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Neural Populations (neural + population)
Selected AbstractsInformation Processing in the Hypothalamus: Peptides and Analogue ComputationJOURNAL OF NEUROENDOCRINOLOGY, Issue 6 2006G. Leng Abstract ,Lovers and madmen have such seething brains,/Such shaping fantasies, that apprehend/More than cool reason ever comprehends'(A Midsummer Night's Dream, Act V Scene I) Peptides in the hypothalamus are not like conventional neurotransmitters; their release is not particularly associated with synapses, and their long half-lives mean that they can diffuse to distant targets. Peptides can act on their cells of origin to facilitate the development of patterned electrical activity, they can act on their neighbours to bind the collective activity of a neural population into a coherent signalling entity, and the co-ordinated population output can transmit waves of peptide secretion that act as a patterned hormonal analogue signal within the brain. At their distant targets, peptides can re-programme neural networks, by effects on gene expression, synaptogenesis, and by functionally rewiring connections by priming activity-dependent release. [source] N-cadherin is regulated by gonadal steroids in adult sexually dimorphic spinal motoneuronsDEVELOPMENTAL NEUROBIOLOGY, Issue 4 2001Douglas A. Monks Abstract Gonadal steroids influence the morphology and function of neurons in the adult spinal cord through cellular and molecular mechanisms that are largely unknown. The cadherins are cell adhesion molecules that participate in the formation and organization of the CNS during embryonic development, and recent evidence suggests that the cadherins continue to regulate neural structure and function in adulthood. Using degenerate oligonucleotides coding conserved regions of the catenin-binding domain of classical cadherins in a RT-PCR cloning strategy, we identified several cadherin subtypes, the most frequently cloned being N-, E-, and R-cadherin, suggesting that these are the major classical cadherin subtypes present in the adult male rat lumbosacral spinal cord. We then examined cadherin expression levels of these cadherin subtypes under steroid conditions known to induce plastic changes in spinal motoneurons. Semiquantitative PCR revealed that mRNA levels of N-cadherin, but not E-cadherin or R-cadherin, are elevated in castrated rats treated with testosterone, 17,-estradiol, or dihydrotestosterone relative to castrate rats not treated with steroids. Immunolocalization of N-cadherin revealed that steroid treatment increased N-cadherin expression levels in functionally related neural populations whose morphology and function are regulated by steroids. These results suggest a role for N-cadherin in steroid-induced neuroplastic change in the adult lumbar spinal cord. © 2001 John Wiley & Sons, Inc. J Neurobiol 47: 255,264, 2001 [source] Using state-dependency of transcranial magnetic stimulation (TMS) to investigate letter selectivity in the left posterior parietal cortex: a comparison of TMS-priming and TMS-adaptation paradigmsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 9 2008Zaira Cattaneo Abstract The state-dependency of transcranial magnetic stimulation (TMS) can be used to investigate the neural properties of subregions of the stimulated region. The objective of the present study was to determine whether state-dependency can reveal letter selectivity in the left posterior parietal cortex (PPC), a region known to contain letter-selective neurons. In two experiments, we used visual priming and adaptation to modulate the initial activation state of the left PPC prior to application of TMS. In the priming experiment, TMS was applied over the left PPC during the delay between the prime and the target stimulus on each experimental trial. Left PPC TMS reversed the effects of priming by facilitating the detection of non-primed letters, whereas detection of primed letters was unaffected. As neurons tuned to non-primed letters were less active at the time of TMS application than neurons tuned to the primed letters, this finding demonstrates that TMS preferentially facilitates the detection of attributes encoded by the less active neural populations. A similar facilitation of the less active neural populations was observed when adaptation was used to suppress letter-selective neurons prior to application of TMS. Our study demonstrates that TMS-priming and TMS-adaptation paradigms can reveal letter selectivity in the left PPC and thus be useful in the study of language processes. Our results also show that the state-dependent TMS effects obtained with visual priming are similar to those found with TMS adaptation: in both cases, attributes encoded by the less active neural populations are preferentially facilitated. [source] Neural Signal Manager: a collection of classical and innovative tools for multi-channel spike train analysisINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 11 2009Antonio Novellino Abstract Recent developments in the neuroengineering field and the widespread use of the micro electrode arrays (MEAs) for electrophysiological investigations made available new approaches for studying the dynamics of dissociated neuronal networks as well as acute/organotypic slices maintained ex vivo. Importantly, the extraction of relevant parameters from these neural populations is likely to involve long-term measurements, lasting from a few hours to entire days. The processing of huge amounts of electrophysiological data, in terms of computational time and automation of the procedures, is actually one of the major bottlenecks for both in vivo and in vitro recordings. In this paper we present a collection of algorithms implemented within a new software package, named the Neural Signal Manager (NSM), aimed at analyzing a huge quantity of data recorded by means of MEAs in a fast and efficient way. The NSM offers different approaches for both spike and burst analysis, and integrates state-of-the-art statistical algorithms, such as the inter-spike interval histogram or the post stimulus time histogram, with some recent ones, such as the burst detection and its related statistics. In order to show the potentialities of the software, the application of the developed algorithms to a set of spontaneous activity recordings from dissociated cultures at different ages is presented in the Results section. Copyright © 2008 John Wiley & Sons, Ltd. [source] Neuropeptide Y and alpha-melanocyte-stimulating hormone: interaction in obesity and possible role in the development of hypertensionINTERNATIONAL JOURNAL OF CLINICAL PRACTICE, Issue 9 2008M. Baltatzi Summary Aim:, Obesity and hypertension frequently coexist and both represent important risk factors for cardiovascular disease. The mechanisms implicated in the regulation of food intake have not been completely elucidated. Recent data suggests that peripheral and central neuropeptides play an important role in the maintenance of energy balance. More specifically, leptin, neuropeptide Y (NPY) and alpha-melanocyte-stimulating hormone (a-MSH) appear to be implicated in the pathogenesis of obesity and also contribute to the development of hypertension in obesity. Methods:, Analysis of the pertinent bibliography published in PubMed database. Results:, Leptin is produced in the adipose tissue directly correlated with fat tissue mass. Leptin acts on two distinct neural populations in the hypothalamus: the first expresses the orexigenic peptides NPY and agouti-related protein (AgRP), the second pro-opiomelanocortin (POMC). The activation of POMC neurons increases the production of the anorexigenic hormone a-MSH and inhibits the release of NPY and AgRP. In addition, the hypothalamus integrates the neuroendocrine systems with the autonomic nervous system and controls the activity of the latter. Stimulation of hypothalamic nuclei elicits sympathetic responses including blood pressure elevation. Both NPY and a-MSH appears to be implicated in the hypothalamic regulation of sympathetic nervous system (SNS) activity. Conclusion:, Alterations in leptin, NPY and a-MSH are frequently observed in obesity and might stimulate SNS activity, contributing to the development of hypertension in obese patients. These neuropeptides might provide a pathophysiologic link between excess weight and hypertension. However, more research is needed before the pharmacologic manipulation of these complex neuroendocrine systems can be applied in the treatment of obesity and hypertension. [source] 4414: Flow cytometry for the characterization of retinal neural populations and the quantification of retinal apoptosisACTA OPHTHALMOLOGICA, Issue 2010PA TSOKA Purpose The primary purpose of this study was to evaluate the potential to quantify the different retinal neuronal populations, as also the retinal detachment-induced apoptosis in Sprague,Dawley rats, in an accurate quantitative way by using flow cytometry. Methods Retinal detachment was performed on the right eye of deeply anesthetized animals. The detachment was induced by a sub-retinal injection of sodium hyaluronate. Rats were sacrifised and the eyes were enuclated to achieve retinal dissection. Tissue dissociation was accomplished with trypsin. The cells were mechanically dissociated into a single-cell suspension. At least 100.000 cells were analyzed with a FACScalibur and FlowJo software. The primary antibodies were anti-rhodopsin against rod photoreceptors, anti-PKC against rod bipolars, anti-calbindin against horizontals, anti-ChAT against cholinergic amacrine cells and anti-MAP1 against ganglion cells. Annexin-V-FITC/Propidium Iodide was used to identify apoptosis. Results Quantification of retinal neuronal cells was possible using flow cytometry. Photoreceptors had the 53.99%, the ganglion the 7%, the bipolars the 2%, the horizontal the 4% and the cholinergic amacrine cells the 1,5% in the hole mixed retinal population. Quantification of the apoptotic rate was also possible. The early apoptotic cells was 22.4% while in the control eye was 6.28% after retinal detachment. The experiments were repeated ten times and these measurements are the mean value. Conclusion Flow cytometry can be used to quantify the apoptotic neuronal cells as well as the healthy retinal neurons. It is quick and precise and it will be very useful in future in studies in neuroprotection and quantification of apoptosis during time. [source] | |||||||||||||