operational unit as an entire ANN, and formalizing the complex computations performed by real n

  8. Mesmerising mirror neurons.

    Science.gov (United States)

    Heyes, Cecilia

    2010-06-01

    Mirror neurons have been hailed as the key to understanding social cognition. I argue that three currents of thought-relating to evolution, atomism and telepathy-have magnified the perceived importance of mirror neurons. When they are understood to be a product of associative learning, rather than an adaptation for social cognition, mirror neurons are no longer mesmerising, but they continue to raise important questions about both the psychology of science and the neural bases of social cognition. Copyright 2010 Elsevier Inc. All rights reserved.

  9. The mirror neuron system.

    Science.gov (United States)

    Cattaneo, Luigi; Rizzolatti, Giacomo

    2009-05-01

    Mirror neurons are a class of neurons, originally discovered in the premotor cortex of monkeys, that discharge both when individuals perform a given motor act and when they observe others perform that same motor act. Ample evidence demonstrates the existence of a cortical network with the properties of mirror neurons (mirror system) in humans. The human mirror system is involved in understanding others' actions and their intentions behind them, and it underlies mechanisms of observational learning. Herein, we will discuss the clinical implications of the mirror system.

  10. Channel properties of Nax expressed in neurons.

    Directory of Open Access Journals (Sweden)

    Masahito Matsumoto

    Full Text Available Nax is a sodium-concentration ([Na+]-sensitive Na channel with a gating threshold of ~150 mM for extracellular [Na+] ([Na+]o in vitro. We previously reported that Nax was preferentially expressed in the glial cells of sensory circumventricular organs including the subfornical organ, and was involved in [Na+] sensing for the control of salt-intake behavior. Although Nax was also suggested to be expressed in the neurons of some brain regions including the amygdala and cerebral cortex, the channel properties of Nax have not yet been adequately characterized in neurons. We herein verified that Nax was expressed in neurons in the lateral amygdala of mice using an antibody that was newly generated against mouse Nax. To investigate the channel properties of Nax expressed in neurons, we established an inducible cell line of Nax using the mouse neuroblastoma cell line, Neuro-2a, which is endogenously devoid of the expression of Nax. Functional analyses of this cell line revealed that the [Na+]-sensitivity of Nax in neuronal cells was similar to that expressed in glial cells. The cation selectivity sequence of the Nax channel in cations was revealed to be Na+ ≈ Li+ > Rb+ > Cs+ for the first time. Furthermore, we demonstrated that Nax bound to postsynaptic density protein 95 (PSD95 through its PSD95/Disc-large/ZO-1 (PDZ-binding motif at the C-terminus in neurons. The interaction between Nax and PSD95 may be involved in promoting the surface expression of Nax channels because the depletion of endogenous PSD95 resulted in a decrease in Nax at the plasma membrane. These results indicated, for the first time, that Nax functions as a [Na+]-sensitive Na channel in neurons as well as in glial cells.

  11. 对、邻二甲苯和醋酸二元液体混合物在不同温度和压力下的密度和超额摩尔体积%Density and Excess Molar Volume of Binary Mixtures of p-Xylene+Acetic Acid and o-Xylene+Acetic Acid at Different Temperatures and Pressures

    Institute of Scientific and Technical Information of China (English)

    杨天宇; 夏淑倩; 邸志国; 马沛生

    2008-01-01

    A new apparatus was designed with a thick-walled glass capillary, electric heater tube with red copper and heat preservation. The thick-walled glass capillary was used for its advantages of resistance to acid corrosion and pressure, and ease of observation. The experimental densities over the entire range of mole fraction for the bi- nary mixture of p-xylene+acetic acid and o-xylene+acetic acid were measured using the new apparatus at tempera- tures ranging from 313.15K to 473.15K and pressure ranging from 0.20 to 2.0 MPa. The density values were used in the determination of excess molar volumes, VE. The Redlich-Kister equation was used to fit the excess molar volume values, and the coefficients and estimate of the standard error values were presented. The experimental re- suits prove that the density measurement apparatus is successful.

  12. Neuromorphic Silicon Neuron Circuits

    Science.gov (United States)

    Indiveri, Giacomo; Linares-Barranco, Bernabé; Hamilton, Tara Julia; van Schaik, André; Etienne-Cummings, Ralph; Delbruck, Tobi; Liu, Shih-Chii; Dudek, Piotr; Häfliger, Philipp; Renaud, Sylvie; Schemmel, Johannes; Cauwenberghs, Gert; Arthur, John; Hynna, Kai; Folowosele, Fopefolu; Saighi, Sylvain; Serrano-Gotarredona, Teresa; Wijekoon, Jayawan; Wang, Yingxue; Boahen, Kwabena

    2011-01-01

    Hardware implementations of spiking neurons can be extremely useful for a large variety of applications, ranging from high-speed modeling of large-scale neural systems to real-time behaving systems, to bidirectional brain–machine interfaces. The specific circuit solutions used to implement silicon neurons depend on the application requirements. In this paper we describe the most common building blocks and techniques used to implement these circuits, and present an overview of a wide range of neuromorphic silicon neurons, which implement different computational models, ranging from biophysically realistic and conductance-based Hodgkin–Huxley models to bi-dimensional generalized adaptive integrate and fire models. We compare the different design methodologies used for each silicon neuron design described, and demonstrate their features with experimental results, measured from a wide range of fabricated VLSI chips. PMID:21747754

  13. Neuromorphic silicon neuron circuits

    Directory of Open Access Journals (Sweden)

    Giacomo eIndiveri

    2011-05-01

    Full Text Available Hardware implementations of spiking neurons can be extremely useful for a large variety of applications, ranging from high-speed modeling of large-scale neural systems to real-time behaving systems, to bidirectional brain-machine interfaces. The specific circuit solutions used to implement silicon neurons depend on the application requirements. In this paper we describe the most common building blocks and techniques used to implement these circuits, and present an overview of a wide range of neuromorphic silicon neurons, which implement different computational models, ranging from biophysically realistic and conductance based Hodgkin-Huxley models to bi-dimensional generalized adaptive Integrate and Fire models. We compare the different design methodologies used for each silicon neuron design described, and demonstrate their features with experimental results, measured from a wide range of fabricated VLSI chips.

  14. NeuronBank: a tool for cataloging neuronal circuitry

    Directory of Open Access Journals (Sweden)

    Paul S Katz

    2010-04-01

    Full Text Available The basic unit of any nervous system is the neuron. Therefore, understanding the operation of nervous systems ultimately requires an inventory of their constituent neurons and synaptic connectivity, which form neural circuits. The presence of uniquely identifiable neurons or classes of neurons in many invertebrates has facilitated the construction of cellular-level connectivity diagrams that can be generalized across individuals within a species. Homologous neurons can also be recognized across species. Here we describe NeuronBank.org, a web-based tool that we are developing for cataloging, searching, and analyzing neuronal circuitry within and across species. Information from a single species is represented in an individual branch of NeuronBank. Users can search within a branch or perform queries across branches to look for similarities in neuronal circuits across species. The branches allow for an extensible ontology so that additional characteristics can be added as knowledge grows. Each entry in NeuronBank generates a unique accession ID, allowing it to be easily cited. There is also an automatic link to a Wiki page allowing an encyclopedic explanation of the entry. All of the 44 previously published neurons plus one previously unpublished neuron from the mollusc, Tritonia diomedea, have been entered into a branch of NeuronBank as have 4 previously published neurons from the mollusc, Melibe leonina. The ability to organize information about neuronal circuits will make this information more accessible, ultimately aiding research on these important models.

  15. Mammography density estimation with automated volumetic breast density measurement

    International Nuclear Information System (INIS)

    Ko, Su Yeon; Kim, Eun Kyung; Kim, Min Jung; Moon, Hee Jung

    2014-01-01

    To compare automated volumetric breast density measurement (VBDM) with radiologists' evaluations based on the Breast Imaging Reporting and Data System (BI-RADS), and to identify the factors associated with technical failure of VBDM. In this study, 1129 women aged 19-82 years who underwent mammography from December 2011 to January 2012 were included. Breast density evaluations by radiologists based on BI-RADS and by VBDM (Volpara Version 1.5.1) were compared. The agreement in interpreting breast density between radiologists and VBDM was determined based on four density grades (D1, D2, D3, and D4) and a binary classification of fatty (D1-2) vs. dense (D3-4) breast using kappa statistics. The association between technical failure of VBDM and patient age, total breast volume, fibroglandular tissue volume, history of partial mastectomy, the frequency of mass > 3 cm, and breast density was analyzed. The agreement between breast density evaluations by radiologists and VBDM was fair (k value = 0.26) when the four density grades (D1/D2/D3/D4) were used and moderate (k value = 0.47) for the binary classification (D1-2/D3-4). Twenty-seven women (2.4%) showed failure of VBDM. Small total breast volume, history of partial mastectomy, and high breast density were significantly associated with technical failure of VBDM (p 0.001 to 0.015). There is fair or moderate agreement in breast density evaluation between radiologists and VBDM. Technical failure of VBDM may be related to small total breast volume, a history of partial mastectomy, and high breast density.

  16. Neuronal avalanches and learning

    Energy Technology Data Exchange (ETDEWEB)

    Arcangelis, Lucilla de, E-mail: dearcangelis@na.infn.it [Department of Information Engineering and CNISM, Second University of Naples, 81031 Aversa (Italy)

    2011-05-01

    Networks of living neurons represent one of the most fascinating systems of biology. If the physical and chemical mechanisms at the basis of the functioning of a single neuron are quite well understood, the collective behaviour of a system of many neurons is an extremely intriguing subject. Crucial ingredient of this complex behaviour is the plasticity property of the network, namely the capacity to adapt and evolve depending on the level of activity. This plastic ability is believed, nowadays, to be at the basis of learning and memory in real brains. Spontaneous neuronal activity has recently shown features in common to other complex systems. Experimental data have, in fact, shown that electrical information propagates in a cortex slice via an avalanche mode. These avalanches are characterized by a power law distribution for the size and duration, features found in other problems in the context of the physics of complex systems and successful models have been developed to describe their behaviour. In this contribution we discuss a statistical mechanical model for the complex activity in a neuronal network. The model implements the main physiological properties of living neurons and is able to reproduce recent experimental results. Then, we discuss the learning abilities of this neuronal network. Learning occurs via plastic adaptation of synaptic strengths by a non-uniform negative feedback mechanism. The system is able to learn all the tested rules, in particular the exclusive OR (XOR) and a random rule with three inputs. The learning dynamics exhibits universal features as function of the strength of plastic adaptation. Any rule could be learned provided that the plastic adaptation is sufficiently slow.

  17. Neuronal avalanches and learning

    International Nuclear Information System (INIS)

    Arcangelis, Lucilla de

    2011-01-01

    Networks of living neurons represent one of the most fascinating systems of biology. If the physical and chemical mechanisms at the basis of the functioning of a single neuron are quite well understood, the collective behaviour of a system of many neurons is an extremely intriguing subject. Crucial ingredient of this complex behaviour is the plasticity property of the network, namely the capacity to adapt and evolve depending on the level of activity. This plastic ability is believed, nowadays, to be at the basis of learning and memory in real brains. Spontaneous neuronal activity has recently shown features in common to other complex systems. Experimental data have, in fact, shown that electrical information propagates in a cortex slice via an avalanche mode. These avalanches are characterized by a power law distribution for the size and duration, features found in other problems in the context of the physics of complex systems and successful models have been developed to describe their behaviour. In this contribution we discuss a statistical mechanical model for the complex activity in a neuronal network. The model implements the main physiological properties of living neurons and is able to reproduce recent experimental results. Then, we discuss the learning abilities of this neuronal network. Learning occurs via plastic adaptation of synaptic strengths by a non-uniform negative feedback mechanism. The system is able to learn all the tested rules, in particular the exclusive OR (XOR) and a random rule with three inputs. The learning dynamics exhibits universal features as function of the strength of plastic adaptation. Any rule could be learned provided that the plastic adaptation is sufficiently slow.

  18. Calculation of the density of liquid radon

    International Nuclear Information System (INIS)

    Herreman, W.

    1980-01-01

    Eleven condensed gases were investigated to relate their critical molar volume Vsub(c) to their molar volume Vsub(o)(Vsub(o) is the molar volume where the fluidity phi = 0). From this relationship the critical density of radon was calculated psub(c) = 1613 kg m -3 . From this principle of corresponding states for viscosity and with this value for psub(c) the density for the saturated liquid state of radon was predicted. (author)

  19. Density of Liquid Ni-Cr Alloy

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The density of liquid Ni-Cr alloy was measured by a modified sessile drop method. The density of liquid Ni-Cr alloywas found to decrease with increasing temperature and Cr concentration in the alloy. The molar volume of liquidNi-Cr alloy increases with increasing the Cr concentration in the alloy. The molar volume of Ni-Cr alloy determinedin the present work shows a positive deviation from the linear molar volume.

  20. Low Bone Density

    Science.gov (United States)

    ... Density Exam/Testing › Low Bone Density Low Bone Density Low bone density is when your bone density ... people with normal bone density. Detecting Low Bone Density A bone density test will determine whether you ...

  1. Prenatal cocaine exposure decreases parvalbumin-immunoreactive neurons and GABA-to-projection neuron ratio in the medial prefrontal cortex.

    Science.gov (United States)

    McCarthy, Deirdre M; Bhide, Pradeep G

    2012-01-01

    Cocaine abuse during pregnancy produces harmful effects not only on the mother but also on the unborn child. The neurotransmitters dopamine and serotonin are known as the principal targets of the action of cocaine in the fetal and postnatal brain. However, recent evidence suggests that cocaine can impair cerebral cortical GABA neuron development and function. We sought to analyze the effects of prenatal cocaine exposure on the number and distribution of GABA and projection neurons (inhibitory interneurons and excitatory output neurons, respectively) in the mouse cerebral cortex. We found that the prenatal cocaine exposure decreased GABA neuron numbers and GABA-to-projection neuron ratio in the medial prefrontal cortex of 60-day-old mice. The neighboring prefrontal cortex did not show significant changes in either of these measures. However, there was a significant increase in projection neuron numbers in the prefrontal cortex but not in the medial prefrontal cortex. Thus, the effects of cocaine on GABA and projection neurons appear to be cortical region specific. The population of parvalbumin-immunoreactive GABA neurons was decreased in the medial prefrontal cortex following the prenatal cocaine exposure. The cocaine exposure also delayed the developmental decline in the volume of the medial prefrontal cortex. Thus, prenatal cocaine exposure produced persisting and region-specific effects on cortical cytoarchitecture and impaired the physiological balance between excitatory and inhibitory neurotransmission. These structural changes may underlie the electrophysiological and behavioral effects of prenatal cocaine exposure observed in animal models and human subjects. Copyright © 2012 S. Karger AG, Basel.

  2. Neuron Morphology Influences Axon Initial Segment Plasticity123

    Science.gov (United States)

    2016-01-01

    In most vertebrate neurons, action potentials are initiated in the axon initial segment (AIS), a specialized region of the axon containing a high density of voltage-gated sodium and potassium channels. It has recently been proposed that neurons use plasticity of AIS length and/or location to regulate their intrinsic excitability. Here we quantify the impact of neuron morphology on AIS plasticity using computational models of simplified and realistic somatodendritic morphologies. In small neurons (e.g., dentate granule neurons), excitability was highest when the AIS was of intermediate length and located adjacent to the soma. Conversely, neurons having larger dendritic trees (e.g., pyramidal neurons) were most excitable when the AIS was longer and/or located away from the soma. For any given somatodendritic morphology, increasing dendritic membrane capacitance and/or conductance favored a longer and more distally located AIS. Overall, changes to AIS length, with corresponding changes in total sodium conductance, were far more effective in regulating neuron excitability than were changes in AIS location, while dendritic capacitance had a larger impact on AIS performance than did dendritic conductance. The somatodendritic influence on AIS performance reflects modest soma-to-AIS voltage attenuation combined with neuron size-dependent changes in AIS input resistance, effective membrane time constant, and isolation from somatodendritic capacitance. We conclude that the impact of AIS plasticity on neuron excitability will depend largely on somatodendritic morphology, and that, in some neurons, a shorter or more distally located AIS may promote, rather than limit, action potential generation. PMID:27022619

  3. Kappe neurons, a novel population of olfactory sensory neurons.

    Science.gov (United States)

    Ahuja, Gaurav; Bozorg Nia, Shahrzad; Zapilko, Veronika; Shiriagin, Vladimir; Kowatschew, Daniel; Oka, Yuichiro; Korsching, Sigrun I

    2014-02-10

    Perception of olfactory stimuli is mediated by distinct populations of olfactory sensory neurons, each with a characteristic set of morphological as well as functional parameters. Beyond two large populations of ciliated and microvillous neurons, a third population, crypt neurons, has been identified in teleost and cartilaginous fishes. We report here a novel, fourth olfactory sensory neuron population in zebrafish, which we named kappe neurons for their characteristic shape. Kappe neurons are identified by their Go-like immunoreactivity, and show a distinct spatial distribution within the olfactory epithelium, similar to, but significantly different from that of crypt neurons. Furthermore, kappe neurons project to a single identified target glomerulus within the olfactory bulb, mdg5 of the mediodorsal cluster, whereas crypt neurons are known to project exclusively to the mdg2 glomerulus. Kappe neurons are negative for established markers of ciliated, microvillous and crypt neurons, but appear to have microvilli. Kappe neurons constitute the fourth type of olfactory sensory neurons reported in teleost fishes and their existence suggests that encoding of olfactory stimuli may require a higher complexity than hitherto assumed already in the peripheral olfactory system.

  4. Altered balance of glutamatergic/GABAergic synaptic input and associated changes in dendrite morphology after BDNF expression in BDNF-deficient hippocampal neurons

    OpenAIRE

    Singh, B.; Henneberger, C.; Betances, D.; Arevalo, M.A.; Rodriguez-Tebar, A.; Meier, J.C.; Grantyn, R.

    2006-01-01

    Cultured neurons from bdnf-/- mice display reduced densities of synaptic terminals, although in vivo these deficits are small or absent. Here we aimed at clarifying the local responses to postsynaptic brain-derived neurotrophic factor (BDNF). To this end, solitary enhanced green fluorescent protein (EGFP)-labeled hippocampal neurons from bdnf-/- mice were compared with bdnf-/- neurons after transfection with BDNF, bdnf-/- neurons after transient exposure to exogenous BDNF, and bdnf+/+ neurons...

  5. Stochastic neuron models

    CERN Document Server

    Greenwood, Priscilla E

    2016-01-01

    This book describes a large number of open problems in the theory of stochastic neural systems, with the aim of enticing probabilists to work on them. This includes problems arising from stochastic models of individual neurons as well as those arising from stochastic models of the activities of small and large networks of interconnected neurons. The necessary neuroscience background to these problems is outlined within the text, so readers can grasp the context in which they arise. This book will be useful for graduate students and instructors providing material and references for applying probability to stochastic neuron modeling. Methods and results are presented, but the emphasis is on questions where additional stochastic analysis may contribute neuroscience insight. An extensive bibliography is included. Dr. Priscilla E. Greenwood is a Professor Emerita in the Department of Mathematics at the University of British Columbia. Dr. Lawrence M. Ward is a Professor in the Department of Psychology and the Brain...

  6. Subcellular location of astrocytic calcium stores favors extrasynaptic neuron-astrocyte communication.

    Science.gov (United States)

    Patrushev, Ilya; Gavrilov, Nikolay; Turlapov, Vadim; Semyanov, Alexey

    2013-11-01

    Neuron-astrocyte interactions are important for brain computations and synaptic plasticity. Perisynaptic astrocytic processes (PAPs) contain a high density of transporters that are responsible for neurotransmitter clearance. Metabotropic glutamate receptors are thought to trigger Ca(2+) release from Ca(2+) stores in PAPs in response to synaptic activity. Our ultrastructural study revealed that PAPs are actually devoid of Ca(2+) stores and have a high surface-to-volume ratio favorable for uptake. Astrocytic processes containing Ca(2+) stores were located further away from the synapses and could therefore respond to changes in ambient glutamate. Thus, the anatomic data do not support communication involving Ca(2+) stores in tripartite synapses, but rather point to extrasynaptic communication. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Measuring single-cell density.

    Science.gov (United States)

    Grover, William H; Bryan, Andrea K; Diez-Silva, Monica; Suresh, Subra; Higgins, John M; Manalis, Scott R

    2011-07-05

    We have used a microfluidic mass sensor to measure the density of single living cells. By weighing each cell in two fluids of different densities, our technique measures the single-cell mass, volume, and density of approximately 500 cells per hour with a density precision of 0.001 g mL(-1). We observe that the intrinsic cell-to-cell variation in density is nearly 100-fold smaller than the mass or volume variation. As a result, we can measure changes in cell density indicative of cellular processes that would be otherwise undetectable by mass or volume measurements. Here, we demonstrate this with four examples: identifying Plasmodium falciparum malaria-infected erythrocytes in a culture, distinguishing transfused blood cells from a patient's own blood, identifying irreversibly sickled cells in a sickle cell patient, and identifying leukemia cells in the early stages of responding to a drug treatment. These demonstrations suggest that the ability to measure single-cell density will provide valuable insights into cell state for a wide range of biological processes.

  8. Postnatal Gene Therapy Improves Spatial Learning Despite the Presence of Neuronal Ectopia in a Model of Neuronal Migration Disorder

    Directory of Open Access Journals (Sweden)

    Huaiyu Hu

    2016-11-01

    Full Text Available Patients with type II lissencephaly, a neuronal migration disorder with ectopic neurons, suffer from severe mental retardation, including learning deficits. There is no effective therapy to prevent or correct the formation of neuronal ectopia, which is presumed to cause cognitive deficits. We hypothesized that learning deficits were not solely caused by neuronal ectopia and that postnatal gene therapy could improve learning without correcting the neuronal ectopia formed during fetal development. To test this hypothesis, we evaluated spatial learning of cerebral cortex-specific protein O-mannosyltransferase 2 (POMT2, an enzyme required for O-mannosyl glycosylation knockout mice and compared to the knockout mice that were injected with an adeno-associated viral vector (AAV encoding POMT2 into the postnatal brains with Barnes maze. The data showed that the knockout mice exhibited reduced glycosylation in the cerebral cortex, reduced dendritic spine density on CA1 neurons, and increased latency to the target hole in the Barnes maze, indicating learning deficits. Postnatal gene therapy restored functional glycosylation, rescued dendritic spine defects, and improved performance on the Barnes maze by the knockout mice even though neuronal ectopia was not corrected. These results indicate that postnatal gene therapy improves spatial learning despite the presence of neuronal ectopia.

  9. Level densities

    International Nuclear Information System (INIS)

    Ignatyuk, A.V.

    1998-01-01

    For any applications of the statistical theory of nuclear reactions it is very important to obtain the parameters of the level density description from the reliable experimental data. The cumulative numbers of low-lying levels and the average spacings between neutron resonances are usually used as such data. The level density parameters fitted to such data are compiled in the RIPL Starter File for the tree models most frequently used in practical calculations: i) For the Gilber-Cameron model the parameters of the Beijing group, based on a rather recent compilations of the neutron resonance and low-lying level densities and included into the beijing-gc.dat file, are chosen as recommended. As alternative versions the parameters provided by other groups are given into the files: jaeri-gc.dat, bombay-gc.dat, obninsk-gc.dat. Additionally the iljinov-gc.dat, and mengoni-gc.dat files include sets of the level density parameters that take into account the damping of shell effects at high energies. ii) For the backed-shifted Fermi gas model the beijing-bs.dat file is selected as the recommended one. Alternative parameters of the Obninsk group are given in the obninsk-bs.dat file and those of Bombay in bombay-bs.dat. iii) For the generalized superfluid model the Obninsk group parameters included into the obninsk-bcs.dat file are chosen as recommended ones and the beijing-bcs.dat file is included as an alternative set of parameters. iv) For the microscopic approach to the level densities the files are: obninsk-micro.for -FORTRAN 77 source for the microscopical statistical level density code developed in Obninsk by Ignatyuk and coworkers, moller-levels.gz - Moeller single-particle level and ground state deformation data base, moller-levels.for -retrieval code for Moeller single-particle level scheme. (author)

  10. Characterization of astrocytic and neuronal benzodiazepine receptors

    Energy Technology Data Exchange (ETDEWEB)

    Bender, A.S.

    1988-01-01

    Primary cultures of astrocytes and neurons express benzodiazepine receptors. Neuronal benzodiazepine receptors were of high-affinity, K{sub D} values were 7.5-43 nM and the densities of receptors (B{sub max}) were 924-4131 fmol/mg protein. Astrocytes posses a high-affinity benzodiazepine receptor, K{sub D} values were 6.6-13 nM. The B{sub max} values were 6,033-12,000 fmol/mg protein. The pharmacological profile of the neuronal benzodiazepine receptor was that of the central-type benzodiazepine receptor, where clonazepam has a high-affinity and Ro 5-4864 (4{prime}-chlorodiazepam) has a low-affinity. Whereas astrocytic benzoidazepine receptor was characteristic of the so called peripheral-type benzodiazepine receptors, which shows a high-affinity towards Ro 5-4863, and a low-affinity towards clonazepam. The astrocytic benzodiazepine receptors was functionally correlated with voltage dependent calcium channels, since dihydropyridines and benzodiazepines interacted with ({sup 3}H) diazepam and ({sup 3}H) nitrendipine receptors with the same rank order of potency, showing a statistically significant correlation. No such correlation was observed in neurons.

  11. Neuronal Migration and Neuronal Migration Disorder in Cerebral Cortex

    OpenAIRE

    SUN, Xue-Zhi; TAKAHASHI, Sentaro; GUI, Chun; ZHANG, Rui; KOGA, Kazuo; NOUYE, Minoru; MURATA, Yoshiharu

    2002-01-01

    Neuronal cell migration is one of the most significant features during cortical development. After final mitosis, neurons migrate from the ventricular zone into the cortical plate, and then establish neuronal lamina and settle onto the outermost layer, forming an "inside-out" gradient of maturation. Neuronal migration is guided by radial glial fibers and also needs proper receptors, ligands, and other unknown extracellular factors, requests local signaling (e.g. some emitted by the Cajal-Retz...

  12. Distribution of glycinergic neuronal somata in the rat spinal cord.

    Science.gov (United States)

    Hossaini, Mehdi; French, Pim J; Holstege, Jan C

    2007-04-20

    Glycine transporter 2 (GlyT2) mRNA is exclusively expressed in glycinergic neurons, and is presently considered a reliable marker for glycinergic neuronal somata. In this study, we have performed non-radioactive in situ hybridization to localize GlyT2 mRNA in fixed free-floating sections of cervical (C2 and C6), thoracic (T5), lumbar (L2 and L5) and sacral (S1) segments of the rat spinal cord. The results showed that in all segments the majority of the GlyT2 mRNA labeled (glycinergic) neuronal somata was present in the deep dorsal horn and the intermediate zone (laminae III-VIII), with around 50% (range 43.7-70.9%) in laminae VII&VIII. In contrast, the superficial dorsal horn, the motoneuronal cell groups and the area around the central canal contained only few glycinergic neuronal somata. The density (number of glycinergic neuronal somata per mm(2)) was also low in these areas, while the highest densities were found in laminae V to VIII. The lateral spinal nucleus and the lateral cervical nucleus also contained a limited number of glycinergic neurons. Our findings showed that the distribution pattern of the glycinergic neuronal somata is similar in all the examined segments. The few differences that were found in the relative laminar distribution between some of the segments, are most likely due to technical reasons. We therefore conclude that the observed distribution pattern of glycinergic neuronal somata is present throughout the spinal cord. Our findings further showed that the non-radioactive in situ hybridization technique for identifying GlyT2 mRNA in fixed free-floating sections is a highly efficient tool for identifying glycinergic neurons in the spinal cord.

  13. Detection of Temperature Difference in Neuronal Cells.

    Science.gov (United States)

    Tanimoto, Ryuichi; Hiraiwa, Takumi; Nakai, Yuichiro; Shindo, Yutaka; Oka, Kotaro; Hiroi, Noriko; Funahashi, Akira

    2016-03-01

    For a better understanding of the mechanisms behind cellular functions, quantification of the heterogeneity in an organism or cells is essential. Recently, the importance of quantifying temperature has been highlighted, as it correlates with biochemical reaction rates. Several methods for detecting intracellular temperature have recently been established. Here we develop a novel method for sensing temperature in living cells based on the imaging technique of fluorescence of quantum dots. We apply the method to quantify the temperature difference in a human derived neuronal cell line, SH-SY5Y. Our results show that temperatures in the cell body and neurites are different and thus suggest that inhomogeneous heat production and dissipation happen in a cell. We estimate that heterogeneous heat dissipation results from the characteristic shape of neuronal cells, which consist of several compartments formed with different surface-volume ratios. Inhomogeneous heat production is attributable to the localization of specific organelles as the heat source.

  14. Diabetes does not accelerate neuronal loss following nerve injury

    DEFF Research Database (Denmark)

    Severinsen, Kaare; Jakobsen, Johannes

    2007-01-01

    To determine the resistance of neuronal dorsal root ganglion (DRG) cells in experimental diabetes, we studied the neuronal cell loss after severe axonal injury in streptozotocin (STZ) diabetic rats with unilateral transection of the L5 spinal nerve for 12 weeks. Fifty 18-week-old inbred male Wistar...... nondiabetic control rats at 18 weeks and five nondiabetic control rats at 30 weeks were included to determine whether DRG cell changes occur without nerve injury during the study period. In group 1, the stereologically determined number of all neuronal DRG cells was unchanged after 12 weeks of diabetes....... The mean perikaryal volume of neuronal DRG cells of the A and B subtypes was reduced by 10% each (p

  15. Neuronal nets in robotics

    International Nuclear Information System (INIS)

    Jimenez Sanchez, Raul

    1999-01-01

    The paper gives a generic idea of the solutions that the neuronal nets contribute to the robotics. The advantages and the inconveniences are exposed that have regarding the conventional techniques. It also describe the more excellent applications as the pursuit of trajectories, the positioning based on images, the force control or of the mobile robots management, among others

  16. Total numbers of neurons and glial cells in cortex and basal ganglia of aged brains with Down syndrome--a stereological study.

    Science.gov (United States)

    Karlsen, Anna Schou; Pakkenberg, Bente

    2011-11-01

    The total numbers of neurons and glial cells in the neocortex and basal ganglia in adults with Down syndrome (DS) were estimated with design-based stereological methods, providing quantitative data on brains affected by delayed development and accelerated aging. Cell numbers, volume of regions, and densities of neurons and glial cell subtypes were estimated in brains from 4 female DS subjects (mean age 66 years) and 6 female controls (mean age 70 years). The DS subjects were estimated to have about 40% fewer neocortical neurons in total (11.1 × 10(9) vs. 17.8 × 10(9), 2p ≤ 0.001) and almost 30% fewer neocortical glial cells with no overlap to controls (12.8 × 10(9) vs. 18.2 × 10(9), 2p = 0.004). In contrast, the total number of neurons in the basal ganglia was the same in the 2 groups, whereas the number of oligodendrocytes in the basal ganglia was reduced by almost 50% in DS (405 × 10(6) vs. 816 × 10(6), 2p = 0.01). We conclude that trisomy 21 affects cortical structures more than central gray matter emphasizing the differential impairment of brain development. Despite concomitant Alzheimer-like pathology, the neurodegenerative outcome in a DS brain deviates from common Alzheimer disease.

  17. Local impermeant anions establish the neuronal chloride concentration

    DEFF Research Database (Denmark)

    Glykys, J; Dzhala, V; Egawa, K

    2014-01-01

    Neuronal intracellular chloride concentration [Cl(-)](i) is an important determinant of γ-aminobutyric acid type A (GABA(A)) receptor (GABA(A)R)-mediated inhibition and cytoplasmic volume regulation. Equilibrative cation-chloride cotransporters (CCCs) move Cl(-) across the membrane, but accumulat...

  18. Local connections of layer 5 GABAergic interneurons to corticospinal neurons

    Directory of Open Access Journals (Sweden)

    Yasuyo H Tanaka

    2011-09-01

    Full Text Available In the local circuit of the cerebral cortex, GABAergic inhibitory interneurons are considered to work in collaboration with excitatory neurons. Although many interneuron subgroups have been described in the cortex, local inhibitory connections of each interneuron subgroup are only partially understood with respect to the functional neuron groups that receive these inhibitory connections. In the present study, we morphologically examined local inhibitory inputs to corticospinal neurons (CSNs in motor areas using transgenic rats in which GABAergic neurons expressed fluorescent protein Venus. By analysis of biocytin-filled axons obtained with whole-cell recording/staining in cortical slices, we classified fast-spiking (FS neurons in layer (L 5 into two types, FS1 and FS2, by their high and low densities of axonal arborization, respectively. We then investigated the connections of FS1, FS2, somatostatin-immunopositive (SOM and other (non-FS/non-SOM interneurons to CSNs that were retrogradely labeled in a Golgi-like manner in motor areas. When close appositions between the axon boutons of the intracellularly labeled interneurons and the somata/dendrites of the retrogradely labeled CSNs were examined electron-microscopically, 74% of these appositions made symmetric synaptic contacts. The axon boutons of single FS1 neurons were 2–4-fold more frequent in appositions to the somata/dendrites of CSNs than those of FS2, SOM and non-FS/non-SOM neurons. Axosomatic appositions were most frequently formed with axon boutons of FS1 and FS2 neurons (approximately 30% and least frequently formed with those of SOM neurons (7%. In contrast, SOM neurons most extensively sent axon boutons to the apical dendrites of CSNs. These results might suggest that motor outputs are controlled differentially by the subgroups of L5 GABAergic interneurons in cortical motor areas. 

  19. Vasculo-Neuronal Coupling: Retrograde Vascular Communication to Brain Neurons.

    Science.gov (United States)

    Kim, Ki Jung; Ramiro Diaz, Juan; Iddings, Jennifer A; Filosa, Jessica A

    2016-12-14

    Continuous cerebral blood flow is essential for neuronal survival, but whether vascular tone influences resting neuronal function is not known. Using a multidisciplinary approach in both rat and mice brain slices, we determined whether flow/pressure-evoked increases or decreases in parenchymal arteriole vascular tone, which result in arteriole constriction and dilation, respectively, altered resting cortical pyramidal neuron activity. We present evidence for intercellular communication in the brain involving a flow of information from vessel to astrocyte to neuron, a direction opposite to that of classic neurovascular coupling and referred to here as vasculo-neuronal coupling (VNC). Flow/pressure increases within parenchymal arterioles increased vascular tone and simultaneously decreased resting pyramidal neuron firing activity. On the other hand, flow/pressure decreases evoke parenchymal arteriole dilation and increased resting pyramidal neuron firing activity. In GLAST-CreERT2; R26-lsl-GCaMP3 mice, we demonstrate that increased parenchymal arteriole tone significantly increased intracellular calcium in perivascular astrocyte processes, the onset of astrocyte calcium changes preceded the inhibition of cortical pyramidal neuronal firing activity. During increases in parenchymal arteriole tone, the pyramidal neuron response was unaffected by blockers of nitric oxide, GABA A , glutamate, or ecto-ATPase. However, VNC was abrogated by TRPV4 channel, GABA B , as well as an adenosine A 1 receptor blocker. Differently to pyramidal neuron responses, increases in flow/pressure within parenchymal arterioles increased the firing activity of a subtype of interneuron. Together, these data suggest that VNC is a complex constitutive active process that enables neurons to efficiently adjust their resting activity according to brain perfusion levels, thus safeguarding cellular homeostasis by preventing mismatches between energy supply and demand. We present evidence for vessel-to-neuron

  20. Neuronal survival in the brain: neuron type-specific mechanisms

    DEFF Research Database (Denmark)

    Pfisterer, Ulrich Gottfried; Khodosevich, Konstantin

    2017-01-01

    Neurogenic regions of mammalian brain produce many more neurons that will eventually survive and reach a mature stage. Developmental cell death affects both embryonically produced immature neurons and those immature neurons that are generated in regions of adult neurogenesis. Removal of substantial...... numbers of neurons that are not yet completely integrated into the local circuits helps to ensure that maturation and homeostatic function of neuronal networks in the brain proceed correctly. External signals from brain microenvironment together with intrinsic signaling pathways determine whether...... for survival in a certain brain region. This review focuses on how immature neurons survive during normal and impaired brain development, both in the embryonic/neonatal brain and in brain regions associated with adult neurogenesis, and emphasizes neuron type-specific mechanisms that help to survive for various...

  1. A comparison of neuronal growth cone and cell body membrane: electrophysiological and ultrastructural properties.

    Science.gov (United States)

    Guthrie, P B; Lee, R E; Kater, S B

    1989-10-01

    This study investigated a broad set of general electrophysiological and ultrastructural features of growth cone and cell body membrane of individual neurons where membrane from different regions of the same neuron can be directly compared. Growth cones were surgically isolated from identified adult Helisoma neurons in culture and compared with the cell body using whole-cell patch-clamp recording techniques. All isolated growth cones generated overshooting regenerative action potentials. Five neurons (buccal neurons B4, B5, and B19; pedal neurons P1 and P5) were selected that displayed distinctive action potential waveforms. In all cases, the growth cone action potential was indistinguishable from the cell body action potential and different from growth cones from other identified neurons. Two of these neurons (B5 and B19) were studied further using voltage-clamp procedures; growth cones and cell bodies again revealed major similarities within one neuron type and differences between neuron types. The only suggested difference between the growth cone and cell body was an apparent reduction in the magnitude of the A-current in the growth cone. Peak inward and outward current densities, as with other electrophysiological features, were different between neuron types, but were, again, similar between the growth cone and the cell body of the same neuron. Freeze-fracture analysis of intramembraneous particles (IMPs) was also performed on identified regions of the same neuron in culture. Both the density and the size distribution of IMPs were the same in growth cone, cell body, and neurite membranes. In these general electrophysiological and ultrastructural characteristics, therefore, growth cone membranes appear to retain the identity of the parent neuron cell body membrane.

  2. Metabolic sensing neurons and the control of energy homeostasis.

    Science.gov (United States)

    Levin, Barry E

    2006-11-30

    The brain and periphery carry on a constant conversation; the periphery informs the brain about its metabolic needs and the brain provides for these needs through its control of somatomotor, autonomic and neurohumoral pathways involved in energy intake, expenditure and storage. Metabolic sensing neurons are the integrators of a variety of metabolic, humoral and neural inputs from the periphery. Such neurons, originally called "glucosensing", also respond to fatty acids, hormones and metabolites from the periphery. They are integrated within neural pathways involved in the regulation of energy homeostasis. Unlike most neurons, they utilize glucose and other metabolites as signaling molecules to regulate their membrane potential and firing rate. For glucosensing neurons, glucokinase acts as the rate-limiting step in glucosensing while the pathways that mediate responses to metabolites like lactate, ketone bodies and fatty acids are less well characterized. Many metabolic sensing neurons also respond to insulin and leptin and other peripheral hormones and receive neural inputs from peripheral organs. Each set of afferent signals arrives with different temporal profiles and by different routes and these inputs are summated at the level of the membrane potential to produce a given neural firing pattern. In some obese individuals, the relative sensitivity of metabolic sensing neurons to various peripheral inputs is genetically reduced. This may provide one mechanism underlying their propensity to become obese when exposed to diets high in fat and caloric density. Thus, metabolic sensing neurons may provide a potential therapeutic target for the treatment of obesity.

  3. Charge density waves in solids

    CERN Document Server

    Gor'kov, LP

    2012-01-01

    The latest addition to this series covers a field which is commonly referred to as charge density wave dynamics.The most thoroughly investigated materials are inorganic linear chain compounds with highly anisotropic electronic properties. The volume opens with an examination of their structural properties and the essential features which allow charge density waves to develop.The behaviour of the charge density waves, where interesting phenomena are observed, is treated both from a theoretical and an experimental standpoint. The role of impurities in statics and dynamics is considered and an

  4. Neuronal synchrony: peculiarity and generality.

    Science.gov (United States)

    Nowotny, Thomas; Huerta, Ramon; Rabinovich, Mikhail I

    2008-09-01

    Synchronization in neuronal systems is a new and intriguing application of dynamical systems theory. Why are neuronal systems different as a subject for synchronization? (1) Neurons in themselves are multidimensional nonlinear systems that are able to exhibit a wide variety of different activity patterns. Their "dynamical repertoire" includes regular or chaotic spiking, regular or chaotic bursting, multistability, and complex transient regimes. (2) Usually, neuronal oscillations are the result of the cooperative activity of many synaptically connected neurons (a neuronal circuit). Thus, it is necessary to consider synchronization between different neuronal circuits as well. (3) The synapses that implement the coupling between neurons are also dynamical elements and their intrinsic dynamics influences the process of synchronization or entrainment significantly. In this review we will focus on four new problems: (i) the synchronization in minimal neuronal networks with plastic synapses (synchronization with activity dependent coupling), (ii) synchronization of bursts that are generated by a group of nonsymmetrically coupled inhibitory neurons (heteroclinic synchronization), (iii) the coordination of activities of two coupled neuronal networks (partial synchronization of small composite structures), and (iv) coarse grained synchronization in larger systems (synchronization on a mesoscopic scale). (c) 2008 American Institute of Physics.

  5. Attentional function and basal forebrain cholinergic neuron morphology during aging in the Ts65Dn mouse model of Down syndrome.

    Science.gov (United States)

    Powers, Brian E; Velazquez, Ramon; Kelley, Christy M; Ash, Jessica A; Strawderman, Myla S; Alldred, Melissa J; Ginsberg, Stephen D; Mufson, Elliott J; Strupp, Barbara J

    2016-12-01

    Individuals with Down syndrome (DS) exhibit intellectual disability and develop Alzheimer's disease-like neuropathology during the third decade of life. The Ts65Dn mouse model of DS exhibits key features of both disorders, including impairments in learning, attention and memory, as well as atrophy of basal forebrain cholinergic neurons (BFCNs). The present study evaluated attentional function in relation to BFCN morphology in young (3 months) and middle-aged (12 months) Ts65Dn mice and disomic (2N) controls. Ts65Dn mice exhibited attentional dysfunction at both ages, with greater impairment in older trisomics. Density of BFCNs was significantly lower for Ts65Dn mice independent of age, which may contribute to attentional dysfunction since BFCN density was positively associated with performance on an attention task. BFCN volume decreased with age in 2N but not Ts65Dn mice. Paradoxically, BFCN volume was greater in older trisomic mice, suggestive of a compensatory response. In sum, attentional dysfunction occurred in both young and middle-aged Ts65Dn mice, which may in part reflect reduced density and/or phenotypic alterations in BFCNs.

  6. Correlations between histology and neuronal activity recorded by microelectrodes implanted chronically in the cerebral cortex

    Science.gov (United States)

    McCreery, Douglas; Cogan, Stuart; Kane, Sheryl; Pikov, Victor

    2016-06-01

    Objective. To quantify relations between the neuronal activity recorded with chronically-implanted intracortical microelectrodes and the histology of the surrounding tissue, using radial distance from the tip sites and time after array implantation as parameters. Approach. ‘Utah’-type intracortical microelectrode arrays were implanted into cats’ sensorimotor cortex for 275-364 days. The brain tissue around the implants was immuno-stained for the neuronal marker NeuN and for the astrocyte marker GFAP. Pearson’s product-moment correlations were used to quantify the relations between these markers and the amplitudes of the recorded neuronal action potentials (APs) and their signal-to-noise ratios (S/N). Main results. S/N was more stable over post-implant time than was AP amplitude, but its increased correlation with neuronal density after many months indicates ongoing loss of neurons around the microelectrodes. S/N was correlated with neuron density out to at least 140 μm from the microelectrodes, while AP amplitude was correlated with neuron density and GFAP density within ˜80 μm. Correlations between AP amplitude and histology markers (GFAP and NeuN density) were strongest immediately after implantation, while correlation between the neuron density and S/N was strongest near the time the animals were sacrificed. Unlike AP amplitude, there was no significant correlation between S/N and density of GFAP around the tip sites. Significance. Our findings indicate an evolving interaction between changes in the tissue surrounding the microelectrodes and the microelectrode’s electrical properties. Ongoing loss of neurons around recording microelectrodes, and the interactions between their delayed electrical deterioration and early tissue scarring around the tips appear to pose the greatest threats to the microelectrodes’ long-term functionality.

  7. From Neurons to Newtons

    DEFF Research Database (Denmark)

    Nielsen, Bjørn Gilbert

    2001-01-01

    proteins generate forces, to the macroscopic levels where overt arm movements are vol- untarily controlled within an unpredictable environment by legions of neurons¯ring in orderly fashion. An extensive computer simulation system has been developed for this thesis, which at present contains a neural...... network scripting language for specifying arbitrary neural architectures, de¯nition ¯les for detailed spinal networks, various biologically realistic models of neurons, and dynamic synapses. Also included are structurally accurate models of intrafusal and extra-fusal muscle ¯bers and a general body...... that an explicit function may be derived which expresses the force that the spindle contractile elements must produce to exactly counter spindle unloading during muscle shortening. This information was used to calculate the corresponding "optimal" °-motoneuronal activity level. For some simple arm movement tasks...

  8. Criticality in Neuronal Networks

    Science.gov (United States)

    Friedman, Nir; Ito, Shinya; Brinkman, Braden A. W.; Shimono, Masanori; Deville, R. E. Lee; Beggs, John M.; Dahmen, Karin A.; Butler, Tom C.

    2012-02-01

    In recent years, experiments detecting the electrical firing patterns in slices of in vitro brain tissue have been analyzed to suggest the presence of scale invariance and possibly criticality in the brain. Much of the work done however has been limited in two ways: 1) the data collected is from local field potentials that do not represent the firing of individual neurons; 2) the analysis has been primarily limited to histograms. In our work we examine data based on the firing of individual neurons (spike data), and greatly extend the analysis by considering shape collapse and exponents. Our results strongly suggest that the brain operates near a tuned critical point of a highly distinctive universality class.

  9. Modern charge-density analysis

    CERN Document Server

    Gatti, Carlo

    2012-01-01

    Focusing on developments from the past 10-15 years, this volume presents an objective overview of the research in charge density analysis. The most promising methodologies are included, in addition to powerful interpretative tools and a survey of important areas of research.

  10. Endogenous neurotrophin-3 promotes neuronal sprouting from dorsal root ganglia.

    Science.gov (United States)

    Wang, Xu-Yang; Gu, Pei-Yuan; Chen, Shi-Wen; Gao, Wen-Wei; Tian, Heng-Li; Lu, Xiang-He; Zheng, Wei-Ming; Zhuge, Qi-Chuan; Hu, Wei-Xing

    2015-11-01

    In the present study, we investigated the role of endogenous neurotrophin-3 in nerve terminal sprouting 2 months after spinal cord dorsal root rhizotomy. The left L1-5 and L7-S2 dorsal root ganglia in adult cats were exposed and removed, preserving the L6 dorsal root ganglia. Neurotrophin-3 was mainly expressed in large neurons in the dorsal root ganglia and in some neurons in spinal lamina II. Two months after rhizotomy, the number of neurotrophin-3-positive neurons in the spared dorsal root ganglia and the density of neurite sprouts emerging from these ganglia were increased. Intraperitoneal injection of an antibody against neurotrophin-3 decreased the density of neurite sprouts. These findings suggest that endogenous neurotrophin-3 is involved in spinal cord plasticity and regeneration, and that it promotes axonal sprouting from the dorsal root ganglia after spinal cord dorsal root rhizotomy.

  11. Hippocampal Neuron Number Is Unchanged 1 Year After Fractionated Whole-Brain Irradiation at Middle Age

    International Nuclear Information System (INIS)

    Shi Lei; Molina, Doris P.; Robbins, Michael E.; Wheeler, Kenneth T.; Brunso-Bechtold, Judy K.

    2008-01-01

    Purpose: To determine whether hippocampal neurons are lost 12 months after middle-aged rats received a fractionated course of whole-brain irradiation (WBI) that is expected to be biologically equivalent to the regimens used clinically in the treatment of brain tumors. Methods and Materials: Twelve-month-old Fischer 344 X Brown Norway male rats were divided into WBI and control (CON) groups (n = 6 per group). Anesthetized WBI rats received 45 Gy of 137 Cs γ rays delivered as 9 5-Gy fractions twice per week for 4.5 weeks. Control rats were anesthetized but not irradiated. Twelve months after WBI completion, all rats were anesthetized and perfused with paraformaldehyde, and hippocampal sections were immunostained with the neuron-specific antibody NeuN. Using unbiased stereology, total neuron number and the volume of the neuronal and neuropil layers were determined in the dentate gyrus, CA3, and CA1 subregions of hippocampus. Results: No differences in tissue integrity or neuron distribution were observed between the WBI and CON groups. Moreover, quantitative analysis demonstrated that neither total neuron number nor the volume of neuronal or neuropil layers differed between the two groups for any subregion. Conclusions: Impairment on a hippocampal-dependent learning and memory test occurs 1 year after fractionated WBI at middle age. The same WBI regimen, however, does not lead to a loss of neurons or a reduction in the volume of hippocampus

  12. Genetic modification of neurons to express bevacizumab for local anti-angiogenesis treatment of glioblastoma.

    Science.gov (United States)

    Hicks, Martin J; Funato, Kosuke; Wang, Lan; Aronowitz, Eric; Dyke, Jonathan P; Ballon, Douglas J; Havlicek, David F; Frenk, Esther Z; De, Bishnu P; Chiuchiolo, Maria J; Sondhi, Dolan; Hackett, Neil R; Kaminsky, Stephen M; Tabar, Viviane; Crystal, Ronald G

    2015-01-01

    The median survival of glioblastoma multiforme (GBM) is approximately 1 year. Following surgical removal, systemic therapies are limited by the blood-brain barrier. To circumvent this, we developed a method to modify neurons with the genetic sequence for therapeutic monoclonal antibodies using adeno-associated virus (AAV) gene transfer vectors, directing persistent, local expression in the tumor milieu. The human U87MG GBM cell line or patient-derived early passage GBM cells were administered to the striatum of NOD/SCID immunodeficient mice. AAVrh.10BevMab, an AAVrh.10-based vector coding for bevacizumab (Avastin), an anti-human vascular endothelial growth factor (VEGF) monoclonal antibody, was delivered to the area of the GBM xenograft. Localized expression of bevacizumab was demonstrated by quantitative PCR, ELISA and western blotting. Immunohistochemistry showed that bevacizumab was expressed in neurons. Concurrent administration of AAVrh.10BevMab with the U87MG tumor reduced tumor blood vessel density and tumor volume, and increased survival. Administration of AAVrh.10BevMab 1 week after U87MG xenograft reduced growth and increased survival. Studies with patient-derived early passage GBM primary cells showed a reduction in primary tumor burden with an increased survival. These data support the strategy of AAV-mediated central nervous system gene therapy to treat GBM, overcoming the blood-brain barrier through local, persistent delivery of an anti-angiogenesis monoclonal antibody.

  13. Orbitofrontal cortex volumes in medication naïve children with major depressive disorder: a magnetic resonance imaging study.

    Science.gov (United States)

    Chen, Hua-Hsuan; Rosenberg, David R; MacMaster, Frank P; Easter, Philip C; Caetano, Sheila C; Nicoletti, Mark; Hatch, John P; Nery, Fabiano G; Soares, Jair C

    2008-12-01

    Adults with major depressive disorder (MDD) are reported to have reduced orbitofrontal cortex (OFC) volumes, which could be related to decreased neuronal density. We conducted a study on medication naïve children with MDD to determine whether abnormalities of OFC are present early in the illness course. Twenty seven medication naïve pediatric Diagnostic and Statistical Manual of Mental Disorders, 4(th) edition (DSM-IV) MDD patients (mean age +/- SD = 14.4 +/- 2.2 years; 10 males) and 26 healthy controls (mean age +/- SD = 14.4 +/- 2.4 years; 12 males) underwent a 1.5T magnetic resonance imaging (MRI) with 3D spoiled gradient recalled acquisition. The OFC volumes were compared using analysis of covariance with age, gender, and total brain volume as covariates. There was no significant difference in either total OFC volume or total gray matter OFC volume between MDD patients and healthy controls. Exploratory analysis revealed that patients had unexpectedly larger total right lateral (F = 4.2, df = 1, 48, p = 0.05) and right lateral gray matter (F = 4.6, df = 1, 48, p = 0.04) OFC volumes compared to healthy controls, but this finding was not significant following statistical correction for multiple comparisons. No other OFC subregions showed a significant difference. The lack of OFC volume abnormalities in pediatric MDD patients suggests the abnormalities previously reported for adults may develop later in life as a result of neural cell loss.

  14. Spectro-temporal characterization of auditory neurons: redundant or necessary?

    NARCIS (Netherlands)

    Eggermont, J.J.; Aertsen, A.M.H.J.; Hermes, D.J.; Johannesma, P.I.M.

    1981-01-01

    For neurons in the auditory midbrain of the grass frog the use of a combined spectro-temporal characterization has been evaluated against the separate characterizations of frequency-sensitivity and temporal response properties. By factoring the joint density function of stimulus intensity, I(f, t),

  15. Noise adaptation in integrate-and fire neurons.

    Science.gov (United States)

    Rudd, M E; Brown, L G

    1997-07-01

    The statistical spiking response of an ensemble of identically prepared stochastic integrate-and-fire neurons to a rectangular input current plus gaussian white noise is analyzed. It is shown that, on average, integrate-and-fire neurons adapt to the root-mean-square noise level of their input. This phenomenon is referred to as noise adaptation. Noise adaptation is characterized by a decrease in the average neural firing rate and an accompanying decrease in the average value of the generator potential, both of which can be attributed to noise-induced resets of the generator potential mediated by the integrate-and-fire mechanism. A quantitative theory of noise adaptation in stochastic integrate-and-fire neurons is developed. It is shown that integrate-and-fire neurons, on average, produce transient spiking activity whenever there is an increase in the level of their input noise. This transient noise response is either reduced or eliminated over time, depending on the parameters of the model neuron. Analytical methods are used to prove that nonleaky integrate-and-fire neurons totally adapt to any constant input noise level, in the sense that their asymptotic spiking rates are independent of the magnitude of their input noise. For leaky integrate-and-fire neurons, the long-run noise adaptation is not total, but the response to noise is partially eliminated. Expressions for the probability density function of the generator potential and the first two moments of the potential distribution are derived for the particular case of a nonleaky neuron driven by gaussian white noise of mean zero and constant variance. The functional significance of noise adaptation for the performance of networks comprising integrate-and-fire neurons is discussed.

  16. Growth and atrophy of neurons labeled at their birth in a song nucleus of the zebra finch

    International Nuclear Information System (INIS)

    Konishi, M.; Akutagawa, E.

    1990-01-01

    The robust nucleus of the archistriatum (RA) is one of the forebrain nuclei that control song production in birds. In the zebra finch (Poephila guttata), this nucleus contains more and larger neurons in the male than in the female. A single injection of tritiated thymidine into the egg on the 6th or 7th day of incubation resulted in labeling of many RA neurons with tritium. The size of tritium-labeled neurons and the tissue volume containing them did not differ between the sexes at 15 days after hatching. In the adult brain, tritium-labeled neurons and the tissue volume containing them were much larger in the male than in the female. Also, tritium-labeled RA neurons were large in females which received an implant of estrogen immediately after hatching. The gender differences in the neuron size and nuclear volume of the zebra finch RA are, therefore, due not to the replacement of old neurons by new ones during development but to the growth and atrophy of neurons born before hatching. Similarly, the masculinizing effects of estrogen on the female RA are due not to neuronal replacement but to the prevention of atrophy and promotion of growth in preexisting neurons

  17. Parvalbumin+ Neurons and Npas1+ Neurons Are Distinct Neuron Classes in the Mouse External Globus Pallidus.

    Science.gov (United States)

    Hernández, Vivian M; Hegeman, Daniel J; Cui, Qiaoling; Kelver, Daniel A; Fiske, Michael P; Glajch, Kelly E; Pitt, Jason E; Huang, Tina Y; Justice, Nicholas J; Chan, C Savio

    2015-08-26

    Compelling evidence suggests that pathological activity of the external globus pallidus (GPe), a nucleus in the basal ganglia, contributes to the motor symptoms of a variety of movement disorders such as Parkinson's disease. Recent studies have challenged the idea that the GPe comprises a single, homogenous population of neurons that serves as a simple relay in the indirect pathway. However, we still lack a full understanding of the diversity of the neurons that make up the GPe. Specifically, a more precise classification scheme is needed to better describe the fundamental biology and function of different GPe neuron classes. To this end, we generated a novel multicistronic BAC (bacterial artificial chromosome) transgenic mouse line under the regulatory elements of the Npas1 gene. Using a combinatorial transgenic and immunohistochemical approach, we discovered that parvalbumin-expressing neurons and Npas1-expressing neurons in the GPe represent two nonoverlapping cell classes, amounting to 55% and 27% of the total GPe neuron population, respectively. These two genetically identified cell classes projected primarily to the subthalamic nucleus and to the striatum, respectively. Additionally, parvalbumin-expressing neurons and Npas1-expressing neurons were distinct in their autonomous and driven firing characteristics, their expression of intrinsic ion conductances, and their responsiveness to chronic 6-hydroxydopamine lesion. In summary, our data argue that parvalbumin-expressing neurons and Npas1-expressing neurons are two distinct functional classes of GPe neurons. This work revises our understanding of the GPe, and provides the foundation for future studies of its function and dysfunction. Until recently, the heterogeneity of the constituent neurons within the external globus pallidus (GPe) was not fully appreciated. We addressed this knowledge gap by discovering two principal GPe neuron classes, which were identified by their nonoverlapping expression of the

  18. Parvalbumin+ Neurons and Npas1+ Neurons Are Distinct Neuron Classes in the Mouse External Globus Pallidus

    Science.gov (United States)

    Hernández, Vivian M.; Hegeman, Daniel J.; Cui, Qiaoling; Kelver, Daniel A.; Fiske, Michael P.; Glajch, Kelly E.; Pitt, Jason E.; Huang, Tina Y.; Justice, Nicholas J.

    2015-01-01

    Compelling evidence suggests that pathological activity of the external globus pallidus (GPe), a nucleus in the basal ganglia, contributes to the motor symptoms of a variety of movement disorders such as Parkinson's disease. Recent studies have challenged the idea that the GPe comprises a single, homogenous population of neurons that serves as a simple relay in the indirect pathway. However, we still lack a full understanding of the diversity of the neurons that make up the GPe. Specifically, a more precise classification scheme is needed to better describe the fundamental biology and function of different GPe neuron classes. To this end, we generated a novel multicistronic BAC (bacterial artificial chromosome) transgenic mouse line under the regulatory elements of the Npas1 gene. Using a combinatorial transgenic and immunohistochemical approach, we discovered that parvalbumin-expressing neurons and Npas1-expressing neurons in the GPe represent two nonoverlapping cell classes, amounting to 55% and 27% of the total GPe neuron population, respectively. These two genetically identified cell classes projected primarily to the subthalamic nucleus and to the striatum, respectively. Additionally, parvalbumin-expressing neurons and Npas1-expressing neurons were distinct in their autonomous and driven firing characteristics, their expression of intrinsic ion conductances, and their responsiveness to chronic 6-hydroxydopamine lesion. In summary, our data argue that parvalbumin-expressing neurons and Npas1-expressing neurons are two distinct functional classes of GPe neurons. This work revises our understanding of the GPe, and provides the foundation for future studies of its function and dysfunction. SIGNIFICANCE STATEMENT Until recently, the heterogeneity of the constituent neurons within the external globus pallidus (GPe) was not fully appreciated. We addressed this knowledge gap by discovering two principal GPe neuron classes, which were identified by their nonoverlapping

  19. Metabolic reprogramming during neuronal differentiation.

    Science.gov (United States)

    Agostini, M; Romeo, F; Inoue, S; Niklison-Chirou, M V; Elia, A J; Dinsdale, D; Morone, N; Knight, R A; Mak, T W; Melino, G

    2016-09-01

    Newly generated neurons pass through a series of well-defined developmental stages, which allow them to integrate into existing neuronal circuits. After exit from the cell cycle, postmitotic neurons undergo neuronal migration, axonal elongation, axon pruning, dendrite morphogenesis and synaptic maturation and plasticity. Lack of a global metabolic analysis during early cortical neuronal development led us to explore the role of cellular metabolism and mitochondrial biology during ex vivo differentiation of primary cortical neurons. Unexpectedly, we observed a huge increase in mitochondrial biogenesis. Changes in mitochondrial mass, morphology and function were correlated with the upregulation of the master regulators of mitochondrial biogenesis, TFAM and PGC-1α. Concomitant with mitochondrial biogenesis, we observed an increase in glucose metabolism during neuronal differentiation, which was linked to an increase in glucose uptake and enhanced GLUT3 mRNA expression and platelet isoform of phosphofructokinase 1 (PFKp) protein expression. In addition, glutamate-glutamine metabolism was also increased during the differentiation of cortical neurons. We identified PI3K-Akt-mTOR signalling as a critical regulator role of energy metabolism in neurons. Selective pharmacological inhibition of these metabolic pathways indicate existence of metabolic checkpoint that need to be satisfied in order to allow neuronal differentiation.

  20. Elucidating the Neuronal Architecture of Olfactory Glomeruli in the Drosophila Antennal Lobe

    Directory of Open Access Journals (Sweden)

    Veit Grabe

    2016-09-01

    Full Text Available Olfactory glomeruli are morphologically conserved spherical compartments of the olfactory system, distinguishable solely by their chemosensory repertoire, anatomical position, and volume. Little is known, however, about their numerical neuronal composition. We therefore characterized their neuronal architecture and correlated these anatomical features with their functional properties in Drosophila melanogaster. We quantitatively mapped all olfactory sensory neurons (OSNs innervating each glomerulus, including sexually dimorphic distributions. Our data reveal the impact of OSN number on glomerular dimensions and demonstrate yet unknown sex-specific differences in several glomeruli. Moreover, we quantified uniglomerular projection neurons for each glomerulus, which unraveled a glomerulus-specific numerical innervation. Correlation between morphological features and functional specificity showed that glomeruli innervated by narrowly tuned OSNs seem to possess a larger number of projection neurons and are involved in less lateral processing than glomeruli targeted by broadly tuned OSNs. Our study demonstrates that the neuronal architecture of each glomerulus encoding crucial odors is unique.

  1. Protective effect of zinc against ischemic neuronal injury in a middle cerebral artery occlusion model.

    Science.gov (United States)

    Kitamura, Youji; Iida, Yasuhiko; Abe, Jun; Ueda, Masashi; Mifune, Masaki; Kasuya, Fumiyo; Ohta, Masayuki; Igarashi, Kazuo; Saito, Yutaka; Saji, Hideo

    2006-02-01

    In this study, we investigated the effect of vesicular zinc on ischemic neuronal injury. In cultured neurons, addition of a low concentration (under 100 microM) of zinc inhibited both glutamate-induced calcium influx and neuronal death. In contrast, a higher concentration (over 150 microM) of zinc decreased neuronal viability, although calcium influx was inhibited. These results indicate that zinc exhibits biphasic effects depending on its concentration. Furthermore, in cultured neurons, co-addition of glutamate and CaEDTA, which binds extra-cellular zinc, increased glutamate-induced calcium influx and aggravated the neurotoxicity of glutamate. In a rat transient middle cerebral artery occlusion (MCAO) model, the infarction volume, which is related to the neurotoxicity of glutamate, increased rapidly on the intracerebral ventricular injection of CaEDTA 30 min prior to occlusion. These results suggest that zinc released from synaptic vesicles may provide a protective effect against ischemic neuronal injury.

  2. Imitation, mirror neurons and autism

    OpenAIRE

    Williams, Justin H.G.; Whiten, Andrew; Suddendorf, Thomas; Perrett, David I.

    2001-01-01

    Various deficits in the cognitive functioning of people with autism have been documented in recent years but these provide only partial explanations for the condition. We focus instead on an imitative disturbance involving difficulties both in copying actions and in inhibiting more stereotyped mimicking, such as echolalia. A candidate for the neural basis of this disturbance may be found in a recently discovered class of neurons in frontal cortex, 'mirror neurons' (MNs). These neurons show ac...

  3. Does cerebellar neuronal integrity relate to cognitive ability?

    International Nuclear Information System (INIS)

    Rae, C.; Lee, M.; Dixon, R.M.; Blamire, A.; Thompson, C.; Styles, P.; Radda, G.K.; University of Sydney, NSW; Karmiloff-Smith, A.; Grant, J.

    1998-01-01

    Full text: Magnetic resonance spectroscopy (MRS) allows the non-invasive measurement of metabolite levels in the brain. One of these is N-acetylaspartate (NA), a molecule found solely in neurones, synthesised there by mitochondria. This compound can be considered as a marker of 1) neuronal density and 2) neuronal mitochondria function. We recently completed a joint MRS and neuropsychological investigation of Williams-Beuren syndrome (WBS), a rare (1/20,000) autosomal dominant disorder caused by a deletion which includes the elastin locus and LIM-kinase. The syndrome has an associated behavioural and cognitive profile which includes hyperactivity, hyperacusis and excessive sociability. Spatial skills are severely affected, while verbal skills are left relatively intact Our investigation showed loss of NA from the cerebellum in WBS compared with normal controls, with the subject population as a whole displaying a continuum of cerebellar NA concentration. Ability at cognitive tests, including the Weschler IQ scale and various verbal and spatial tests, was shown to correlate significantly and positively with the concentration of NA in the cerebellum. This finding can be interpreted in one of two ways: 1. Our sampling of cerebellar metabolite levels represents a 'global' sampling of total brain neuronal density and, as such, is independent of cerebellar integrity. 2. Cerebellar neuronal integrity is associated with performance at cognitive tests. If the latter interpretation is shown to be the case, it will have important implications for our current understanding of cerebellar function. Copyright (1998) Australian Neuroscience Society

  4. No postnatal doubling of number of neurons in human Broca's areas (Brodmann areas 44 and 45)? A stereological study.

    Science.gov (United States)

    Uylings, H B M; Malofeeva, L I; Bogolepova, I N; Jacobsen, A M; Amunts, K; Zilles, K

    2005-01-01

    In this study we explored whether a postnatal doubling of the total number of neurons occurs in the human Brodmann areas 44 and 45 (Broca's area). We describe the most recent error prediction formulae and their application for the modern stereological estimators for volume and number of neurons. We estimated the number of neurons in 3D optical disector probes systematically random sampled throughout the entire Brodmann areas (BA) 44 and 45 in developing and young adult cases. In the relatively small number of male and female cases studied no substantial postnatal increase in total number of neurons occurred in areas 44 and 45; the volume of these areas reached adult values around 7 years. In addition, we did find indications that a shift from a right-over-left to a left-over-right asymmetry may occur in the volume of BA 45 during postnatal development. No major asymmetry in total number of neurons in BA 44 and 45 was detected.

  5. The biophysics of neuronal growth

    International Nuclear Information System (INIS)

    Franze, Kristian; Guck, Jochen

    2010-01-01

    For a long time, neuroscience has focused on biochemical, molecular biological and electrophysiological aspects of neuronal physiology and pathology. However, there is a growing body of evidence indicating the importance of physical stimuli for neuronal growth and development. In this review we briefly summarize the historical background of neurobiophysics and give an overview over the current understanding of neuronal growth from a physics perspective. We show how biophysics has so far contributed to a better understanding of neuronal growth and discuss current inconsistencies. Finally, we speculate how biophysics may contribute to the successful treatment of lesions to the central nervous system, which have been considered incurable until very recently.

  6. Dissociation between vascular endothelial growth factor receptor-2 and blood vessel density in the caudate nucleus after chronic hydrocephalus.

    Science.gov (United States)

    Deshpande, Abhishek; Dombrowski, Stephen M; Leichliter, Anna; Krajcir, Natalie; Zingales, Nicholas; Inoue, Masahiro; Schenk, Soren; Fukamachi, Kiyotaka; Luciano, Mark G

    2009-11-01

    Chronic hydrocephalus (CH) is characterized by the presence of ventricular enlargement, decreased cerebral blood flow (CBF), and brain tissue oxygen delivery. Although the underlying pathophysiological role of vascular endothelial growth factor (VEGF) is not clear, ischemic-hypoxic events in CH are known to trigger its release. Previously, we have shown increased VEGF receptor-2 (VEGFR-2) and blood vessel density (BVd) in the hippocampus after CH. We investigated changes in neuronal and glial VEGFR-2 density and BVd in the caudate nucleus in an experimental model of CH. Animals with CH were divided into short term (ST, 2 to 4 weeks) and long term (LT, 12 to 16 weeks) and were compared with surgical controls (SCs, 12 to 16 weeks). The cellular and BVds were estimated using immunohistochemical and stereological counting methods. Overall, percentage (%)VEGFR-2 neurons were approximately two times greater in CH (ST, LT) than in SC. By comparison, glial cell %VEGFR-2 was greater by 10% to 17% in ST and 4% to 11% lower in LT compared with that in SC. Blood vessel density was significantly lower in CH than in SC in the superficial caudate. Changes in cerebrospinal fluid ventricular volume and pressure, as well as in CBF did not correlate with either VEGFR-2 or BVd. These observed findings suggest that destructive forces may outweigh angiogenic forces and possibly show a disassociation between VEGFR-2 and BV expressions.

  7. Spindle neurons of the human anterior cingulate cortex

    Science.gov (United States)

    Nimchinsky, E. A.; Vogt, B. A.; Morrison, J. H.; Hof, P. R.; Bloom, F. E. (Principal Investigator)

    1995-01-01

    The human anterior cingulate cortex is distinguished by the presence of an unusual cell type, a large spindle neuron in layer Vb. This cell has been noted numerous times in the historical literature but has not been studied with modern neuroanatomic techniques. For instance, details regarding the neuronal class to which these cells belong and regarding their precise distribution along both ventrodorsal and anteroposterior axes of the cingulate gyrus are still lacking. In the present study, morphological features and the anatomic distribution of this cell type were studied using computer-assisted mapping and immunocytochemical techniques. Spindle neurons are restricted to the subfields of the anterior cingulate cortex (Brodmann's area 24), exhibiting a greater density in anterior portions of this area than in posterior portions, and tapering off in the transition zone between anterior and posterior cingulate cortex. Furthermore, a majority of the spindle cells at any level is located in subarea 24b on the gyral surface. Immunocytochemical analysis revealed that the neurofilament protein triple was present in a large percentage of these neurons and that they did not contain calcium-binding proteins. Injections of the carbocyanine dye DiI into the cingulum bundle revealed that these cells are projection neurons. Finally, spindle cells were consistently affected in Alzheimer's disease cases, with an overall loss of about 60%. Taken together, these observations indicate that the spindle cells of the human cingulate cortex represent a morphological subpopulation of pyramidal neurons whose restricted distribution may be associated with functionally distinct areas.

  8. Pure state consciousness and its local reduction to neuronal space

    Science.gov (United States)

    Duggins, A. J.

    2013-01-01

    The single neuronal state can be represented as a vector in a complex space, spanned by an orthonormal basis of integer spike counts. In this model a scalar element of experience is associated with the instantaneous firing rate of a single sensory neuron over repeated stimulus presentations. Here the model is extended to composite neural systems that are tensor products of single neuronal vector spaces. Depiction of the mental state as a vector on this tensor product space is intended to capture the unity of consciousness. The density operator is introduced as its local reduction to the single neuron level, from which the firing rate can again be derived as the objective correlate of a subjective element. However, the relational structure of perceptual experience only emerges when the non-local mental state is considered. A metric of phenomenal proximity between neuronal elements of experience is proposed, based on the cross-correlation function of neurophysiology, but constrained by the association of theoretical extremes of correlation/anticorrelation in inseparable 2-neuron states with identical and opponent elements respectively.

  9. Complete and phase synchronization in a heterogeneous small-world neuronal network

    International Nuclear Information System (INIS)

    Fang, Han; Qi-Shao, Lu; Quan-Bao, Ji; Marian, Wiercigroch

    2009-01-01

    Synchronous firing of neurons is thought to be important for information communication in neuronal networks. This paper investigates the complete and phase synchronization in a heterogeneous small-world chaotic Hindmarsh–Rose neuronal network. The effects of various network parameters on synchronization behaviour are discussed with some biological explanations. Complete synchronization of small-world neuronal networks is studied theoretically by the master stability function method. It is shown that the coupling strength necessary for complete or phase synchronization decreases with the neuron number, the node degree and the connection density are increased. The effect of heterogeneity of neuronal networks is also considered and it is found that the network heterogeneity has an adverse effect on synchrony. (general)

  10. α-Synuclein fibril-induced paradoxical structural and functional defects in hippocampal neurons.

    Science.gov (United States)

    Froula, Jessica M; Henderson, Benjamin W; Gonzalez, Jose Carlos; Vaden, Jada H; Mclean, John W; Wu, Yumei; Banumurthy, Gokulakrishna; Overstreet-Wadiche, Linda; Herskowitz, Jeremy H; Volpicelli-Daley, Laura A

    2018-05-01

    Neuronal inclusions composed of α-synuclein (α-syn) characterize Parkinson's Disease (PD) and Dementia with Lewy bodies (DLB). Cognitive dysfunction defines DLB, and up to 80% of PD patients develop dementia. α-Syn inclusions are abundant in the hippocampus, yet functional consequences are unclear. To determine if pathologic α-syn causes neuronal defects, we induced endogenous α-syn to form inclusions resembling those found in diseased brains by treating hippocampal neurons with α-syn fibrils. At seven days after adding fibrils, α-syn inclusions are abundant in axons, but there is no cell death at this time point, allowing us to assess for potential alterations in neuronal function that are not caused by neuron death. We found that exposure of neurons to fibrils caused a significant reduction in mushroom spine densities, adding to the growing body of literature showing that altered spine morphology is a major pathologic phenotype in synucleinopathies. The reduction in spine densities occurred only in wild type neurons and not in neurons from α-syn knockout mice, suggesting that the changes in spine morphology result from fibril-induced corruption of endogenously expressed α-syn. Paradoxically, reduced postsynaptic spine density was accompanied by increased frequency of miniature excitatory postsynaptic currents (EPSCs) and presynaptic docked vesicles, suggesting enhanced presynaptic function. Action-potential dependent activity was unchanged, suggesting compensatory mechanisms responding to synaptic defects. Although activity at the level of the synapse was unchanged, neurons exposed to α-syn fibrils, showed reduced frequency and amplitudes of spontaneous Ca 2+ transients. These findings open areas of research to determine the mechanisms that alter neuronal function in brain regions critical for cognition at time points before neuron death.

  11. Cell swelling and volume regulation

    DEFF Research Database (Denmark)

    Hoffmann, Else Kay

    1992-01-01

    The extracellular space in the brain is typically 20% of the tissue volume and is reduced to at least half its size under conditions of neural insult. Whether there is a minimum size to the extracellular space was discussed. A general model for cell volume regulation was presented, followed...... by a discussion on how many of the generally involved mechanisms are identified in neural cells and (or) in astrocytes. There seems to be clear evidence suggesting that parallel K+ and Cl- channels mediate regulatory volume decrease in primary cultures of astrocytes, and a stretch-activated cation channel has...... been reported. The role of the different channels was discussed. A taurine leak pathway is clearly activated after cell swelling both in astrocytes and in neurones. The relations between the effect of glutamate and cell swelling were discussed. Discussion on the clearance of potassium from...

  12. Neurons in the white matter of the adult human neocortex

    Directory of Open Access Journals (Sweden)

    M Luisa Suarez-Sola

    2009-06-01

    Full Text Available The white matter (WM of the adult human neocortex contains the so-called “interstitial neurons”. They are most numerous in the superficial WM underlying the cortical gyri, and decrease in density toward the deep WM. They are morphologically heterogeneous. A subgroup of interstitial neurons display pyramidal-cell like morphologies, characterized by a polarized dendritic tree with a dominant apical dendrite, and covered with a variable number of dendritic spines. In addition, a large contingent of interstitial neurons can be classified as interneurons based on their neurochemical profile as well as on morphological criteria. WM- interneurons have multipolar or bipolar shapes and express GABA and a variety of other neuronal markers, such as calbindin and calretinin, the extracellular matrix protein reelin, or neuropeptide Y, somatostatin, and nitric oxide synthase. The heterogeneity of interstitial neurons may be relevant for the pathogenesis of Alzheimer disease and schizophrenia. Interstitial neurons are most prominent in human brain, and only rudimentary in the brain of non-primate mammals. These evolutionary differences have precluded adequate experimental work on this cell population, which is usually considered as a relict of the subplate, a transient compartment proper of development and without a known function in the adult brain. The primate-specific prominence of the subplate in late fetal stages points to an important role in the establishment of interstitial neurons. Neurons in the adult WM may be actively involved in coordinating inter-areal connectivity and regulation of blood flow. Further studies in primates will be needed to elucidate the developmental history, adult components and activities of this large neuronal system.

  13. Characterization of neurons in the cortical white matter in human temporal lobe epilepsy.

    Science.gov (United States)

    Richter, Zsófia; Janszky, József; Sétáló, György; Horváth, Réka; Horváth, Zsolt; Dóczi, Tamás; Seress, László; Ábrahám, Hajnalka

    2016-10-01

    The aim of the present work was to characterize neurons in the archi- and neocortical white matter, and to investigate their distribution in mesial temporal sclerosis. Immunohistochemistry and quantification of neurons were performed on surgically resected tissue sections of patients with therapy-resistant temporal lobe epilepsy. Temporal lobe tissues of patients with tumor but without epilepsy and that from autopsy were used as controls. Neurons were identified with immunohistochemistry using antibodies against NeuN, calcium-binding proteins, transcription factor Tbr1 and neurofilaments. We found significantly higher density of neurons in the archi- and neocortical white matter of patients with temporal lobe epilepsy than in that of controls. Based on their morphology and neurochemical content, both excitatory and inhibitory cells were present among these neurons. A subset of neurons in the white matter was Tbr-1-immunoreactive and these neurons coexpressed NeuN and neurofilament marker SMI311R. No colocalization of Tbr1 was observed with the inhibitory neuronal markers, calcium-binding proteins. We suggest that a large population of white matter neurons comprises remnants of the subplate. Furthermore, we propose that a subset of white matter neurons was arrested during migration, highlighting the role of cortical maldevelopment in epilepsy associated with mesial temporal sclerosis. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

  14. Gonadotropin-Releasing Hormone Modulates Vomeronasal Neuron Response to Male Salamander Pheromone

    Directory of Open Access Journals (Sweden)

    Celeste R. Wirsig-Wiechmann

    2012-01-01

    Full Text Available Electrophysiological studies have shown that gonadotropin-releasing hormone (GnRH modifies chemosensory neurons responses to odors. We have previously demonstrated that male Plethodon shermani pheromone stimulates vomeronasal neurons in the female conspecific. In the present study we used agmatine uptake as a relative measure of the effects of GnRH on this pheromone-induced neural activation of vomeronasal neurons. Whole male pheromone extract containing 3 millimolar agmatine with or without 10 micromolar GnRH was applied to the nasolabial groove of female salamanders for 45 minutes. Immunocytochemical procedures were conducted to visualize and quantify relative agmatine uptake as measured by labeling density of activated vomeronasal neurons. The relative number of labeled neurons did not differ between the two groups: pheromone alone or pheromone-GnRH. However, vomeronasal neurons exposed to pheromone-GnRH collectively demonstrated higher labeling intensity, as a percentage above background (75% as compared with neurons exposed to pheromone alone (63%, P < 0.018. Since the labeling intensity of agmatine within neurons signifies the relative activity levels of the neurons, these results suggest that GnRH increases the response of female vomeronasal neurons to male pheromone.

  15. Individualized volume CT dose index determined by cross-sectional area and mean density of the body to achieve uniform image noise of contrast-enhanced pediatric chest CT obtained at variable kV levels and with combined tube current modulation

    International Nuclear Information System (INIS)

    Goo, Hyun Woo

    2011-01-01

    A practical body-size adaptive protocol providing uniform image noise at various kV levels is not available for pediatric CT. To develop a practical contrast-enhanced pediatric chest CT protocol providing uniform image noise by using an individualized volume CT dose index (CTDIvol) determined by the cross-sectional area and density of the body at variable kV levels and with combined tube current modulation. A total of 137 patients (mean age, 7.6 years) underwent contrast-enhanced pediatric chest CT based on body weight. From the CTDIvol, image noise, and area and mean density of the cross-section at the lung base in the weight-based group, the best fit equation was estimated with a very high correlation coefficient (γ 2 = 0.86, P 2 vs. 326.3 ± 124.8 cm 2 ), mean density (-212.9 ± 53.1 HU vs. -221.1 ± 56.3 HU), and image noise (13.8 ± 2.3 vs. 13.6 ± 1.7 HU) between the weight-based and the CTDIvol groups (P > 0.05). Contrast-enhanced pediatric chest CT with the CTDIvol determined individually by the cross-sectional area and density of the body provides more uniform noise and better dose adaptation to body habitus than does weight-based CT at variable kV levels and with combined tube current modulation. (orig.)

  16. The Neuronal Ceroid-Lipofuscinoses

    Science.gov (United States)

    Bennett, Michael J.; Rakheja, Dinesh

    2013-01-01

    The neuronal ceroid-lipofuscinoses (NCL's, Batten disease) represent a group of severe neurodegenerative diseases, which mostly present in childhood. The phenotypes are similar and include visual loss, seizures, loss of motor and cognitive function, and early death. At autopsy, there is massive neuronal loss with characteristic storage in…

  17. The straintronic spin-neuron

    International Nuclear Information System (INIS)

    Biswas, Ayan K; Bandyopadhyay, Supriyo; Atulasimha, Jayasimha

    2015-01-01

    In artificial neural networks, neurons are usually implemented with highly dissipative CMOS-based operational amplifiers. A more energy-efficient implementation is a ‘spin-neuron’ realized with a magneto-tunneling junction (MTJ) that is switched with a spin-polarized current (representing weighted sum of input currents) that either delivers a spin transfer torque or induces domain wall motion in the soft layer of the MTJ to mimic neuron firing. Here, we propose and analyze a different type of spin-neuron in which the soft layer of the MTJ is switched with mechanical strain generated by a voltage (representing weighted sum of input voltages) and term it straintronic spin-neuron. It dissipates orders of magnitude less energy in threshold operations than the traditional current-driven spin neuron at 0 K temperature and may even be faster. We have also studied the room-temperature firing behaviors of both types of spin neurons and find that thermal noise degrades the performance of both types, but the current-driven type is degraded much more than the straintronic type if both are optimized for maximum energy-efficiency. On the other hand, if both are designed to have the same level of thermal degradation, then the current-driven version will dissipate orders of magnitude more energy than the straintronic version. Thus, the straintronic spin-neuron is superior to current-driven spin neurons. (paper)

  18. Energy density of marine pelagic fish eggs

    DEFF Research Database (Denmark)

    Riis-Vestergaard, J.

    2002-01-01

    Analysis of the literature on pelagic fish eggs enabled generalizations to be made of their energy densities, because the property of being buoyant in sea water appears to constrain the proximate composition of the eggs and thus to minimize interspecific variation. An energy density of 1.34 J mul......(-1) of total egg volume is derived for most species spawning eggs without visible oil globules. The energy density of eggs with oil globules is predicted by (σ) over cap = 1.34 + 40.61 x (J mul(-1)) where x is the fractional volume of the oil globule. (C) 2002 The Fisheries Society of the British...

  19. Simultaneous viscosity and density measurement of small volumes of liquids using a vibrating microcantilever† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c6an02674e Click here for additional data file.

    Science.gov (United States)

    Payam, A. F.; Trewby, W.

    2017-01-01

    Many industrial and technological applications require precise determination of the viscosity and density of liquids. Such measurements can be time consuming and often require sampling substantial amounts of the liquid. These problems can partly be overcome with the use of microcantilevers but most existing methods depend on the specific geometry and properties of the cantilever, which renders simple, accurate measurement difficult. Here we present a new approach able to simultaneously quantify both the density and the viscosity of microliters of liquids. The method, based solely on the measurement of two characteristic frequencies of an immersed microcantilever, is completely independent of the choice of a cantilever. We derive analytical expressions for the liquid's density and viscosity and validate our approach with several simple liquids and different cantilevers. Application of our model to non-Newtonian fluids shows that the calculated viscosities are remarkably robust when compared to measurements obtained from a standard rheometer. However, the results become increasingly dependent on the cantilever geometry as the frequency-dependent nature of the liquid's viscosity becomes more significant. PMID:28352874

  20. FOREWORD: Special issue on density

    Science.gov (United States)

    Fujii, Kenichi

    2004-04-01

    This special issue on density was undertaken to provide readers with an overview of the present state of the density standards for solids, liquids and gases, as well as the technologies developed for measuring density. This issue also includes topics on the refractive index of gases and on techniques used for calibrating hydrometers so that almost all areas concerned with density standards are covered in four review articles and seven original articles, most of which describe current research being conducted at national metrology institutes (NMIs). A review article was invited from the Ruhr-Universität Bochum to highlight research on the magnetic suspension densimeters. In metrology, the determinations of the volume of a weight and the density of air are of primary importance in establishing a mass standard because the effect of the buoyancy force of air acting on the weight must be known accurately to determine the mass of the weight. A density standard has therefore been developed at many NMIs with a close relation to the mass standard. Hydrostatic weighing is widely used to measure the volume of a solid. The most conventional hydrostatic weighing method uses water as a primary density standard for measuring the volume of a solid. A brief history of the determination of the density of water is therefore given in a review article, as well as a recommended value for the density of water with a specified isotopic abundance. The most modern technique for hydrostatic weighing uses a solid density standard instead of water. For this purpose, optical interferometers for measuring the diameters of silicon spheres have been developed to convert the length standard into the volume standard with a small uncertainty. A review article is therefore dedicated to describing the state-of-the-art optical interferometers developed for silicon spheres. Relative combined standard uncertainties of several parts in 108 have been achieved today for measuring the volume and density of

  1. Neuronal discrimination capacity

    International Nuclear Information System (INIS)

    Deng Yingchun; Williams, Peter; Feng Jianfeng; Liu Feng

    2003-01-01

    We explore neuronal mechanisms of discriminating between masked signals. It is found that when the correlation between input signals is zero, the output signals are separable if and only if input signals are separable. With positively (negatively) correlated signals, the output signals are separable (mixed) even when input signals are mixed (separable). Exact values of discrimination capacity are obtained for two most interesting cases: the exactly balanced inhibitory and excitatory input case and the uncorrelated input case. Interestingly, the discrimination capacity obtained in these cases is independent of model parameters, input distribution and is universal. Our results also suggest a functional role of inhibitory inputs and correlated inputs or, more generally, the large variability of efferent spike trains observed in in vivo experiments: the larger the variability of efferent spike trains, the easier it is to discriminate between masked input signals

  2. Neuronal discrimination capacity

    Energy Technology Data Exchange (ETDEWEB)

    Deng Yingchun [Department of Mathematics, Hunan Normal University 410081, Changsha (China); COGS, University of Sussex at Brighton, BN1 9QH (United Kingdom); Williams, Peter; Feng Jianfeng [COGS, University of Sussex at Brighton, BN1 9QH (United Kingdom); Liu Feng [COGS, University of Sussex at Brighton, BN1 9QH (United Kingdom); Physics Department, Nanjing University (China)

    2003-12-19

    We explore neuronal mechanisms of discriminating between masked signals. It is found that when the correlation between input signals is zero, the output signals are separable if and only if input signals are separable. With positively (negatively) correlated signals, the output signals are separable (mixed) even when input signals are mixed (separable). Exact values of discrimination capacity are obtained for two most interesting cases: the exactly balanced inhibitory and excitatory input case and the uncorrelated input case. Interestingly, the discrimination capacity obtained in these cases is independent of model parameters, input distribution and is universal. Our results also suggest a functional role of inhibitory inputs and correlated inputs or, more generally, the large variability of efferent spike trains observed in in vivo experiments: the larger the variability of efferent spike trains, the easier it is to discriminate between masked input signals.

  3. Visualization of Sensory Neurons and Their Projections in an Upper Motor Neuron Reporter Line.

    Science.gov (United States)

    Genç, Barış; Lagrimas, Amiko Krisa Bunag; Kuru, Pınar; Hess, Robert; Tu, Michael William; Menichella, Daniela Maria; Miller, Richard J; Paller, Amy S; Özdinler, P Hande

    2015-01-01

    Visualization of peripheral nervous system axons and cell bodies is important to understand their development, target recognition, and integration into complex circuitries. Numerous studies have used protein gene product (PGP) 9.5 [a.k.a. ubiquitin carboxy-terminal hydrolase L1 (UCHL1)] expression as a marker to label sensory neurons and their axons. Enhanced green fluorescent protein (eGFP) expression, under the control of UCHL1 promoter, is stable and long lasting in the UCHL1-eGFP reporter line. In addition to the genetic labeling of corticospinal motor neurons in the motor cortex and degeneration-resistant spinal motor neurons in the spinal cord, here we report that neurons of the peripheral nervous system are also fluorescently labeled in the UCHL1-eGFP reporter line. eGFP expression is turned on at embryonic ages and lasts through adulthood, allowing detailed studies of cell bodies, axons and target innervation patterns of all sensory neurons in vivo. In addition, visualization of both the sensory and the motor neurons in the same animal offers many advantages. In this report, we used UCHL1-eGFP reporter line in two different disease paradigms: diabetes and motor neuron disease. eGFP expression in sensory axons helped determine changes in epidermal nerve fiber density in a high-fat diet induced diabetes model. Our findings corroborate previous studies, and suggest that more than five months is required for significant skin denervation. Crossing UCHL1-eGFP with hSOD1G93A mice generated hSOD1G93A-UeGFP reporter line of amyotrophic lateral sclerosis, and revealed sensory nervous system defects, especially towards disease end-stage. Our studies not only emphasize the complexity of the disease in ALS, but also reveal that UCHL1-eGFP reporter line would be a valuable tool to visualize and study various aspects of sensory nervous system development and degeneration in the context of numerous diseases.

  4. Orexin neurons receive glycinergic innervations.

    Directory of Open Access Journals (Sweden)

    Mari Hondo

    Full Text Available Glycine, a nonessential amino-acid that acts as an inhibitory neurotransmitter in the central nervous system, is currently used as a dietary supplement to improve the quality of sleep, but its mechanism of action is poorly understood. We confirmed the effects of glycine on sleep/wakefulness behavior in mice when administered peripherally. Glycine administration increased non-rapid eye movement (NREM sleep time and decreased the amount and mean episode duration of wakefulness when administered in the dark period. Since peripheral administration of glycine induced fragmentation of sleep/wakefulness states, which is a characteristic of orexin deficiency, we examined the effects of glycine on orexin neurons. The number of Fos-positive orexin neurons markedly decreased after intraperitoneal administration of glycine to mice. To examine whether glycine acts directly on orexin neurons, we examined the effects of glycine on orexin neurons by patch-clamp electrophysiology. Glycine directly induced hyperpolarization and cessation of firing of orexin neurons. These responses were inhibited by a specific glycine receptor antagonist, strychnine. Triple-labeling immunofluorescent analysis showed close apposition of glycine transporter 2 (GlyT2-immunoreactive glycinergic fibers onto orexin-immunoreactive neurons. Immunoelectron microscopic analysis revealed that GlyT2-immunoreactive terminals made symmetrical synaptic contacts with somata and dendrites of orexin neurons. Double-labeling immunoelectron microscopy demonstrated that glycine receptor alpha subunits were localized in the postsynaptic membrane of symmetrical inhibitory synapses on orexin neurons. Considering the importance of glycinergic regulation during REM sleep, our observations suggest that glycine injection might affect the activity of orexin neurons, and that glycinergic inhibition of orexin neurons might play a role in physiological sleep regulation.

  5. Densities and apparent molar volumes of atmospherically important electrolyte solutions. 1. The solutes H2SO4, HNO3, HCl, Na2SO4, NaNO3, NaCl, (NH4)2SO4, NH4NO3, and NH4Cl from 0 to 50 °C, including extrapolations to very low temperature and to the pure liquid state, and NaHSO4, NaOH, and NH3 at 25 °C.

    Science.gov (United States)

    Clegg, S L; Wexler, A S

    2011-04-21

    Calculations of the size and density of atmospheric aerosols are complicated by the fact that they can exist at concentrations highly supersaturated with respect to dissolved salts and supercooled with respect to ice. Densities and apparent molar volumes of solutes in aqueous solutions containing the solutes H(2)SO(4), HNO(3), HCl, Na(2)SO(4), NaNO(3), NaCl, (NH(4))(2)SO(4), NH(4)NO(3), and NH(4)Cl have been critically evaluated and represented using fitted equations from 0 to 50 °C or greater and from infinite dilution to concentrations saturated or supersaturated with respect to the dissolved salts. Using extrapolated densities of high-temperature solutions and melts, the relationship between density and concentration is extended to the hypothetical pure liquid solutes. Above a given reference concentration of a few mol kg(-1), it is observed that density increases almost linearly with decreasing temperature, and comparisons with available data below 0 °C suggest that the fitted equations for density can be extrapolated to very low temperatures. As concentration is decreased below the reference concentration, the variation of density with temperature tends to that of water (which decreases as temperature is reduced below 3.98 °C). In this region below the reference concentration, and below 0 °C, densities are calculated using extrapolated apparent molar volumes which are constrained to agree at the reference concentrations with an equation for the directly fitted density. Calculated volume properties agree well with available data at low temperatures, for both concentrated and dilute solutions. Comparisons are made with literature data for temperatures of maximum density. Apparent molar volumes at infinite dilution are consistent, on a single ion basis, to better than ±0.1 cm(3) mol(-1) from 0 to 50 °C. Volume properties of aqueous NaHSO(4), NaOH, and NH(3) have also been evaluated, at 25 °C only. In part 2 of this work (ref 1 ) an ion interaction (Pitzer

  6. Brain scaling in mammalian evolution as a consequence of concerted and mosaic changes in numbers of neurons and average neuronal cell size

    Directory of Open Access Journals (Sweden)

    Suzana eHerculano-Houzel

    2014-08-01

    Full Text Available Enough species have now been subject to systematic quantitative analysis of the relationship between the morphology and cellular composition of their brain that patterns begin to emerge and shed light on the evolutionary path that led to mammalian brain diversity. Based on an analysis of the shared and clade-specific characteristics of 41 modern mammalian species in 6 clades, and in light of the phylogenetic relationships among them, here we propose that ancestral mammal brains were composed and scaled in their cellular composition like modern afrotherian and glire brains: with an addition of neurons that is accompanied by a decrease in neuronal density and very little modification in glial cell density, implying a significant increase in average neuronal cell size in larger brains, and the allocation of approximately 2 neurons in the cerebral cortex and 8 neurons in the cerebellum for every neuron allocated to the rest of brain. We also propose that in some clades the scaling of different brain structures has diverged away from the common ancestral layout through clade-specific (or clade-defining changes in how average neuronal cell mass relates to numbers of neurons in each structure, and how numbers of neurons are differentially allocated to each structure relative to the number of neurons in the rest of brain. Thus, the evolutionary expansion of mammalian brains has involved both concerted and mosaic patterns of scaling across structures. This is, to our knowledge, the first mechanistic model that explains the generation of brains large and small in mammalian evolution, and it opens up new horizons for seeking the cellular pathways and genes involved in brain evolution.

  7. A Virtual Reality Visualization Tool for Neuron Tracing.

    Science.gov (United States)

    Usher, Will; Klacansky, Pavol; Federer, Frederick; Bremer, Peer-Timo; Knoll, Aaron; Yarch, Jeff; Angelucci, Alessandra; Pascucci, Valerio

    2018-01-01

    Tracing neurons in large-scale microscopy data is crucial to establishing a wiring diagram of the brain, which is needed to understand how neural circuits in the brain process information and generate behavior. Automatic techniques often fail for large and complex datasets, and connectomics researchers may spend weeks or months manually tracing neurons using 2D image stacks. We present a design study of a new virtual reality (VR) system, developed in collaboration with trained neuroanatomists, to trace neurons in microscope scans of the visual cortex of primates. We hypothesize that using consumer-grade VR technology to interact with neurons directly in 3D will help neuroscientists better resolve complex cases and enable them to trace neurons faster and with less physical and mental strain. We discuss both the design process and technical challenges in developing an interactive system to navigate and manipulate terabyte-sized image volumes in VR. Using a number of different datasets, we demonstrate that, compared to widely used commercial software, consumer-grade VR presents a promising alternative for scientists.

  8. Systematic Three-Dimensional Coculture Rapidly Recapitulates Interactions between Human Neurons and Astrocytes

    Directory of Open Access Journals (Sweden)

    Robert Krencik

    2017-12-01

    Full Text Available Summary: Human astrocytes network with neurons in dynamic ways that are still poorly defined. Our ability to model this relationship is hampered by the lack of relevant and convenient tools to recapitulate this complex interaction. To address this barrier, we have devised efficient coculture systems utilizing 3D organoid-like spheres, termed asteroids, containing pre-differentiated human pluripotent stem cell (hPSC-derived astrocytes (hAstros combined with neurons generated from hPSC-derived neural stem cells (hNeurons or directly induced via Neurogenin 2 overexpression (iNeurons. Our systematic methods rapidly produce structurally complex hAstros and synapses in high-density coculture with iNeurons in precise numbers, allowing for improved studies of neural circuit function, disease modeling, and drug screening. We conclude that these bioengineered neural circuit model systems are reliable and scalable tools to accurately study aspects of human astrocyte-neuron functional properties while being easily accessible for cell-type-specific manipulations and observations. : In this article, Krencik and colleagues show that high-density cocultures of pre-differentiated human astrocytes with induced neurons, from pluripotent stem cells, elicit mature characteristics by 3–5 weeks. This provides a faster and more defined alternative method to organoid cultures for investigating human neural circuit function. Keywords: human pluripotent stem cells, neurons, astrocytes, synapses, coculture, three-dimensional spheres, organoids, disease modeling

  9. Generalized Freud's equation and level densities with polynomial

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 81; Issue 2. Generalized Freud's equation and level densities with polynomial potential. Akshat Boobna Saugata Ghosh. Research Articles Volume 81 ... Keywords. Orthogonal polynomial; Freud's equation; Dyson–Mehta method; methods of resolvents; level density.

  10. Pathogenesis of motor neuron disease

    Institute of Scientific and Technical Information of China (English)

    Xuefei Wang

    2006-01-01

    OBJECTIVE: To summarize and analyze the factors and theories related to the attack of motor neuron disease, and comprehensively investigate the pathogenesis of motor neuron disease.DATA SOURCES: A search of Pubmed database was undertaken to identify articles about motor neuron disease published in English from January 1994 to June 2006 by using the keywords of "neurodegenerative diseases". Other literatures were collected by retrieving specific journals and articles.STUDY SELECTION: The data were checked primarily, articles related to the pathogenesis of motor neuron disease were involved, and those obviously irrelated to the articles were excluded.DATA EXTRACTION: Totally 54 articles were collected, 30 of them were involved, and the other 24 were excluded.DATA SYNTHESIS: The pathogenesis of motor neuron disease has multiple factors, and the present related theories included free radical oxidation, excitotoxicity, genetic and immune factors, lack of neurotrophic factor,injury of neurofilament, etc. The studies mainly come from transgenic animal models, cell culture in vitro and patients with familial motor neuron disease, but there are still many restrictions and disadvantages.CONCLUSION: It is necessary to try to find whether there is internal association among different mechanisms,comprehensively investigate the pathogenesis of motor neuron diseases, in order to provide reliable evidence for the clinical treatment.

  11. Astrocyte-neuronal interactions in epileptogenesis.

    Science.gov (United States)

    Hadera, Mussie Ghezu; Eloqayli, Haytham; Jaradat, Saied; Nehlig, Astrid; Sonnewald, Ursula

    2015-07-01

    Pentylenetetrazol, kainic acid, or pilocarpine can be used to induce seizures in animal models of epilepsy. The present Review describes disturbances in astrocyte-neuron interactions in the acute, latent, and chronic phases analyzed by magnetic resonance spectroscopy of brain tissue extracts from rats injected with [1-(13)C]glucose and [1,2-(13)C]acetate. The most consistent change after onset of seizures was the decrease in (13)C labeling of glutamate (GLU) from [1-(13) C]glucose regardless of brain area, severity, or duration of the period with seizures and toxin used. In most cases this decrease was accompanied by a reduction in glutamine (GLN) labeling from [1-(13)C]glucose, presumably as a direct consequence of the reduction in labeling of GLU and the GLU-GLN cycle. Amounts of GLN were never changed. Reduction in the content of N-acetyl aspartate (NAA) was first detectable some time after status epilepticus but before the occurrence of spontaneous seizures. This decrease can be an indication of neuronal death and/or mitochondrial impairment and might indicate beginning gliosis. It is known that gliosis occurs in the chronic phase of temporal lobe epilepsy in hippocampus, but astrocyte metabolism appears normal in this phase, indicating that the gliotic astrocytes have a somewhat reduced metabolism per volume. A decrease in (13)C labeling of GLU from [1-(13)C]glucose is a very sensitive measure for the onset of epileptogenesis, whereas reduction of NAA is first detectable later. In the chronic phases of the hippocampal formation, astrocyte metabolism is upregulated given that the number of neurons is reduced. © 2015 Wiley Periodicals, Inc.

  12. Simulating synchronization in neuronal networks

    Science.gov (United States)

    Fink, Christian G.

    2016-06-01

    We discuss several techniques used in simulating neuronal networks by exploring how a network's connectivity structure affects its propensity for synchronous spiking. Network connectivity is generated using the Watts-Strogatz small-world algorithm, and two key measures of network structure are described. These measures quantify structural characteristics that influence collective neuronal spiking, which is simulated using the leaky integrate-and-fire model. Simulations show that adding a small number of random connections to an otherwise lattice-like connectivity structure leads to a dramatic increase in neuronal synchronization.

  13. Glial tumors with neuronal differentiation.

    Science.gov (United States)

    Park, Chul-Kee; Phi, Ji Hoon; Park, Sung-Hye

    2015-01-01

    Immunohistochemical studies for neuronal differentiation in glial tumors revealed subsets of tumors having both characteristics of glial and neuronal lineages. Glial tumors with neuronal differentiation can be observed with diverse phenotypes and histologic grades. The rosette-forming glioneuronal tumor of the fourth ventricle and papillary glioneuronal tumor have been newly classified as distinct disease entities. There are other candidates for classification, such as the glioneuronal tumor without pseudopapillary architecture, glioneuronal tumor with neuropil-like islands, and the malignant glioneuronal tumor. The clinical significance of these previously unclassified tumors should be confirmed. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. From Neurons to Brain: Adaptive Self-Wiring of Neurons

    OpenAIRE

    Segev, Ronen; Ben-Jacob, Eshel

    1998-01-01

    During embryonic morpho-genesis, a collection of individual neurons turns into a functioning network with unique capabilities. Only recently has this most staggering example of emergent process in the natural world, began to be studied. Here we propose a navigational strategy for neurites growth cones, based on sophisticated chemical signaling. We further propose that the embryonic environment (the neurons and the glia cells) acts as an excitable media in which concentric and spiral chemical ...

  15. Density measurements of small amounts of high-density solids by a floatation method

    International Nuclear Information System (INIS)

    Akabori, Mitsuo; Shiba, Koreyuki

    1984-09-01

    A floatation method for determining the density of small amounts of high-density solids is described. The use of a float combined with an appropriate floatation liquid allows us to measure the density of high-density substances in small amounts. Using the sample of 0.1 g in weight, the floatation liquid of 3.0 g cm -3 in density and the float of 1.5 g cm -3 in apparent density, the sample densities of 5, 10 and 20 g cm -3 are determined to an accuracy better than +-0.002, +-0.01 and +-0.05 g cm -3 , respectively that correspond to about +-1 x 10 -5 cm 3 in volume. By means of appropriate degassing treatments, the densities of (Th,U)O 2 pellets of --0.1 g in weight and --9.55 g cm -3 in density were determined with an accuracy better than +-0.05 %. (author)

  16. A rapid method combining Golgi and Nissl staining to study neuronal morphology and cytoarchitecture.

    Science.gov (United States)

    Pilati, Nadia; Barker, Matthew; Panteleimonitis, Sofoklis; Donga, Revers; Hamann, Martine

    2008-06-01

    The Golgi silver impregnation technique gives detailed information on neuronal morphology of the few neurons it labels, whereas the majority remain unstained. In contrast, the Nissl staining technique allows for consistent labeling of the whole neuronal population but gives very limited information on neuronal morphology. Most studies characterizing neuronal cell types in the context of their distribution within the tissue slice tend to use the Golgi silver impregnation technique for neuronal morphology followed by deimpregnation as a prerequisite for showing that neuron's histological location by subsequent Nissl staining. Here, we describe a rapid method combining Golgi silver impregnation with cresyl violet staining that provides a useful and simple approach to combining cellular morphology with cytoarchitecture without the need for deimpregnating the tissue. Our method allowed us to identify neurons of the facial nucleus and the supratrigeminal nucleus, as well as assessing cellular distribution within layers of the dorsal cochlear nucleus. With this method, we also have been able to directly compare morphological characteristics of neuronal somata at the dorsal cochlear nucleus when labeled with cresyl violet with those obtained with the Golgi method, and we found that cresyl violet-labeled cell bodies appear smaller at high cellular densities. Our observation suggests that cresyl violet staining is inadequate to quantify differences in soma sizes.

  17. Serotonin Neuron Abnormalities in the BTBR Mouse Model of Autism

    Science.gov (United States)

    Guo, Yue-Ping; Commons, Kathryn G.

    2017-01-01

    The inbred mouse strain BTBR T+ Itpr3tf/J (BTBR) i studied as a model of idiopathic autism because they are less social and more resistant to change than other strains. Forebrain serotonin receptors and the response to serotonin drugs are altered in BTBR mice, yet it remains unknown if serotonin neurons themselves are abnormal. In this study, we found that serotonin tissue content and the density of serotonin axons is reduced in the hippocampus of BTBR mice in comparison to C57BL/6J (C57) mice. This was accompanied by possible compensatory changes in serotonin neurons that were most pronounced in regions known to provide innervation to the hippocampus: the caudal dorsal raphe (B6) and the median raphe. These changes included increased numbers of serotonin neurons and hyperactivation of Fos expression. Metrics of serotonin neurons in the rostral 2/3 of the dorsal raphe and serotonin content of the prefrontal cortex were less impacted. Thus, serotonin neurons exhibit region-dependent abnormalities in the BTBR mouse that may contribute to their altered behavioral profile. PMID:27478061

  18. Integrate-and-fire neurons driven by asymmetric dichotomous noise.

    Science.gov (United States)

    Droste, Felix; Lindner, Benjamin

    2014-12-01

    We consider a general integrate-and-fire (IF) neuron driven by asymmetric dichotomous noise. In contrast to the Gaussian white noise usually used in the so-called diffusion approximation, this noise is colored, i.e., it exhibits temporal correlations. We give an analytical expression for the stationary voltage distribution of a neuron receiving such noise and derive recursive relations for the moments of the first passage time density, which allow us to calculate the firing rate and the coefficient of variation of interspike intervals. We study how correlations in the input affect the rate and regularity of firing under variation of the model's parameters for leaky and quadratic IF neurons. Further, we consider the limit of small correlation times and find lowest order corrections to the first passage time moments to be proportional to the square root of the correlation time. We show analytically that to this lowest order, correlations always lead to a decrease in firing rate for a leaky IF neuron. All theoretical expressions are compared to simulations of leaky and quadratic IF neurons.

  19. All-memristive neuromorphic computing with level-tuned neurons

    Science.gov (United States)

    Pantazi, Angeliki; Woźniak, Stanisław; Tuma, Tomas; Eleftheriou, Evangelos

    2016-09-01

    In the new era of cognitive computing, systems will be able to learn and interact with the environment in ways that will drastically enhance the capabilities of current processors, especially in extracting knowledge from vast amount of data obtained from many sources. Brain-inspired neuromorphic computing systems increasingly attract research interest as an alternative to the classical von Neumann processor architecture, mainly because of the coexistence of memory and processing units. In these systems, the basic components are neurons interconnected by synapses. The neurons, based on their nonlinear dynamics, generate spikes that provide the main communication mechanism. The computational tasks are distributed across the neural network, where synapses implement both the memory and the computational units, by means of learning mechanisms such as spike-timing-dependent plasticity. In this work, we present an all-memristive neuromorphic architecture comprising neurons and synapses realized by using the physical properties and state dynamics of phase-change memristors. The architecture employs a novel concept of interconnecting the neurons in the same layer, resulting in level-tuned neuronal characteristics that preferentially process input information. We demonstrate the proposed architecture in the tasks of unsupervised learning and detection of multiple temporal correlations in parallel input streams. The efficiency of the neuromorphic architecture along with the homogenous neuro-synaptic dynamics implemented with nanoscale phase-change memristors represent a significant step towards the development of ultrahigh-density neuromorphic co-processors.

  20. All-memristive neuromorphic computing with level-tuned neurons.

    Science.gov (United States)

    Pantazi, Angeliki; Woźniak, Stanisław; Tuma, Tomas; Eleftheriou, Evangelos

    2016-09-02

    In the new era of cognitive computing, systems will be able to learn and interact with the environment in ways that will drastically enhance the capabilities of current processors, especially in extracting knowledge from vast amount of data obtained from many sources. Brain-inspired neuromorphic computing systems increasingly attract research interest as an alternative to the classical von Neumann processor architecture, mainly because of the coexistence of memory and processing units. In these systems, the basic components are neurons interconnected by synapses. The neurons, based on their nonlinear dynamics, generate spikes that provide the main communication mechanism. The computational tasks are distributed across the neural network, where synapses implement both the memory and the computational units, by means of learning mechanisms such as spike-timing-dependent plasticity. In this work, we present an all-memristive neuromorphic architecture comprising neurons and synapses realized by using the physical properties and state dynamics of phase-change memristors. The architecture employs a novel concept of interconnecting the neurons in the same layer, resulting in level-tuned neuronal characteristics that preferentially process input information. We demonstrate the proposed architecture in the tasks of unsupervised learning and detection of multiple temporal correlations in parallel input streams. The efficiency of the neuromorphic architecture along with the homogenous neuro-synaptic dynamics implemented with nanoscale phase-change memristors represent a significant step towards the development of ultrahigh-density neuromorphic co-processors.

  1. Quantum volume hologram

    International Nuclear Information System (INIS)

    Vasilyev, Denis V.; Sokolov, Ivan V.; Polzik, Eugene S.

    2010-01-01

    We propose a scheme for parallel spatially multimode quantum memory for light. The scheme is based on a counterpropagating quantum signal wave and a strong classical reference wave as in a classical volume hologram and therefore can be called a quantum volume hologram. The medium for the hologram consists of a spatially extended ensemble of atoms placed in a magnetic field. The write-in and readout of this quantum hologram is as simple as that of its classical counterpart and consists of a single-pass illumination. In addition, we show that the present scheme for a quantum hologram is less sensitive to diffraction and therefore is capable of achieving a higher density of storage of spatial modes as compared to previous proposals. We present a feasibility study and show that experimental implementation is possible with available cold atomic samples. A quantum hologram capable of storing entangled images can become an important ingredient in quantum information processing and quantum imaging.

  2. Tinbergen on mirror neurons

    Science.gov (United States)

    Heyes, Cecilia

    2014-01-01

    Fifty years ago, Niko Tinbergen defined the scope of behavioural biology with his four problems: causation, ontogeny, survival value and evolution. About 20 years ago, there was another highly significant development in behavioural biology—the discovery of mirror neurons (MNs). Here, I use Tinbergen's original four problems (rather than the list that appears in textbooks) to highlight the differences between two prominent accounts of MNs, the genetic and associative accounts; to suggest that the latter provides the defeasible ‘best explanation’ for current data on the causation and ontogeny of MNs; and to argue that functional analysis, of the kind that Tinbergen identified somewhat misleadingly with studies of ‘survival value’, should be a high priority for future research. In this kind of functional analysis, system-level theories would assign MNs a small, but potentially important, role in the achievement of action understanding—or another social cognitive function—by a production line of interacting component processes. These theories would be tested by experimental intervention in human and non-human animal samples with carefully documented and controlled developmental histories. PMID:24778376

  3. Neurons on the couch.

    Science.gov (United States)

    Marić, Nadja P; Jašović-Gašić, Miroslava

    2010-12-01

    A hundred years after psychoanalysis was introduced, neuroscience has taken a giant step forward. It seems nowadays that effects of psychotherapy could be monitored and measured by state-of-the art brain imaging techniques. Today, the psychotherapy is considered as a strategic and purposeful environmental influence intended to enhance learning. Since gene expression is regulated by environmental influences throughout life and these processes create brain architecture and influence the strength of synaptic connections, psychotherapy (as a kind of learning) should be explored in the context of aforementioned paradigm. In other words, when placing a client on the couch, therapist actually placed client's neuronal network; while listening and talking, expressing and analyzing, experiencing transference and counter transference, therapist tends to stabilize synaptic connections and influence dendritic growth by regulating gene-transcriptional activity. Therefore, we strongly believe that, in the near future, an increasing knowledge on cellular and molecular interactions and mechanisms of action of different psycho- and pharmaco-therapeutic procedures will enable us to tailor a sophisticated therapeutic approach toward a person, by combining major therapeutic strategies in psychiatry on the basis of rational goals and evidence-based therapeutic expectations.

  4. Tinbergen on mirror neurons.

    Science.gov (United States)

    Heyes, Cecilia

    2014-01-01

    Fifty years ago, Niko Tinbergen defined the scope of behavioural biology with his four problems: causation, ontogeny, survival value and evolution. About 20 years ago, there was another highly significant development in behavioural biology-the discovery of mirror neurons (MNs). Here, I use Tinbergen's original four problems (rather than the list that appears in textbooks) to highlight the differences between two prominent accounts of MNs, the genetic and associative accounts; to suggest that the latter provides the defeasible 'best explanation' for current data on the causation and ontogeny of MNs; and to argue that functional analysis, of the kind that Tinbergen identified somewhat misleadingly with studies of 'survival value', should be a high priority for future research. In this kind of functional analysis, system-level theories would assign MNs a small, but potentially important, role in the achievement of action understanding-or another social cognitive function-by a production line of interacting component processes. These theories would be tested by experimental intervention in human and non-human animal samples with carefully documented and controlled developmental histories.

  5. Fetal brain extracellular matrix boosts neuronal network formation in 3D bioengineered model of cortical brain tissue.

    Science.gov (United States)

    Sood, Disha; Chwalek, Karolina; Stuntz, Emily; Pouli, Dimitra; Du, Chuang; Tang-Schomer, Min; Georgakoudi, Irene; Black, Lauren D; Kaplan, David L

    2016-01-01

    The extracellular matrix (ECM) constituting up to 20% of the organ volume is a significant component of the brain due to its instructive role in the compartmentalization of functional microdomains in every brain structure. The composition, quantity and structure of ECM changes dramatically during the development of an organism greatly contributing to the remarkably sophisticated architecture and function of the brain. Since fetal brain is highly plastic, we hypothesize that the fetal brain ECM may contain cues promoting neural growth and differentiation, highly desired in regenerative medicine. Thus, we studied the effect of brain-derived fetal and adult ECM complemented with matricellular proteins on cortical neurons using in vitro 3D bioengineered model of cortical brain tissue. The tested parameters included neuronal network density, cell viability, calcium signaling and electrophysiology. Both, adult and fetal brain ECM as well as matricellular proteins significantly improved neural network formation as compared to single component, collagen I matrix. Additionally, the brain ECM improved cell viability and lowered glutamate release. The fetal brain ECM induced superior neural network formation, calcium signaling and spontaneous spiking activity over adult brain ECM. This study highlights the difference in the neuroinductive properties of fetal and adult brain ECM and suggests that delineating the basis for this divergence may have implications for regenerative medicine.

  6. Decreased pyramidal neuron size in Brodmann areas 44 and 45 in patients with autism.

    Science.gov (United States)

    Jacot-Descombes, Sarah; Uppal, Neha; Wicinski, Bridget; Santos, Micaela; Schmeidler, James; Giannakopoulos, Panteleimon; Heinsen, Helmut; Heinsein, Helmut; Schmitz, Christoph; Hof, Patrick R

    2012-07-01

    Autism is a neurodevelopmental disorder characterized by deficits in social interaction and social communication, as well as by the presence of repetitive and stereotyped behaviors and interests. Brodmann areas 44 and 45 in the inferior frontal cortex, which are involved in language processing, imitation function, and sociality processing networks, have been implicated in this complex disorder. Using a stereologic approach, this study aims to explore the presence of neuropathological differences in areas 44 and 45 in patients with autism compared to age- and hemisphere-matched controls. Based on previous evidence in the fusiform gyrus, we expected to find a decrease in the number and size of pyramidal neurons as well as an increase in volume of layers III, V, and VI in patients with autism. We observed significantly smaller pyramidal neurons in patients with autism compared to controls, although there was no difference in pyramidal neuron numbers or layer volumes. The reduced pyramidal neuron size suggests that a certain degree of dysfunction of areas 44 and 45 plays a role in the pathology of autism. Our results also support previous studies that have shown specific cellular neuropathology in autism with regionally specific reduction in neuron size, and provide further evidence for the possible involvement of the mirror neuron system, as well as impairment of neuronal networks relevant to communication and social behaviors, in this disorder.

  7. Understanding Neuronal Mechanisms of Epilepsy ...

    Indian Academy of Sciences (India)

    Admin

    α subunit of Rat Brain type IIA Voltage Gated Sodium Channel and geneticin selection ..... scaling the mother wavelet. Scale = 1/ .... through dynamic clamp. Dynamic Clamp ... It has been shown that like in vivo neurons, cortical networks in.

  8. Imitation, mirror neurons and autism.

    Science.gov (United States)

    Williams, J H; Whiten, A; Suddendorf, T; Perrett, D I

    2001-06-01

    Various deficits in the cognitive functioning of people with autism have been documented in recent years but these provide only partial explanations for the condition. We focus instead on an imitative disturbance involving difficulties both in copying actions and in inhibiting more stereotyped mimicking, such as echolalia. A candidate for the neural basis of this disturbance may be found in a recently discovered class of neurons in frontal cortex, 'mirror neurons' (MNs). These neurons show activity in relation both to specific actions performed by self and matching actions performed by others, providing a potential bridge between minds. MN systems exist in primates without imitative and 'theory of mind' abilities and we suggest that in order for them to have become utilized to perform social cognitive functions, sophisticated cortical neuronal systems have evolved in which MNs function as key elements. Early developmental failures of MN systems are likely to result in a consequent cascade of developmental impairments characterised by the clinical syndrome of autism.

  9. Information processing by neuronal populations

    National Research Council Canada - National Science Library

    Hölscher, Christian; Munk, Matthias

    2009-01-01

    ... simultaneously recorded spike trains 120 Mark Laubach, Nandakumar S. Narayanan, and Eyal Y. Kimchi Part III Neuronal population information coding and plasticity in specific brain areas 149 7 F...

  10. Digital radioisotope moisture-density meter

    International Nuclear Information System (INIS)

    Bychvarov, N.; Vankov, I.; Dimitrov, L.

    1982-01-01

    The primary information from the detectors of a combined radioisotope moisture-density meter is obtained as pulses, their counting rate being functionally dependent on the humidity per unit volume and the wet density. However, most practical cases demand information on the moisture per unit weight and the mass density of the dry skeleton. The paper describes how the proposed electronic circuit processes the input primary information to obtain the moisture in weight % and the mass density of the dry skeleton in g/cm 3 . (authors)

  11. Prenatal NMDA Receptor Antagonism Impaired Proliferation of Neuronal Progenitor, Leading to Fewer Glutamatergic Neurons in the Prefrontal Cortex

    Science.gov (United States)

    Toriumi, Kazuya; Mouri, Akihiro; Narusawa, Shiho; Aoyama, Yuki; Ikawa, Natsumi; Lu, Lingling; Nagai, Taku; Mamiya, Takayoshi; Kim, Hyoung-Chun; Nabeshima, Toshitaka

    2012-01-01

    N-methyl--aspartate (NMDA) receptor is a glutamate receptor which has an important role on mammalian brain development. We have reported that prenatal treatment with phencyclidine (PCP), a NMDA receptor antagonist, induces long-lasting behavioral deficits and neurochemical changes. However, the mechanism by which the prenatal antagonism of NMDA receptor affects neurodevelopment, resulting in behavioral deficits, has remained unclear. Here, we report that prenatal NMDA receptor antagonism impaired the proliferation of neuronal progenitors, leading to a decrease in the progenitor pool in the ventricular and the subventricular zone. Furthermore, using a PCR array focused on neurogenesis and neuronal stem cells, we evaluated changes in gene expression causing the impairment of neuronal progenitor proliferation and found aberrant gene expression, such as Notch2 and Ntn1, in prenatal PCP-treated mice. Consequently, the density of glutamatergic neurons in the prefrontal cortex was decreased, probably resulting in glutamatergic hypofunction. Prenatal PCP-treated mice displayed behavioral deficits in cognitive memory and sensorimotor gating until adulthood. These findings suggest that NMDA receptors regulate the proliferation and maturation of progenitor cells for glutamatergic neuron during neurodevelopment, probably via the regulation of gene expression. PMID:22257896

  12. Chimera states in bursting neurons

    OpenAIRE

    Bera, Bidesh K.; Ghosh, Dibakar; Lakshmanan, M.

    2015-01-01

    We study the existence of chimera states in pulse-coupled networks of bursting Hindmarsh-Rose neurons with nonlocal, global and local (nearest neighbor) couplings. Through a linear stability analysis, we discuss the behavior of stability function in the incoherent (i.e. disorder), coherent, chimera and multi-chimera states. Surprisingly, we find that chimera and multi-chimera states occur even using local nearest neighbor interaction in a network of identical bursting neurons alone. This is i...

  13. Effects of channel noise on firing coherence of small-world Hodgkin-Huxley neuronal networks

    Science.gov (United States)

    Sun, X. J.; Lei, J. Z.; Perc, M.; Lu, Q. S.; Lv, S. J.

    2011-01-01

    We investigate the effects of channel noise on firing coherence of Watts-Strogatz small-world networks consisting of biophysically realistic HH neurons having a fraction of blocked voltage-gated sodium and potassium ion channels embedded in their neuronal membranes. The intensity of channel noise is determined by the number of non-blocked ion channels, which depends on the fraction of working ion channels and the membrane patch size with the assumption of homogeneous ion channel density. We find that firing coherence of the neuronal network can be either enhanced or reduced depending on the source of channel noise. As shown in this paper, sodium channel noise reduces firing coherence of neuronal networks; in contrast, potassium channel noise enhances it. Furthermore, compared with potassium channel noise, sodium channel noise plays a dominant role in affecting firing coherence of the neuronal network. Moreover, we declare that the observed phenomena are independent of the rewiring probability.

  14. Phosphoinositide-3-kinase activation controls synaptogenesis and spinogenesis in hippocampal neurons.

    Science.gov (United States)

    Cuesto, Germán; Enriquez-Barreto, Lilian; Caramés, Cristina; Cantarero, Marta; Gasull, Xavier; Sandi, Carmen; Ferrús, Alberto; Acebes, Ángel; Morales, Miguel

    2011-02-23

    The possibility of changing the number of synapses may be an important asset in the treatment of neurological diseases. In this context, the synaptogenic role of the phosphoinositide-3-kinase (PI3K) signaling cascade has been previously demonstrated in Drosophila. This study shows that treatment with a PI3K-activating transduction peptide is able to promote synaptogenesis and spinogenesis in primary cultures of rat hippocampal neurons, as well as in CA1 hippocampal neurons in vivo. In culture, the peptide increases synapse density independently of cell density, culture age, dendritic complexity, or synapse type. The induced synapses also increase neurotransmitter release from cultured neurons. The synaptogenic signaling pathway includes PI3K-Akt. Furthermore, the treatment is effective on adult neurons, where it induces spinogenesis and enhances the cognitive behavior of treated animals in a fear-conditioning assay. These findings demonstrate that functional synaptogenesis can be induced in mature mammalian brains through PI3K activation.

  15. Distribution of the P2X2 receptor and chemical coding in ileal enteric neurons of obese male mice (ob/ob)

    Science.gov (United States)

    Mizuno, Márcia Sanae; Crisma, Amanda Rabello; Borelli, Primavera; Schäfer, Bárbara Tavares; Silveira, Mariana Póvoa; Castelucci, Patricia

    2014-01-01

    AIM: To investigate the colocalization, density and profile of neuronal areas of enteric neurons in the ileum of male obese mice. METHODS: The small intestinal samples of male mice in an obese group (OG) (C57BL/6J ob/ob) and a control group (CG) (+/+) were used. The tissues were analyzed using a double immunostaining technique for immunoreactivity (ir) of the P2X2 receptor, nitric oxide synthase (NOS), choline acetyl transferase (ChAT) and calretinin (Calr). Also, we investigated the density and profile of neuronal areas of the NOS-, ChAT- and Calr-ir neurons in the myenteric plexus. Myenteric neurons were labeled using an NADH-diaphorase histochemical staining method. RESULTS: The analysis demonstrated that the P2X2 receptor was expressed in the cytoplasm and in the nuclear and cytoplasmic membranes only in the CG. Neuronal density values (neuron/cm2) decreased 31% (CG: 6579 ± 837; OG: 4556 ± 407) and 16.5% (CG: 7796 ± 528; OG: 6513 ± 610) in the NOS-ir and calretinin-ir neurons in the OG, respectively (P < 0.05). Density of ChAT-ir (CG: 6200 ± 310; OG: 8125 ± 749) neurons significantly increased 31% in the OG (P < 0.05). Neuron size studies demonstrated that NOS, ChAT, and Calr-ir neurons did not differ significantly between the CG and OG groups. The examination of NADH-diaphorase-positive myenteric neurons revealed an overall similarity between the OG and CG. CONCLUSION: Obesity may exert its effects by promoting a decrease in P2X2 receptor expression and modifications in the density of the NOS-ir, ChAT-ir and CalR-ir myenteric neurons. PMID:25320527

  16. Basketball training increases striatum volume.

    Science.gov (United States)

    Park, In Sung; Lee, Kea Joo; Han, Jong Woo; Lee, Nam Joon; Lee, Won Teak; Park, Kyung Ah; Rhyu, Im Joo

    2011-02-01

    The striatum is associated with the learning and retention of motor skills. Several studies have shown that motor learning induces neuronal changes in the striatum. We investigated whether macroscopic change in striatum volume occurs in a segment of the human population who learned basketball-related motor skills and practiced them throughout their entire athletic life. Three-dimensional magnetic resonance imaging volumetry was performed in basketball players and healthy controls, and striatum volumes were compared based on basketball proficiency, region and side. We identified morphological enlargement in the striatum of basketball players in comparison with controls. Our results suggest that continued practice and repetitive performance of basketball-related motor skills may induce plastic structural changes in the human striatum. Copyright © 2010 Elsevier B.V. All rights reserved.

  17. Glial cell morphological and density changes through the lifespan of rhesus macaques.

    Science.gov (United States)

    Robillard, Katelyn N; Lee, Kim M; Chiu, Kevin B; MacLean, Andrew G

    2016-07-01

    How aging impacts the central nervous system (CNS) is an area of intense interest. Glial morphology is known to affect neuronal and immune function as well as metabolic and homeostatic balance. Activation of glia, both astrocytes and microglia, occurs at several stages during development and aging. The present study analyzed changes in glial morphology and density through the entire lifespan of rhesus macaques, which are physiologically and anatomically similar to humans. We observed apparent increases in gray matter astrocytic process length and process complexity as rhesus macaques matured from juveniles through adulthood. These changes were not attributed to cell enlargement because they were not accompanied by proportional changes in soma or process volume. There was a decrease in white matter microglial process length as rhesus macaques aged. Aging was shown to have a significant effect on gray matter microglial density, with a significant increase in aged macaques compared with adults. Overall, we observed significant changes in glial morphology as macaques age indicative of astrocytic activation with subsequent increase in microglial density in aged macaques. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Inflammation-induced increase in nicotinic acetylcholine receptor current in cutaneous nociceptive DRG neurons from the adult rat.

    Science.gov (United States)

    Zhang, X-L; Albers, K M; Gold, M S

    2015-01-22

    The goals of the present study were to determine (1) the properties of the nicotinic acetylcholine receptor (nAChR) currents in rat cutaneous dorsal root ganglion (DRG) neurons; (2) the impact of nAChR activation on the excitability of cutaneous DRG neurons; and (3) the impact of inflammation on the density and distribution of nAChR currents among cutaneous DRG neurons. Whole-cell patch-clamp techniques were used to study retrogradely labeled DRG neurons from naïve and complete Freund's adjuvant inflamed rats. Nicotine-evoked currents were detectable in ∼70% of the cutaneous DRG neurons, where only one of two current types, fast or slow currents based on rates of activation and inactivation, was present in each neuron. The biophysical and pharmacological properties of the fast current were consistent with nAChRs containing an α7 subunit while those of the slow current were consistent with nAChRs containing α3/β4 subunits. The majority of small diameter neurons with fast current were IB4- while the majority of small diameter neurons with slow current were IB4+. Preincubation with nicotine (1 μM) produced a transient (1 min) depolarization and increase in the excitability of neurons with fast current and a decrease in the amplitude of capsaicin-evoked current in neurons with slow current. Inflammation increased the current density of both slow and fast currents in small diameter neurons and increased the percentage of neurons with the fast current. With the relatively selective distribution of nAChR currents in putative nociceptive cutaneous DRG neurons, our results suggest that the role of these receptors in inflammatory hyperalgesia is likely to be complex and dependent on the concentration and timing of acetylcholine release in the periphery. Copyright © 2014 IBRO. Published by Elsevier Ltd. All rights reserved.

  19. Inhibiting cholesterol degradation induces neuronal sclerosis and epileptic activity in mouse hippocampus

    Science.gov (United States)

    Chali, Farah; Djelti, Fathia; Eugene, Emmanuel; Valderrama, Mario; Marquer, Catherine; Aubourg, Patrick; Duykaerts, Charles; Miles, Richard; Cartier, Nathalie; Navarro, Vincent

    2015-01-01

    Elevations in neuronal cholesterol have been associated with several degenerative diseases. An enhanced excitability and synchronous firing in surviving neurons are among the sequels of neuronal death in these diseases and also in some epileptic syndromes. Here, we attempted to increase neuronal cholesterol levels, using a short hairpin RNA (shRNA) to suppress expression of the enzyme CYP46A1. This protein hydroxylates cholesterol and so facilitates trans-membrane extrusion. A sh-RNA CYP46A1construction coupled to an adeno-associated virus (AAV5) was injected focally and unilaterally into mouse hippocampus. It was selectively expressed first in neurons of the CA3a region. Cytoplasmic and membrane cholesterol increased, neuronal soma volume increased and then decreased before pyramidal cells died. As CA3a pyramidal cells died, inter-ictal EEG events occurred during exploration and non-REM sleep. With time, neuronal death spread to involve pyramidal cells and interneurons of the CA1 region. CA1 neuronal death was correlated with a delayed local expression of phosphorylated tau. Astrocytes were activated throughout the hippocampus and microglial activation was specific to regions of neuronal death. CA1 neuronal death was correlated with distinct aberrant EEG activity. During exploratory behaviour and rapid eye movement sleep, EEG oscillations at 7-10 Hz (theta) could accelerate to 14-21 Hz (beta) waves. They were accompanied by low amplitude, high-frequency oscillations of peak power at ~300Hz and a range of 250-350 Hz. While episodes of EEG acceleration were not correlated with changes in exploratory behaviour, they were followed in some animals by structured seizure-like discharges. These data strengthen links between increased cholesterol, neuronal sclerosis and epileptic behavior PMID:25847620

  20. Antho-RFamide-containing neurons in the primitive nervous system of the anthozoan Renilla koellikeri

    DEFF Research Database (Denmark)

    Pernet, Vincent; Anctil, Michel; Grimmelikhuijzen, Cornelis J P

    2004-01-01

    -RFamide-containing neurons in this species would contribute to our understanding of the early evolution of nervous systems. Using antisera raised against RFamide and FMRFamide, we detected immunostaining in numerous neurons throughout the nervous system of the sea pansy. The antisera revealed ectodermal nerve......-nets on the upper and lower sides of the colony and on the oral side of tentacles, in the oral disk, and in the pharynx of feeding polyps. Neurons were immunostained also in the mesogleal nerve-net of feeding polyps and in the through-conducting mesogleal nerve-net of the colonial mass. Varying densities of stained...

  1. Brain-derived neurotrophic factor/neurotrophin 3 regulate axon initial segment location and affect neuronal excitability in cultured hippocampal neurons.

    Science.gov (United States)

    Guo, Yu; Su, Zi-Jun; Chen, Yi-Kun; Chai, Zhen

    2017-07-01

    Plasticity of the axon initial segment (AIS) has aroused great interest in recent years because it regulates action potential initiation and neuronal excitability. AIS plasticity manifests as modulation of ion channels or variation in AIS structure. However, the mechanisms underlying structural plasticity of the AIS are not well understood. Here, we combined immunofluorescence, patch-clamp recordings, and pharmacological methods in cultured hippocampal neurons to investigate the factors participating in AIS structural plasticity during development. With lowered neuronal density, the distance between the AIS and the soma increased, while neuronal excitability decreased, as shown by the increased action potential threshold and current threshold for firing an action potential. This variation in the location of the AIS was associated with cellular secretory substances, including brain-derived neurotrophic factor (BDNF) and neurotrophin 3 (NT3). Indeed, blocking BDNF and NT3 with TrkB-Fc eliminated the effect of conditioned medium collected from high-density cultures on AIS relocation. Elevating the extracellular concentration of BDNF or NT3 promoted movement of the AIS proximally to the soma and increased neuronal excitability. Furthermore, knockdown of neurotrophin receptors TrkB and TrkC caused distal movement of the AIS. Our results demonstrate that BDNF and NT3 regulate AIS location and neuronal excitability. These regulatory functions of neurotrophic factors provide insight into the molecular mechanisms underlying AIS biology. © 2017 International Society for Neurochemistry.

  2. Brain-derived neurotrophic factor mediates estradiol-induced dendritic spine formation in hippocampal neurons

    Science.gov (United States)

    Murphy, Diane D.; Cole, Nelson B.; Segal, Menahem

    1998-01-01

    Dendritic spines are of major importance in information processing and memory formation in central neurons. Estradiol has been shown to induce an increase of dendritic spine density on hippocampal neurons in vivo and in vitro. The neurotrophin brain-derived neurotrophic factor (BDNF) recently has been implicated in neuronal maturation, plasticity, and regulation of GABAergic interneurons. We now demonstrate that estradiol down-regulates BDNF in cultured hippocampal neurons to 40% of control values within 24 hr of exposure. This, in turn, decreases inhibition and increases excitatory tone in pyramidal neurons, leading to a 2-fold increase in dendritic spine density. Exogenous BDNF blocks the effects of estradiol on spine formation, and BDNF depletion with a selective antisense oligonucleotide mimics the effects of estradiol. Addition of BDNF antibodies also increases spine density, and diazepam, which facilitates GABAergic neurotransmission, blocks estradiol-induced spine formation. These observations demonstrate a functional link between estradiol, BDNF as a potent regulator of GABAergic interneurons, and activity-dependent formation of dendritic spines in hippocampal neurons. PMID:9736750

  3. Asymmetry of radial and symmetry of tangential neuronal migration pathways in developing human fetal brains

    Directory of Open Access Journals (Sweden)

    Yuta eMiyazaki

    2016-01-01

    Full Text Available AbstractThe radial and tangential neural migration pathways are two major neuronal migration streams in humans that are critical during corticogenesis. Corticogenesis is a complex process of neuronal proliferation that is followed by neuronal migration and the formation of axonal connections. Existing histological assessments of these two neuronal migration pathways have limitations inherent to microscopic studies and are confined to small anatomic regions of interest. Thus, little evidence is available about their three-dimensional fiber pathways and development throughout the entire brain. In this study, we imaged and analyzed radial and tangential migration pathways in the whole human brain using high-angular resolution diffusion MR imaging (HARDI tractography. We imaged ten fixed, postmortem fetal (17 gestational weeks (GW, 18 GW, 19 GW, three 20 GW, three 21 GW and 22 GW and eight in vivo newborn (two 30 GW, 34 GW, 35 GW and four 40 GW brains with no neurological/pathological conditions. We statistically compared the volume of the left and right radial and tangential migration pathways, and the volume of the radial migration pathways of the anterior and posterior regions of the brain. In specimens 22 GW or younger, the volume of radial migration pathways of the left hemisphere was significantly larger than that of the right hemisphere. The volume of posterior radial migration pathways was also larger when compared to the anterior pathways in specimens 22 GW or younger. In contrast, no significant differences were observed in the radial migration pathways of brains older than 22 GW. Moreover, our study did not identify any significant differences in volumetric laterality in the tangential migration pathways. These results suggest that these two neuronal migration pathways develop and regress differently, and radial neuronal migration varies regionally based on hemispheric and anterior-posterior laterality, potentially explaining regional

  4. Mechanosensitive enteric neurons in the guinea pig gastric corpus

    Directory of Open Access Journals (Sweden)

    Gemma eMazzuoli-Weber

    2015-11-01

    Full Text Available For long it was believed that a particular population of enteric neurons, referred to as intrinsic primary afferent neuron (IPANs, encodes mechanical stimulation. We recently proposed a new concept suggesting that there are in addition mechanosensitive enteric neurons (MEN that are multifunctional. Based on firing pattern MEN behaved as rapidly, slowly or ultra-slowly adapting RAMEN, SAMEN or USAMEN, respectively. We aimed to validate this concept in the myenteric plexus of the gastric corpus, a region where IPANs were not identified and existence of enteric sensory neurons was even questioned. The gastric corpus is characterized by a particularly dense extrinsic sensory innervation. Neuronal activity was recorded with voltage sensitive dye imaging after deformation of ganglia by compression (intraganglionic volume injection or von Fry hair or tension (ganglionic stretch. We demonstrated that 27% of the gastric neurons were MEN and responded to intraganglionic volume injection. Of these 73% were RAMEN, 25% SAMEN and 2% USAMEN with a firing frequency of 1.7 (1.1/ 2.2 Hz, 5.1 (2.2/7.7 Hz and of 5.4 (5.0/15.5 Hz, respectively. The responses were reproducible and stronger with increased stimulus strength. Even after adaptation another deformation evoked spike discharge again suggesting a resetting mode of the mechanoreceptors. All MEN received fast synaptic input. 55% of all MEN were cholinergic and 45% nitrergic. Responses in some MEN significantly decreased after perfusion of TTX, low Ca++/high Mg++ Krebs solution, capsaicin induced nerve defunctionalization and capsazepine indicating the involvement of TRPV1 expressing extrinsic mechanosensitive nerves. Half of gastric MEN responded to intraganglionic volume injection as well as to ganglionic stretch and 23% responded to stretch only. Tension-sensitive MEN were to a large proportion USAMEN (44%. In summary, we demonstrated for the first time compression and tension-sensitive MEN in the stomach

  5. Learning of time series through neuron-to-neuron instruction

    Energy Technology Data Exchange (ETDEWEB)

    Miyazaki, Y [Department of Physics, Kyoto University, Kyoto 606-8502, (Japan); Kinzel, W [Institut fuer Theoretische Physik, Universitaet Wurzburg, 97074 Wurzburg (Germany); Shinomoto, S [Department of Physics, Kyoto University, Kyoto (Japan)

    2003-02-07

    A model neuron with delayline feedback connections can learn a time series generated by another model neuron. It has been known that some student neurons that have completed such learning under the instruction of a teacher's quasi-periodic sequence mimic the teacher's time series over a long interval, even after instruction has ceased. We found that in addition to such faithful students, there are unfaithful students whose time series eventually diverge exponentially from that of the teacher. In order to understand the circumstances that allow for such a variety of students, the orbit dimension was estimated numerically. The quasi-periodic orbits in question were found to be confined in spaces with dimensions significantly smaller than that of the full phase space.

  6. Learning of time series through neuron-to-neuron instruction

    International Nuclear Information System (INIS)

    Miyazaki, Y; Kinzel, W; Shinomoto, S

    2003-01-01

    A model neuron with delayline feedback connections can learn a time series generated by another model neuron. It has been known that some student neurons that have completed such learning under the instruction of a teacher's quasi-periodic sequence mimic the teacher's time series over a long interval, even after instruction has ceased. We found that in addition to such faithful students, there are unfaithful students whose time series eventually diverge exponentially from that of the teacher. In order to understand the circumstances that allow for such a variety of students, the orbit dimension was estimated numerically. The quasi-periodic orbits in question were found to be confined in spaces with dimensions significantly smaller than that of the full phase space

  7. GDNF family ligands display distinct action profiles on cultured GABAergic and serotonergic neurons of rat ventral mesencephalon

    DEFF Research Database (Denmark)

    Ducray, Angélique; Krebs, Sandra H:; Schaller, Benoft

    2006-01-01

    the effects of GFLs on other neuronal populations in the VM is essential for their potential application as therapeutic molecules for Parkinson's disease. Hence, in a comparative study, we investigated the effects of GFLs on cell densities and morphological differentiation of gamma-aminobutyric acid......Glial-cell-line-derived neurotrophic factor (GDNF), neurturin (NRTN), artemin (ARTN) and persephin (PSPN), known as the GDNF family ligands (GFLs), influence the development, survival and differentiation of cultured dopaminergic neurons from ventral mesencephalon (VM). Detailed knowledge about......-immunoreactive (GABA-ir) and serotonin-ir (5-HT-ir) neurons in primary cultures of E14 rat VM. We observed that all GFLs [10 ng/ml] significantly increased GABA-ir cell densities (1.6-fold) as well as neurite length/neuron. However, only GDNF significantly increased the number of primary neurites/neuron, and none...

  8. Impact of entrainment and impingement on fish populations in the Hudson River Estuary. Volume II. Impingement impact analyses, evaluations of alternative screening devices, and critiques of utility testimony relating to density-dependent growth, the age-composition of the striped bass spawning stock, and the LMS real-time life cycle model

    International Nuclear Information System (INIS)

    Barnthouse, L.W.; Van Winkle, W.; Golumbek, J.; Cada, G.F.; Goodyear, C.P.; Christensen, S.W.; Cannon, J.B.; Lee, D.W.

    1982-04-01

    This volume includes a series of four exhibits relating to impacts of impingement on fish populations, together with a collection of critical evaluations of testimony prepared for the utilities by their consultants. The first exhibit is a quantitative evaluation of four sources of bias (collection efficiency, reimpingement, impingement on inoperative screens, and impingement survival) affecting estimates of the number of fish killed at Hudson River power plants. The two following exhibits contain, respectively, a detailed assessment of the impact of impingement on the Hudson River white perch population and estimates of conditional impingement mortality rates for seven Hudson River fish populations. The fourth exhibit is an evaluation of the engineering feasibility and potential biological effectiveness of several types of modified intake structures proposed as alternatives to cooling towers for reducing impingement impacts. The remainder of Volume II consists of critical evaluations of the utilities' empirical evidence for the existence of density-dependent growth in young-of-the-year striped bass and white perch, of their estimate of the age-composition of the striped bass spawning stock in the Hudson River, and of their use of the Lawler, Matusky, and Skelly (LMS) Real-Time Life Cycle Model to estimate the impact of entrainment and impingement on the Hudson River striped bass population

  9. Sparse PDF Volumes for Consistent Multi-Resolution Volume Rendering

    KAUST Repository

    Sicat, Ronell Barrera

    2014-12-31

    This paper presents a new multi-resolution volume representation called sparse pdf volumes, which enables consistent multi-resolution volume rendering based on probability density functions (pdfs) of voxel neighborhoods. These pdfs are defined in the 4D domain jointly comprising the 3D volume and its 1D intensity range. Crucially, the computation of sparse pdf volumes exploits data coherence in 4D, resulting in a sparse representation with surprisingly low storage requirements. At run time, we dynamically apply transfer functions to the pdfs using simple and fast convolutions. Whereas standard low-pass filtering and down-sampling incur visible differences between resolution levels, the use of pdfs facilitates consistent results independent of the resolution level used. We describe the efficient out-of-core computation of large-scale sparse pdf volumes, using a novel iterative simplification procedure of a mixture of 4D Gaussians. Finally, our data structure is optimized to facilitate interactive multi-resolution volume rendering on GPUs.

  10. The mirror-neuron system.

    Science.gov (United States)

    Rizzolatti, Giacomo; Craighero, Laila

    2004-01-01

    A category of stimuli of great importance for primates, humans in particular, is that formed by actions done by other individuals. If we want to survive, we must understand the actions of others. Furthermore, without action understanding, social organization is impossible. In the case of humans, there is another faculty that depends on the observation of others' actions: imitation learning. Unlike most species, we are able to learn by imitation, and this faculty is at the basis of human culture. In this review we present data on a neurophysiological mechanism--the mirror-neuron mechanism--that appears to play a fundamental role in both action understanding and imitation. We describe first the functional properties of mirror neurons in monkeys. We review next the characteristics of the mirror-neuron system in humans. We stress, in particular, those properties specific to the human mirror-neuron system that might explain the human capacity to learn by imitation. We conclude by discussing the relationship between the mirror-neuron system and language.

  11. Energy Model of Neuron Activation.

    Science.gov (United States)

    Romanyshyn, Yuriy; Smerdov, Andriy; Petrytska, Svitlana

    2017-02-01

    On the basis of the neurophysiological strength-duration (amplitude-duration) curve of neuron activation (which relates the threshold amplitude of a rectangular current pulse of neuron activation to the pulse duration), as well as with the use of activation energy constraint (the threshold curve corresponds to the energy threshold of neuron activation by a rectangular current pulse), an energy model of neuron activation by a single current pulse has been constructed. The constructed model of activation, which determines its spectral properties, is a bandpass filter. Under the condition of minimum-phase feature of the neuron activation model, on the basis of Hilbert transform, the possibilities of phase-frequency response calculation from its amplitude-frequency response have been considered. Approximation to the amplitude-frequency response by the response of the Butterworth filter of the first order, as well as obtaining the pulse response corresponding to this approximation, give us the possibility of analyzing the efficiency of activating current pulses of various shapes, including analysis in accordance with the energy constraint.

  12. Hyperactivity of newborn Pten knock-out neurons results from increased excitatory synaptic drive.

    Science.gov (United States)

    Williams, Michael R; DeSpenza, Tyrone; Li, Meijie; Gulledge, Allan T; Luikart, Bryan W

    2015-01-21

    Developing neurons must regulate morphology, intrinsic excitability, and synaptogenesis to form neural circuits. When these processes go awry, disorders, including autism spectrum disorder (ASD) or epilepsy, may result. The phosphatase Pten is mutated in some patients having ASD and seizures, suggesting that its mutation disrupts neurological function in part through increasing neuronal activity. Supporting this idea, neuronal knock-out of Pten in mice can cause macrocephaly, behavioral changes similar to ASD, and seizures. However, the mechanisms through which excitability is enhanced following Pten depletion are unclear. Previous studies have separately shown that Pten-depleted neurons can drive seizures, receive elevated excitatory synaptic input, and have abnormal dendrites. We therefore tested the hypothesis that developing Pten-depleted neurons are hyperactive due to increased excitatory synaptogenesis using electrophysiology, calcium imaging, morphological analyses, and modeling. This was accomplished by coinjecting retroviruses to either "birthdate" or birthdate and knock-out Pten in granule neurons of the murine neonatal dentate gyrus. We found that Pten knock-out neurons, despite a rapid onset of hypertrophy, were more active in vivo. Pten knock-out neurons fired at more hyperpolarized membrane potentials, displayed greater peak spike rates, and were more sensitive to depolarizing synaptic input. The increased sensitivity of Pten knock-out neurons was due, in part, to a higher density of synapses located more proximal to the soma. We determined that increased synaptic drive was sufficient to drive hypertrophic Pten knock-out neurons beyond their altered action potential threshold. Thus, our work contributes a developmental mechanism for the increased activity of Pten-depleted neurons. Copyright © 2015 the authors 0270-6474/15/350943-17$15.00/0.

  13. Modeling the diffusion magnetic resonance imaging signal inside neurons

    International Nuclear Information System (INIS)

    Nguyen, D V; Li, J R; Grebenkov, D S; Le Bihan, D

    2014-01-01

    The Bloch-Torrey partial differential equation (PDE) describes the complex transverse water proton magnetization due to diffusion-encoding magnetic field gradient pulses. The integral of the solution of this PDE yields the diffusion magnetic resonance imaging (dMRI) signal. In a complex medium such as cerebral tissue, it is difficult to explicitly link the dMRI signal to biological parameters such as the cellular geometry or the cellular volume fraction. Studying the dMRI signal arising from a single neuron can provide insight into how the geometrical structure of neurons influences the measured signal. We formulate the Bloch-Torrey PDE inside a single neuron, under no water exchange condition with the extracellular space, and show how to reduce the 3D simulation in the full neuron to a 3D simulation around the soma and 1D simulations in the neurites. We show that this latter approach is computationally much faster than full 3D simulation and still gives accurate results over a wide range of diffusion times

  14. Hybrid Scheme for Modeling Local Field Potentials from Point-Neuron Networks.

    Science.gov (United States)

    Hagen, Espen; Dahmen, David; Stavrinou, Maria L; Lindén, Henrik; Tetzlaff, Tom; van Albada, Sacha J; Grün, Sonja; Diesmann, Markus; Einevoll, Gaute T

    2016-12-01

    With rapidly advancing multi-electrode recording technology, the local field potential (LFP) has again become a popular measure of neuronal activity in both research and clinical applications. Proper understanding of the LFP requires detailed mathematical modeling incorporating the anatomical and electrophysiological features of neurons near the recording electrode, as well as synaptic inputs from the entire network. Here we propose a hybrid modeling scheme combining efficient point-neuron network models with biophysical principles underlying LFP generation by real neurons. The LFP predictions rely on populations of network-equivalent multicompartment neuron models with layer-specific synaptic connectivity, can be used with an arbitrary number of point-neuron network populations, and allows for a full separation of simulated network dynamics and LFPs. We apply the scheme to a full-scale cortical network model for a ∼1 mm 2 patch of primary visual cortex, predict laminar LFPs for different network states, assess the relative LFP contribution from different laminar populations, and investigate effects of input correlations and neuron density on the LFP. The generic nature of the hybrid scheme and its public implementation in hybridLFPy form the basis for LFP predictions from other and larger point-neuron network models, as well as extensions of the current application with additional biological detail. © The Author 2016. Published by Oxford University Press.

  15. Protracted dendritic growth in the typically developing human amygdala and increased spine density in young ASD brains.

    Science.gov (United States)

    Weir, R K; Bauman, M D; Jacobs, B; Schumann, C M

    2018-02-01

    The amygdala is a medial temporal lobe structure implicated in social and emotional regulation. In typical development (TD), the amygdala continues to increase volumetrically throughout childhood and into adulthood, while other brain structures are stable or decreasing in volume. In autism spectrum disorder (ASD), the amygdala undergoes rapid early growth, making it volumetrically larger in children with ASD compared to TD children. Here we explore: (a) if dendritic arborization in the amygdala follows the pattern of protracted growth in TD and early overgrowth in ASD and (b), if spine density in the amygdala in ASD cases differs from TD from youth to adulthood. The amygdala from 32 postmortem human brains (7-46 years of age) were stained using a Golgi-Kopsch impregnation. Ten principal neurons per case were selected in the lateral nucleus and traced using Neurolucida software in their entirety. We found that both ASD and TD individuals show a similar pattern of increasing dendritic length with age well into adulthood. However, spine density is (a) greater in young ASD cases compared to age-matched TD controls (ASD age into adulthood, a phenomenon not found in TD. Therefore, by adulthood, there is no observable difference in spine density in the amygdala between ASD and TD age-matched adults (≥18 years old). Our findings highlight the unique growth trajectory of the amygdala and suggest that spine density may contribute to aberrant development and function of the amygdala in children with ASD. © 2017 Wiley Periodicals, Inc.

  16. Measurement and analyses of molten Ni-Co alloy density

    Institute of Scientific and Technical Information of China (English)

    XIAO Feng; K. MUKAI; FANG Liang; FU Ya; YANG Ren-hui

    2006-01-01

    With the advent of powerful mathematical modeling techniques for material phenomena, there is renewed interest in reliable data for the density of the Ni-based superalloys. Up to now, there has been few report on the density of molten Ni-Co alloy.In order to obtain more accurate density data for molten Ni-Co alloy, the density of molten Ni-Co alloy was measured with a modified sessile drop method, and the accommodation of different atoms in molten Ni-Co alloy was analyzed. The density of alloy is found to decrease with increasing temperature and Co concentration in the alloy. The molar volume of molten Ni-Co alloy increases with increasing Co concentration. The molar volume of Ni-Co alloy determined shows a positive deviation from the linear molar volume, and the deviation of molar volume from ideal mixing increases with increasing Co concentration over the experimental concentration range.

  17. High density hydrogen research

    International Nuclear Information System (INIS)

    Hawke, R.S.

    1977-01-01

    The interest in the properties of very dense hydrogen is prompted by its abundance in Saturn and Jupiter and its importance in laser fusion studies. Furthermore, it has been proposed that the metallic form of hydrogen may be a superconductor at relatively high temperatures and/or exist in a metastable phase at ambient pressure. For ten years or more, laboratories have been developing the techniques to study hydrogen in the megabar region (1 megabar = 100 GPa). Three major approaches to study dense hydrogen experimentally have been used, static presses, shockwave compression, and magnetic compression. Static tchniques have crossed the megabar threshold in stiff materials but have not yet been convincingly successful in very compressible hydrogen. Single and double shockwave techniques have improved the precision of the pressure, volume, temperature Equation of State (EOS) of molecular hydrogen (deuterium) up to near 1 Mbar. Multiple shockwave and magnetic techniques have compressed hydrogen to several megabars and densities in the range of the metallic phase. The net result is that hydrogen becomes conducting at a pressure between 2 and 4 megabars. Hence, the possibility of making a significant amount of hydrogen into a metal in a static press remains a formidable challenge. The success of such experiments will hopefully answer the questions about hydrogen's metallic vs. conducting molecular phase, superconductivity, and metastability. 4 figures, 15 references

  18. Interstitial cells of the adult neocortical white matter are the remnant of the early generated subplate neuron population

    International Nuclear Information System (INIS)

    Chun, J.J.; Shatz, C.J.

    1989-01-01

    The postnatal fate of the first-generated neurons of the cat cerebral cortex was examined. These neurons can be identified uniquely by 3H-thymidine exposure during the week preceding the neurogenesis of cortical layer 6. Previous studies in which 3H-thymidine birthdating at embryonic day 27 (E27) was combined with immunohistochemistry have shown that these neurons are present in large numbers during fetal and early postnatal life within the subplate (future white matter), that they are immunoreactive for the neuron-specific protein MAP2 and for the putative neurotransmitters GABA, NPY, SRIF, and CCK. Here, the same techniques were used to follow the postnatal location and disappearance of the early generated subplate neuron population. At birth (P0), subplate neurons showing immunoreactivity for GABA, NPY, SRIF, or CCK are present in large numbers and at high density within the white matter throughout the neocortex, and the entire population can be observed as a dense MAP2-immunoreactive band situated beneath cortical layer 6. Between P0 and P401 (adulthood), the MAP2-immunostained band disappears so that comparatively few MAP2-immunoreactive neurons remain within the white matter. There is a corresponding decrease in the number and density of neurons stained with antibodies against neurotransmitters. In each instance, these neurons could be double-labeled by the administration of 3H-thymidine at E27, indicating that they are the remnants of the early generated subplate neuron population. The major period of decrease occurs during the first 4 postnatal weeks, and adult values are attained by 5 months. Within the white matter of the lateral gyrus (visual cortex), the density of immunostained neurons decreases dramatically: MAP2, 82%, SRIF, 81%, and NPY, 96%

  19. Individualized volume CT dose index determined by cross-sectional area and mean density of the body to achieve uniform image noise of contrast-enhanced pediatric chest CT obtained at variable kV levels and with combined tube current modulation

    Energy Technology Data Exchange (ETDEWEB)

    Goo, Hyun Woo [University of Ulsan College of Medicine, Department of Radiology and Research Institute of Radiology, Asan Medical Center, Seoul (Korea, Republic of)

    2011-07-15

    A practical body-size adaptive protocol providing uniform image noise at various kV levels is not available for pediatric CT. To develop a practical contrast-enhanced pediatric chest CT protocol providing uniform image noise by using an individualized volume CT dose index (CTDIvol) determined by the cross-sectional area and density of the body at variable kV levels and with combined tube current modulation. A total of 137 patients (mean age, 7.6 years) underwent contrast-enhanced pediatric chest CT based on body weight. From the CTDIvol, image noise, and area and mean density of the cross-section at the lung base in the weight-based group, the best fit equation was estimated with a very high correlation coefficient ({gamma}{sup 2} = 0.86, P < 0.001). For the next study, 177 patients (mean age, 7.9 years; the CTDIvol group) underwent contrast-enhanced pediatric chest CT with the CTDIvol determined individually by the best fit equation. CTDIvol values on the dose report after CT scanning, noise differences from the target noise, areas, and mean densities were compared between these two groups. The CTDIvol values (mean{+-}standard deviation, 1.6 {+-} 0.7 mGy) and the noise differences from the target noise (1.1 {+-} 0.9 HU) of the CTDIvol group were significantly lower than those of the weight-based group (2.0 {+-} 1.0 mGy, 1.8 {+-} 1.4 HU) (P < 0.001). In contrast, no statistically significant difference was found in area (317.0 {+-} 136.8 cm{sup 2} vs. 326.3 {+-} 124.8 cm{sup 2}), mean density (-212.9 {+-} 53.1 HU vs. -221.1 {+-} 56.3 HU), and image noise (13.8 {+-} 2.3 vs. 13.6 {+-} 1.7 HU) between the weight-based and the CTDIvol groups (P > 0.05). Contrast-enhanced pediatric chest CT with the CTDIvol determined individually by the cross-sectional area and density of the body provides more uniform noise and better dose adaptation to body habitus than does weight-based CT at variable kV levels and with combined tube current modulation. (orig.)

  20. Turning skin into dopamine neurons

    Institute of Scientific and Technical Information of China (English)

    Malin Parmar; Johan Jakobsson

    2011-01-01

    The possibility to generate neurons from fibroblasts became a reality with the development of iPS technology a few years ago.By reprogramming somatic cells using transcription factor (TF) overexpression,it is possible to generate pluripotent stem cells that then can be differentiated into any somatic cell type including various subtypes of neurons.This raises the possibility of using donor-matched or even patientspecific cells for cell therapy of neurological disorders such as Parkinson's disease (PD),Huntington's disease and stroke.Supporting this idea,dopamine neurons,which are the cells dying in PD,derived from human iPS cells have been demonstrated to survive transplantation and reverse motor symptoms in animal models of PD [1].

  1. Neuronal involvement in cisplatin neuropathy

    DEFF Research Database (Denmark)

    Krarup-Hansen, A; Helweg-Larsen, Susanne Elisabeth; Schmalbruch, H

    2007-01-01

    of large dorsal root ganglion cells. Motor conduction studies, autonomic function and warm and cold temperature sensation remained unchanged at all doses of cisplatin treatment. The results of these studies are consistent with degeneration of large sensory neurons whereas there was no evidence of distal......Although it is well known that cisplatin causes a sensory neuropathy, the primary site of involvement is not established. The clinical symptoms localized in a stocking-glove distribution may be explained by a length dependent neuronopathy or by a distal axonopathy. To study whether the whole neuron...

  2. Calcium signals in olfactory neurons.

    Science.gov (United States)

    Tareilus, E; Noé, J; Breer, H

    1995-11-09

    Laser scanning confocal microscopy in combination with the fluorescent calcium indicators Fluo-3 and Fura-Red was employed to estimate the intracellular concentration of free calcium ions in individual olfactory receptor neurons and to monitor temporal and spatial changes in the Ca(2+)-level upon stimulation. The chemosensory cells responded to odorants with a significant increase in the calcium concentration, preferentially in the dendritic knob. Applying various stimulation paradigma, it was found that in a population of isolated cells, subsets of receptor neurons display distinct patterns of responsiveness.

  3. A national and international analysis of changing forest density.

    Directory of Open Access Journals (Sweden)

    Aapo Rautiainen

    Full Text Available Like cities, forests grow by spreading out or by growing denser. Both inventories taken steadily by a single nation and other inventories gathered recently from many nations by the United Nations confirm the asynchronous effects of changing area and of density or volume per hectare. United States forests spread little after 1953, while growing density per hectare increased national volume and thus sequestered carbon. The 2010 United Nations appraisal of global forests during the briefer span of two decades after 1990 reveals a similar pattern: A slowing decline of area with growing volume means growing density in 68 nations encompassing 72% of reported global forest land and 68% of reported global carbon mass. To summarize, the nations were placed in 5 regions named for continents. During 1990-2010 national density grew unevenly, but nevertheless grew in all regions. Growing density was responsible for substantially increasing sequestered carbon in the European and North American regions, despite smaller changes in area. Density nudged upward in the African and South American regions as area loss outstripped the loss of carbon. For the Asian region, density grew in the first decade and fell slightly in the second as forest area expanded. The different courses of area and density disqualify area as a proxy for volume and carbon. Applying forestry methods traditionally used to measure timber volumes still offers a necessary route to measuring carbon stocks. With little expansion of forest area, managing for timber growth and density offered a way to increase carbon stocks.

  4. Acetaminophen inhibits neuronal inflammation and protects neurons from oxidative stress

    Directory of Open Access Journals (Sweden)

    Grammas Paula

    2009-03-01

    Full Text Available Abstract Background Recent studies have demonstrated a link between the inflammatory response, increased cytokine formation, and neurodegeneration in the brain. The beneficial effects of anti-inflammatory drugs in neurodegenerative diseases, such as Alzheimer's disease (AD, have been documented. Increasing evidence suggests that acetaminophen has unappreciated anti-oxidant and anti-inflammatory properties. The objectives of this study are to determine the effects of acetaminophen on cultured brain neuronal survival and inflammatory factor expression when exposed to oxidative stress. Methods Cerebral cortical cultured neurons are pretreated with acetaminophen and then exposed to the superoxide-generating compound menadione (5 μM. Cell survival is assessed by MTT assay and inflammatory protein (tumor necrosis factor alpha, interleukin-1, macrophage inflammatory protein alpha, and RANTES release quantitated by ELISA. Expression of pro- and anti-apoptotic proteins is assessed by western blots. Results Acetaminophen has pro-survival effects on neurons in culture. Menadione, a superoxide releasing oxidant stressor, causes a significant (p Conclusion These data show that acetaminophen has anti-oxidant and anti-inflammatory effects on neurons and suggest a heretofore unappreciated therapeutic potential for this drug in neurodegenerative diseases such as AD that are characterized by oxidant and inflammatory stress.

  5. Neuronal coherence and its functional role in communication between neurons

    NARCIS (Netherlands)

    Zeitler-Geurds, M.

    2010-01-01

    Neuronal oscillations are observed in many brain areas in various frequency bands. Each of the frequency bands is associated with a particular functional role. Gamma oscillations (30-80 Hz) are thought to be related to cognitive tasks like memory and attention and possibly also involved in the

  6. Postresuscitative Changes of Brain-Derived Neurotrophic Factor (BDNF Protein Expression: Association With Neuronal Death

    Directory of Open Access Journals (Sweden)

    M. Sh. Avrushchenko

    2017-01-01

    Full Text Available Aim of the study: to evaluate expression level of BDNF and its association with the postresuscitative neuronal death in highly hypoxia-sensitive brain regions.Materials and methods. Cardiac arrest in adult albino male rats was evoked by intrathoracic clamping of supracardiac bundle of vessels for 10 min. Pyramidal neurons of the hippocampus and Purkinje cells of the cerebellum were analyzed at various time points after resuscitation (days 1, 4, 7, 14. Shame-operated rats served as controls. The expression of BDNF protein was immunohistochemically determined. The BDNF expression level was determined by evalution on the base of the average optical density. The number of neurons with different BDNF expression levels and the total number of neurons per 1 mm of the layer length were computed. Image analysis systems (Intel personal computer, Olympus BX-41 microscope, ImageScopeM, ImageJ 1,48v and MS Excel 2007 software packages were used in the study. Data statistical processing was performed with the aid of Statistica 7.0 program and Kolmogorov-Smirnov λ-test, Mann-Whitney U-test and Student's t-test.Results. The dynamics of postresuscitative shifts of BDNF immunoreactivity in neuronal populations of hippocampal pyramidal cells and cerebellar Purkinje cells was established. It was shown that the level of BDNF expression within the two neuronal populations decreased, that was accompanied by neuronal death. In the Purkinje cell population the neuronal death occurred by the 4th day after resuscitation, while in the hippocampus, it occurs only by the 7th day. Notably, only BDNF-negative neurons or neurons with low level of BDNF expression died in both neuronal populations.Conclusion. The results of the study indicate the existence of an interrelation between the shifts in BDNF expression and the postresuscitative neuronal death. It was shown that only the cells with none or poor BDNF expression underwent death in highly hypoxia-sensitive neuronal

  7. Relating neuronal firing patterns to functional differentiation of cerebral cortex.

    Directory of Open Access Journals (Sweden)

    Shigeru Shinomoto

    2009-07-01

    Full Text Available It has been empirically established that the cerebral cortical areas defined by Brodmann one hundred years ago solely on the basis of cellular organization are closely correlated to their function, such as sensation, association, and motion. Cytoarchitectonically distinct cortical areas have different densities and types of neurons. Thus, signaling patterns may also vary among cytoarchitectonically unique cortical areas. To examine how neuronal signaling patterns are related to innate cortical functions, we detected intrinsic features of cortical firing by devising a metric that efficiently isolates non-Poisson irregular characteristics, independent of spike rate fluctuations that are caused extrinsically by ever-changing behavioral conditions. Using the new metric, we analyzed spike trains from over 1,000 neurons in 15 cortical areas sampled by eight independent neurophysiological laboratories. Analysis of firing-pattern dissimilarities across cortical areas revealed a gradient of firing regularity that corresponded closely to the functional category of the cortical area; neuronal spiking patterns are regular in motor areas, random in the visual areas, and bursty in the prefrontal area. Thus, signaling patterns may play an important role in function-specific cerebral cortical computation.

  8. High density energy storage capacitor

    International Nuclear Information System (INIS)

    Whitham, K.; Howland, M.M.; Hutzler, J.R.

    1979-01-01

    The Nova laser system will use 130 MJ of capacitive energy storage and have a peak power capability of 250,000 MW. This capacitor bank is a significant portion of the laser cost and requires a large portion of the physical facilities. In order to reduce the cost and volume required by the bank, the Laser Fusion Program funded contracts with three energy storage capacitor producers: Aerovox, G.E., and Maxwell Laboratories, to develop higher energy density, lower cost energy storage capacitors. This paper describes the designs which resulted from the Aerovox development contract, and specifically addresses the design and initial life testing of a 12.5 kJ, 22 kV capacitor with a density of 4.2 J/in 3 and a projected cost in the range of 5 cents per joule

  9. Growth of cortical neuronal network in vitro: Modeling and analysis

    International Nuclear Information System (INIS)

    Lai, P.-Y.; Jia, L. C.; Chan, C. K.

    2006-01-01

    We present a detailed analysis and theoretical growth models to account for recent experimental data on the growth of cortical neuronal networks in vitro [Phys. Rev. Lett. 93, 088101 (2004)]. The experimentally observed synchronized firing frequency of a well-connected neuronal network is shown to be proportional to the mean network connectivity. The growth of the network is consistent with the model of an early enhanced growth of connection, but followed by a retarded growth once the synchronized cluster is formed. Microscopic models with dominant excluded volume interactions are consistent with the observed exponential decay of the mean connection probability as a function of the mean network connectivity. The biological implications of the growth model are also discussed

  10. X-ray measurements of water fog density

    International Nuclear Information System (INIS)

    Camp, A.L.

    1982-11-01

    Water-fog densities were measured in a laboratory experiment using x-ray diagnostics. Fog densities were measured, varying the flow rate, nozzle type, nozzle configuration, nozzle height above the x-ray beam, and water surface tension. Suspended water volume fractions between 0.0008 and 0.0074 percent were measured. The fog density increases approximately as the square root of the flow rate; the other parameters had little effect on the density

  11. Laboratory Density Functionals

    OpenAIRE

    Giraud, B. G.

    2007-01-01

    We compare several definitions of the density of a self-bound system, such as a nucleus, in relation with its center-of-mass zero-point motion. A trivial deconvolution relates the internal density to the density defined in the laboratory frame. This result is useful for the practical definition of density functionals.

  12. The Fourier transform of tubular densities

    KAUST Repository

    Prior, C B

    2012-05-18

    We consider the Fourier transform of tubular volume densities, with arbitrary axial geometry and (possibly) twisted internal structure. This density can be used to represent, among others, magnetic flux or the electron density of biopolymer molecules. We consider tubes of both finite radii and unrestricted radius. When there is overlap of the tube structure the net density is calculated using the super-position principle. The Fourier transform of this density is composed of two expressions, one for which the radius of the tube is less than the curvature of the axis and one for which the radius is greater (which must have density overlap). This expression can accommodate an asymmetric density distribution and a tube structure which has non-uniform twisting. In addition we give several simpler expressions for isotropic densities, densities of finite radius, densities which decay at a rate sufficient to minimize local overlap and finally individual surfaces of the tube manifold. These simplified cases can often be expressed as arclength integrals and can be evaluated using a system of first-order ODEs. © 2012 IOP Publishing Ltd.

  13. The Fourier transform of tubular densities

    International Nuclear Information System (INIS)

    Prior, C B; Goriely, A

    2012-01-01

    We consider the Fourier transform of tubular volume densities, with arbitrary axial geometry and (possibly) twisted internal structure. This density can be used to represent, among others, magnetic flux or the electron density of biopolymer molecules. We consider tubes of both finite radii and unrestricted radius. When there is overlap of the tube structure the net density is calculated using the super-position principle. The Fourier transform of this density is composed of two expressions, one for which the radius of the tube is less than the curvature of the axis and one for which the radius is greater (which must have density overlap). This expression can accommodate an asymmetric density distribution and a tube structure which has non-uniform twisting. In addition we give several simpler expressions for isotropic densities, densities of finite radius, densities which decay at a rate sufficient to minimize local overlap and finally individual surfaces of the tube manifold. These simplified cases can often be expressed as arclength integrals and can be evaluated using a system of first-order ODEs. (paper)

  14. Fluid Density and Impact Cavity Formation

    Directory of Open Access Journals (Sweden)

    Ga-Chun Lin

    2018-01-01

    Full Text Available Characteristics of the impact cavity formed when a steel ball is dropped into aqueous solutions of densities ranging from 0.98 g·cm-3 to 1.63 g·cm-3 were investigated. A high-speed camera was used to record the formation and collapse of the cavity. The results showed cavity diameter, volume, and pinch-off time are independent of fluid density, on average. There was an unexplained reduction in cavity formation for densities of 1.34 g·cm-3 and 1.45 g·cm-3.

  15. Increased gray matter volume of left pars opercularis in male orchestral musicians correlate positively with years of musical performance.

    Science.gov (United States)

    Abdul-Kareem, Ihssan A; Stancak, Andrej; Parkes, Laura M; Sluming, Vanessa

    2011-01-01

    To compare manual volumetry of gray matter (GM) / white matter (WM) of Broca's area subparts: pars opercularis (POP) and pars triangularis (PTR) in both hemispheres between musicians and nonmusician, as it has been shown that these regions are crucial for musical abilities. A previous voxel-based morphometric (VBM) study conducted in our laboratory reported increased GM density in Broca's area of left hemisphere in male orchestral musicians. Functional segregation of POP/PTR justified separate volumetric analysis of these parts. We used the same cohort for the VBM study. Manual morphometry (stereology) was used to compare volumes between 26/26 right-handed orchestral musicians/nonmusicians. As expected, musicians showed significantly increased GM volume in the Broca's area, specifically in the left POP. No significant results were detected in right POP, left/right PTR GM volumes, and WM volumes for all regions. Results were positively correlated with years of musical performance (r = 0.7, P = 0.0001). This result corroborates the VBM study and is in line with the hypothesis of critical involvement of POP in hearing-action integration being an integral component of frontoparietotemporal mirror neuron network. We hypothesize that increased size of musicians' left POP represent use-dependent structural adaptation in response to intensive audiomotor skill acquisition. Copyright © 2010 Wiley-Liss, Inc.

  16. Effects of Cerebral Ischemia in Mice Deficient in Neuronal Nitric Oxide Synthase

    Science.gov (United States)

    Huang, Zhihong; Huang, Paul L.; Panahian, Nariman; Dalkara, Turgay; Fishman, Mark C.; Moskowitz, Michael A.

    1994-09-01

    The proposal that nitric oxide (NO) or its reactant products mediate toxicity in brain remains controversial in part because of the use of nonselective agents that block NO formation in neuronal, glial, and vascular compartments. In mutant mice deficient in neuronal NO synthase (NOS) activity, infarct volumes decreased significantly 24 and 72 hours after middle cerebral artery occlusion, and the neurological deficits were less than those in normal mice. This result could not be accounted for by differences in blood flow or vascular anatomy. However, infarct size in the mutant became larger after endothelial NOS inhibition by nitro-L-arginine administration. Hence, neuronal NO production appears to exacerbate acute ischemic injury, whereas vascular NO protects after middle cerebral artery occlusion. The data emphasize the importance of developing selective inhibitors of the neuronal isoform.

  17. Prenatal Nicotine Exposure Impairs the Proliferation of Neuronal Progenitors, Leading to Fewer Glutamatergic Neurons in the Medial Prefrontal Cortex

    Science.gov (United States)

    Aoyama, Yuki; Toriumi, Kazuya; Mouri, Akihiro; Hattori, Tomoya; Ueda, Eriko; Shimato, Akane; Sakakibara, Nami; Soh, Yuka; Mamiya, Takayoshi; Nagai, Taku; Kim, Hyoung-Chun; Hiramatsu, Masayuki; Nabeshima, Toshitaka; Yamada, Kiyofumi

    2016-01-01

    Cigarette smoking during pregnancy is associated with various disabilities in the offspring such as attention deficit/hyperactivity disorder, learning disabilities, and persistent anxiety. We have reported that nicotine exposure in female mice during pregnancy, in particular from embryonic day 14 (E14) to postnatal day 0 (P0), induces long-lasting behavioral deficits in offspring. However, the mechanism by which prenatal nicotine exposure (PNE) affects neurodevelopment, resulting in behavioral deficits, has remained unclear. Here, we report that PNE disrupted the proliferation of neuronal progenitors, leading to a decrease in the progenitor pool in the ventricular and subventricular zones. In addition, using a cumulative 5-bromo-2′-deoxyuridine labeling assay, we evaluated the rate of cell cycle progression causing the impairment of neuronal progenitor proliferation, and uncovered anomalous cell cycle kinetics in mice with PNE. Accordingly, the density of glutamatergic neurons in the medial prefrontal cortex (medial PFC) was reduced, implying glutamatergic dysregulation. Mice with PNE exhibited behavioral impairments in attentional function and behavioral flexibility in adulthood, and the deficits were ameliorated by microinjection of D-cycloserine into the PFC. Collectively, our findings suggest that PNE affects the proliferation and maturation of progenitor cells to glutamatergic neuron during neurodevelopment in the medial PFC, which may be associated with cognitive deficits in the offspring. PMID:26105135

  18. Unbalanced Neuronal Circuits in Addiction

    OpenAIRE

    Volkow, Nora D.; Wang, Gen-Jack; Tomasi, Dardo; Baler, Ruben D.

    2013-01-01

    Through sequential waves of drug-induced neurochemical stimulation, addiction co-opts the brain's neuronal circuits that mediate reward, motivation, , to behavioral inflexibility and a severe disruption of self-control and compulsive drug intake. Brain imaging technologies have allowed neuroscientists to map out the neural landscape of addiction in the human brain and to understand how drugs modify it.

  19. Computing with Spiking Neuron Networks

    NARCIS (Netherlands)

    H. Paugam-Moisy; S.M. Bohte (Sander); G. Rozenberg; T.H.W. Baeck (Thomas); J.N. Kok (Joost)

    2012-01-01

    htmlabstractAbstract Spiking Neuron Networks (SNNs) are often referred to as the 3rd gener- ation of neural networks. Highly inspired from natural computing in the brain and recent advances in neurosciences, they derive their strength and interest from an ac- curate modeling of synaptic interactions

  20. What do mirror neurons mirror?

    NARCIS (Netherlands)

    Uithol, S.; Rooij, I.J.E.I. van; Bekkering, H.; Haselager, W.F.G.

    2011-01-01

    Single cell recordings in monkeys provide strong evidence for an important role of the motor system in action understanding. This evidence is backed up by data from studies of the (human) mirror neuron system using neuroimaging or TMS techniques, and behavioral experiments. Although the data

  1. Optimal compensation for neuron loss

    Science.gov (United States)

    Barrett, David GT; Denève, Sophie; Machens, Christian K

    2016-01-01

    The brain has an impressive ability to withstand neural damage. Diseases that kill neurons can go unnoticed for years, and incomplete brain lesions or silencing of neurons often fail to produce any behavioral effect. How does the brain compensate for such damage, and what are the limits of this compensation? We propose that neural circuits instantly compensate for neuron loss, thereby preserving their function as much as possible. We show that this compensation can explain changes in tuning curves induced by neuron silencing across a variety of systems, including the primary visual cortex. We find that compensatory mechanisms can be implemented through the dynamics of networks with a tight balance of excitation and inhibition, without requiring synaptic plasticity. The limits of this compensatory mechanism are reached when excitation and inhibition become unbalanced, thereby demarcating a recovery boundary, where signal representation fails and where diseases may become symptomatic. DOI: http://dx.doi.org/10.7554/eLife.12454.001 PMID:27935480

  2. Hypothalamic neurones governing glucose homeostasis.

    Science.gov (United States)

    Coppari, R

    2015-06-01

    The notion that the brain directly controls the level of glucose in the blood (glycaemia) independent of its known action on food intake and body weight has been known ever since 1849. That year, the French physiologist Dr Claude Bernard reported that physical puncture of the floor of the fourth cerebral ventricle rapidly leads to an increased level of sugar in the blood (and urine) in rabbits. Despite this important discovery, it took approximately 150 years before significant efforts aimed at understanding the underlying mechanism of brain-mediated control of glucose metabolism were made. Technological developments allowing for genetically-mediated manipulation of selected molecular pathways in a neurone-type-specific fashion unravelled the importance of specific molecules in specific neuronal populations. These neuronal pathways govern glucose metabolism in the presence and even in the absence of insulin. Also, a peculiarity of these pathways is that certain biochemically-defined neurones govern glucose metabolism in a tissue-specific fashion. © 2015 British Society for Neuroendocrinology.

  3. Large-scale Exploration of Neuronal Morphologies Using Deep Learning and Augmented Reality.

    Science.gov (United States)

    Li, Zhongyu; Butler, Erik; Li, Kang; Lu, Aidong; Ji, Shuiwang; Zhang, Shaoting

    2018-02-12

    Recently released large-scale neuron morphological data has greatly facilitated the research in neuroinformatics. However, the sheer volume and complexity of these data pose significant challenges for efficient and accurate neuron exploration. In this paper, we propose an effective retrieval framework to address these problems, based on frontier techniques of deep learning and binary coding. For the first time, we develop a deep learning based feature representation method for the neuron morphological data, where the 3D neurons are first projected into binary images and then learned features using an unsupervised deep neural network, i.e., stacked convolutional autoencoders (SCAEs). The deep features are subsequently fused with the hand-crafted features for more accurate representation. Considering the exhaustive search is usually very time-consuming in large-scale databases, we employ a novel binary coding method to compress feature vectors into short binary codes. Our framework is validated on a public data set including 58,000 neurons, showing promising retrieval precision and efficiency compared with state-of-the-art methods. In addition, we develop a novel neuron visualization program based on the techniques of augmented reality (AR), which can help users take a deep exploration of neuron morphologies in an interactive and immersive manner.

  4. Direct effects of endogenous pyrogen on medullary temperature-responsive neurons in rabbits.

    Science.gov (United States)

    Sakata, Y; Morimoto, A; Takase, Y; Murakami, N

    1981-01-01

    The effect of endogenous pyrogen (E.P.) injected directly into the tissue near the recording site were examined on the activities of the medullary temperature-responsive (TR) neurons in rabbits anesthetized with urethane. Endogenous pyrogen prepared from rabbit's whole blood was administered by a fine glass cannula (100-200 micrometer in diameter) in a fluid volume of 1 to 4 microliter. The cannula was fixed to the manipulator in parallel with a microelectrode and their tips were less than 0.05 mm apart. In rabbits with the intact preoptic/anterior hypothalamic (PO/AH) region, 4 warm-responsive neurons out of 7 were inhibited and 6 cold-responsive neuron out of 7 were excited by the direct administration of the E.P. In rabbits with lesions of the PO/AH, 5 warm-responsive neurons out of 9 were inhibited and 6 cold-responsive neurons out of 8 were facilitated by E.P. Antipyretics administered locally after the E.P. antagonized the pyretic effect, causing a return of the discharge of TR neuron to the control rate within 2.4 +/- 1.2 (mean +/- S.D.) min. The medullary TR neuron itself has the ability to respond to the E.P. and contributes to the development of fever.

  5. A Comparative study for striatal-direct and -indirect pathway neurons to DA depletion-induced lesion in a PD rat model.

    Science.gov (United States)

    Zheng, Xuefeng; Wu, Jiajia; Zhu, Yaofeng; Chen, Si; Chen, Zhi; Chen, Tao; Huang, Ziyun; Wei, Jiayou; Li, Yanmei; Lei, Wanlong

    2018-04-16

    Striatal-direct and -indirect Pathway Neurons showed different vulnerability in basal ganglia disorders. Therefore, present study aimed to examine and compare characteristic changes of densities, protein and mRNA levels of soma, dendrites, and spines between striatal-direct and -indirect pathway neurons after DA depletion by using immunohistochemistry, Western blotting, real-time PCR and immunoelectron microscopy techniques. Experimental results showed that: 1) 6OHDA-induced DA depletion decreased the soma density of striatal-direct pathway neurons (SP+), but no significant changes for striatal-indirect pathway neurons (ENK+). 2) DA depletion resulted in a decline of dendrite density for both striatal-direct (D1+) and -indirect (D2+) pathway neurons, and D2+ dendritic density declined more obviously. At the ultrastructure level, the densities of D1+ and D2+ dendritic spines reduced in the 6OHDA groups compared with their control groups, but the density of D2+ dendritic spines reduced more significant than that of D1. 3) Striatal DA depletion down-regulated protein and mRNA expression levels of SP and D1, on the contrary, ENK and D2 protein and mRNA levels of indirect pathway neurons were up-regulated significantly. Present results suggested that indirect pathway neurons be more sensitive to 6OHDA-induced DA depletion. Copyright © 2018 Elsevier Ltd. All rights reserved.

  6. Homeostatic regulation of excitatory synapses on striatal medium spiny neurons expressing the D2 dopamine receptor.

    Science.gov (United States)

    Thibault, Dominic; Giguère, Nicolas; Loustalot, Fabien; Bourque, Marie-Josée; Ducrot, Charles; El Mestikawy, Salah; Trudeau, Louis-Éric

    2016-05-01

    Striatal medium spiny neurons (MSNs) are contacted by glutamatergic axon terminals originating from cortex, thalamus and other regions. The striatum is also innervated by dopaminergic (DAergic) terminals, some of which release glutamate as a co-transmitter. Despite evidence for functional DA release at birth in the striatum, the role of DA in the establishment of striatal circuitry is unclear. In light of recent work suggesting activity-dependent homeostatic regulation of glutamatergic terminals on MSNs expressing the D2 DA receptor (D2-MSNs), we used primary co-cultures to test the hypothesis that stimulation of DA and glutamate receptors regulates the homeostasis of glutamatergic synapses on MSNs. Co-culture of D2-MSNs with mesencephalic DA neurons or with cortical neurons produced an increase in spines and functional glutamate synapses expressing VGLUT2 or VGLUT1, respectively. The density of VGLUT2-positive terminals was reduced by the conditional knockout of this gene from DA neurons. In the presence of both mesencephalic and cortical neurons, the density of synapses reached the same total, compatible with the possibility of a homeostatic mechanism capping excitatory synaptic density. Blockade of D2 receptors increased the density of cortical and mesencephalic glutamatergic terminals, without changing MSN spine density or mEPSC frequency. Combined blockade of AMPA and NMDA glutamate receptors increased the density of cortical terminals and decreased that of mesencephalic VGLUT2-positive terminals, with no net change in total excitatory terminal density or in mEPSC frequency. These results suggest that DA and glutamate signaling regulate excitatory inputs to striatal D2-MSNs at both the pre- and postsynaptic level, under the influence of a homeostatic mechanism controlling functional output of the circuit.

  7. CORRELATION BETWEEN GROUP LOCAL DENSITY AND GROUP LUMINOSITY

    Energy Technology Data Exchange (ETDEWEB)

    Deng Xinfa [School of Science, Nanchang University, Jiangxi 330031 (China); Yu Guisheng [Department of Natural Science, Nanchang Teachers College, Jiangxi 330103 (China)

    2012-11-10

    In this study, we investigate the correlation between group local number density and total luminosity of groups. In four volume-limited group catalogs, we can conclude that groups with high luminosity exist preferentially in high-density regions, while groups with low luminosity are located preferentially in low-density regions, and that in a volume-limited group sample with absolute magnitude limit M{sub r} = -18, the correlation between group local number density and total luminosity of groups is the weakest. These results basically are consistent with the environmental dependence of galaxy luminosity.

  8. Volume and biomass for curlleaf cercocarpus in Nevada

    Science.gov (United States)

    David C. Chojnacky

    1984-01-01

    Volume and biomass equations were developed for curlleaf cercocarpus (Cercocarpus ledifolius Nutt.) in the Egan and Schell Mountains near Ely, NV. The equations predict cubic foot volume of wood and bark for variable minimum branch diameters. Wood density factors are given to convert volume predictions to pounds of fiber biomass. The reliability of...

  9. Hyperpolarization-activated current (In is reduced in hippocampal neurons from Gabra5-/- mice.

    Directory of Open Access Journals (Sweden)

    Robert P Bonin

    Full Text Available Changes in the expression of γ-aminobutyric acid type A (GABAA receptors can either drive or mediate homeostatic alterations in neuronal excitability. A homeostatic relationship between α5 subunit-containing GABAA (α5GABAA receptors that generate a tonic inhibitory conductance, and HCN channels that generate a hyperpolarization-activated cation current (Ih was recently described for cortical neurons, where a reduction in Ih was accompanied by a reciprocal increase in the expression of α5GABAA receptors resulting in the preservation of dendritosomatic synaptic function. Here, we report that in mice that lack the α5 subunit gene (Gabra5-/-, cultured embryonic hippocampal pyramidal neurons and ex vivo CA1 hippocampal neurons unexpectedly exhibited a decrease in Ih current density (by 40% and 28%, respectively, compared with neurons from wild-type (WT mice. The resting membrane potential and membrane hyperpolarization induced by blockade of Ih with ZD-7288 were similar in cultured WT and Gabra5-/- neurons. In contrast, membrane hyperpolarization measured after a train of action potentials was lower in Gabra5-/- neurons than in WT neurons. Also, membrane impedance measured in response to low frequency stimulation was greater in cultured Gabra5-/- neurons. Finally, the expression of HCN1 protein that generates Ih was reduced by 41% in the hippocampus of Gabra5-/- mice. These data indicate that loss of a tonic GABAergic inhibitory conductance was followed by a compensatory reduction in Ih. The results further suggest that the maintenance of resting membrane potential is preferentially maintained in mature and immature hippocampal neurons through the homeostatic co-regulation of structurally and biophysically distinct cation and anion channels.

  10. BlastNeuron for Automated Comparison, Retrieval and Clustering of 3D Neuron Morphologies.

    Science.gov (United States)

    Wan, Yinan; Long, Fuhui; Qu, Lei; Xiao, Hang; Hawrylycz, Michael; Myers, Eugene W; Peng, Hanchuan

    2015-10-01

    Characterizing the identity and types of neurons in the brain, as well as their associated function, requires a means of quantifying and comparing 3D neuron morphology. Presently, neuron comparison methods are based on statistics from neuronal morphology such as size and number of branches, which are not fully suitable for detecting local similarities and differences in the detailed structure. We developed BlastNeuron to compare neurons in terms of their global appearance, detailed arborization patterns, and topological similarity. BlastNeuron first compares and clusters 3D neuron reconstructions based on global morphology features and moment invariants, independent of their orientations, sizes, level of reconstruction and other variations. Subsequently, BlastNeuron performs local alignment between any pair of retrieved neurons via a tree-topology driven dynamic programming method. A 3D correspondence map can thus be generated at the resolution of single reconstruction nodes. We applied BlastNeuron to three datasets: (1) 10,000+ neuron reconstructions from a public morphology database, (2) 681 newly and manually reconstructed neurons, and (3) neurons reconstructions produced using several independent reconstruction methods. Our approach was able to accurately and efficiently retrieve morphologically and functionally similar neuron structures from large morphology database, identify the local common structures, and find clusters of neurons that share similarities in both morphology and molecular profiles.

  11. The saucor, a new stereological tool for analysing the spatial distributions of cells, exemplified by human neocortical neurons and glial cells

    DEFF Research Database (Denmark)

    Stark, Anette K.; Gundersen, Hans Jørgen Gottlieb; Gardi, Jonathan Eyal

    The three dimensional spatial arrangement of particles or cells, for example glial cells, with respect to other particles or cells, for example neurons, can be characterized by the radial number density function, which expresses the number density of so called “secondary” particles as a function....... Estimation formulae based on the Horvitz-Thompson theorem are derived for both IUR and VUR designs. The method is illustrated with an example where the radial number density of neurons and glial cells around neurons in the human neocortex is estimated using thick vertical sections for light microscopy....... The results indicate that the glial cells are clustered around the neurons and the neurons have a tendency towards repulsion from each other....

  12. The saucor, a new stereological tool for analysing the spatial distributions of cells, exemplified by human neocortical neurons and glial cells

    DEFF Research Database (Denmark)

    Stark, Anette K; Gundersen, Hans Jørgen Gottlieb; Gardi, Jonathan Eyal

    2011-01-01

    The 3D spatial arrangement of particles or cells, for example glial cells, with respect to other particles or cells, for example neurons, can be characterized by the radial number density function, which expresses the number density of so-called ‘secondary’ particles as a function of their distance...... formulae based on the Horvitz–Thompson theorem are derived for both isotropic uniform random and vertical uniform random designs. The method is illustrated with an example where the radial number density of neurons and glial cells around neurons in the human neocortex is estimated using thick vertical...... sections for light microscopy. The results indicate that the glial cells are clustered around the neurons and the neurons have a tendency towards repulsion from each other....

  13. Density-dependence of functional spiking networks in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Ham, Michael I [Los Alamos National Laboratory; Gintautuas, Vadas [Los Alamos National Laboratory; Rodriguez, Marko A [Los Alamos National Laboratory; Bettencourt, Luis M A [Los Alamos National Laboratory; Bennett, Ryan [UNIV OF NORTH TEXAS; Santa Maria, Cara L [UNIV OF NORTH TEXAS

    2008-01-01

    During development, the mammalian brain differentiates into specialized regions with unique functional abilities. While many factors contribute to this functional specialization, we explore the effect neuronal density can have on neuronal interactions. Two types of networks, dense (50,000 neurons and glia support cells) and sparse (12,000 neurons and glia support cells), are studied. A competitive first response model is applied to construct activation graphs that represent pairwise neuronal interactions. By observing the evolution of these graphs during development in vitro we observe that dense networks form activation connections earlier than sparse networks, and that link-!llltropy analysis of the resulting dense activation graphs reveals that balanced directional connections dominate. Information theoretic measures reveal in addition that early functional information interactions (of order 3) are synergetic in both dense and sparse networks. However, during development in vitro, such interactions become redundant in dense, but not sparse networks. Large values of activation graph link-entropy correlate strongly with redundant ensembles observed in the dense networks. Results demonstrate differences between dense and sparse networks in terms of informational groups, pairwise relationships, and activation graphs. These differences suggest that variations in cell density may result in different functional specialization of nervous system tissue also in vivo.

  14. Oscillating from Neurosecretion to Multitasking Dopamine Neurons

    Directory of Open Access Journals (Sweden)

    David R. Grattan

    2016-04-01

    Full Text Available In this issue of Cell Reports, Stagkourakis et al. (2016 report that oscillating hypothalamic TIDA neurons, previously thought to be simple neurosecretory neurons controlling pituitary prolactin secretion, control dopamine output via autoregulatory mechanisms and thus could potentially regulate other physiologically important hypothalamic neuronal circuits.

  15. Densities of carbon foils

    International Nuclear Information System (INIS)

    Stoner, J.O. Jr.

    1991-01-01

    The densities of arc-evaporated carbon target foils have been measured by several methods. The density depends upon the method used to measure it; for the same surface density, values obtained by different measurement techniques may differ by fifty percent or more. The most reliable density measurements are by flotation, yielding a density of 2.01±0.03 g cm -3 , and interferometric step height with the surface density known from auxiliary measurements, yielding a density of 2.61±0.4 g cm -3 . The difference between these density values mayy be due in part to the compressive stresses that carbon films have while still on their substrates, uncertainties in the optical calibration of surface densities of carbon foils, and systematic errors in step-height measurements. Mechanical thickness measurements by micrometer caliper are unreliable due to nonplanarity of these foils. (orig.)

  16. Stochastic optimal control of single neuron spike trains

    DEFF Research Database (Denmark)

    Iolov, Alexandre; Ditlevsen, Susanne; Longtin, Andrë

    2014-01-01

    stimulation of a neuron to achieve a target spike train under the physiological constraint to not damage tissue. Approach. We pose a stochastic optimal control problem to precisely specify the spike times in a leaky integrate-and-fire (LIF) model of a neuron with noise assumed to be of intrinsic or synaptic...... origin. In particular, we allow for the noise to be of arbitrary intensity. The optimal control problem is solved using dynamic programming when the controller has access to the voltage (closed-loop control), and using a maximum principle for the transition density when the controller only has access...... to the spike times (open-loop control). Main results. We have developed a stochastic optimal control algorithm to obtain precise spike times. It is applicable in both the supra-threshold and sub-threshold regimes, under open-loop and closed-loop conditions and with an arbitrary noise intensity; the accuracy...

  17. Amyloid protein unfolding and insertion kinetics on neuronal membrane mimics

    Science.gov (United States)

    Qiu, Liming; Buie, Creighton; Vaughn, Mark; Cheng, Kwan

    2010-03-01

    Atomistic details of beta-amyloid (Aβ ) protein unfolding and lipid interaction kinetics mediated by the neuronal membrane surface are important for developing new therapeutic strategies to prevent and cure Alzheimer's disease. Using all-atom MD simulations, we explored the early unfolding and insertion kinetics of 40 and 42 residue long Aβ in binary lipid mixtures with and without cholesterol that mimic the cholesterol-depleted and cholesterol-enriched lipid nanodomains of neurons. The protein conformational transition kinetics was evaluated from the secondary structure profile versus simulation time plot. The extent of membrane disruption was examined by the calculated order parameters of lipid acyl chains and cholesterol fused rings as well as the density profiles of water and lipid headgroups at defined regions across the lipid bilayer from our simulations. Our results revealed that both the cholesterol content and the length of the protein affect the protein-insertion and membrane stability in our model lipid bilayer systems.

  18. Simulation of a spiking neuron circuit using carbon nanotube transistors

    International Nuclear Information System (INIS)

    Najari, Montassar; El-Grour, Tarek; Jelliti, Sami; Hakami, Othman Mousa

    2016-01-01

    Neuromorphic engineering is related to the existing analogies between the physical semiconductor VLSI (Very Large Scale Integration) and biophysics. Neuromorphic systems propose to reproduce the structure and function of biological neural systems for transferring their calculation capacity on silicon. Since the innovative research of Carver Mead, the neuromorphic engineering continues to emerge remarkable implementation of biological system. This work presents a simulation of an elementary neuron cell with a carbon nanotube transistor (CNTFET) based technology. The model of the cell neuron which was simulated is called integrate and fire (I&F) model firstly introduced by G. Indiveri in 2009. This circuit has been simulated with CNTFET technology using ADS environment to verify the neuromorphic activities in terms of membrane potential. This work has demonstrated the efficiency of this emergent device; i.e CNTFET on the design of such architecture in terms of power consumption and technology integration density.

  19. Simulation of a spiking neuron circuit using carbon nanotube transistors

    Energy Technology Data Exchange (ETDEWEB)

    Najari, Montassar, E-mail: malnjar@jazanu.edu.sa [Departement of Physics, Faculty of Sciences, University of Gabes, Gabes (Tunisia); IKCE unit, Jazan University, Jazan (Saudi Arabia); El-Grour, Tarek, E-mail: grour-tarek@hotmail.fr [Departement of Physics, Faculty of Sciences, University of Gabes, Gabes (Tunisia); Jelliti, Sami, E-mail: sjelliti@jazanu.edu.sa [IKCE unit, Jazan University, Jazan (Saudi Arabia); Hakami, Othman Mousa, E-mail: omhakami@jazanu.edu.sa [IKCE unit, Jazan University, Jazan (Saudi Arabia); Faculty of Sciences, Jazan University, Jazan (Saudi Arabia)

    2016-06-10

    Neuromorphic engineering is related to the existing analogies between the physical semiconductor VLSI (Very Large Scale Integration) and biophysics. Neuromorphic systems propose to reproduce the structure and function of biological neural systems for transferring their calculation capacity on silicon. Since the innovative research of Carver Mead, the neuromorphic engineering continues to emerge remarkable implementation of biological system. This work presents a simulation of an elementary neuron cell with a carbon nanotube transistor (CNTFET) based technology. The model of the cell neuron which was simulated is called integrate and fire (I&F) model firstly introduced by G. Indiveri in 2009. This circuit has been simulated with CNTFET technology using ADS environment to verify the neuromorphic activities in terms of membrane potential. This work has demonstrated the efficiency of this emergent device; i.e CNTFET on the design of such architecture in terms of power consumption and technology integration density.

  20. Densities and apparent molar volumes of atmospherically important electrolyte solutions. 2. The systems H(+)-HSO4(-)-SO4(2-)-H2O from 0 to 3 mol kg(-1) as a function of temperature and H(+)-NH4(+)-HSO4(-)-SO4)2-)-H2O from 0 to 6 mol kg(-1) at 25 °C using a Pitzer ion interaction model, and NH4HSO4-H2O and (NH4)3H(SO4)2-H2O over the entire concentration range.

    Science.gov (United States)

    Clegg, S L; Wexler, A S

    2011-04-21

    A Pitzer ion interaction model has been applied to the systems H(2)SO(4)-H(2)O (0-3 mol kg(-1), 0-55 °C) and H(2)SO(4)-(NH(4))(2)SO(4)-H(2)O (0-6 mol kg(-1), 25 °C) for the calculation of apparent molar volume and density. The dissociation reaction HSO(4)(-)((aq)) ↔ H(+)((aq)) + SO(4)(2-)((aq)) is treated explicitly. Apparent molar volumes of the SO(4)(2-) ion at infinite dilution were obtained from part 1 of this work, (1) and the value for the bisulfate ion was determined in this study from 0 to 55 °C. In dilute solutions of both systems, the change in the degree of dissociation of the HSO(4)(-) ion with concentration results in much larger variations of the apparent molar volumes of the solutes than for conventional strong (fully dissociated) electrolytes. Densities and apparent molar volumes are tabulated. Apparent molar volumes calculated using the model are combined with other data for the solutes NH(4)HSO(4) and (NH(4))(3)H(SO(4))(2) at 25 °C to obtain apparent molar volumes and densities over the entire concentration range (including solutions supersaturated with respect to the salts).

  1. Coherence resonance in globally coupled neuronal networks with different neuron numbers

    International Nuclear Information System (INIS)

    Ning Wei-Lian; Zhang Zheng-Zhen; Zeng Shang-You; Luo Xiao-Shu; Hu Jin-Lin; Zeng Shao-Wen; Qiu Yi; Wu Hui-Si

    2012-01-01

    Because a brain consists of tremendous neuronal networks with different neuron numbers ranging from tens to tens of thousands, we study the coherence resonance due to ion channel noises in globally coupled neuronal networks with different neuron numbers. We confirm that for all neuronal networks with different neuron numbers there exist the array enhanced coherence resonance and the optimal synaptic conductance to cause the maximal spiking coherence. Furthermoremore, the enhancement effects of coupling on spiking coherence and on optimal synaptic conductance are almost the same, regardless of the neuron numbers in the neuronal networks. Therefore for all the neuronal networks with different neuron numbers in the brain, relative weak synaptic conductance (0.1 mS/cm 2 ) is sufficient to induce the maximal spiking coherence and the best sub-threshold signal encoding. (interdisciplinary physics and related areas of science and technology)

  2. Responses of single neurons and neuronal ensembles in frog first- and second-order olfactory neurons

    Czech Academy of Sciences Publication Activity Database

    Rospars, J. P.; Šanda, Pavel; Lánský, Petr; Duchamp-Viret, P.

    2013-01-01

    Roč. 1536, NOV 6 (2013), s. 144-158 ISSN 0006-8993 R&D Projects: GA ČR(CZ) GBP304/12/G069; GA ČR(CZ) GAP103/11/0282 Institutional support: RVO:67985823 Keywords : olfaction * spiking activity * neuronal model Subject RIV: JD - Computer Applications, Robotics Impact factor: 2.828, year: 2013

  3. Activity of Tachykinin1-Expressing Pet1 Raphe Neurons Modulates the Respiratory Chemoreflex.

    Science.gov (United States)

    Hennessy, Morgan L; Corcoran, Andrea E; Brust, Rachael D; Chang, YoonJeung; Nattie, Eugene E; Dymecki, Susan M

    2017-02-15

    Homeostatic control of breathing, heart rate, and body temperature relies on circuits within the brainstem modulated by the neurotransmitter serotonin (5-HT). Mounting evidence points to specialized neuronal subtypes within the serotonergic neuronal system, borne out in functional studies, for the modulation of distinct facets of homeostasis. Such functional differences, read out at the organismal level, are likely subserved by differences among 5-HT neuron subtypes at the cellular and molecular levels, including differences in the capacity to coexpress other neurotransmitters such as glutamate, GABA, thyrotropin releasing hormone, and substance P encoded by the Tachykinin-1 ( Tac1 ) gene. Here, we characterize in mice a 5-HT neuron subtype identified by expression of Tac1 and the serotonergic transcription factor gene Pet1 , referred to as the Tac1-Pet1 neuron subtype. Transgenic cell labeling showed Tac1-Pet1 soma resident largely in the caudal medulla. Chemogenetic [clozapine -N- oxide (CNO)-hM4Di] perturbation of Tac1-Pet1 neuron activity blunted the ventilatory response of the respiratory CO 2 chemoreflex, which normally augments ventilation in response to hypercapnic acidosis to restore normal pH and PCO 2 Tac1-Pet1 axonal boutons were found localized to brainstem areas implicated in respiratory modulation, with highest density in motor regions. These findings demonstrate that the activity of a Pet1 neuron subtype with the potential to release both 5-HT and substance P is necessary for normal respiratory dynamics, perhaps via motor outputs that engage muscles of respiration and maintain airway patency. These Tac1-Pet1 neurons may act downstream of Egr2-Pet1 serotonergic neurons, which were previously established in respiratory chemoreception, but do not innervate respiratory motor nuclei. SIGNIFICANCE STATEMENT Serotonin (5-HT) neurons modulate physiological processes and behaviors as diverse as body temperature, respiration, aggression, and mood. Using

  4. Factors influencing the density of aerobic granular sludge.

    NARCIS (Netherlands)

    Winkler, M.K.; Kleerebezem, R.; Strous, M.; Chandran, K.; Loosdrecht, M.C. van

    2013-01-01

    In the present study, the factors influencing density of granular sludge particles were evaluated. Granules consist of microbes, precipitates and of extracellular polymeric substance. The volume fractions of the bacterial layers were experimentally estimated by fluorescent in situ hybridisation

  5. Neuron-inspired flexible memristive device on silicon (100)

    KAUST Repository

    Ghoneim, Mohamed T.

    2017-06-18

    Comprehensive understanding of the world\\'s most energy efficient powerful computer, the human brain, is an elusive scientific issue. Still, already gained knowledge indicates memristors can be used as a building block to model the brain. At the same time, brain cortex is folded allowing trillions of neurons to be integrated in a compact volume. Therefore, we report flexible aluminium oxide based memristive devices fabricated and then derived from widely used bulk mono-crystalline silicon (100). We use complementary metal oxide semiconductor based processes to layout the foundation for ultra large scale integration (ULSI) of such memory devices to advance the task of comprehending a physical model of human brain.

  6. Characterization of neuronal damage by iomazenil binding and cerebral blood flow in an ischemic rat model

    International Nuclear Information System (INIS)

    Toyama, Hiroshi; Takeuchi, Akira; Koga, Sukehiko; Matsumura, Kaname; Nakashima, Hiromichi; Takeda, Kan; Yoshida, Toshimichi; Ichise, Masanori

    1998-01-01

    I-123-iomazenil is a SPECT probe for central benzodiazepine receptors (BZR) which may reflect intact cortical neuron density after ischemic insults. We evaluated whether neuronal damage in rats could be characterized by iomazenil as compared with cerebral blood flow (CBF). Serial changes in I-125-iomazenil for BZR and I-123-IMP for CBF were analyzed after the unilateral middle cerebral artery occlusion in rats by using an in vivo dualtracer technique. Uptake ratios of affected to contralateral regions were calculated. The iomazenil as well as IMP were decreased in all regions except for the cerebellum (remote area). Both iomazenil and IMP increased over time except in the temporal region (ischemic core). The iomazenil uptake was higher than IMP except in the ischemic core between 1 and 3-4 wk when iomazenil was lower than IMP. Iomazenil showed a moderate decrease in the proximal and middle parietal regions (peri-infarct areas) at 3-4 wk. The triphenyl-tetrazolium-chloride (TTC) stain at 1 wk demonstrated unstained tissue in the temporal region indicating tissue necrosis. With hematoxylin-eosin (HE) stain at 1 wk, widespread neuronal necrosis with occasional intact neurons were found in the proximal parietal region, and isolated necrotic neurons were represented in the distal parietal region. Iomazenil correlated well with the neuron distribution and the finding of a discrepancy between iomazenil and IMP might be useful in evaluating the neuronal damage. (author)

  7. Dogs Have the Most Neurons, Though Not the Largest Brain: Trade-Off between Body Mass and Number of Neurons in the Cerebral Cortex of Large Carnivoran Species

    Directory of Open Access Journals (Sweden)

    Débora Jardim-Messeder

    2017-12-01

    Full Text Available Carnivorans are a diverse group of mammals that includes carnivorous, omnivorous and herbivorous, domesticated and wild species, with a large range of brain sizes. Carnivory is one of several factors expected to be cognitively demanding for carnivorans due to a requirement to outsmart larger prey. On the other hand, large carnivoran species have high hunting costs and unreliable feeding patterns, which, given the high metabolic cost of brain neurons, might put them at risk of metabolic constraints regarding how many brain neurons they can afford, especially in the cerebral cortex. For a given cortical size, do carnivoran species have more cortical neurons than the herbivorous species they prey upon? We find they do not; carnivorans (cat, mongoose, dog, hyena, lion share with non-primates, including artiodactyls (the typical prey of large carnivorans, roughly the same relationship between cortical mass and number of neurons, which suggests that carnivorans are subject to the same evolutionary scaling rules as other non-primate clades. However, there are a few important exceptions. Carnivorans stand out in that the usual relationship between larger body, larger cortical mass and larger number of cortical neurons only applies to small and medium-sized species, and not beyond dogs: we find that the golden retriever dog has more cortical neurons than the striped hyena, African lion and even brown bear, even though the latter species have up to three times larger cortices than dogs. Remarkably, the brown bear cerebral cortex, the largest examined, only has as many neurons as the ten times smaller cat cerebral cortex, although it does have the expected ten times as many non-neuronal cells in the cerebral cortex compared to the cat. We also find that raccoons have dog-like numbers of neurons in their cat-sized brain, which makes them comparable to primates in neuronal density. Comparison of domestic and wild species suggests that the neuronal

  8. Scanning Ultrasound (SUS Causes No Changes to Neuronal Excitability and Prevents Age-Related Reductions in Hippocampal CA1 Dendritic Structure in Wild-Type Mice.

    Directory of Open Access Journals (Sweden)

    Robert John Hatch

    Full Text Available Scanning ultrasound (SUS is a noninvasive approach that has recently been shown to ameliorate histopathological changes and restore memory functions in an Alzheimer's disease mouse model. Although no overt neuronal damage was reported, the short- and long-term effects of SUS on neuronal excitability and dendritic tree morphology had not been investigated. To address this, we performed patch-clamp recordings from hippocampal CA1 pyramidal neurons in wild-type mice 2 and 24 hours after a single SUS treatment, and one week and 3 months after six weekly SUS treatments, including sham treatments as controls. In both treatment regimes, no changes in CA1 neuronal excitability were observed in SUS-treated neurons when compared to sham-treated neurons at any time-point. For the multiple treatment groups, we also determined the dendritic morphology and spine densities of the neurons from which we had recorded. The apical trees of sham-treated neurons were reduced at the 3 month time-point when compared to one week; however, surprisingly, no longitudinal change was detected in the apical dendritic trees of SUS-treated neurons. In contrast, the length and complexity of the basal dendritic trees were not affected by SUS treatment at either time-point. The apical dendritic spine densities were reduced, independent of the treatment group, at 3 months compared to one week. Collectively, these data suggest that ultrasound can be employed to prevent an age-associated loss of dendritic structure without impairing neuronal excitability.

  9. Effect of reinforcement volume fraction on the density & elastic ...

    African Journals Online (AJOL)

    صﺧﻟﻣ. ق. ﻲﻧدﻌﻣﻟا جﺎﺟزﻟا نﻣ سﮐﯾرﺗﺎﻣ وﻧ طﯾﻟﺧﻟﻟ ﺔﯾﻟوطﻟا ﺔﻧورﻣﻟا تﺑاوﺛ و ﺔﻓﺎﺛﮐﻟا ﯽﻟﻋ ﺔﯾوﻘﻣﻟا فﺎﯾﻟﻷا ﺔﺑﺳﻧ رﯾﻐﺗ رﯾﺛﺄﺗ ﺔﺳاردﺑ ﺎﻧﻣ. ) Zr41.2Ti13.8Cu12.5Ni10Be22.5. (. نﻣ فﺎﯾﻟﺄﺑ ﺔﻣﻋدﻣﻟا. : glass E. ,. Fe.

  10. Future Road Density

    Data.gov (United States)

    U.S. Environmental Protection Agency — Road density is generally highly correlated with amount of developed land cover. High road densities usually indicate high levels of ecological disturbance. More...

  11. How to make spinal motor neurons.

    Science.gov (United States)

    Davis-Dusenbery, Brandi N; Williams, Luis A; Klim, Joseph R; Eggan, Kevin

    2014-02-01

    All muscle movements, including breathing, walking, and fine motor skills rely on the function of the spinal motor neuron to transmit signals from the brain to individual muscle groups. Loss of spinal motor neuron function underlies several neurological disorders for which treatment has been hampered by the inability to obtain sufficient quantities of primary motor neurons to perform mechanistic studies or drug screens. Progress towards overcoming this challenge has been achieved through the synthesis of developmental biology paradigms and advances in stem cell and reprogramming technology, which allow the production of motor neurons in vitro. In this Primer, we discuss how the logic of spinal motor neuron development has been applied to allow generation of motor neurons either from pluripotent stem cells by directed differentiation and transcriptional programming, or from somatic cells by direct lineage conversion. Finally, we discuss methods to evaluate the molecular and functional properties of motor neurons generated through each of these techniques.

  12. Firing dynamics of an autaptic neuron

    International Nuclear Information System (INIS)

    Wang Heng-Tong; Chen Yong

    2015-01-01

    Autapses are synapses that connect a neuron to itself in the nervous system. Previously, both experimental and theoretical studies have demonstrated that autaptic connections in the nervous system have a significant physiological function. Autapses in nature provide self-delayed feedback, thus introducing an additional timescale to neuronal activities and causing many dynamic behaviors in neurons. Recently, theoretical studies have revealed that an autapse provides a control option for adjusting the response of a neuron: e.g., an autaptic connection can cause the electrical activities of the Hindmarsh–Rose neuron to switch between quiescent, periodic, and chaotic firing patterns; an autapse can enhance or suppress the mode-locking status of a neuron injected with sinusoidal current; and the firing frequency and interspike interval distributions of the response spike train can also be modified by the autapse. In this paper, we review recent studies that showed how an autapse affects the response of a single neuron. (topical review)

  13. Trafficking of cholesterol from cell bodies to distal axons in Niemann Pick C1-deficient neurons.

    Science.gov (United States)

    Karten, Barbara; Vance, Dennis E; Campenot, Robert B; Vance, Jean E

    2003-02-07

    Niemann Pick type C (NPC) disease is a progressive neurodegenerative disorder. In cells lacking functional NPC1 protein, endocytosed cholesterol accumulates in late endosomes/lysosomes. We utilized primary neuronal cultures in which cell bodies and distal axons reside in separate compartments to investigate the requirement of NPC1 protein for transport of cholesterol from cell bodies to distal axons. We have recently observed that in NPC1-deficient neurons compared with wild-type neurons, cholesterol accumulates in cell bodies but is reduced in distal axons (Karten, B., Vance, D. E., Campenot, R. B., and Vance, J. E. (2002) J. Neurochem. 83, 1154-1163). We now show that NPC1 protein is expressed in both cell bodies and distal axons. In NPC1-deficient neurons, cholesterol delivered to cell bodies from low density lipoproteins (LDLs), high density lipoproteins, or cyclodextrin complexes was transported into axons in normal amounts, whereas transport of endogenously synthesized cholesterol was impaired. Inhibition of cholesterol synthesis with pravastatin in wild-type and NPC1-deficient neurons reduced axonal growth. However, LDLs restored a normal rate of growth to wild-type but not NPC1-deficient neurons treated with pravastatin. Thus, although LDL cholesterol is transported into axons of NPC1-deficient neurons, this source of cholesterol does not sustain normal axonal growth. Over the lifespan of NPC1-deficient neurons, these defects in cholesterol transport might be responsible for the observed altered distribution of cholesterol between cell bodies and axons and, consequently, might contribute to the neurological dysfunction in NPC disease.

  14. Neurons from the adult human dentate nucleus: neural networks in the neuron classification.

    Science.gov (United States)

    Grbatinić, Ivan; Marić, Dušica L; Milošević, Nebojša T

    2015-04-07

    Topological (central vs. border neuron type) and morphological classification of adult human dentate nucleus neurons according to their quantified histomorphological properties using neural networks on real and virtual neuron samples. In the real sample 53.1% and 14.1% of central and border neurons, respectively, are classified correctly with total of 32.8% of misclassified neurons. The most important result present 62.2% of misclassified neurons in border neurons group which is even greater than number of correctly classified neurons (37.8%) in that group, showing obvious failure of network to classify neurons correctly based on computational parameters used in our study. On the virtual sample 97.3% of misclassified neurons in border neurons group which is much greater than number of correctly classified neurons (2.7%) in that group, again confirms obvious failure of network to classify neurons correctly. Statistical analysis shows that there is no statistically significant difference in between central and border neurons for each measured parameter (p>0.05). Total of 96.74% neurons are morphologically classified correctly by neural networks and each one belongs to one of the four histomorphological types: (a) neurons with small soma and short dendrites, (b) neurons with small soma and long dendrites, (c) neuron with large soma and short dendrites, (d) neurons with large soma and long dendrites. Statistical analysis supports these results (pneurons can be classified in four neuron types according to their quantitative histomorphological properties. These neuron types consist of two neuron sets, small and large ones with respect to their perykarions with subtypes differing in dendrite length i.e. neurons with short vs. long dendrites. Besides confirmation of neuron classification on small and large ones, already shown in literature, we found two new subtypes i.e. neurons with small soma and long dendrites and with large soma and short dendrites. These neurons are

  15. Achieving maximum baryon densities

    International Nuclear Information System (INIS)

    Gyulassy, M.

    1984-01-01

    In continuing work on nuclear stopping power in the energy range E/sub lab/ approx. 10 GeV/nucleon, calculations were made of the energy and baryon densities that could be achieved in uranium-uranium collisions. Results are shown. The energy density reached could exceed 2 GeV/fm 3 and baryon densities could reach as high as ten times normal nuclear densities

  16. Mirror neurons and motor intentionality.

    Science.gov (United States)

    Rizzolatti, Giacomo; Sinigaglia, Corrado

    2007-01-01

    Our social life rests to a large extent on our ability to understand the intentions of others. What are the bases of this ability? A very influential view is that we understand the intentions of others because we are able to represent them as having mental states. Without this meta-representational (mind-reading) ability their behavior would be meaningless to us. Over the past few years this view has been challenged by neurophysiological findings and, in particular, by the discovery of mirror neurons. The functional properties of these neurons indicate that intentional understanding is based primarily on a mechanism that directly matches the sensory representation of the observed actions with one's own motor representation of those same actions. These findings reveal how deeply motor and intentional components of action are intertwined, suggesting that both can be fully comprehended only starting from a motor approach to intentionality.

  17. Oscillatory integration windows in neurons

    Science.gov (United States)

    Gupta, Nitin; Singh, Swikriti Saran; Stopfer, Mark

    2016-01-01

    Oscillatory synchrony among neurons occurs in many species and brain areas, and has been proposed to help neural circuits process information. One hypothesis states that oscillatory input creates cyclic integration windows: specific times in each oscillatory cycle when postsynaptic neurons become especially responsive to inputs. With paired local field potential (LFP) and intracellular recordings and controlled stimulus manipulations we directly test this idea in the locust olfactory system. We find that inputs arriving in Kenyon cells (KCs) sum most effectively in a preferred window of the oscillation cycle. With a computational model, we show that the non-uniform structure of noise in the membrane potential helps mediate this process. Further experiments performed in vivo demonstrate that integration windows can form in the absence of inhibition and at a broad range of oscillation frequencies. Our results reveal how a fundamental coincidence-detection mechanism in a neural circuit functions to decode temporally organized spiking. PMID:27976720

  18. Characterizing the Spatial Density Functions of Neural Arbors

    Science.gov (United States)

    Teeter, Corinne Michelle

    Recently, it has been proposed that a universal function describes the way in which all arbors (axons and dendrites) spread their branches over space. Data from fish retinal ganglion cells as well as cortical and hippocampal arbors from mouse, rat, cat, monkey and human provide evidence that all arbor density functions (adf) can be described by a Gaussian function truncated at approximately two standard deviations. A Gaussian density function implies that there is a minimal set of parameters needed to describe an adf: two or three standard deviations (depending on the dimensionality of the arbor) and an amplitude. However, the parameters needed to completely describe an adf could be further constrained by a scaling law found between the product of the standard deviations and the amplitude of the function. In the following document, I examine the scaling law relationship in order to determine the minimal set of parameters needed to describe an adf. First, I find that the at, two-dimensional arbors of fish retinal ganglion cells require only two out of the three fundamental parameters to completely describe their density functions. Second, the three-dimensional, volume filling, cortical arbors require four fundamental parameters: three standard deviations and the total length of an arbor (which corresponds to the amplitude of the function). Next, I characterize the shape of arbors in the context of the fundamental parameters. I show that the parameter distributions of the fish retinal ganglion cells are largely homogenous. In general, axons are bigger and less dense than dendrites; however, they are similarly shaped. The parameter distributions of these two arbor types overlap and, therefore, can only be differentiated from one another probabilistically based on their adfs. Despite artifacts in the cortical arbor data, different types of arbors (apical dendrites, non-apical dendrites, and axons) can generally be differentiated based on their adfs. In addition, within

  19. Crowding and Density

    Science.gov (United States)

    Design and Environment, 1972

    1972-01-01

    Three-part report pinpointing problems and uncovering solutions for the dual concepts of density (ratio of people to space) and crowding (psychological response to density). Section one, A Primer on Crowding,'' reviews new psychological and social findings; section two, Density in the Suburbs,'' shows conflict between status quo and increased…

  20. Forced swimming sabotages the morphological and synaptic maturation of newborn granule neurons and triggers a unique pro-inflammatory milieu in the hippocampus.

    Science.gov (United States)

    Llorens-Martín, María; Jurado-Arjona, Jerónimo; Bolós, Marta; Pallas-Bazarra, Noemí; Ávila, Jesús

    2016-03-01

    Recent experimental data suggest that mood disorders are related to inflammatory phenomena and have led to the "inflammatory hypothesis of depression". Given that the hippocampus is one of the most affected areas in these disorders, we used a model of acute stress (the Porsolt test) to evaluate the consequences of forced swimming on two crucial events related to the pathophysiology of major depression: the functional maturation of newborn granule neurons; and the hippocampal inflammatory milieu. Using PSD95:GFP-expressing retroviruses, we found that forced swimming selectively alters the dendritic morphology of newborn neurons and impairs their connectivity by reducing the number and volume of their postsynaptic densities. In addition, acute stress triggered a series of morphological changes in microglial cells, together with an increase in microglial CD68 expression, thus suggesting the functional and morphological activation of this cell population. Furthermore, we observed an intriguing change in the hippocampal inflammatory milieu in response to forced swimming. Importantly, the levels of several molecules affected by acute stress (such as Interleukin-6 and eotaxin) have been described to also be altered in patients with depression and other mood disorders. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Unbalanced neuronal circuits in addiction.

    Science.gov (United States)

    Volkow, Nora D; Wang, Gen-Jack; Tomasi, Dardo; Baler, Ruben D

    2013-08-01

    Through sequential waves of drug-induced neurochemical stimulation, addiction co-opts the brain's neuronal circuits that mediate reward, motivation to behavioral inflexibility and a severe disruption of self-control and compulsive drug intake. Brain imaging technologies have allowed neuroscientists to map out the neural landscape of addiction in the human brain and to understand how drugs modify it. Published by Elsevier Ltd.

  2. Neurochemical phenotypes of cardiorespiratory neurons.

    Science.gov (United States)

    Pilowsky, Paul M

    2008-12-10

    Interactions between the cardiovascular and respiratory systems have been known for many years but the functional significance of the interactions is still widely debated. Here I discuss the possible role of metabotropic receptors in regulating cardiorespiratory neurons in the brainstem and spinal cord. It is clear that, although much has been discovered, cardiorespiratory regulation is certainly one area that still has a long way to go before its secrets are fully divulged and their function in controlling circulatory and respiratory function is revealed.

  3. Mirror Neurons from Associative Learning

    OpenAIRE

    Catmur, Caroline; Press, Clare; Heyes, Cecilia

    2016-01-01

    Mirror neurons fire both when executing actions and observing others perform similar actions. Their sensorimotor matching properties have generally been considered a genetic adaptation for social cognition; however, in the present chapter we argue that the evidence in favor of this account is not compelling. Instead we present evidence supporting an alternative account: that mirror neurons’ matching properties arise from associative learning during individual development. Notably, this proces...

  4. Trafficking of neuronal calcium channels

    Czech Academy of Sciences Publication Activity Database

    Weiss, Norbert; Zamponi, G. W.

    2017-01-01

    Roč. 1, č. 1 (2017), č. článku NS20160003. ISSN 2059-6553 R&D Projects: GA ČR GA15-13556S; GA MŠk 7AMB15FR015 Institutional support: RVO:61388963 Keywords : calcium channel * neuron * trafficing Subject RIV: ED - Physiology OBOR OECD: Physiology (including cytology) http://www.neuronalsignaling.org/content/1/1/NS20160003

  5. Selective serotonergic excitation of callosal projection neurons

    Directory of Open Access Journals (Sweden)

    Daniel eAvesar

    2012-03-01

    Full Text Available Serotonin (5-HT acting as a neurotransmitter in the cerebral cortex is critical for cognitive function, yet how 5-HT regulates information processing in cortical circuits is not well understood. We tested the serotonergic responsiveness of layer 5 pyramidal neurons (L5PNs of the mouse medial prefrontal cortex (mPFC, and found 3 distinct response types: long-lasting 5-HT1A (1A receptor-dependent inhibitory responses (84% of L5PNs, 5-HT2A (2A receptor-dependent excitatory responses (9%, and biphasic responses in which 2A-dependent excitation followed brief inhibition (5%. Relative to 5-HT-inhibited neurons, those excited by 5-HT had physiological properties characteristic of callosal/commissural (COM neurons that project to the contralateral cortex. We tested whether serotonergic responses in cortical pyramidal neurons are correlated with their axonal projection pattern using retrograde fluorescent labeling of COM and corticopontine-projecting (CPn neurons. 5-HT generated excitatory or biphasic responses in all 5-HT-responsive layer 5 COM neurons. Conversely, CPn neurons were universally inhibited by 5-HT. Serotonergic excitation of COM neurons was blocked by the 2A antagonist MDL 11939, while serotonergic inhibition of CPn neurons was blocked by the 1A antagonist WAY 100635, confirming a role for these two receptor subtypes in regulating pyramidal neuron activity. Selective serotonergic excitation of COM neurons was not layer-specific, as COM neurons in layer 2/3 were also selectively excited by 5-HT relative to their non-labeled pyramidal neuron neighbors. Because neocortical 2A receptors are implicated in the etiology and pathophysiology of schizophrenia, we propose that COM neurons may represent a novel cellular target for intervention in psychiatric disease.

  6. Thermodynamic fluctuations and the monopole density of the early Universe

    International Nuclear Information System (INIS)

    Diosi, L.; Lukacs, B.

    1984-10-01

    The probability of thermodynamic fluctuations is calculated by explicitly using the Riemannian structure of the thermodynamic state space. By means of this probability distribution, a correlation volume can be defined. Identifying this volume with one domain in the GUT continuum at the symmetry breaking phase transition in the early Universe, a prediction can be obtained for the primordial monopole density. (author)

  7. Subgroup-Elimination Transcriptomics Identifies Signaling Proteins that Define Subclasses of TRPV1-Positive Neurons and a Novel Paracrine Circuit

    Science.gov (United States)

    Isensee, Jörg; Wenzel, Carsten; Buschow, Rene; Weissmann, Robert; Kuss, Andreas W.; Hucho, Tim

    2014-01-01

    Normal and painful stimuli are detected by specialized subgroups of peripheral sensory neurons. The understanding of the functional differences of each neuronal subgroup would be strongly enhanced by knowledge of the respective subgroup transcriptome. The separation of the subgroup of interest, however, has proven challenging as they can hardly be enriched. Instead of enriching, we now rapidly eliminated the subgroup of neurons expressing the heat-gated cation channel TRPV1 from dissociated rat sensory ganglia. Elimination was accomplished by brief treatment with TRPV1 agonists followed by the removal of compromised TRPV1(+) neurons using density centrifugation. By differential microarray and sequencing (RNA-Seq) based expression profiling we compared the transcriptome of all cells within sensory ganglia versus the same cells lacking TRPV1 expressing neurons, which revealed 240 differentially expressed genes (adj. p1.5). Corroborating the specificity of the approach, many of these genes have been reported to be involved in noxious heat or pain sensitization. Beyond the expected enrichment of ion channels, we found the TRPV1 transcriptome to be enriched for GPCRs and other signaling proteins involved in adenosine, calcium, and phosphatidylinositol signaling. Quantitative population analysis using a recent High Content Screening (HCS) microscopy approach identified substantial heterogeneity of expressed target proteins even within TRPV1-positive neurons. Signaling components defined distinct further subgroups within the population of TRPV1-positive neurons. Analysis of one such signaling system showed that the pain sensitizing prostaglandin PGD2 activates DP1 receptors expressed predominantly on TRPV1(+) neurons. In contrast, we found the PGD2 producing prostaglandin D synthase to be expressed exclusively in myelinated large-diameter neurons lacking TRPV1, which suggests a novel paracrine neuron-neuron communication. Thus, subgroup analysis based on the elimination

  8. Results on a Binding Neuron Model and Their Implications for Modified Hourglass Model for Neuronal Network

    Directory of Open Access Journals (Sweden)

    Viswanathan Arunachalam

    2013-01-01

    Full Text Available The classical models of single neuron like Hodgkin-Huxley point neuron or leaky integrate and fire neuron assume the influence of postsynaptic potentials to last till the neuron fires. Vidybida (2008 in a refreshing departure has proposed models for binding neurons in which the trace of an input is remembered only for a finite fixed period of time after which it is forgotten. The binding neurons conform to the behaviour of real neurons and are applicable in constructing fast recurrent networks for computer modeling. This paper develops explicitly several useful results for a binding neuron like the firing time distribution and other statistical characteristics. We also discuss the applicability of the developed results in constructing a modified hourglass network model in which there are interconnected neurons with excitatory as well as inhibitory inputs. Limited simulation results of the hourglass network are presented.

  9. Firing pattern of fasciculations in ALS: evidence for axonal and neuronal origin.

    NARCIS (Netherlands)

    Kleine, B.U.; Stegeman, D.F.; Schelhaas, H.J.; Zwarts, M.J.

    2008-01-01

    BACKGROUND: In amyotrophic lateral sclerosis (ALS), the origin of fasciculations is disputed. We hypothesized that the discharge pattern of fasciculation potentials (FPs) would be different for FPs arising in the motor axon or in the spinal motor neuron. METHOD: FPs were recorded by high-density

  10. Single-cell axotomy of cultured hippocampal neurons integrated in neuronal circuits.

    Science.gov (United States)

    Gomis-Rüth, Susana; Stiess, Michael; Wierenga, Corette J; Meyn, Liane; Bradke, Frank

    2014-05-01

    An understanding of the molecular mechanisms of axon regeneration after injury is key for the development of potential therapies. Single-cell axotomy of dissociated neurons enables the study of the intrinsic regenerative capacities of injured axons. This protocol describes how to perform single-cell axotomy on dissociated hippocampal neurons containing synapses. Furthermore, to axotomize hippocampal neurons integrated in neuronal circuits, we describe how to set up coculture with a few fluorescently labeled neurons. This approach allows axotomy of single cells in a complex neuronal network and the observation of morphological and molecular changes during axon regeneration. Thus, single-cell axotomy of mature neurons is a valuable tool for gaining insights into cell intrinsic axon regeneration and the plasticity of neuronal polarity of mature neurons. Dissociation of the hippocampus and plating of hippocampal neurons takes ∼2 h. Neurons are then left to grow for 2 weeks, during which time they integrate into neuronal circuits. Subsequent axotomy takes 10 min per neuron and further imaging takes 10 min per neuron.

  11. Glutamate neurons are intermixed with midbrain dopamine neurons in nonhuman primates and humans

    Science.gov (United States)

    Root, David H.; Wang, Hui-Ling; Liu, Bing; Barker, David J.; Mód, László; Szocsics, Péter; Silva, Afonso C.; Maglóczky, Zsófia; Morales, Marisela

    2016-01-01

    The rodent ventral tegmental area (VTA) and substantia nigra pars compacta (SNC) contain dopamine neurons intermixed with glutamate neurons (expressing vesicular glutamate transporter 2; VGluT2), which play roles in reward and aversion. However, identifying the neuronal compositions of the VTA and SNC in higher mammals has remained challenging. Here, we revealed VGluT2 neurons within the VTA and SNC of nonhuman primates and humans by simultaneous detection of VGluT2 mRNA and tyrosine hydroxylase (TH; for identification of dopamine neurons). We found that several VTA subdivisions share similar cellular compositions in nonhuman primates and humans; their rostral linear nuclei have a high prevalence of VGluT2 neurons lacking TH; their paranigral and parabrachial pigmented nuclei have mostly TH neurons, and their parabrachial pigmented nuclei have dual VGluT2-TH neurons. Within nonhuman primates and humans SNC, the vast majority of neurons are TH neurons but VGluT2 neurons were detected in the pars lateralis subdivision. The demonstration that midbrain dopamine neurons are intermixed with glutamate or glutamate-dopamine neurons from rodents to humans offers new opportunities for translational studies towards analyzing the roles that each of these neurons play in human behavior and in midbrain-associated illnesses such as addiction, depression, schizophrenia, and Parkinson’s disease. PMID:27477243

  12. Examining Neuronal Connectivity and Its Role in Learning and Memory

    Science.gov (United States)

    Gala, Rohan

    Learning and long-term memory formation are accompanied with changes in the patterns and weights of synaptic connections in the underlying neuronal network. However, the fundamental rules that drive connectivity changes, and the precise structure-function relationships within neuronal networks remain elusive. Technological improvements over the last few decades have enabled the observation of large but specific subsets of neurons and their connections in unprecedented detail. Devising robust and automated computational methods is critical to distill information from ever-increasing volumes of raw experimental data. Moreover, statistical models and theoretical frameworks are required to interpret the data and assemble evidence into understanding of brain function. In this thesis, I first describe computational methods to reconstruct connectivity based on light microscopy imaging experiments. Next, I use these methods to quantify structural changes in connectivity based on in vivo time-lapse imaging experiments. Finally, I present a theoretical model of associative learning that can explain many stereotypical features of experimentally observed connectivity.

  13. Linking macroscopic with microscopic neuroanatomy using synthetic neuronal populations.

    Science.gov (United States)

    Schneider, Calvin J; Cuntz, Hermann; Soltesz, Ivan

    2014-10-01

    Dendritic morphology has been shown to have a dramatic impact on neuronal function. However, population features such as the inherent variability in dendritic morphology between cells belonging to the same neuronal type are often overlooked when studying computation in neural networks. While detailed models for morphology and electrophysiology exist for many types of single neurons, the role of detailed single cell morphology in the population has not been studied quantitatively or computationally. Here we use the structural context of the neural tissue in which dendritic trees exist to drive their generation in silico. We synthesize the entire population of dentate gyrus granule cells, the most numerous cell type in the hippocampus, by growing their dendritic trees within their characteristic dendritic fields bounded by the realistic structural context of (1) the granule cell layer that contains all somata and (2) the molecular layer that contains the dendritic forest. This process enables branching statistics to be linked to larger scale neuroanatomical features. We find large differences in dendritic total length and individual path length measures as a function of location in the dentate gyrus and of somatic depth in the granule cell layer. We also predict the number of unique granule cell dendrites invading a given volume in the molecular layer. This work enables the complete population-level study of morphological properties and provides a framework to develop complex and realistic neural network models.

  14. The 5-HT1A serotonin receptor is located on calbindin- and parvalbumin-containing neurons in the rat brain

    DEFF Research Database (Denmark)

    Aznar, Susana; Qian, Zhaoxia; Shah, Reshma

    2003-01-01

    distributed in the rat brain, with a particularly high density in the limbic system. The receptor's localization in the different neuronal subtypes, which may be of importance for understanding its role in neuronal circuitries, is, however, unknown. In this study we show by immunocytochemical double......-labeling techniques, that the 5-HT(1A) receptor is present on both pyramidal and principal cells, and calbindin- and parvalbumin-containing neurons, which generally define two different subtypes of interneurons. Moreover, semiquantitative analysis showed that the receptor's distribution in the different neuronal...... types varies between brain areas. In cortex, hippocampus, hypothalamus, and amygdala the receptor was located on both principal cells and calbindin- and parvalbumin-containing neurons. In septum and thalamus, the receptor was mostly present on calbindin- and parvalbumin-containing cells. Especially...

  15. Late maturation of adult-born neurons in the temporal dentate gyrus.

    Science.gov (United States)

    Snyder, Jason S; Ferrante, Sarah C; Cameron, Heather A

    2012-01-01

    Hippocampal function varies along its septotemporal axis, with the septal (dorsal) pole more frequently involved in spatial learning and memory and the temporal (ventral) pole playing a greater role in emotional behaviors. One feature that varies across these subregions is adult neurogenesis. New neurons are more numerous in the septal hippocampus but are more active in the temporal hippocampus during water maze training. However, many other aspects of adult neurogenesis remain unexplored in the context of septal versus temporal subregions. In addition, the dentate gyrus contains another functionally important anatomical division along the transverse axis, with the suprapyramidal blade showing greater experience-related activity than the infrapyramidal blade. Here we ask whether new neurons differ in their rates of survival and maturation along the septotemporal and transverse axes. We found that neurogenesis is initially higher in the infrapyramidal than suprapyramidal blade, but these cells are less likely to survive, resulting in similar densities of neurons in the two blades by four weeks. Across the septotemporal axis, neurogenesis was higher in septal than temporal pole, while the survival rate of new neurons did not differ. Maturation was assessed by immunostaining for the neuronal marker, NeuN, which increases in expression level with maturation, and for the immediate-early gene, Arc, which suggests a neuron is capable of undergoing activity-dependent synaptic plasticity. Maturation occurred approximately 1-2 weeks earlier in the septal pole than in the temporal pole. This suggests that septal neurons may contribute to function sooner; however, the prolonged maturation of new temporal neurons may endow them with a longer window of plasticity during which their functions could be distinct from those of the mature granule cell population. These data point to subregional differences in new neuron maturation and suggest that changes in neurogenesis could alter

  16. Long term delivery of pulsed magnetic fields does not alter visual discrimination learning or dendritic spine density in the mouse CA1 pyramidal or dentate gyrus neurons [v2; ref status: indexed, http://f1000r.es/2gk

    Directory of Open Access Journals (Sweden)

    Matthew Sykes

    2013-12-01

    Full Text Available Repetitive transcranial magnetic stimulation (rTMS is thought to facilitate brain plasticity. However, few studies address anatomical changes following rTMS in relation to behaviour. We delivered 5 weeks of daily pulsed rTMS stimulation to adult ephrin-A2-/- and wildtype (C57BI/6j mice (n=10 per genotype undergoing a visual learning task and analysed learning performance, as well as spine density, in the dentate gyrus molecular and CA1 pyramidal cell layers in Golgi-stained brain sections. We found that neither learning behaviour, nor hippocampal spine density was affected by long term rTMS. Our negative results highlight the lack of deleterious side effects in normal subjects and are consistent with previous studies suggesting that rTMS has a bigger effect on abnormal or injured brain substrates than on normal/control structures.

  17. Progressive neuronal degeneration of childhood with liver disease

    International Nuclear Information System (INIS)

    Kendall, B.E.; Boyd, S.G.; Egger, J.; Harding, B.N.

    1987-01-01

    The clinical, electrophysiological and neuroradiological features of thirteen patients suffering from progressive neuronal degeneration of childhood with liver failure are presented. The disease commonly presents very early in life with progressive mental retardation, followed by intractable epilepsy, and should be suspected clinically especially if there is a family history of similar disorder in a sibling. On computed tomography there are low density regions, particularly in the occipital and posterior temporal lobes, involving both cortex and white matter, combined with or followed by progressive atrophy. Typical EEG findings may be confirmatory. (orig.)

  18. Neuronal Differentiation Modulated by Polymeric Membrane Properties.

    Science.gov (United States)

    Morelli, Sabrina; Piscioneri, Antonella; Drioli, Enrico; De Bartolo, Loredana

    2017-01-01

    In this study, different collagen-blend membranes were successfully constructed by blending collagen with chitosan (CHT) or poly(lactic-co-glycolic acid) (PLGA) to enhance their properties and thus create new biofunctional materials with great potential use for neuronal tissue engineering and regeneration. Collagen blending strongly affected membrane properties in the following ways: (i) it improved the surface hydrophilicity of both pure CHT and PLGA membranes, (ii) it reduced the stiffness of CHT membranes, but (iii) it did not modify the good mechanical properties of PLGA membranes. Then, we investigated the effect of the different collagen concentrations on the neuronal behavior of the membranes developed. Morphological observations, immunocytochemistry, and morphometric measures demonstrated that the membranes developed, especially CHT/Col30, PLGA, and PLGA/Col1, provided suitable microenvironments for neuronal growth owing to their enhanced properties. The most consistent neuronal differentiation was obtained in neurons cultured on PLGA-based membranes, where a well-developed neuronal network was achieved due to their improved mechanical properties. Our findings suggest that tensile strength and elongation at break are key material parameters that have potential influence on both axonal elongation and neuronal structure and organization, which are of fundamental importance for the maintenance of efficient neuronal growth. Hence, our study has provided new insights regarding the effects of membrane mechanical properties on neuronal behavior, and thus it may help to design and improve novel instructive biomaterials for neuronal tissue engineering. © 2017 S. Karger AG, Basel.

  19. Neuroprotection, learning and memory improvement of a standardized extract from Renshen Shouwu against neuronal injury and vascular dementia in rats with brain ischemia.

    Science.gov (United States)

    Wan, Li; Cheng, Yufang; Luo, Zhanyuan; Guo, Haibiao; Zhao, Wenjing; Gu, Quanlin; Yang, Xu; Xu, Jiangping; Bei, Weijian; Guo, Jiao

    2015-05-13

    The Renshen Shouwu capsule (RSSW) is a patented Traditional Chinese Medicine (TCM), that has been proven to improve memory and is widely used in China to apoplexy syndrome and memory deficits. To investigate the neuroprotective and therapeutic effect of the Renshen Shouwu standardized extract (RSSW) on ischemic brain neuronal injury and impairment of learning and memory related to Vascular Dementia (VD) induced by a focal and global cerebral ischemia-reperfusion injury in rats. Using in vivo rat models of both focal ischemia/reperfusion (I/R) injuries induced by a middle cerebral artery occlusion (MCAO), and VD with transient global brain I/R neuronal injuries induced by a four-vessel occlusion (4-VO) in Sprague-Dawley (SD) rats, RSSW (50,100, and 200 mg kg(-1) body weights) and Egb761® (80 mg kg(-1)) were administered orally for 20 days (preventively 6 days+therapeutically 14 days) in 4-VO rats, and for 7 days (3 days preventively+4 days therapeutically) in MCAO rats. Learning and memory behavioral performance was assayed using a Morris water maze test including a place navigation trial and a spatial probe trial. Brain histochemical morphology and hippocampal neuron survival was quantified using microscope assay of a puffin brain/hippocampus slice with cresyl violet staining. MCAO ischemia/reperfusion caused infarct damage in rat brain tissue. 4-VO ischemia/reperfusion caused a hippocampal neuronal lesion and learning and memory deficits in rats. Administration of RSSW (50, 100, and 200mg/kg) or EGb761 significantly reduced the size of the insulted brain hemisphere lesion and improved the neurological behavior of MCAO rats. In addition, RSSW markedly reduced an increase in the brain infarct volume from an I/R-induced MCAO and reduced the cerebral water content in a dose-dependent way. Administration of RSSW also increased the pyramidal neuronal density in the hippocampus of surviving rats after transient global brain ischemia and improved the learning and memory

  20. Synaptic Circuit Organization of Motor Corticothalamic Neurons

    Science.gov (United States)

    Yamawaki, Naoki

    2015-01-01

    Corticothalamic (CT) neurons in layer 6 constitute a large but enigmatic class of cortical projection neurons. How they are integrated into intracortical and thalamo-cortico-thalamic circuits is incompletely understood, especially outside of sensory cortex. Here, we investigated CT circuits in mouse forelimb motor cortex (M1) using multiple circuit-analysis methods. Stimulating and recording from CT, intratelencephalic (IT), and pyramidal tract (PT) projection neurons, we found strong CT↔ CT and CT↔ IT connections; however, CT→IT connections were limited to IT neurons in layer 6, not 5B. There was strikingly little CT↔ PT excitatory connectivity. Disynaptic inhibition systematically accompanied excitation in these pathways, scaling with the amplitude of excitation according to both presynaptic (class-specific) and postsynaptic (cell-by-cell) factors. In particular, CT neurons evoked proportionally more inhibition relative to excitation (I/E ratio) than IT neurons. Furthermore, the amplitude of inhibition was tuned to match the amount of excitation at the level of individual neurons; in the extreme, neurons receiving no excitation received no inhibition either. Extending these studies to dissect the connectivity between cortex and thalamus, we found that M1-CT neurons and thalamocortical neurons in the ventrolateral (VL) nucleus were remarkably unconnected in either direction. Instead, VL axons in the cortex excited both IT and PT neurons, and CT axons in the thalamus excited other thalamic neurons, including those in the posterior nucleus, which additionally received PT excitation. These findings, which contrast in several ways with previous observations in sensory areas, illuminate the basic circuit organization of CT neurons within M1 and between M1 and thalamus. PMID:25653383

  1. Comparative neuronal morphology of the cerebellar cortex in afrotherians, carnivores, cetartiodactyls, and primates

    Directory of Open Access Journals (Sweden)

    Bob eJacobs

    2014-04-01

    Full Text Available Although the basic morphological characteristics of neurons in the cerebellar cortex have been documented in several species, virtually nothing is known about the quantitative morphological characteristics of these neurons across different taxa. To that end, the present study investigated cerebellar neuronal morphology among eight different, large-brained mammalian species comprising a broad phylogenetic range: afrotherians (African elephant, Florida manatee, carnivores (Siberian tiger, clouded leopard, cetartiodactyls (humpback whale, giraffe and primates (human, common chimpanzee. Specifically, several neuron types (e.g., stellate, basket, Lugaro, Golgi, and granule neurons; N = 317 of the cerebellar cortex were stained with a modified rapid Golgi technique and quantified on a computer-assisted microscopy system. There was a 64-fold variation in brain mass across species in our sample (from clouded leopard to the elephant and a 103-fold variation in cerebellar volume. Most dendritic measures tended to increase with cerebellar volume. The cerebellar cortex in these species exhibited the trilaminate pattern common to all mammals. Morphologically, neuron types in the cerebellar cortex were generally consistent with those described in primates (Fox et al., 1967 and rodents (Palay and Chan-Palay, 1974, although there was substantial quantitative variation across species. In particular, Lugaro neurons in the elephant appeared to be disproportionately larger than those in other species. To explore potential quantitative differences in dendritic measures across species, MARSplines analyses were used to evaluate whether species could be differentiated from each other based on dendritic characteristics alone. Results of these analyses indicated that there were significant differences among all species in dendritic measures.

  2. Probability densities and Lévy densities

    DEFF Research Database (Denmark)

    Barndorff-Nielsen, Ole Eiler

    For positive Lévy processes (i.e. subordinators) formulae are derived that express the probability density or the distribution function in terms of power series in time t. The applicability of the results to finance and to turbulence is briefly indicated.......For positive Lévy processes (i.e. subordinators) formulae are derived that express the probability density or the distribution function in terms of power series in time t. The applicability of the results to finance and to turbulence is briefly indicated....

  3. Volumetric Two-photon Imaging of Neurons Using Stereoscopy (vTwINS)

    Science.gov (United States)

    Song, Alexander; Charles, Adam S.; Koay, Sue Ann; Gauthier, Jeff L.; Thiberge, Stephan Y.; Pillow, Jonathan W.; Tank, David W.

    2017-01-01

    Two-photon laser scanning microscopy of calcium dynamics using fluorescent indicators is a widely used imaging method for large scale recording of neural activity in vivo. Here we introduce volumetric Two-photon Imaging of Neurons using Stereoscopy (vTwINS), a volumetric calcium imaging method that employs an elongated, V-shaped point spread function to image a 3D brain volume. Single neurons project to spatially displaced “image pairs” in the resulting 2D image, and the separation distance between images is proportional to depth in the volume. To demix the fluorescence time series of individual neurons, we introduce a novel orthogonal matching pursuit algorithm that also infers source locations within the 3D volume. We illustrate vTwINS by imaging neural population activity in mouse primary visual cortex and hippocampus. Our results demonstrate that vTwINS provides an effective method for volumetric two-photon calcium imaging that increases the number of neurons recorded while maintaining a high frame-rate. PMID:28319111

  4. Density and Specific Gravity Metrics in Biomass Research

    Science.gov (United States)

    Micheal C. Wiemann; G. Bruce Williamson

    2012-01-01

    Following the 2010 publication of Measuring Wood Specific Gravity… Correctly in the American Journal of Botany, readers contacted us to inquire about application of wood density and specific gravity to biomass research. Here we recommend methods for sample collection, volume measurement, and determination of wood density and specific gravity for...

  5. Density variations in a reactor during liquid full dimerization

    NARCIS (Netherlands)

    Golombok, M.; Bruijn, J.

    2000-01-01

    In a liquid full plug flow reactor during lower olefin dimerization, the assumption of constant density is not valid—the volume of a plug changes as it proceeds along the reactor. The observed kinetics depend on the density variation in the reactor as the conversion proceeds towards a distribution

  6. Electrophoretic deposition of titania nanoparticles: Wet density of ...

    Indian Academy of Sciences (India)

    Administrator

    field has a dual effect on the packing density of particles in the deposits formed by .... Saturated calomel electrode (SCE) and a platinum wire mesh were used as .... density of the deposit, the smaller the volume of liquid phase, which should be.

  7. Probing the density content of the nuclear symmetry energy

    Indian Academy of Sciences (India)

    Abstract. The nature of equation of state for the neutron star matter is crucially governed by the density dependence of the nuclear symmetry energy. We attempt to probe the behaviour of the nuclear symmetry energy around the saturation density by exploiting the empirical values for volume and surface symmetry energy ...

  8. High-voltage-activated calcium current subtypes in mouse DRG neurons adapt in a subpopulation-specific manner after nerve injury.

    Science.gov (United States)

    Murali, Swetha S; Napier, Ian A; Mohammadi, Sarasa A; Alewood, Paul F; Lewis, Richard J; Christie, MacDonald J

    2015-03-01

    Changes in ion channel function and expression are characteristic of neuropathic pain. Voltage-gated calcium channels (VGCCs) are integral for neurotransmission and membrane excitability, but relatively little is known about changes in their expression after nerve injury. In this study, we investigate whether peripheral nerve ligation is followed by changes in the density and proportion of high-voltage-activated (HVA) VGCC current subtypes in dorsal root ganglion (DRG) neurons, the contribution of presynaptic N-type calcium channels in evoked excitatory postsynaptic currents (EPSCs) recorded from dorsal horn neurons in the spinal cord, and the changes in expression of mRNA encoding VGCC subunits in DRG neurons. Using C57BL/6 mice [8- to 11-wk-old males (n = 91)] for partial sciatic nerve ligation or sham surgery, we performed whole cell patch-clamp recordings on isolated DRG neurons and dorsal horn neurons and measured the expression of all VGCC subunits with RT-PCR in DRG neurons. After nerve injury, the density of P/Q-type current was reduced overall in DRG neurons. There was an increase in the percentage of N-type and a decrease in that of P/Q-type current in medium- to large-diameter neurons. No changes were found in the contribution of presynaptic N-type calcium channels in evoked EPSCs recorded from dorsal horn neurons. The α2δ-1 subunit was upregulated by 1.7-fold and γ-3, γ-2, and β-4 subunits were all downregulated 1.7-fold in injured neurons compared with sham-operated neurons. This comprehensive characterization of HVA VGCC subtypes in mouse DRG neurons after nerve injury revealed changes in N- and P/Q-type current proportions only in medium- to large-diameter neurons. Copyright © 2015 the American Physiological Society.

  9. Initial density affects biomass – density and allometric relationships in self-thinning populations of Fagopyrum esculentum

    DEFF Research Database (Denmark)

    Li, Lei; Weiner, Jacob; Zhou, Daowei

    2013-01-01

    and the biomass–density trajectory, we grew Fagopyrum esculentum populations at three high densities and measured shoot biomass, density and the height and diameter of individual plants at six harvests. * Initial density did not affect the slope of the log biomass–log density relationship, but there was a clear...... by the biomass density: the relationship between mass and volume. Initial density could affect this by altering allometric growth in a way that influences architectural compactness. An alternative hypothesis is that competition at higher initial density is more size symmetric, which has been shown to reduce...

  10. Neuronal damage in chick and rat embryos following X-irradiation

    International Nuclear Information System (INIS)

    Schneider, B.F.; Norton, S.

    1980-01-01

    Exposure of rat and chick embryos to X-irradiation at the time of development of neurons at the telencephalic-diencephalic border results in prolonged damage to neurons in this area as measured by neuronal nuclear size. A dose of 100 rads to the seven-day-old chick embryo has about the same effect as 125 rads to the 15-day-old rat fetus. The nuclear volume of large, multipolar neurons in the chick paleostriatum primitivum and the rat lateral preoptic area are reduced from 10 to 15%. Larger doses of X-irradiation to the chick (150 and 200 rads) cause progressively greater reductions in nuclear size. The large neurons which were measured in the rat and chick are morphologically similar in the two species. Both contain cytoplasmic acetylcholinesterase and have several branched, spiny dendritic processes. The similarity of response of chick and rat neurons to X-irradiation diminishes the significance of maternal factors as the cause of the effects of fetal irradiation in these experiments

  11. Apoptosis of supraoptic AVP neurons is involved in the development of central diabetes insipidus after hypophysectomy in rats

    Directory of Open Access Journals (Sweden)

    Huang Lijin

    2008-06-01

    Full Text Available Abstract Background It has been reported that various types of axonal injury of hypothalamo-neurohypophyseal tract can result in degeneration of the magnocellular neurons (MCNs in hypothalamus and development of central diabetes insipidus (CDI. However, the mechanism of the degeneration and death of MCNs after hypophysectomy in vivo is still unclear. This present study was aimed to disclose it and to figure out the dynamic change of central diabetes insipidus after hypophysectomy. Results The analysis on the dynamic change of daily water consumption (DWC, daily urine volume(DUV, specific gravity of urine(USG and plasma vasopressin concentration showed that the change pattern of them was triphasic and neuron counting showed that the degeneration of vasopressin neurons began at 10 d, aggravated at 20 d and then stabilized at 30 d after hypophysectomy. There was marked upregulation of cleaved Caspase-3 expression of vasopressin neurons in hypophysectomy rats. A "ladder" pattern of migration of DNA internucleosomal fragments was detected and apoptotic ultrastructure was found in these neurons. There was time correlation among the occurrence of diabetes insipidus, the changes of plasma vasopressin concentration and the degeneration of vasopressin neurons after hypophysectomy. Conclusion This study firstly demonstrated that apoptosis was involved in degeneration of supraoptic vasopressin neurons after hypophysectomy in vivo and development of CDI. Our study on time course and correlations among water metabolism, degeneration and apoptosis of vasopressin neurons suggested that there should be an efficient therapeutic window in which irreversible CDI might be prevented by anti-apoptosis.

  12. Anomalous atomic volume of alpha-Pu

    DEFF Research Database (Denmark)

    Kollar, J.; Vitos, Levente; Skriver, Hans Lomholt

    1997-01-01

    We have performed full charge-density calculations for the equilibrium atomic volumes of the alpha-phase light actinide metals using the local density approximation (LDA) and the generalized gradient approximation (GGA). The average deviation between the experimental and the GGA atomic radii is 1.......3%. The comparison between the LDA and GGA results show that the anomalously large atomic volume of alpha-Pu relative to alpha-Np can be ascribed to exchange-correlation effects connected with the presence of low coordinated sites in the structure where the f electrons are close to the onset of localization...

  13. Parameter Diversity Induced Multiple Spatial Coherence Resonances and Spiral Waves in Neuronal Network with and Without Noise

    International Nuclear Information System (INIS)

    Li Yuye; Jia Bing; Gu Huaguang; An Shucheng

    2012-01-01

    Diversity in the neurons and noise are inevitable in the real neuronal network. In this paper, parameter diversity induced spiral waves and multiple spatial coherence resonances in a two-dimensional neuronal network without or with noise are simulated. The relationship between the multiple resonances and the multiple transitions between patterns of spiral waves are identified. The coherence degrees induced by the diversity are suppressed when noise is introduced and noise density is increased. The results suggest that natural nervous system might profit from both parameter diversity and noise, provided a possible approach to control formation and transition of spiral wave by the cooperation between the diversity and noise. (general)

  14. Submucosal neurons and enteric glial cells expressing the P2X7 receptor in rat experimental colitis.

    Science.gov (United States)

    da Silva, Marcos Vinícius; Marosti, Aline Rosa; Mendes, Cristina Eusébio; Palombit, Kelly; Castelucci, Patricia

    2017-06-01

    The aim of this study was to evaluate the effect of ulcerative colitis on the submucosal neurons and glial cells of the submucosal ganglia of rats. 2,4,6-Trinitrobenzene sulfonic acid (TNBS; colitis group) was administered in the colon to induce ulcerative colitis, and distal colons were collected after 24h. The colitis rats were compared with those in the sham and control groups. Double labelling of the P2X7 receptor with calbindin (marker for intrinsic primary afferent neurons, IPANs, submucosal plexus), calretinin (marker for secretory and vasodilator neurons of the submucosal plexus), HuC/D and S100β was performed in the submucosal plexus. The density (neurons per area) of submucosal neurons positive for the P2X7 receptor, calbindin, calretinin and HuC/D decreased by 21%, 34%, 8.2% and 28%, respectively, in the treated group. In addition, the density of enteric glial cells in the submucosal plexus decreased by 33%. The profile areas of calbindin-immunoreactive neurons decreased by 25%. Histological analysis revealed increased lamina propria and decreased collagen in the colitis group. This study demonstrated that ulcerative colitis affected secretory and vasodilatory neurons, IPANs and enteric glia of the submucosal plexus expressing the P2X7 receptor. Copyright © 2017 Elsevier GmbH. All rights reserved.

  15. Hindbrain Catecholamine Neurons Activate Orexin Neurons During Systemic Glucoprivation in Male Rats.

    Science.gov (United States)

    Li, Ai-Jun; Wang, Qing; Elsarelli, Megan M; Brown, R Lane; Ritter, Sue

    2015-08-01

    Hindbrain catecholamine neurons are required for elicitation of feeding responses to glucose deficit, but the forebrain circuitry required for these responses is incompletely understood. Here we examined interactions of catecholamine and orexin neurons in eliciting glucoprivic feeding. Orexin neurons, located in the perifornical lateral hypothalamus (PeFLH), are heavily innervated by hindbrain catecholamine neurons, stimulate food intake, and increase arousal and behavioral activation. Orexin neurons may therefore contribute importantly to appetitive responses, such as food seeking, during glucoprivation. Retrograde tracing results showed that nearly all innervation of the PeFLH from the hindbrain originated from catecholamine neurons and some raphe nuclei. Results also suggested that many catecholamine neurons project collaterally to the PeFLH and paraventricular hypothalamic nucleus. Systemic administration of the antiglycolytic agent, 2-deoxy-D-glucose, increased food intake and c-Fos expression in orexin neurons. Both responses were eliminated by a lesion of catecholamine neurons innervating orexin neurons using the retrogradely transported immunotoxin, anti-dopamine-β-hydroxylase saporin, which is specifically internalized by dopamine-β-hydroxylase-expressing catecholamine neurons. Using designer receptors exclusively activated by designer drugs in transgenic rats expressing Cre recombinase under the control of tyrosine hydroxylase promoter, catecholamine neurons in cell groups A1 and C1 of the ventrolateral medulla were activated selectively by peripheral injection of clozapine-N-oxide. Clozapine-N-oxide injection increased food intake and c-Fos expression in PeFLH orexin neurons as well as in paraventricular hypothalamic nucleus neurons. In summary, catecholamine neurons are required for the activation of orexin neurons during glucoprivation. Activation of orexin neurons may contribute to appetitive responses required for glucoprivic feeding.

  16. Statistics of a neuron model driven by asymmetric colored noise.

    Science.gov (United States)

    Müller-Hansen, Finn; Droste, Felix; Lindner, Benjamin

    2015-02-01

    Irregular firing of neurons can be modeled as a stochastic process. Here we study the perfect integrate-and-fire neuron driven by dichotomous noise, a Markovian process that jumps between two states (i.e., possesses a non-Gaussian statistics) and exhibits nonvanishing temporal correlations (i.e., represents a colored noise). Specifically, we consider asymmetric dichotomous noise with two different transition rates. Using a first-passage-time formulation, we derive exact expressions for the probability density and the serial correlation coefficient of the interspike interval (time interval between two subsequent neural action potentials) and the power spectrum of the spike train. Furthermore, we extend the model by including additional Gaussian white noise, and we give approximations for the interspike interval (ISI) statistics in this case. Numerical simulations are used to validate the exact analytical results for pure dichotomous noise, and to test the approximations of the ISI statistics when Gaussian white noise is included. The results may help to understand how correlations and asymmetry of noise and signals in nerve cells shape neuronal firing statistics.

  17. Neuronal plasticity in the hedgehog supraoptic nucleus during hibernation.

    Science.gov (United States)

    Sanchez-Toscano, F; Caminero, A A; Machin, C; Abella, G

    1989-01-01

    The purpose of the present study was to identify processes of plasticity in the receptive field of neurosecretory neurons of the supraoptic nucleus during hibernation in the hedgehog, in order to correlate them with the increased neurosecretory activity observed in this nucleus during this annual period. Using the Rapid Golgi method, a quantitative study was conducted in the receptive field of bipolar and multipolar neurons (the main components of the nucleus). Results indicate a generalized increase in the following characteristics: (1) number of dendritic spines per millimeter along the dendritic shafts; (2) degree of branching in the dendritic field; and (3) dendritic density around the neuronal soma. These data demonstrate modification of the dendritic field in the supraoptic nucleus during hibernation, a change undoubtedly related to functional conditions. Since the observed changes affect structures such as dendritic spines which are directly related to the arrival of neural afferences, the discussion is centered on the types of stimuli which may be responsible for the observed processes.

  18. A chimeric path to neuronal synchronization

    Science.gov (United States)

    Essaki Arumugam, Easwara Moorthy; Spano, Mark L.

    2015-01-01

    Synchronization of neuronal activity is associated with neurological disorders such as epilepsy. This process of neuronal synchronization is not fully understood. To further our understanding, we have experimentally studied the progression of this synchronization from normal neuronal firing to full synchronization. We implemented nine FitzHugh-Nagumo neurons (a simplified Hodgkin-Huxley model) via discrete electronics. For different coupling parameters (synaptic strengths), the neurons in the ring were either unsynchronized or completely synchronized when locally coupled in a ring. When a single long-range connection (nonlocal coupling) was introduced, an intermediate state known as a chimera appeared. The results indicate that (1) epilepsy is likely not only a dynamical disease but also a topological disease, strongly tied to the connectivity of the underlying network of neurons, and (2) the synchronization process in epilepsy may not be an "all or none" phenomenon, but can pass through an intermediate stage (chimera).

  19. A chimeric path to neuronal synchronization

    Energy Technology Data Exchange (ETDEWEB)

    Essaki Arumugam, Easwara Moorthy; Spano, Mark L. [School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona 85287-9709 (United States)

    2015-01-15

    Synchronization of neuronal activity is associated with neurological disorders such as epilepsy. This process of neuronal synchronization is not fully understood. To further our understanding, we have experimentally studied the progression of this synchronization from normal neuronal firing to full synchronization. We implemented nine FitzHugh-Nagumo neurons (a simplified Hodgkin-Huxley model) via discrete electronics. For different coupling parameters (synaptic strengths), the neurons in the ring were either unsynchronized or completely synchronized when locally coupled in a ring. When a single long-range connection (nonlocal coupling) was introduced, an intermediate state known as a chimera appeared. The results indicate that (1) epilepsy is likely not only a dynamical disease but also a topological disease, strongly tied to the connectivity of the underlying network of neurons, and (2) the synchronization process in epilepsy may not be an “all or none” phenomenon, but can pass through an intermediate stage (chimera)

  20. Mini Review: Biomaterials for Enhancing Neuronal Repair

    Science.gov (United States)

    Cangellaris, Olivia V.; Gillette, Martha U.

    2018-04-01

    As they differentiate from neuroblasts, nascent neurons become highly polarized and elongate. Neurons extend and elaborate fine and fragile cellular extensions that form circuits enabling long-distance communication and signal integration within the body. While other organ systems are developing, projections of differentiating neurons find paths to distant targets. Subsequent post-developmental neuronal damage is catastrophic because the cues for reinnervation are no longer active. Advances in biomaterials are enabling fabrication of micro-environments that encourage neuronal regrowth and restoration of function by recreating these developmental cues. This mini-review considers new materials that employ topographical, chemical, electrical, and/or mechanical cues for use in neuronal repair. Manipulating and integrating these elements in different combinations will generate new technologies to enhance neural repair.