Tesi sul tema "Noyau de tangente neuronale"
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Mallik, Mohammed Tariqul Hassan. "Electromagnetic Field Exposure Reconstruction by Artificial Intelligence". Electronic Thesis or Diss., Université de Lille (2022-....), 2023. https://pepite-depot.univ-lille.fr/ToutIDP/EDENGSYS/2023/2023ULILN052.pdf.
The topic of exposure to electromagnetic fields has received muchattention in light of the current deployment of the fifth generation(5G) cellular network. Despite this, accurately reconstructing theelectromagnetic field across a region remains difficult due to a lack ofsufficient data. In situ measurements are of great interest, but theirviability is limited, making it difficult to fully understand the fielddynamics. Despite the great interest in localized measurements, thereare still untested regions that prevent them from providing a completeexposure map. The research explored reconstruction strategies fromobservations from certain localized sites or sensors distributed inspace, using techniques based on geostatistics and Gaussian processes.In particular, recent initiatives have focused on the use of machinelearning and artificial intelligence for this purpose. To overcome theseproblems, this work proposes new methodologies to reconstruct EMFexposure maps in a specific urban area in France. The main objective isto reconstruct exposure maps to electromagnetic waves from some datafrom sensors distributed in space. We proposed two methodologies basedon machine learning to estimate exposure to electromagnetic waves. Forthe first method, the exposure reconstruction problem is defined as animage-to-image translation task. First, the sensor data is convertedinto an image and the corresponding reference image is generated using aray tracing-based simulator. We proposed an adversarial network cGANconditioned by the environment topology to estimate exposure maps usingthese images. The model is trained on sensor map images while anenvironment is given as conditional input to the cGAN model.Furthermore, electromagnetic field mapping based on the GenerativeAdversarial Network is compared to simple Kriging. The results show thatthe proposed method produces accurate estimates and is a promisingsolution for exposure map reconstruction. However, producing referencedata is a complex task as it involves taking into account the number ofactive base stations of different technologies and operators, whosenetwork configuration is unknown, e.g. powers and beams used by basestations. Additionally, evaluating these maps requires time andexpertise. To answer these questions, we defined the problem as amissing data imputation task. The method we propose takes into accountthe training of an infinite neural network to estimate exposure toelectromagnetic fields. This is a promising solution for exposure mapreconstruction, which does not require large training sets. The proposedmethod is compared with other machine learning approaches based on UNetnetworks and conditional generative adversarial networks withcompetitive results
Hadj-Idris, Farah. "Activité neuronale du globus pallidus et du noyau subthalamique pendant l’inhibition motrice". Thesis, Sorbonne université, 2021. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2021SORUS543.pdf.
Response inhibition is crucial for adaptive behavior that allows the deliberate selection of one action from many. Inhibition is reactive after the identification of specific stimuli, or proactive in the absence of stimuli and when triggered by a specific context. Interactions between cortex and basal ganglia (BG) are important for implementing reactive and proactive inhibition. We recorded neurons in the external and internal segments of the globus pallidus (GPe and GPi) as well as in the subthalamic nucleus (STN) in monkeys during a Go/No Go task. In the GPe, we identified four types of neurons based on electrophysiological properties: two types exhibiting high-frequency discharge, with spontaneous pauses in activity (GPe-HFD-p) or without (GPe-HFD), and two types exhibiting low-frequency discharge, those exhibiting spontaneous bursting (GPe-LFD-b) and those that did not (GPe-LFD). GPi neurons were relatively homogenous, exhibiting high-frequency discharge without spontaneous pausing (GPi-HFD). According to their patterns of activities, we classified STN neurons into four classes: positive, negative, polyphasic positive and polyphasic negative. All neuronal types of GPe, GPi and STN encode reactive, proactive inhibition, direction and execution of movement. We identified one subtype of pallidal neuron (GPe-LFD-b) and one subtype of STN neuron (polyphasic negative) that responded rapidly to the stimulus signalling the need to withhold response (No Go). These neurons may be specifically involved in action restraint by activating motor programs related to maintaining current motor state despite the urge to respond
Hoyk, Zsófia. "Ösztradiol által kiváltott szinaptikus átrendeződés mechanizmusának vizsgálata patkány nucleus arcuatus-ban". Bordeaux 2, 2001. http://www.theses.fr/2001BOR28852.
Robbe, David. "Régulation et plasticité de la transmission synaptique dans le noyau accumbens. Modulation par les drogues addictives". Montpellier 2, 2002. http://www.theses.fr/2002MON20076.
Bosch, Clémentine. "Transmission et plasticité au sein de la voie hyperdirecte des ganglions de la base". Paris 6, 2011. http://www.theses.fr/2011PA066232.
Derambure, Philippe. "Etude electrophysiologique in vitro des mecanismes neuronaux determinant la fonction circadienne des noyaux suprachiasmatiques de l'hypothalamus ; place de la thermosensibilite neuronale". Lille 2, 1997. http://www.theses.fr/1997LIL2T008.
Zennou-Azogui, Yoh'i. "Compensation vestibulaire : substitution visuelle dans le noyau de Deiters chez le chat éveillé : période sensible et rôle de l'activité visuomotrice". Aix-Marseille 1, 1993. http://www.theses.fr/1993AIX11051.
Saliba, Layal. "Etude de la transmission glutamatergique et des effets de l'ozone dans le noyau du tractus solitaire de rat adulte". Aix-Marseille 2, 2009. http://www.theses.fr/2009AIX20722.
This work joins within the framework of studies about the mechanisms of integration of the visceral information in response to environmental disturbances. In the first part of this work, our results suggest that neurons of the nucleus of tractus solitarii (NTS) could use different neurotransmission modes according to their projection pathway. In neurons involved in vital reflexes such as those regulating respiration, the lack of important iA current, as well as a synaptic transmission which depends mostly on AMPA receptors with less accessible NMDA receptors, would induce a very precise and highly reliable treatment of the information. On the contrary, in neurons implicated in the elaboration of visceral sensations such as respiratory distress, the presence of an important iA current, as well as a synaptic transmission involving perisynaptic NMDA receptors, would allow an easy modulation of the neurotransmission and a global activation of some brain areas. In the second part of this work, we show that ozone inhalation induces a neuronal activity in regions of adult rat NTS receiving pulmonary afferences, at doses causing a lung inflammation comparable to that provoked by atmospheric peaks of pollution to certain humans. Pulmonary inflammation and neuronal activity inferred by ozone inhalation increase from the first hours of exposure and remain high as long as stimuli is present. The continuation of this work aims to determine if ozone induces a neuronal inflammation, and to characterize its effects on the neurotransmission particularly in the NTS
Sargolini, Francesca. "Rôle du noyau accumbens dans la mémoire spatiale et non spatiale : implications des récepteurs glutamatergiques NMDA et AMPA". Toulouse 3, 2002. http://www.theses.fr/2002TOU30207.
Panatier, Aude. "Rôle des astrocytes dans le contrôle de l'activité des récepteurs NMDA et dans laplasticité synaptique à long terme dans le noyau supraoptique chez le rat". Bordeaux 2, 2006. http://www.theses.fr/2006BOR21384.
Increasing evidence indicates that beside pre- and postsynaptic neuronal elements, astrocyte is the third element of the synapse. Indeed, it can detect, integrate and modulate synaptic signals. My work focuses on the role of astrocytes in glutamatergic synaptic transmission and more precisely in NMDA receptor (NMDAR) activity. The NMDAR is a key player in excitatory transmission. I showed that NMDARs are responsible for the induction of long-term synaptic plasticity in hypothalamic supraoptic nuclei (SON). It is known that their activation depends on the binding of both, glutamate, and a co-agonist like glycine or D-serine. Interestingly, D-serine is synthezized and released by astrocyte. Thus, this amino acid offers a unique opportunity to test the influence of astrocytic coverage of synapses on glutamatergic synaptic transmission. To this end, I took advantage of the extensive reduction of astrocytic ensheathing of neurons and synapses that SON undergoes during lactation. By combining electrophysiological recordings with biochemistry and immunochemistry, I provided direct evidence that astrocytic D-serine is the only endogenous co-agonist of NMDARs in the SON. Thus, the activation of SON NMDARs requires the binding of glutamate and D-serine, but not glycine. Moreover, by comparing NMDAR activity under different astrocytic coverage of neurons and synapses, I found that astrocytes, by releasing D-serine at glutamatergic synapses, control not only the level of activation of synaptic NMDARs but also, the activity-dependence of long-term synaptic changes. Such a mechanism might be extended to all brain regions where D-serine is present. My work clearly identifies astrocytes as key players in signalling and storage of information in the brain
Dos, Santos Marc. "Dynamique et mécanismes moléculaires de la plasticité structurale des neurones du noyau Accumbens en réponse à la cocaïne". Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066378/document.
Brief life occurrences can leave durable changes at the level of neuronal networks. These networks consist of neurons connected by synapses, which transmission efficacy is regulated at the functional and structural levels. Drugs of abuse highjack neuronal circuits involved in reward-driven learning by activating the Extracellular Regulated Kinase (ERK) pathway and induce an increase in the dendritic spines density –protrusions which host the glutamatergic pre-synaptic element- of SPN. The goal of my thesis work was to study the consequences of acute and chronic cocaine exposures on the mode of synapse formation in SPN from the NAc and to decipher the precise roles of ERK pathway in this phenomenon. I demonstrated that acute and chronic cocaine treatments induced the formation of persisting glutamatergic synapses in SPN in vivo. Time-lapse imaging using two-photon microscopy in acute striatal slices allowed me to dissociate the phases of growth and stabilization of the new dendritic spines. I could indeed demonstrate a key role for ERK in those two phases, although through distinct molecular mechanisms. Firstly, the growth phase is dependent on ERK. Secondly, the stabilization of newly grown spines is controlled by MNK-1, a cytosolic kinase downstream ERK, and by protein synthesis. This work brings new results on the mode of synapse formation as well as on the associated molecular mechanisms
San-Galli, Aurore. "Aspects comportementaux et neurobiologiques de la réévaluation rétrospective chez le rat". Toulouse 3, 2010. http://thesesups.ups-tlse.fr/890/.
Retrospective revaluation (RR) refers to the ability of humans or animals to make inferences about an absent event, on the basis of events that were associated with it: After conditioning (reinforced presentations) of a compound stimulus, altering the predictive value of one of the elements of the compound (competitor) affects the predictive value of the other, absent, element (target). RR involves a competitive mechanism, so that reinforced presentation (inflation) or non-reinforced presentation (extinction) of the competitor stimulus respectively decrease or increase the predictive value of the target stimulus. Studying RR in rats, and its neurobiological bases, was the aim of this thesis. We first sought to identify an experimental situation allowing the observation of the RR phenomenon, still rarely described in animals. A conditioned taste aversion procedure revealed non-competitive mediation processes that were opposite to those expected in RR. A novel olfacto-tactile preference task provided some evidence for competitive effects, but without sufficient reliability. Finally, a conditioned magazine approach was used to demonstrate RR with the inflation procedure, highlighting an important role of the relative salience of competitor and target stimuli. These results, confronted with current theoretical models of RR, support retrieval-based models such as the comparator hypothesis (Miller & Matzel, 1988). In a final part, we addressed the neuroanatomical bases of RR. A c-Fos immunohistochemistry study revealed an activation of a prefronto-striatal circuit (infralimbic and orbitofrontal cortices as well as nucleus accumbens) at the time of testing, consistent with the notion that important RR processes occur during retrieval of the competing associations. Although preliminary, this work opens the possibility to investigate in animals the neurobiological processes involved in a complex cognitive ability closely related to human causal reasoning
Deroche, Marion. "Etudes optogénétique et pharmacologique de la connectivité et de la plasticité endocannabinoïde des synapses glutamatergiques du noyau accumbens de souris". Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0086.
The nucleus accumbens (NAc) plays a key role in action selection by integrating cognitive and affective information. The NAc is implicated in numerous neuropsychiatric disorders, however a complete understanding of its circuits and their regulation in physiological conditions is missing. The principal cell type in the NAc, medium-spiny neurons MSNs are GABAergic projection neurons that express either D1 or D2 receptors. They receive and integrate glutamatergic inputs most notably from the prefrontal cortex (PFC), ventral hippocampus (vHipp) and basolateral amygdala (BLA).We combined optogenetic and electrophysiological methods to draw a functional portrait of excitatory disambiguated synapses onto D1 and D2 MSNs in the adult mouse NAc core. We first observed that adult D1- are inherently more excitable than D2-MSNs. Next, the synaptic properties of vHipp, BLA and PFC inputs revealed a hierarchy of synaptic inputs dependent on the identity of the postsynaptic target MSN and on circuit specific feedforward inhibition. We found that the BLA is the dominant excitatory pathway onto D1- while PFC inputs dominate D2-MSNs. Additionally, we tested the hypothesis that the endocannabinoid system endows excitatory circuits with pathway- and cell-specific plasticity. Thus, while CB1 receptors (CB1R) uniformly depress excitatory pathways irrespective of MSNs’ identity, TRPV1 receptors (TRPV1R) bidirectionally control inputs onto the NAc core in a pathway- and cell- specific manner. Finally, we clarified how the interplay of TRPV1R/CB1R shapes plasticity at identified BLA-NAc synapses. Together these data reveal a high degree of synapse and circuit specificity in the adult NAc core
Amadou, Boubacar Habiboulaye. "Classification Dynamique de données non-stationnaires :Apprentissage et Suivi de Classes évolutives". Phd thesis, Université des Sciences et Technologie de Lille - Lille I, 2006. http://tel.archives-ouvertes.fr/tel-00106968.
Renouard, Leslie. "Mécanismes responsables de l'activation corticale pendant le sommeil paradoxal". Thesis, Lyon 1, 2011. http://www.theses.fr/2011LYO10278/document.
To move forward on the PS function, it is necessary to study its impact on the cortical functioning. We so compared the cortical genic expression by using DNA microarrays in three groups of rats with different PS amounts: control, deprived of PS and in PS hypersomnia. 71 and 83 transcripts have an expression level modified by our protocol in the neocortex and the hippocampal formation, respectively. These molecular results were confirmed by quantitative PCR. In the hippocampal formation the genes involved in synaptic plasticity (Fos, Arc, Cox2, Homer1) have an expression level increased after PS hypersomnia. In the contrary, in the neocortex the expression level of these genes increases after PS deprivation. At the systemic level, limbic areas (the dentate gyrus, anterior cingulate and retrosplenial cortex and claustrum) contain a number of FOS immunoreactive neurons, an indirect marker of neuronal activation, increased after PS hypersomnia. On the other hand, the number of FOS immunoreactive neurons in the sensory-motor cortices is decreased after PS hypersomnia compare to PS deprivation. The ejection of retrograde tracers in the dentate gyrus, retrosplenial and anterior cingulate cortex in PS hypersomniac rats showed that active neurons project to the supramammillary nucleus and claustrum. We then observed that the number of FOS and ARC immunoreactive neurons in the dentate gyrus, claustrum and limbic structures is strongly decreased during PS hypersomnia in rats bearing a supramammillary nucleus lesion. Furthermore, the supramammillary nucleus lesion leads to a decrease of the theta power recorded by electroencephalogram during PS in hypersomnia. It thus seems that the supramammillary nucleus projections are responsible for the limbic cortical regions activation during PS
Klein, Marie-Muguet. "Rôle des noyaux réuniens (Re) et rhomboïde (Rh) du thalamus dans la plasticité structurale associée à la persistance d’un souvenir spatial chez le rat". Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAJ089.
The standard model of systemic consolidation posits that information is initially encoded in the hippocampo-neocortical network, the memory trace being first created in the sole hippocampus (HIP). Over time, the trace is progressively transferred to modules of the medial prefrontal cortex (mPFC), particularly to the anterior cingulate cortex (ACC). Following lesions of the thalamic reuniens and rhomboid nuclei (ReRh), which are reciprocally connected with both the Hipp and mPFC, a spatial memory forms normally but does not persist (Loureiro et al 2012). Therefore, we assessed the impact of ReRh lesions on structural plasticity underlying spatial memory persistence. Male Long-Evans rats subjected to NMDA lesions of the ReRh nuclei were trained in the Morris Water Maze and tested for retrieval of recent (5 days) or remote (25 days) memory. Structural plasticity was assessed on Golgi-stained material in the HIP and CPFm. ReRh lesions had no effect on learning and recent memory, but altered remote memory. In the HIP (CA1) of sham-operated rats, the spine number was increased at both 5 and 25 days post-acquisition vs baseline. After ReRh lesion, the increase did not persist from 5 to 25 days. In the mPFC (ACC) of sham-operated rats, the spine number was increased only at 25 days vs baseline, a modification not observed in ReRh lesioned rats. Thus, following lesion of ReRh nuclei, structural plasticity underlying remote spatial memory formation does not operate correctly in the mPFC and Hip, pointing to a crucial role of ReRh in memory persistence
Bonneau, Nicolas. "Substrats neuronaux impliqués dans le sevrage des opiacés et dans le rappel des mémoires affectives associées". Thesis, Bordeaux 2, 2010. http://www.theses.fr/2010BOR21791/document.
Addiction is a psychobiological disorder that is characterized by repeated drug intakes, inability to control its consumption and a chronic tendency to relapse. Concerning opiate addiction (heroin, morphine), cessation of drug consumption induces a withdrawal syndrome, which can be strongly and persistently associated with the environment in which it is experimented. This association is so tight that a single re-exposure to this specific environment is enough to provoke a negative emotional state, which may promote drug relapse. In opiate dependence, it becomes clearer and clearer that reactivation of the affective memories associated with drug withdrawal play a major role in drug seeking. In terms of neurobiological processes, previous works conducted in the lab have shown that synaptic plasticity takes place during the conditioning of stimuli to opiate withdrawal, in limbic structures known to be involved in associative learning. It has been suggested that the consequences of the re-exposition to withdrawal conditioned stimuli are due to the reactivation of these specific limbic regions. In theses studies, environmental stimuli were both associated to the early aversive state of withdrawal and to somatic symptoms. This represents a first step in the understanding of the cellular processes involved in the formation and retrieval of withdrawal memories. However, in order to better understand how these memories could play a role in relapse, it is necessary to analyze the neuronal substrates involved in the conditioned effects of the sole early aversive motivational component of opiate withdrawal. Indeed, this motivational component is considered as exerting a strong influence on the maintaining of drug consumption, and eventually on the vulnerability to relapse in abstinent addicts. The aim of my work was to specify the neurobiological substrates involved in opiate withdrawal and in the retrieval of the aversive memories especially the memories associated with the motivational component of withdrawal. We first developed an in situ hybridization approach (catFISH) whose main advantage is to add a dynamical dimension to the neuronal activations induced by a stimulation. We validated the use of the catFISH method by studying the dynamics of neuronal activations in the prefrontal cortex (PFC), the nucleus accumbens (Nac), the central (CeA) and basolateral (BLA) nucleus of the amygdala as a consequence of the precipitation of opiate withdrawal. Our results show that catFISH allows determining persistent neuronal activations and that the CeA and the Nac have a different dynamics of activation in response to opiate withdrawal. In the second part, we studied the neuronal substrates involved when the retrieval of opiate withdrawal memories modifies an operant goal-directed behaviour, according to the withdrawal intensity. The use of catFISH allowed us to differentiate the neuronal activations induced by the re-exposition to the withdrawal context or to the conditioned stimuli. Our results show that the PFC and the Nac shell are involved in the retrieval of contextual memories of withdrawal and that PFC, Nac core and BLA are activated by the retrieval of more specific conditioned stimuli.Lastly, we analysed, using a conditioned place aversion protocol, the neuronal structures recruited by the retrieval of the memories associated with the motivational component of opiate withdrawal. Our results suggest that the Nac shell and the BLA are the brain structures that are the most sensible to the retrieval of the memories of opiate withdrawal.Overall, our work emphasized the crucial role played by the Nac shell and the BLA within a network of neuronal substrates involved in the processing of aversive emotional memories associated with opiate withdrawal. These structures could be considered as the common substrates to the processing of emotional memories associated with the effects of drugs of abuse. These results will be compared with an in vivo electrophysiology on behaving animals’ approach that we initiated during my PhD. This study will consist of detailing longitudinally the dynamics of the PFC/Nac/BLA network during the formation and the retrieval of the memories of opiate withdrawal. This study will also provide more details on the specific functions of the previously studied neuronal substrates in the processing of opiate withdrawal memories
Morquette, Philippe. "Rôle des astrocytes dans la décharge rythmique neuronale du noyau sensoriel principal du trijumeau". Thèse, 2015. http://hdl.handle.net/1866/18377.
Communication between neurons rests on their capacity to change their firing pattern to encode different messages. For several vital functions, such as respiration and mastication, neurons need to generate a repetitive firing pattern, and the groups of neurons responsible for these rhythmic discharges are called central pattern generator (CPG). Despite intense research in this field, the exact mechanisms underlying rhythmogenesis in CPGs are not completely defined. In most instances, the potential contribution of astrocytes is largely unexplored, even though these cells are now well known to be involved in neuronal synaptic modulation. In our work, the trigeminal main sensory nucleus (NVsnpr) was used as a model owing to its central role in the rhythmic movement of mastication. Previous work have shown that rhythmic bursting discharge is triggered in NVsnpr neurons when extracellular calcium concentration ([Ca2+]e) is artificially decreased. Based on this observation, our first hypothesis postulated that the reduction of [Ca2+]e could also happen physiologically in relation to relevant sensory stimulation. Secondly, because astrocytes have been involved in the buffering and the homeostasis of extracellular ions like potassium, we have postulated that these cells could also play a role in the control of [Ca2+]e. The results presented in this thesis show that astrocytes can regulate [Ca2+]e and thus control the ability of neurons to change their firing pattern. First, we showed that stimulation of sensory afferent fibers to the NVsnpr induced neuronal rhythmic bursting and in parallel reduction of [Ca2+]e . Secondly, we have demonstrated that astrocytes respond to the same sensory stimuli that induce neuronal rhythmic activity, and their blockade with a Ca2+ chelator prevents generation of neuronal rhythmic bursting. This ability is restored by adding S100β, an astrocytic Ca2+-binding protein, to the extracellular space, while the application of an anti- S100β antibody prevents generation of rhythmic activity. These results indicate that astrocytes regulate a fundamental neuronal property: that is the capacity to change their firing pattern. Thus, CPG functions result from integrated neuronal and glial activities. These findings may have broad implications for many other neural networks whose functions depend on the generation of rhythmic activity.