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Articles de revues sur le sujet "Neurones NPY"
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Williams, Gareth, Joanne A. Harrold et David J. Cutler. « The hypothalamus and the regulation of energy homeostasis : lifting the lid on a black box ». Proceedings of the Nutrition Society 59, no 3 (août 2000) : 385–96. http://dx.doi.org/10.1017/s0029665100000434.
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The hypothalamus is the focus of many peripheral signals and neural pathways that control energy homeostasis and body weight. Emphasis has moved away from anatomical concepts of ‘feeding’ and ‘satiety’ centres to the specific neurotransmitters that modulate feeding behaviour and energy expenditure. We have chosen three examples to illustrate the physiological roles of hypothalamic neurotransmitters and their potential as targets for the development of new drugs to treat obesity and other nutritional disorders. Neuropeptide Y (NPY) is expressed by neurones of the hypothalamic arcuate nucleus (ARC) that project to important appetite-regulating nuclei, including the paraventricular nucleus (PVN). NPY injected into the PVN is the most potent central appetite stimulant known, and also inhibits thermogenesis; repeated administration rapidly induces obesity. The ARC NPY neurones are stimulated by starvation, probably mediated by falls in circulating leptin and insulin (which both inhibit these neurones), and contribute to the increased hunger in this and other conditions of energy deficit. They therefore act homeostatically to correct negative energy balance. ARC NPY neurones also mediate hyperphagia and obesity in the ob/ob and db/db mice and fa/fa rat, in which leptin inhibition is lost through mutations affecting leptin or its receptor. Antagonists of the Y5 receptor (currently thought to be the NPY ‘feeding’ receptor) have anti-obesity effects. Melanocortin-4 receptors (MC4-R) are expressed in various hypothalamic regions, including the ventromedial nucleus and ARC. Activation of MC4-R by agonists such as α-melanocyte-stimulating hormone (a cleavage product of pro-opiomelanocortin which is expressed in ARC neurones) inhibits feeding and causes weight loss. Conversely, MC4-R antagonists such as ‘agouti’ protein and agouti gene-related peptide (AGRP) stimulate feeding and cause obesity. Ectopic expression of agouti in the hypothalamus leads to obesity in the AVY mouse, while AGRP is co-expressed by NPY neurones in the ARC. Synthetic MC4-R agonists may ultimately find use as anti-obesity drugs in human subjects Orexins-A and -B, derived from prepro-orexin, are expressed in specific neurones of the lateral hypothalamic area (LHA). Orexin-A injected centrally stimulates eating and prepro-orexin mRNA is up regulated by fasting and hypoglycaemia. The LHA is important in receiving sensory signals from the gut and liver, and in sensing glucose, and orexin neurones may be involved in stimulating feeding in response to falls in plasma glucose.
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Adams, Eric F., Maria S. Venetikou, Christine A. Woods, S. Lacoumenta et J. M. Burrin. « Neuropeptide Y directly inhibits growth hormone secretion by human pituitary somatotropic tumours ». Acta Endocrinologica 115, no 1 (mai 1987) : 149–54. http://dx.doi.org/10.1530/acta.0.1150149.
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Abstract. Neuropeptide Y (NPY) is a 36 amino acid peptide, widely distributed throughout the brain and is found in hypothalamic neurones. This latter finding suggests that NPY may possess a hypophysiotropic function. A number of studies have demonstrated effects of NPY on LH and GH secretion by rat pituitary cells. We report here the results of experiments investigating the effects of NPY on GH secretion by tumorous human somatotropic pituitary cells in culture. NPY (0.25–25 nmol/l) inhibited GH secretion by 20–53%, the maximal effect depending upon the tumour studied. The potency of NPY was less than that of somatostatin (SRIH). The stimulatory effects of growth hormone releasing factor (GHRH) and theophylline were reduced by NPY, but NPY did not modify the inhibitory effect of SRIH on GH secretion. It is concluded that NPY may be involved in the control of GH secretion, at least by tumorous human pituitary somatotropes.
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Gładysz, A., P. Krejci, J. Simůnek et J. Polkowska. « Effects of central infusions of neuropeptide Y on the somatotropic axis in sheep fed on two levels of protein ». Acta Neurobiologiae Experimentalis 61, no 4 (31 décembre 2001) : 255–66. http://dx.doi.org/10.55782/ane-2001-1401.
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Effects of infusions of neuropeptide Y (NPY) into 3rd ventricle of growing sheep fed on diets containing restricted (R) or elevated (E) levels of protein on the immunoreactive (ir) somatostatin neurones, ir somatotrophs, growth hormone (GH) concentration in the blood plasma were studied. The long-term restriction of protein in the diet elicited: enhancing irSS content in periventricular perikarya; diminishing irSS stores in the median eminence and elevating the number ir somatotrophs and content of irGH. NPY infusions enhanced the content of irSS in perikarya in sheep fed on E diet and diminished the number of ir somatotrophs and content of irGH of sheep fed on R diet. The R diet as well as NPY infusions caused an increase in GH mean concentrations in the blood plasma. Obtained results suggest that timulatory effect of restricted feeding and/or NPY action on GH secretion can be due to attenuated SS output. Since dietary restrictions and exogenous NPY have similar influence on the activation of GH secretion, we suggest that NPY could be a neuromodulatory link between nutritional cues and somatotropic axis in sheep.
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Sienkiewicz, W., A. Chrószcz, A. Dudek, M. Janeczek et J. Kaleczyc. « Caudal mesenteric ganglion in the sheep – macroanatomical and immunohistochemical study ». Polish Journal of Veterinary Sciences 18, no 2 (1 juin 2015) : 379–89. http://dx.doi.org/10.1515/pjvs-2015-0049.
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Abstract The caudal mesenteric ganglion (CaMG) is a prevetrebral ganglion which provides innervation to a number of organs in the abdominal and pelvic cavity. The morphology of CaMG and the chemical coding of neurones in this ganglion have been described in humans and many animal species, but data on this topic in the sheep are entirely lacking. This prompted us to undertake a study to determine the localization and morphology of sheep CaMG as well as immunohistochemical properties of its neurons. The study was carried out on 8 adult sheep, weighing from 40 to 60 kg each. The sheep were deeply anaesthetised and transcardially perfused with 4% paraformaldehyde. CaMG-s were exposed and their location was determined. Macroanatomical observations have revealed that the ovine CaMG is located at the level of last two lumbar (L5 or L6) and the first sacral (S1) vertebrae. The ganglion represents an unpaired structure composed of several, sequentially arranged aggregates of neurons. Immunohistochemical investigations revealed that nearly all (99.5%) the neurons were DβH-IR and were richly supplied by VACHT-IR nerve terminals forming „basket-like” structures around the perikarya. VACHT-IR neurones were not determined. Many neurons (55%) contained immunoreactivity to NPY, some of them (10%) stained for Met-ENK and solitary nerve cells were GAL-positive. CGRP-IR nerve fibres were numerous and a large number of them simultaneously expressed immunoreactivity to SP. Single, weakly stained neurones were SP-IR and only very few nerve cells weakly stained for VIP.
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Károly, Norbert, Endre Dobó et András Mihály. « Comparative immunohistochemical study of the effects of pilocarpine on the mossy cells, mossy fibres and inhibitory neurones in murine dentate gyrus ». Acta Neurobiologiae Experimentalis 75, no 2 (30 juin 2015) : 220–37. http://dx.doi.org/10.55782/ane-2015-2030.
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Treatment with pilocarpine (PILO) induces variable degrees of loss of mossy cells (MCs) and mossy fibre (MF) sprouting in rodents, the relationships of which have not been examined in individual animals. Our aim was to test whether the loss of MCs and MF sprouting are coupled processes in PILO-treated rodents. Animals which exhibited intense PILO-induced convulsions for at least 30 min were used in this study. After a 2-month survival period, the incidence of epileptic seizures was checked individually by neuropeptide-Y (NPY) immunohistochemistry, and the numbers of MCs were counted by means of immunohistochemistry, for calretinin (CR) in mice and calcitonin gene-related peptide (CGRP) in rats. MF sprouting was checked by using Timm’s silver-sulphide method for zinc. In our comparative studies, NPY immunohistochemistry resulted in more positive animals than on zinc staining. The CR immunoreactivity remained unchanged even in those mice that displayed MF sprouting and greatly increased NPY immunoreactivity. CR immunoreactivity was also verified after transection of the fornix to exclude the extrahippocampal source of this peptide. However, the CGRP immunoreactivity was severely reduced in those rats that exhibited simultaneous increases in zinc content and NPY immunoreactivity in the supragranular layer and stratum lucidum. Our findings suggest that the MCs survive PILO treatment in mice, but not in rats. There is direct evidence of a close relationship between the loss of MCs and MF sprouting in rats, but not in mice. Thus, similar PILO seizures may result from different changes in the neuronal circuits of rodents.
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Chan, Y. Y., D. K. Clifton et R. A. Steiner. « Role of NPY Neurones in GH-Dependent Feedback Signalling to the Brain ». Hormone Research 45, no 1 (1996) : 12–14. http://dx.doi.org/10.1159/000184820.
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Joly, A., R. Denis, J. Castel, R. Palmiter, C. Magnan et S. Luquet. « O35 Rôle des Neurones NPY/AgRP dans le contrôle de la balance énergétique ». Diabetes & ; Metabolism 36 (mars 2010) : A10. http://dx.doi.org/10.1016/s1262-3636(10)70039-2.
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Brooks, P. A., J. S. Kelly, J. M. Allen, D. A. S. Smith et T. W. Stone. « Direct excitatory effects of neuropeptide Y (NPY) on rat hippocampal neurones in vitro ». Brain Research 408, no 1-2 (avril 1987) : 295–98. http://dx.doi.org/10.1016/0006-8993(87)90391-x.
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le Roux, C. W., et S. R. Bloom. « Peptide YY, appetite and food intake ». Proceedings of the Nutrition Society 64, no 2 (mai 2005) : 213–16. http://dx.doi.org/10.1079/pns2005427.
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Obesity is taking on pandemic proportions. The laws of thermodynamics, however, remain unchanged, as energy will be stored if less energy is expended than consumed; the storage is usually in the form of adipose tissue. Several neural, humeral and psychological factors control the complex process known as appetite. Recently, a close evolutionary relationship between the gut and brain has become apparent. The gut hormones regulate important gastrointestinal functions such as motility, secretion, absorption, provide feedback to the central nervous system on availability of nutrients and may play a part in regulating food intake. Peptide YY (PYY) is a thirty-six amino acid peptide related to neuropeptide Y (NPY) and is co-secreted with glucagon-like peptide 1. Produced by the intestinal L-cells, the highest tissue concentrations of PYY are found in distal segments of the gastrointestinal tract, although it is present throughout the gut. Following food intake PYY is released into the circulation. PYY concentrations are proportional to meal energy content and peak plasma levels appear postprandially after 1 h. PYY3-36 is a major form of PYY in both the gut mucosal endocrine cells and the circulation. Peripheral administration of PYY3-36 inhibits food intake for several hours in both rodents and man. The binding of PYY3-36 to the Y2 receptor leads to an inhibition of the NPY neurones and a possible reciprocal stimulation of the pro-opiomelanocortin neurones. Thus, PYY3-36 appears to control food intake by providing a powerful feedback on the hypothalamic circuits. The effect on food intake has been demonstrated at physiological concentrations and, therefore, PYY3-36 may be important in the everyday regulation of food intake.
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Håkansson, Marie-Louise, Anna-Lena Hulting et Björn Meister. « Expression of leptin receptor mRNA in the hypothalamic arcuate nucleus - relationship with NPY neurones ». NeuroReport 7, no 18 (novembre 1996) : 3087–92. http://dx.doi.org/10.1097/00001756-199611250-00059.
Texte intégralThèses sur le sujet "Neurones NPY"
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King, Peter John. « The study of NPY neurones in the rat hypothalamus ». Thesis, University of Liverpool, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367248.
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Leclerc, Clémence. « Caractérisation multiparamétrique des neurones du hilus du gyrus denté chez la souris ». Phd thesis, Université Pierre et Marie Curie - Paris VI, 2012. http://tel.archives-ouvertes.fr/tel-00833326.
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Dans le hilus du gyrus denté de l'hippocampe, les cellules moussues excitatrices et les interneurones GABAergiques constituent des acteurs clés du réseau. Cependant, en raison en partie de leur grande diversité, la fonction des interneurones GABAergiques du hilus dans la physiologie du gyrus denté reste peu détaillée. Nous avons utilisé des souris transgéniques GAD67-GFP, exprimant la GFP sous le contrôle du promoteur de la GAD67, et évalué les densités de neurones GABAergiques marqués pour la Calretinine (CR), Parvalbumine (PV), Somatostatine (SOM), Neuropeptide Y (NPY) et l'oxyde nitrique synthase (NOS-1) dans le hilus et la couche granulaire. Pour mieux caractériser les différentes populations d'interneurones, nous avons caractérisé les propriétés de 123 neurones en utilisant la technique de RT-PCR sur cellule unique sur des tranches de cerveaux de souris C57Bl6 âgées de 2 à 3 mois. Une analyse non supervisée en clusters basée sur 18 paramètres électrophysiologiques et 7 paramètres moléculaires a clairement mis en évidence un cluster de cellules moussues excitatrices (n=67) et 3 clusters de cellules GABAergiques (n=56). Les deux premiers clusters d'interneurones GABAergiques comprennent des neurones (n=18 et n=16) qui co-expriment le NPY et la SOM mais se différencient clairement par leurs propriétés élcetrophysiologiques. Le troisième cluster d'interneurones comprend des neurones à décharge rapide exprimant soit la PV (n=9) soit la NOS-1 (n=13). Cette caractérisation multiparamétrique supporte l'existence de classes fonctionnelles distinctes parmi les interneurones GABAergiques du gyrus denté
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Fioramonti, Xavier. « Mise en évidence et caractérisation de neurones sensibles au glucose dans le noyau arqué de souris : approche in vitro par électrophysiologie et étude in vivo ». Toulouse 3, 2005. http://www.theses.fr/2005TOU30139.
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Le glucose, en plus d'être un substrat métabolique, agit en tant que molécule informative en modulant l'activité de certains neurones dits " sensibles au glucose ". Nos enregistrements électrophysiologiques menés dans le noyau arqué de souris montrent que 4 sous-populations de neurones sont présentes dans ce noyau. Les neurones dits GE et GI sont respectivement excités et inhibés par une hypoglycémie (5-0 mM de glucose) ; les neurones HGE et HGI sont respectivement excités et inhibés par une hyperglycémie (5-20 mM de glucose). Nous avons entrepris de déterminer la nature des ces neurones sensibles au glucose en étudiant les neurotransmetteurs qu'ils expriment. En utilisant des souris NPY-GFP, nous montrons que les neurones GI sont des neurones à NPY. L'utilisation de souris POMC-GFP montre que les neurones GE et HGE n'expriment pas la POMC. Ce résultat a été confirmé in vivo en utilisant le marqueur d'activité neuronale c-fosGlucose is known to regulate energetic homeostasis in controlling the electrical activity of glucose-sensing neurones. Using electrophysiological recordings on mouse brain slice, we show that 4 distinct glucose-sensitive neurones subpopulations exist in the arcuate nucleus. GE and GI neurones are respectively excited and inhibited by a hypoglycaemia (5-0 mM glucose); HGE and HGI neurones are respectively excited and inhibited by a hyperglycaemia (5-20 mM glucose). Then, in order to suggest a physiologic relevance of these neurones, we decided to characterize the neuropeptides express in these cells. Using NPY-GFP mouse, we show that GI neurones express NPY. Nevertheless, using POMC-GFP mouse, we show that GE or HGE neurones do not express POMC. This result was confirmed in vivo, in using the neuronal activating marker c-fos. This work replaces these glucose-sensitive neurones in the neural network involved in the control of energetic homeostasis
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Mounien, Lourdes. « Etude du rôle des neurones à POMC du noyau arqué dans le contrôle de la prise alimentaire : Relations avec les systèmes neuropeptidergiques à NPY et à PACAP ». Rouen, 2006. http://www.theses.fr/2006ROUES018.
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La prise alimentaire est soumise à des processus de régulation complexes dans lesquels interviennent de nombreux neuropeptides hypothalamiques. Parmi eux, le neuropeptide Y (NPY) exerce un puissant effet orexigène alors que les mélanocortines, issues du clivage protéolytique de la proopiomélanocortine (POMC), et le pituitary adenylate cyclase-activating polypeptide (PACAP) diminuent la prise de nourriture. L'objectif de notre étude a été de déterminer les relations neuroanatomiques et fonctionnelles entre les neurones synthétisant la POMC dans le noyau arqué (NA) hypothalamique et les systèmes neuropeptidergiques à NPY et à PACAP. Ce travail de thèse apporte de nouvelles informations sur la contribution des neurones à POMC du NA dans la régulation de l'homéostasie énergétique. Il apparaît que les neurones à POMC sont capables de contrôler directement l'activité des neurones à NPY du NA et qu'ils sont eux-mêmes soumis à une modulation par le PACAPThe food intake is under control of a complex regulation mechanism involving several hypothalamic neuropeptides. Among them, neuropeptide Y (NPY) is orexigenic whereas α-melanocyte-stimulating hormone (α-MSH), a peptide generated by processing of proopiomelanocortin (POMC), and pituitary adenylate cyclase-activating polypeptide (PACAP) reduce food consumption. We have investigated the neuroanatomic and functional relations between POMC neurons of arcuate nucleus and the NPY and PACAP neuropeptidergic systems. Our data provide additionnal evidence for the function of arcuate POMC neurons in the regulation of energy homeostasis. Thus, it appears that POMC neurons are able to directly control the activity of the arcuate NPY system and that they are subjected to modulation by PACAP
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Qu, Mengdi. « Molecular mechanism underlying CaMK1D-dependent function in AgRP neurons ». Electronic Thesis or Diss., Strasbourg, 2024. http://www.theses.fr/2024STRAJ029.
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La perturbation des mécanismes de réponse au stress chez les organismes peut entraîner une dysfonction cellulaire et des maladies telles que le syndrome métabolique. L'équilibre énergétique est principalement régulé par le système nerveux central (SNC), qui intègre des signaux hormonaux, neuronaux et alimentaires provenant de divers tissus. Une dysfonction de ce système est liée à l'obésité et au syndrome métabolique, qui sont tous deux des précurseurs du diabète de type 2 (T2D). Notre laboratoire a découvert que la protéine kinase ID dépendante du calcium/calmoduline (CaMK1D), un gène associé au T2D, favorise la prise alimentaire médiée par la ghréline chez les souris. Cependant, le rôle de la signalisation de CaMK1D dans les neurones NPY/AgRP reste encore à éclaircir. Dans cette étude, nous avons réalisé un séquençage de l'ARN en utilisant la lignée cellulaire hypothalamique GT1-7. Nous avons ainsi découvert que CalHM6 est une cible potentielle en aval de la signalisation de CaMK1D. Les niveaux d'ARNm de CalHM6 sont ainsi significativement augmentés dans les cellules CaMK1D-/- et sont réduits lorsque CaMK1D est ré-exprimé. Cela a également été confirmé in vivo dans l'hypothalamus des souris CaMK1D-/-. CalHM6, probablement un canal calcique dépendant du voltage, a montré des niveaux intracellulaires de Ca2+ augmentés en réponse à la ghréline dans les cellules CaMK1D-/- par rapport aux cellules CaMK1D+/+ en utilisant la méthode jGCamps. En résumé, notre travail a montré que CalHM6 est une nouvelle cible de CaMK1D. Une expression élevée de CaMK1D, entraînant une faible expression de CalHM6, pourrait ainsi favoriser la prise alimentaire et l'obésité en modulant la signalisation dépendante du calcium dans les neurones NPY/AgRPDisruption of stress response mechanisms in organisms can lead to cellular dysfunction and diseases like metabolic syndrome. Energy balance is mainly regulated by the central nervous system (CNS), which integrates hormonal, neuronal, and dietary signals from various tissues. Dysfunction in this system is linked to obesity and metabolic syndrome, both precursors to type 2 diabetes (T2D). Our laboratory discovered that calcium/calmodulin-dependent protein kinase ID (CaMK1D), a gene associated with T2D, promotes ghrelin-mediated food intake in mice. However, CaMK1D signaling in NPY/AgRP neurons still remains questions. In this work, we proformed RNA sequencing using the GT1-7 hypothalamic cell line. To this end, we found that CalHM6 is a downstream target of CaMK1D signaling. CalHM6 mRNA levels were significantly upregulated in CaMK1D-/- cells and downregulated when CaMK1D was re-expressed. This was confirmed in vivo in the hypothalamus of CaMK1D-/- mice. CalHM6, likely a voltage-gated calcium channel, showed increased intracellular Ca2+ levels in response to ghrelin in CaMK1D-/- cells compared to CaMK1D+/+ cells using jGCamps method. Altogether, our work showed CalHM6 is a novel target of CaMK1D. High CaMK1D, leading to low CalHM6 expression, may enhance food intake and obesity by modulating calcium-dependent signaling in NPY/AgRP neuron
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Joly, Aurélie. « Rôle du système nerveux dans le développement du syndrôme métabolique : étude de l'effet du glucose portal sur la sensibilité à l'insuline chez le rat : implication des neurones NPY/AgRP dans le contrôle de la balance énergétique chez la souris ». Paris 7, 2011. http://www.theses.fr/2011PA077091.
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Le système nerveux central (SNC) intègre en permanence des signaux périphériques tels que les variations de concentration en hormones et en nutriments, et module en réponse le comportement alimentaire ainsi que la dépense énergétique et le métabolisme. Au niveau du noyau arqué de l'hypothalamus, la barrière hématoencéphalique est plus perméable, ce qui lui confère un rôle de premier ordre dans l'intégration des signaux périphériques. Les neurones du noyau arqué de l'hypothalamus qui sécrètent le neuropeptide Y et l'Agouti Related Protein (NPY/AgRP) sont impliqués dans la stimulation de la prise alimentaire et la diminution de la dépense énergétique. Contrairement aux résultats attendus, l'ablation de ces neurones oréxigènes au stade néonatal chez la souris conduit au développement d'une obésité massive à l'âge adulte. Cette obésité se développe sans hyperphagie, et les analyses métaboliques montrent que les animaux ont une dépense énergétique similaire aux témoins. Les souris déficientes ne sont pas diabétiques contrairement à d'autres modèles d'obésité, mais sont caractérisées par une hyperinsulinémie basale associé à une altération du métabolisme lipidique. Nous montrons que la perte de ces neurones induit une modulation du renouvellement des catécholamines qui se traduit en périphérie par une redistribution des flux métaboliques, favorisant le métabolisme lipidique. Cette redistribution serait responsable du développement de l'obésité en favorisant les mécanismes de stockage, mais permettrait de limiter les effets d'un régime gras sur l'homéostasie glucidiqueSeveral neuronal populations are involved in the regulation of energy balance. Among these, the hypothalamic agouti-related protein neurons (AgRP-neurons) are well characterized for their ability to promote food intake. Using cell-specific ablation we investigated a possible role of AgRP neurons in nutrient partitioning independent from food intake. We show that mice lacking AgRP neuron developed a non-hyperphagic obesity due to increased feed efficiency (weight gain/kcal consumed) on regular chow. At a time that preceded obesity catecholamine turnover rate was selectively decreased in the pancreas, liver, and glycolytic muscle, while it was increased in oxidative muscle. Respiratory quotient measurements revealed a change in substrate utilization towards lipid oxidation enhanced by synergistic increase in liver triglyceride synthesis and lipid substrate preference in oxidative muscle mitochondria. On high fat diet, mice lacking AgRP neurons displayed reduced body weight gain and paradoxical improvement in glucose tolerance. Finally we evidenced that Gamma Aminobutyric Acid (GABA) made by AgRP neurons is important in the central control of peripheral substrate utilization. This study reveals a new function for AgRP neurons in the coordination, via the sympathetic nervous System, of inter-organs communication and nutrient partitioning. These results offer a new conceptual framework for the understanding of obesity-related disorders
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Lapray, Miroslawa. « Role of intercalated and NPY-expressing cells in neuronal circuit of the amygdala ». Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:91017ce3-7c42-4310-94fb-be659ec2e52e.
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Local inhibitory microcircuit of amygdala is an active component in processing emotional information. Despite prominent evidence of its importance, our understanding of GABAergic cell types, their connectivity and role in amygdala network is limited. The aim of this thesis is to understand connectivity and physiology of two specific components of GABAergic microcircuit of amygdala: so-called intercalated cells and neuropeptide Y (NPY) expressing interneurons. Intercalated cells (ITCs) of the amygdala are clusters of GABAergic neurons that surround the basolateral complex of amygdala (BLA). There is growing evidence suggesting that ITCs are required for the expression of fear extinction. The main intercalated nucleus (Im) is the largest of the ITC clusters and could be also important for emotional processing. Using patch-clamp whole-cell recordings paired with subsequent anatomical analysis I described basic physiology and anatomy of neurons within the Im. I found that these neurons share common characteristics to earlier described neurons within the medial ITC cluster, yet they can be divided into three distinct groups. Next, I provided anatomical and functional evidence that Im neurons project to central and basal nucleus of amygdala and that they are reciprocally connected with medial and lateral ITCs clusters. I found that Im neurons receive excitatory inputs from BLA as well as cortex; next I verified that heterogeneous inputs do not interact with each other. I have shown that the Im neurons express both AMPA and NMDA receptors, suggesting that they may undergo NMDA-dependent plasticity. I have reported that dopamine hyperpolarizes Im neurons via dopamine receptor 1, therefore providing a cellular substrate for disinhibition of the amygdala at the systemic level. Thus, the Im is likely to be an additional site of integration of the distributed network underlying acquisition, expression and extinction of conditioned fear. In another project, I report novel interneuron type of the BLA and call it neurogliaform cell (NGFC) of amygdala. I used a mouse line expressing green fluorescent protein (GFP) under NPY promoter and patch clamp technique combined with pharmacology and electron microscope analysis. I performed paired recordings between presynaptic NPY-GFP positive (+) cells and postsynaptic principal neurons (PNs). Presynaptic NPY-GFP+ neurons display small soma and short dendrites embedded in a cloud of highly arborized axon. I showed that NPY-GFP+ cells are source of GABAA receptor-mediated slow inhibitory postsynaptic currents (IPSCs, decay time constant > 30 ms) evoked in PNs and in themselves (autapses). These slow IPSCs are known in literature as GABAA,slow. My results indicate that the slow kinetics of these IPSCs was likely caused by the low concentration and spillover of extracellular GABA. Physiologically-relevant in vivo firing re-played in NPY+-NGFCs in vitro evoked a transient depression of the IPSCs. Presynaptic GABAB receptors controlled the strength of this short-term plasticity. Interestingly, synaptic contacts made by NGFCs showed close appositions, without identifiable classical synaptic structures, between presynaptic boutons of the recorded cells and postsynaptic profiles. Thus, volume transmission of GABA is likely to be generated by this interneuron of the amygdala. NPY+-NGFC is a novel interneuron type of the BLA. The peculiar functional mode of NGFCs makes them unique amongst all GABAergic cell types of the amygdala identified so far.
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St-Pierre, Jacques-André. « Cellular and pharmacological characterization of NPY YI receptor expression in cultured rat hippocampal neurons and astrocytes ». Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36838.
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Neuropeptide Y (NPY) and NPY receptors are concentrated in the hippocampal formation where they modulate cognitive functions and seizures. The cellular mechanisms underlying the physiological roles of NPY in the hippocampus are still rather elusive. Cultured hippocampal cells offer a simple model to study the expression of hippocampal NPY receptor subtypes and their respective cellular distribution.The present thesis examines the presence of NPY receptors in primary dissociated hippocampal cells in culture using a combination of molecular, pharmacological and immunocytochemical approaches. Receptor binding experiments revealed the preferential expression of Y1-like receptors over the Y2, Y4 and Y5 subtypes in rat hippocampal cultures. Cultured hippocampal cells expressed high level of Y1 receptors and very low amounts (below detection) of the Y2, Y 4 and Y5 receptor binding sites. The genuine nature of the Y1-like receptor expressed in these cells was confirmed using amplification (RT-PCR) of Y1 receptor mRNAs. The cellular phenotype expressing Y1 receptor was investigated using double labeling methods. Specific autoradiographic and immunolabeling signals of Y1-like receptors were observed on neurons (70% of the total population of neurons) and astrocytes (20% of the total population of glia cells) as revealed respectively by neuron specific enolase (NSE) and glial fibrillary acidic protein (GFAP) immunostaining. The Y1 receptor labeling is distributed uniformly over neuronal cell bodies and processes compared to a non-uniform and clustered distribution on type I astrocytes. Neurons labeled by the various Y1 receptor markers were mostly glutamate-positive as revealed by double labeling. Interestingly, a small proportion (2--5%) of NPY-positive hippocampal neurons (NPY-positive cells represent around 10% of the total population of neurons) were also enriched with Y1 receptor labeling. These results suggest the possible autoregulatory role for the Y1 receptor on NPY release.
Taken together, these anatomical and pharmacological results suggest that Y1 receptor may play an important role in the hippocampus via the regulation of astrocytic and/or neuronal functions and the modulation of the release of glutamate and/or NPY.
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Thiaw, Lamine Madani Kurosh. « Identification de systèmes dynamiques non-linéaires par réseaux de neurones et multimodèles ». S. l. : S. n, 2008. http://doxa.scd.univ-paris12.fr:8080/theses-npd/th0407109.pdf.
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Idoux, Erwin. « Propriétés électrophysiologiques intrinsèques et modélisation des neurones responsables de l'intégration mathématique dans le noyau prepositus hypoglossi ». Paris 6, 2007. http://www.theses.fr/2007PA066030.
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Cette thèse concerne les mécanismes neuronaux impliqués dans l’intégration mathématique d’un signal de vitesse en signal de position. Dans le cadre du contrôle des mouvements horizontaux de l’œil, cette intégration est réalisée par les neurones du noyau prepositus hypoglossi (nNPH). Les nNPH ont été classés, selon leur profil électrophysiologique, en 3 types (A, B et D) et modélisés. Contrairement aux neurones de type A et B présents aussi dans les noyaux vestibulaires médian et latéral, les neurones de type D sont spécifiques du NPH et leur potentiel de membrane présente des oscillations. De plus, la conductance sodique persistante est cruciale pour l’électrophysiologie de tous les nNPH, quoique son impact et sa localisation diffèrent selon les types cellulaires. Enfin, les propriétés intrinsèques des neurones du NPH et des noyaux vestibulaires ont été comparées afin de comprendre le lien entre les fonctions de ces noyaux et les propriétés intrinsèques spécifiques de leurs neuronesThe rationale behind this thesis is the understanding of the neural mechanisms involved in the mathematical integration of a velocity signal into a position signal. For eye movements in the horizontal plane, neurons of the prepositus hypoglossi nucleus (PHNn) are responsible for this integration. Here, PHNn have been classified in 3 types (A, B and D) according to their electrophysiological profile and then modeled. Unlike type A and B neurons, which are also found in the medial and lateral vestibular nuclei, type D neurons are specific to the NPH and their membrane potential shows subthreshold oscillations. Besides, persistent sodium conductance is crucial to the electrophysiology of the PHNn, however its impact and location are type-dependant. The intrinsic properties of neurons of the PHN and the vestibular nuclei have been compared to understand the link between the functions of these nuclei and the specific intrinsic properties of their respective neurons
Livres sur le sujet "Neurones NPY"
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Bushnell, Candace. Sex and the city. London : Abacus, 1999.
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Bushnell, Candace. Sex and the city. New York : Warner Books, 1997.
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Bushnell, Candace. Sexo en Nueva York. [México, D.F.] : Debolsillo, 2008.
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Bushnell, Candace. Sex and the city. New York : Warner Books, 2001.
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Bushnell, Candace. Seks v Bolʹshom gorode. Moskva : Tornton i Sagden, 2003.
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Bushnell, Candace. Sex v bolʹshom gorode. Moskva : Izd-vo "AST", 2008.
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Bushnell, Candace. Sexo en Nueva York. [México, D.F.] : Debolsillo, 2008.
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Bushnell, Candace. Sex and the city. London : Abacus, 1997.
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Bushnell, Candace. Sex and the city. Oxford : ISIS, 2004.
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Bushnell, Candace. Sex and the city. New York : Atlantic Monthly Press, 1996.
Trouver le texte intégralChapitres de livres sur le sujet "Neurones NPY"
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Swistowski, Andrzej, et Xianmin Zeng. « Directed Differentiation of Human NSC/NPC into Dopaminergic Neurons ». Dans Neural Stem Cell Assays, 81–89. Hoboken, NJ, USA : John Wiley & Sons, Inc, 2015. http://dx.doi.org/10.1002/9781118308295.ch9.
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Wong, Agnes. « Ocular Motor Disorders Caused by Lesions in the Cerebellum ». Dans Eye Movement Disorders. Oxford University Press, 2008. http://dx.doi.org/10.1093/oso/9780195324266.003.0018.
Texte intégralRésumé :
The vestibulocerebellum consists of the flocculus, ventral paraflocculus, nodulus, and uvula. ■ The flocculus receives inputs from the vestibular nucleus and nerve, nucleus prepositus hypoglossi (NPH), inferior olivary nucleus, cell groups of the paramedian tracts (PMT), nucleus reticularis tegmenti pontis (NRTP), and mesencephalic reticular formation. ■ The ventral paraflocculus receives inputs from contralateral pontine nuclei. ■ Project to ipsilateral superior and medial vestibular nuclei, and the y-group ■ Receive input from the medial and inferior vestibular nuclei, vestibular nerve, NPH, and inferior olivary nucleus ■ Project to the vestibular nuclei ■ The oculomotor vermis consists of parts of the declive, folium, tuber, and pyramis. ■ Receives inputs from the inferior olivary nucleus, vestibular nuclei, NPH, paramedian pontine reticular formation (PPRF), NRTP, and dorsolateral and dorsomedial pontine nuclei ■ Projects to the caudal fastigial nucleus ■ Stimulation of the Purkinje cells in the dorsal vermis elicits contralaterally directed saccades and smooth pursuit ■ Receives inputs from the dorsal vermis, inferior olivary nucleus, and NRTP ■ Decussates and projects via the uncinate fasciculus of the brachium conjunctivum to the contralateral PPRF, rostral interstitial nucleus of the medial longitudinal fasciculus, nucleus of the posterior commissure, omnipause neurons in nucleus raphe interpositus, the mesencephalic reticular formation, and superior colliculus ■ Neurons in the fastigial oculomotor region (FOR) fire during both ipsilateral and contralateral saccades. 1. The contralateral FOR neurons burst before the onset of saccade, and the onset of firing is not correlated with any property of the saccade. 2. Conversely, the time of onset for neurons in the ipsilateral FOR varies, with bursts occurring later for larger saccades. 3. Thus, the difference in time of onset between contralateral and ipsilateral FOR activity encodes the amplitude of saccades (i.e., the larger the difference in time of onset, the larger the saccade amplitude). Eye movement abnormalities in uncinate fasciculus lesion include hypometric ipsilesional saccades and hypermetric contralesional saccades (“contrapulsion”). Arnold-Chiari malformation is a malformation of the medullary–spinal junction with herniation of intracranial contents through the foramen magnum. The three types are illustrated in the figure below.
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Morello, Roy, Jennifer N. Lennington, et Brendan Lee. « LMX1B and the Nail Patella Syndrome ». Dans Inborn Errors Of Development, 778–86. Oxford University PressNew York, NY, 2008. http://dx.doi.org/10.1093/oso/9780195306910.003.0082.
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Abstract Nail patella syndrome (NPS) is a dominantly inherited skeletal malformation syndrome. Patients have characteristic features including nail and patella hypoplasia, elbow and knee deformities, nephropathy, and ocular defects. The condition is characterized by high penetrance, variable expressivity, and signi)cant intrafamilial variability. Diagnosis is based on clinical criteria. Morbidity is associated with functional limitations caused by joint abnormalities, risk of developing nephrotic syndrome [which may progress to end-stage renal disease (ESRD)], and risk of developing glaucoma and ocular hypertension. NPS is caused by loss-of-function mutations in the LIM homeodomain (LHX) transcription factor LMX1B. LMX1B speci)es a transcriptional network important in pattern formation of the limb as well as cell maturation and differentiation in both the kidney and the central nervous system (CNS). In the limb, LMX1B is a unique mesenchymal determinant of dorsal cell fate. In the kidney, it regulates podocyte-speci)c expression of glomerular basement membrane (GBM) type IV collagen. Moreover, it speci)es morphogenesis of secondary foot processes and directs the expression of unique components of a specialized cell–cell adhesion complex, the slit diaphragm. Finally, it has important roles during CNS formation, including the survival of mesencephalic dopaminergic neurons, the development of all serotonergic neurons, and the differentiation of periocular mesenchyme. The pathogenesis of NPS re%ects a loss of dorsal speci)cation of soft tissues of the limb and disrupted proliferation of anterior relative to posterior skeletal elements. The nephropathy arises in part owing to an architectural defect in a primary component of the )ltration barrier of the kidney, the GBM. Glaucoma is likely secondary to anterior segment dysgenesis in the eye. How the function of LMX1B in other developmental programs impacts the pathogenesis of the NPS phenotype is still unclear.
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Zheng, Jialin, Hui Peng, Jeremy Rose, et Shelley Herek. « Neurogenesis and its links to brain development, developmental therapeutics, and the pathogenesis of neurodegenerative disorders including HIV-1-associated dementia ». Dans The Neurology of AIDS, 239–54. Oxford University PressOxford, 2005. http://dx.doi.org/10.1093/oso/9780198526100.003.0022.
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Abstract Past studies have supported the concept that the adult mammalian brain is incapable of regeneration. Indeed, neurons are terminally differentiated cells incapable of mitosis and, until recently, a compensatory production of neural cells following brain injury was not recognized (Korr 1980; Sturrock 1982). However, research performed in the past decade unequivocally demonstrates that the adult human brain contains populations of dormant and proliferating late neural progenitor cells (NPC; Carpenter et al. 1999; Eriksson et al. 1998; Gould et al. 1998, 1999b; Kaplan and Bell 1984; Kirschenbaum and Goldman 1995; Palmer et al. 1997; Seri et al. 2001; Shimazaki et al. 2001; Shingo et al. 2001; Uchida et al. 2000; Weiss et al. 1996).
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Northoff, Georg. « Spatiotemporal Model of Consciousness II : Spatiotemporal Alignment—Neuro-ecological Continuum and World–Brain Relation ». Dans The Spontaneous Brain, 195–236. The MIT Press, 2018. http://dx.doi.org/10.7551/mitpress/9780262038072.003.0008.
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Consciousness is neuronal as it is based on the brain and its neural activity. This is what neuroscience tell us citing strong empirical evidence. At the same time, consciousness is ecological in that it extends beyond the brain to body and world – this is what philosophers tell us when they invoke concepts like embodiment, embeddedness, extendedness, and enactment. Is consciousness neuronal or ecological? This amounts to what I describe as “argument of inclusion”: do we need to include body and world in our account of the brain and how is that very same inclusion important for consciousness? I argue that the “spatiotemporal model” of consciousness can well address the “argument of inclusion” by linking and integrating both neuronal and ecological characterizations of consciousness. I demonstrate various data showing how the brain’s spontaneous activity couples and aligns itself to the spatiotemporal structure in the ongoing activities of both body and world. That amounts to a specific spatiotemporal mechanism of the brain that I describe as ‘spatiotemporal alignment’. Conceptually, such ‘spatiotemporal alignment’ corresponds to “body-brain relation” and “world-brain relation”, as I say. World-brain relation and body-brain relation allow for spatiotemporal relation and integration between the different spatiotemporal scales or ranges of world, body, and brain with all three being spatiotemporally aligned and nested within each other. Based on various empirical findings, I argue that such spatiotemporal nestedness between world, body, and brain establishes a “neuro-ecological continuum” and world-brain relation. Both neuro-ecological continuum and world-brain relation are here understood in an empirical sense and can be regarded as necessary condition of possible consciousness, i.e., neural predisposition of consciousness (NPC) (as distinguished from the neural correlates of consciousness/NCC). In sum, the spatiotemporal model determines consciousness by “neuro-ecological continuum” and world-brain relation (with body-brain relation being a subset). Taken in such sense, the spatiotemporal model can well address the “argument of inclusion”. We need to include body and world in our account of the brain in terms of “neuro-ecological continuum” and world-brain relation since otherwise, due to their role as NPC, consciousness remains impossible.
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González-Maciel, Angélica, Rafael Reynoso-Robles, Ricardo Torres-Jardón, Partha S. Mukherjee et Lilian Calderón-Garcidueñas. « Combustion-Derived Nanoparticles in Key Brain Target Cells and Organelles in Young Urbanites : Culprit Hidden in Plain Sight in Alzheimer’s Disease Development ». Dans Advances in Alzheimer’s Disease. IOS Press, 2021. http://dx.doi.org/10.3233/aiad210005.
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Millions of children and young adults are exposed to fine particulate matter (PM2.5) and ozone, associated with Alzheimer’s disease (AD) risk. Mexico City (MC) children exhibit systemic and brain inflammation, low cerebrospinal fluid (CSF) Aβ1-42, breakdown of nasal, olfactory, alveolar-capillary, duodenal, and blood-brain barriers, volumetric and metabolic brain changes, attention and short-term memory deficits, and hallmarks of AD and Parkinson’s disease. Airborne iron-rich strongly magnetic combustion-derived nanoparticles (CDNPs) are present in young urbanites’ brains. Using transmission electron microscopy, we documented CDNPs in neurons, glia, choroid plexus, and neurovascular units of young MC residents versus matched clean air controls. CDNPs are associated with pathology in mitochondria, endoplasmic reticulum (ER), mitochondria-ER contacts (MERCs), axons,and dendrites. There is a significant difference in size and numbers between spherical CDNPs (>85%) and the angular, euhedral endogenous NPs (<15%). Spherical CDNPs (dogs 21.2 ± 7.1 nm in diameter versus humans 29.1 ± 11.2 nm, p = 0.002) are present in neurons, glia, choroid plexus, endothelium, nasal and olfactory epithelium, and in CSF at significantly higher in numbers in MC residents (p < 0.0001). Degenerated MERCs, abnormal mitochondria, and dilated ER are widespread, and CDNPs in close contact with neurofilaments, glial fibers, and chromatin are a potential source for altered microtubule dynamics, mitochondrial dysfunction, accumulation and aggregation of unfolded proteins, abnormal endosomal systems, altered insulin signaling, calcium homeostasis, apoptotic signaling, autophagy, and epigenetic changes. Highly oxidative, ubiquitous CDNPs constitute a novel path into AD pathogenesis. Exposed children and young adults need early neuroprotection and multidisciplinary prevention efforts to modify the course of AD at early stages.
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Northoff, Georg. « Spatiotemporal Model of Consciousness I : Spatiotemporal Specificity and Neuronal-Phenomenal Correspondence ». Dans The Spontaneous Brain, 151–94. The MIT Press, 2018. http://dx.doi.org/10.7551/mitpress/9780262038072.003.0007.
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How and why can neural activity in general and specifically stimulus-induced activity be associated with consciousness? This is the central question in the present chapter. I suggest a Spatiotemporal model that conceives both brain and consciousness in predominantly Spatiotemporal terms rather than being based on specific contents and their neural processing by the brain. This amounts to a Spatiotemporal theory of consciousness (STC). I discuss two specific Spatiotemporal mechanisms that I deem relevant for consciousness. The first Spatiotemporal mechanism refers to “Spatiotemporal integration and nestedness” that describe how different frequencies/regions are coupled and linked, i.e., integrated, and subsequently contained, i.e., nested, with each other. Again, based on empirical findings, “Spatiotemporal integration and nestedness” may predispose the level/state of consciousness, i.e., NPC. The second Spatiotemporal mechanism consists in “Spatiotemporal expansion” that allows to expand the stimuli’ specific points in time and space beyond itself by the brain’s spontaneous activity and its spatiotemporal structure. Based on various empirical findings, I suggest “Spatiotemporal expansion” a sufficient neural condition of consciousness, i.e., a neural correlate of the content of consciousness (NCC). Both spatiotemporal mechanisms are specific in that they can distinguish consciousness and unconsciousness: there is “Spatiotemporal expansion” rather than “Spatiotemporal constriction” and there is “Spatiotemporal nestedness” rather than “Spatiotemporal isolation”. This illustrates the specificity of the Spatiotemporal mechanisms which argues against what can be described as “argument of non-specificity”. Moreover, the STC is based on Spatiotemporal mechanisms rather than mere Spatiotemporal features which renders our Spatiotemporal model non-trivial which can be put forward against what can be described as “argument of triviality”. Taken together, the Spatiotemporal model of consciousness as suggested in the STC is neither non-specific but specific in empirical terms nor trivial on conceptual-logical, phenomenal, and ontological grounds.
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Bousoulas, P., et D. Tsoukalas. « Silicon Oxide-based CBRAM Memory and Neuromorphic Properties ». Dans Advanced Memory Technology, 515–29. Royal Society of Chemistry, 2023. http://dx.doi.org/10.1039/bk9781839169946-00515.
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The constant scaling of the conventional field-effect transistors (FETs) over the last half century has permitted the development of memory elements with enhanced density. However, since continuous miniaturization is practically impossible, novel device architectures have been proposed. Among them, resistive switching memories (RRAMs) emerge as quite promising candidates due to their simple structure, which permits aggressive scaling, and inherent stochastic performance, which is leveraged for the implementation of neuromorphic functionalities. Along these lines, a detailed analysis from a material point of view is presented, as far as the fabrication of SiO2-based resistive switching elements is concerned. The incorporation of metal nanoparticles (NPs) with various surface densities, as well as the employment of bilayer configurations, is thoroughly investigated in enhancing the total memory performance. More specifically, low-power operation (∼ 200 mV), enhanced variability (σ/μ < 0.2) and multibit capabilities (4 bits) were demonstrated. Moreover, the manifestation of two switching modes (bipolar and threshold) was leveraged to emulate artificial neuron and synaptic functionalities. As a result, integrate and fire (IF) properties were produced from single memristive cells, whereas enhanced analog synaptic weight modulation was also recorded. Physics-driven device engineering is thus of great importance for attaining reconfigurable memory and neuromorphic properties.
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Ding, Yuxin. « Artificial Higher Order Neural Networks for Modeling Combinatorial Optimization Problems ». Dans Artificial Higher Order Neural Networks for Modeling and Simulation, 44–57. IGI Global, 2013. http://dx.doi.org/10.4018/978-1-4666-2175-6.ch003.
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Traditional Hopfield networking has been widely used to solve combinatorial optimization problems. However, high order Hopfiled networks, as an expansion of traditional Hopfield networks, are seldom used to solve combinatorial optimization problems. In theory, compared with low order networks, high order networks have better properties, such as stronger approximations and faster convergence rates. In this chapter, the authors focus on how to use high order networks to model combinatorial optimization problems. Firstly, the high order discrete Hopfield Network is introduced, then the authors discuss how to find the high order inputs of a neuron. Finally, the construction method of energy function and the neural computing algorithm are presented. In this chapter, the N queens problem and the crossbar switch problem, which are NP-complete problems, are used as examples to illustrate how to model practical problems using high order neural networks. The authors also discuss the performance of high order networks for modeling the two combinatorial optimization problems.
Actes de conférences sur le sujet "Neurones NPY"
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Previtera, Michelle L., Mason Hui, Malav Desai, Devendra Verma, Rene Schloss et Noshir A. Langrana. « Neuronal Precursor Cell Proliferation on Elastic Substrates ». Dans ASME 2011 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2011. http://dx.doi.org/10.1115/sbc2011-53246.
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Numerous stem cells therapies have been studied for the replacement of damaged neurons due to spinal cord injury. Our laboratory’s goal is to design an implantable platform for spinal cord neuron (SCN) proliferation and differentiation in order to replace damaged neurons in the injured spinal cord. Based on previous literature, we suspect we can promote neuronal precursor cell (NPC) proliferation and differentiation utilizing elastic matrices.
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Kennedy, Lance, Issouf Kindo et Arthur Choi. « On Training Neurons with Bounded Compilations ». Dans 20th International Conference on Principles of Knowledge Representation and Reasoning {KR-2023}. California : International Joint Conferences on Artificial Intelligence Organization, 2023. http://dx.doi.org/10.24963/kr.2023/39.
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Knowledge compilation offers a formal approach to explaining and verifying the behavior of machine learning systems, such as neural networks. Unfortunately, compiling even an individual neuron into a tractable representation such as an Ordered Binary Decision Diagram (OBDD), is an NP-hard problem. In this paper, we consider the problem of training a neuron from data, subject to the constraint that it has a compact representation as an OBDD. Our approach is based on the observation that a neuron can be compiled into an OBDD in polytime if (1) the neuron has integer weights, and (2) its aggregate weight is bounded. Unfortunately, we first show that it is also NP-hard to train a neuron, subject to these two constraints. On the other hand, we show that if we train a neuron generatively, rather than discriminatively, a neuron with bounded aggregate weight can be trained in pseudo-polynomial time. Hence, we propose the first efficient algorithm for training a neuron that is guaranteed to have a compact representation as an OBDD. Empirically, we show that our approach can train neurons with higher accuracy and more compact OBDDs.
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Carstens, Niko, Matteo Mirigliano, Thomas Strunskus, Franz Faupe, Oleg Lupan, Paolo Milan et Alexander Vahl. « Nanoparticles as building units for bio-inspired electronics –switching and sensing ». Dans 11th International Conference on Electronics, Communications and Computing. Technical University of Moldova, 2022. http://dx.doi.org/10.52326/ic-ecco.2021/el.01.
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In this work, gas phase synthesis of NPs is applied as it offers the benefit of a high purity, surfactant free deposition that is compatible with a broad range of substrates. At the example of three fundamentally different NP assemblies it is showcased, how the unique properties of NPs make them promising building units for electronic devices with neuron-inspired functionalities.
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Agranat, A., C. F. Neugebauer et Amnon Yariv. « Combined optical-microelectronic realization of neural network models ». Dans OSA Annual Meeting. Washington, D.C. : Optica Publishing Group, 1988. http://dx.doi.org/10.1364/oam.1988.thj5.
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We describe a new generic approach for realizing neural network models. Schematically the basic system consists of a special purpose electronic integrated circuit—the neural processor (NP) and a 2-D spatial light modulator (SLM). The synaptic efficacies matrix is stored on the SLM and loaded in parallel into the NP. This is done by imaging the contents of the SLM onto an array detector which acts as the input unit of the NP. The NP processes the state of the network by using the synaptic efficacies supplied by the SLM. Several different architectures for the NP are described which enable the construction of networks with both binary and analog neurons, analog programmable synapses, and either synchronous or asynchronous updating. The expected properties of these systems are discussed based on the state of the art of microelectronic signal processing and SLM technology. It is shown that networks with 102–103 neurons can be built with update rates of typically 10 kHz for the complete networks. Finally, preliminary experimental results are described.
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Kreshchenko, N. D., et D. E. Mitkovskii. « THE PARTICIPATION OF NEUROPEPTIDE F IN THE INNERVATION OF FLATWORM MUSCULATE ». Dans THEORY AND PRACTICE OF PARASITIC DISEASE CONTROL. VNIIP – FSC VIEV, 2024. http://dx.doi.org/10.31016/978-5-6050437-8-2.2024.25.221-225.
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Free-living flatworms, planarians, are often used as a biological model to study the morphogenesis and regeneration processes, as well as structure and function of their muscle system. In this study, the spatial relationships between musculature and the nervous system were examined in planarians Girardia tigrina (Turbellaria, Platyhelminthes) using confocal laser scanning microscopy, histochemical staining of filamentous actin with fluorescently labelled phalloidin, and immunocytochemical staining of the nervous system with parasitic worm neuropeptide F antibodies. The body wall musculature contains three layers: an outer circular layer, an inner longitudinal layer, and a layer of rare diagonal muscle fibers in-between running in two perpendicular directions. The results showed that the body wall musculature was intensively supplied with NPF-immunopositive (-IP) nerve fibers. Thus, NPF-IP nerve fibers were localized in the body wall muscle layer of worms including the tail region musculature. Such identification of NPF-IP neurons and its endings near the somatic muscle fibers of the body wall may indicate the potential neuropeptide F participation in the muscle contractility regulation in flatworms.
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Wang, Yuan. « Estimation and Comparison of Linear Regions for ReLU Networks ». Dans Thirty-First International Joint Conference on Artificial Intelligence {IJCAI-22}. California : International Joint Conferences on Artificial Intelligence Organization, 2022. http://dx.doi.org/10.24963/ijcai.2022/492.
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We study the relationship between the arrangement of neurons and the complexity of the ReLU-activated neural networks measured by the number of linear regions. More specifically, we provide both theoretical and empirical evidence for the point of view that shallow networks tend to have higher complexity than deep ones when the total number of neurons is fixed. In the theoretical part, we prove that this is the case for networks whose neurons in the hidden layers are arranged in the forms of 1x2n, 2xn and nx2; in the empirical part, we implement an algorithm that precisely tracks (hence counts) all the linear regions, and run it on networks with various structures. Although the time complexity of the algorithm is quite high, we verify that the problem of calculating the number of linear regions of a ReLU network is itself NP-hard. So currently there is no surprisingly efficient way to solve it. Roughly speaking, in the algorithm we divide the linear regions into subregions called the "activation regions", which are convex and easy to propagate through the network. The relationship between the number of the linear regions and that of the activation regions is also discussed.
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De Paula Neto, Fernando M., Teresa B. Ludermir, Wilson R. De Oliveira et Adenilton J. Da Silva. « Solving NP-complete Problems Using Quantum Weightless Neuron Nodes ». Dans 2015 Brazilian Conference on Intelligent Systems (BRACIS). IEEE, 2015. http://dx.doi.org/10.1109/bracis.2015.22.
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IRITA, Takahiro, Minoru FUJISHIMA et Koichiro HOH. « Analysis of Chaos in Capacitance-npn-Transistor Pair and Its Application to Neuron Element ». Dans 1995 International Conference on Solid State Devices and Materials. The Japan Society of Applied Physics, 1995. http://dx.doi.org/10.7567/ssdm.1995.b-4-6.
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Hanc, Pavel, Siyi Huang et Ulrich H. von Andrian. « Abstract B159 : Investigating the neuroimmune interaction between nociceptive neurons and dendritic cells ». Dans Abstracts : Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference : Translating Science into Survival ; September 30 - October 3, 2018 ; New York, NY. American Association for Cancer Research, 2019. http://dx.doi.org/10.1158/2326-6074.cricimteatiaacr18-b159.
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Chen, Changchang, Guodong Ji, Hongyuan Zhang, Yuqi Sun, Qiang Wu et Zehao Lv. « LSTM Recurrent Neural Network Based Method for Identification of Drilling Operating Conditions and its Application ». Dans 58th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2024. http://dx.doi.org/10.56952/arma-2024-0666.
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ABSTRACT: Polycrystalline Diamond Compact (PDC) bit underground operating conditions identification is one of the difficulties during the drilling operation. It is of great significant for the drilling improvement and accurate construction formation to accurately identify the complex operating conditions during drilling the operation such as PDC bit wearing and stick-slip vibration, etc. In this paper, data of relationship between torque, rate of penetration (ROP) signal and weight on bit (WOB), rev were obtained through lab simulation experiment, after which, a relationship database of torque, ROP signal and WOB, rev was established, a single-layer Long Short Term Memory (LSTM) recurrent neural network (LSTM) was constructed, the number of neurons, batch size and optimizer type of LSTM layer were optimized. With BPTT algorithm, LSTM model was trained and tested on the training set containing 6000 groups of data, and achieved the goal of identifying the bit operation conditions against the input of WOB, torque, rev and ROP signal parameters. Based on this model, the PDC bit underground operating conditions identification software was compiled, and was connected to the logging unit to realize real-time identification of bit underground operating conditions, and field test application was successfully carried out in Mahu 1 Well Region. The research showed that the convergence speed was fast and the time cost was at the lowest when the number of neurons of LSTM model was 50, and that the optimized Adam optimizer model could meet the requirements of convergence speed and prediction accuracy with the lowest loss value. The classification accuracy of this model on the test set reached 94% and the accuracy of the prediction method was also verified by field test application. 1. INTRODUCTION During the drilling, complex underground conditions such as PDC bit wearing and stick slip may a impact the drilling cycle and drilling cost directly, in that bit wearing reduces the rock breaking efficiency. Either too early or too late pulling out of the hole(POOH) can affect the drilling effectiveness. After the bit stick-slip vibration, the cutting teeth can not effectively eat the rock, hence reducing the rock breaking efficiency. Serious bit stick-slip vibration may cause accidents such as increase of drill string torque and even breaking of drilling tool[1-3]. Therefore, real-time and accurate prediction of underground operating conditions of PDC bit and accurate guidance of tripping operation can effectively improve the mechanical ROP, reduce NPT and shorten the well construction cycle[4].