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Bennett, David Lawrence Harvey. "Neurotrophins and sensory neuron development and plasticity." Thesis, University of London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267645.
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McNair, Nicolas A. "Input-specificity of sensory-induced neural plasticity in humans." Thesis, University of Auckland, 2008. http://hdl.handle.net/2292/3285.
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The aim of this thesis was to investigate the input-specificity of sensory-induced plasticity in humans. This was achieved by varying the characteristics of sine gratings so that they selectively targeted distinct populations of neurons in the visual cortex. In Experiments 1-3, specificity was investigated with electroencephalography using horizontally- and vertically-oriented sine gratings (Experiment 1) or gratings of differing spatial frequency (Experiments 2 & 3). Increases in the N1b potential were observed only for sine gratings that were the same in orientation or spatial frequency as that used as the tetanus, suggesting that the potentiation is specific to the visual pathways stimulated during the induction of the tetanus. However, the increase in the amplitude of the N1b in Experiment 1 was not maintained when tested again at 50 minutes post-tetanus. This may have been due to depotentiation caused by the temporal frequency of stimulus presentation in the first post-tetanus block. To try to circumvent this potential confound, immediate and maintained (tested 30 minutes post-tetanus) spatial-frequency-specific potentiation were tested separately in Experiments 2 and 3, respectively. Experiment 3 demonstrated that the increased N1b was maintained for up to half an hour post-tetanus. In addition, the findings from Experiment 1, as well as the pattern of results from Experiments 2 and 3, indicate that the potentiation must be occurring in the visual cortex rather than further upstream at the lateral geniculate nucleus. In Experiment 4 functional magnetic resonance imaging was used to more accurately localise where these plastic changes were taking place using sine gratings of differing spatial frequency. A small, focal post-tetanic increase in the blood-oxygen-level-dependent (BOLD) response was observed for the tetanised grating in the right temporo-parieto-occipital junction. For the non-tetanised grating, decreases in BOLD were found in the primary visual cortex and bilaterally in the cuneus and pre-cuneus. These decreases may have been due to inhibitory interconnections between neurons tuned to different spatial frequencies. These data indicate that tetanic sensory stimulation selectively targets and potentiates specific populations of neurons in the visual cortex.
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Dunfield, Derek James. "Sensory experience driven network plasticity in the awake developing brain." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/13655.
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During embryonic activity‐dependent brain circuit refinement, neurons receiving the same natural sensory input may undergo either long‐term potentiation (LTP) or depression (LTD). While the origin of variable plasticity in vivo is unknown, the type of plasticity induced plays a key role in shaping dynamic neural circuit synaptogenesis and growth. Here, we investigate the effects of natural visual stimuli on functional neuronal firing within the intact and awake developing brain using calcium imaging of 100s of central neurons in the Xenopus retinotectal system. We find that specific patterns of visual stimuli shift population responses towards either potentiation or depression in an N‐methyl‐D‐aspartate receptor (NMDAR)‐dependent manner. In agreement with the Bienenstock‐Cooper‐Munro (BCM) theory, our results show that functional potentiation or depression in individual neurons can be predicted by their specific receptive field properties and endogenous firing rates prior to plasticity induction. Enhancing pre‐training activity shifts plasticity outcomes as predicted by BCM, and this induced metaplasticity is also NMDAR dependent. Furthermore, network analysis reveals an increase in correlated firing of neurons that undergo potentiation. These findings implicate metaplasticity as a natural property governing experience‐dependent refinement of nascent embryonic brain circuits.
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Vahdat, Shahabeddin. "Training-induced plasticity in resting-state sensory and motor networks." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=114465.
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Research on plasticity in motor systems has for the most part developed separately from work on sensory plasticity, as if training-induced changes to the brain affected each of these systems in isolation. The aim of this thesis is to explore the association between the sensory and motor systems when a new skill is acquired. The experiments reported in this dissertation systematically examine two hypotheses about neuroplasticity: (i) that motor learning changes perceptual function and the function of somatosensory areas of the brain, and (ii) that somatosensory training changes both motor function and motor areas of the brain. The first study aimed at providing a unified approach to test the first hypothesis. We combined both psychophysical and neuroimaging procedures to examine the connection between changes in the behavior and brain as a result of motor learning. We used a dynamics adaptation task as a model of motor learning in conjunction with somatosensory discrimination of the limb's movement direction which permits quantification of perceptual changes that occurs in conjunction with motor learning. We used functional magnetic resonance imaging (fMRI) to calculate measures of functional connectivity during resting-state periods following learning. This technique allowed us to study longer lasting plasticity in the sensorimotor system, during the period in which the motor memory is being consolidated. We developed a new hypothesis-driven technique which enables us to incorporate psychophysical measures in functional connectivity analysis to identify behaviorally-related neuroplasticity as a result of learning. Using this technique, we identified a new network in motor learning involving second somatosensory cortex, ventral premotor cortex and supplementary motor area whose activation is specifically related to perceptual changes that occur in conjunction with motor learning. Subjects who showed greater change in functional connectivity within this network, also showed a greater change in perceptual function. In study two, we proposed and implemented a new analytic data-driven method based on independent component analysis (ICA), which enabled us to systematically extract and classify shared and condition-specific networks corresponding to the pre-learning and post-learning conditions. The proposed algorithm was specifically designed to solve the problems of the regular ICA approach in conducting between-condition comparisons. Using this method we identified a specific network corresponding to the post-learning condition comprising clusters in contralateral superior parietal lobule, second somatosensory cortex, premotor cortex, and supplementary motor area. The third study was aimed at testing the second hypothesis described above. Using similar procedures and techniques to those used in the first study, we found that somatosensory discrimination training combined with periods of passive movement as short as 45 minutes increased functional connectivity between sensory and motor areas of the brain and, importantly, in motor areas alone. In behavioral terms, somatosensory training facilitates motor learning. Improvements were seen in both the rate and extent of learning and they persisted for at least one day. Sensory repetition without perceptual learning was less able to induce plasticity in the motor system. This suggests that somatosensory training can induce reorganization in the motor system and benefits from cognitive involvement and skill acquisition in the sensory domain. Overall, our studies point to a unified model of sensorimotor plasticity in which the effects of learning are not local to either sensory or motor systems, but rather each has effects that spread into functionally related areas of the brain beyond the base modality.<br>La recherche sur la plasticité dans les systèmes moteurs a été développée en grande partie séparément des travaux sur la plasticité sensorielle, comme si des changements au cerveau apportés par l'apprentissage affectaient chacun de ces systèmes séparément. Le but de cette these est d'explorer le lien entre le système sensoriel et le système moteur lorsqu'une nouvelle aptitude est acquise. Les expériences rapportées dans cette dissertation examinant systématiquement deux hypothèses sur la neuroplasticité: (i) l'apprentissage moteur modifie le fonction perceptuelle, ainsi que la fonction des régions somesthésiques du cerveau, et (ii) que l'apprentissage somestésique modifie les fonctions motrices et des régions motrices du cerveau.La première étude vise à donner une approche unifiée pour tester la première hypothèse. Nous avons combiné des procédures psychophysiques et de neuroimagerie pour observer le lien entre les changements de comportement et ceux au niveau du cerveau suite à de l'apprentissage moteur. Nous avons utilisé une tâche d'adaptation dynamique comme modèle d'apprentissage moteur ainsi que de la discrimination somesthésique de la direction de mouvement du membre, ce qui permet la quantification des changements perceptuels qui se produisent suite à l'apprentissage moteur. Nous avons utilisé l'imagerie par resonance magnétique fonctionnelle (IRMf) pour calculer des measures de connectivité fonctionnelle lors de péridoes de repos suivant l'apprentissage. Cette technique nous a permis d'étudier la plasticité de plus longue durée dans le système sensori-moteur, lors de la période pendant laquelle la mémoire motrice est en train de se consolider. Nous avons développé une nouvelle technique fondée à partir d'hypothèses qui nous permet d'inclure des mesures psychophysiques dans l'analyse de connectivité fonctionnelle pour identifier la neuroplasticité liée au comportement comme résultat de l'apprentissage. En utilisant cette technique, nous avons identifié un nouveau réseaux d'apprentissage moteur impliquant le deuxième cortex somesthésique, le cortex prémoteur ventral et une région motrice supplémentaire dont l'activation est spécifiquement reliée aux changements perceptuels qui se produisent suite à l'apprentissage moteur. Les sujets qui démontraient de plus grands changements de connectivité fonctionnelle démontraient aussi un plus grand changement au niveau de la fonction perceptuelle. Dans la deuxième étude, nous avons proposé et implémenté une nouvelle méthode analytique fondée sur des données et basée sur l'analyse en composantes indépendantes (ACI), ce qui nous a permis de systématiquement extraire et classer des réseaux partagés et spécifiques à la condition correspondant aux conditions avant et après l'apprentissage. La troisième étude visait à tester la deuxième hypothèse décrite ci-dessus. En utilisant des procédures et des techniques similaires à celles utilisées dans la première étude, nous avons trouvé que l'apprentissage somesthésique discriminatoire, combiné avec des périodes de mouvements passifs pouvant duré seulement 45 minutes, augmentait la connectivité fonctionnelle entre les régions sensorielles et motrices du cerveau, et, notamment, dans des régions motrices. En termes comportementaux, l'entrainement somesthésique facilite l'apprentissage moteur. Des ameliorations ont été constatées au niveau du taux et de l'étendue de l'apprentissage, et elles demeuraient pour au moins une journée. La repetition sensorielle sans apprentissage perceptuel était moins apte à induire de la plasticité dans le système moteur. En général, nos études mènent vers un modèle unifié de plasticité sensori-moteur dans laquelle les effets de l'apprentissage ne sont pas spécifiques aux systèmes moteurs ou sensoriels, mais chacun des systèmes a des effets qui s'étendent dans des régions du cerveau fonctionnellement reliées, au-delà de la modalité de base.
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Ramer, Matthew Stephen. "Sympathetic and sensory neuronal plasticity, peripheral substrates of neuropathic pain." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ31950.pdf.
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He, Haiyan. "Molecular mechanisms of synaptic plasticity in adult mammalian sensory cortex." College Park, Md. : University of Maryland, 2007. http://hdl.handle.net/1903/6712.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2007.<br>Thesis research directed by: Biology. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Dolan, Sharron. "Plasticity in the adult rat somatosensory system following sensory deprivation." Thesis, University of Stirling, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244606.
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Eilers, Wouter. "Sensory pathways of muscle phenotypic plasticity : calcium signalling through CaMKII." Thesis, Manchester Metropolitan University, 2012. http://e-space.mmu.ac.uk/315671/.
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Skeletal muscle can adapt its structure to cope with the mechanical and metabolic stresses placed on it by various amounts and patterns of human movement. The release of calcium into the cytoplasm of muscle fibres is thought to have an important role in these adaptations, yet the calcium-dependent signalling pathways involved haven’t been fully defined. Calcium/calmodulin-dependent protein kinase II (CaMKII) has been presumed to drive mitochondrial biogenesis in skeletal muscle, but this has not been investigated in vivo. The experiments in this thesis aimed to address how CaMKII is activated in response to electrical stimulation of skeletal muscle and how CaMKII affects the muscle phenotype. A rat model was used for two main reasons: 1) it allowed for imposing well-defined stimulation patterns onto phenotypically homogenous muscle fibre populations under controlled conditions in situ, and investigating the molecular response to these stimulation patterns, and 2) it allowed for manipulation of CaMKII signalling in muscle fibres in vivo through the use of electro-assisted somatic gene transfer. It was hypothesised that CaMKII would be activated in a muscle and recruitment pattern specific manner. Furthermore, it was hypothesised that CaMKII overexpression would increase the expression of mitochondrial markers. In chapter 2, the effect of recruitment frequency on CaMKII phosphorylation in slow-twitch m. soleus and fast-twitch m. gastrocnemius medialis is investigated. Furthermore, the time course of CaMKII phosphorylation after muscle stimulation is studied. Chapter 3 presents a study into the effects of in vivo CaMKII overexpression in m. soleus and m. gastrocnemius on mitochondrial gene expression and muscle contractile function. The effects of CaMKII overexpression on skeletal alpha-actin transcription are presented in chapter 4. In chapter 5, a mathematical model of CaMKII activation in sarcomeres is described, and used to investigate the effects of CaMKII overexpression on calcium handling and on contractile properties of a muscle fibre. It was concluded that CaMKII is activated by very brief stimulation in a recruitment frequency-independent manner, and that increased CaMKII protein levels increase SERCA expression, but not mitochondrial gene expression.
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Fasthén, Patrick. "The Virtual Self : Sensory-Motor Plasticity of Virtual Body-Ownership." Thesis, Högskolan i Skövde, Institutionen för biovetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-10501.
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The distinction between the sense of body-ownership and the sense of agency has attracted considerable empirical and theoretical interest lately. However, the respective contributions of multisensory and sensorimotor integration to these two varieties of body experience are still the subject of ongoing research. In this study, I examine the various methodological problems encountered in the empirical study of body-ownership and agency with the use of novel immersive virtual environment technology to investigate the interplay between sensory and motor information. More specifically, the focus is on testing the relative contributions and possible interactions of visual-tactile and visual-motor contingencies implemented under the same experimental protocol. The effect of this is supported by physiological measurements obtained from skin conductance responses and heart rate. The findings outline a relatively simple method for identifying the necessary and sufficient conditions for the experience of body-ownership and agency, as studied with immersive virtual environment technology.
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Neumann, Simona. "A-fibre plasticity : phenotype switch and regenerative capacity." Thesis, University College London (University of London), 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267611.
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Pattinson, Damian Thomas. "The role of CAMKIIa in a development and plasticity of sensory pathways." Thesis, University College London (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412584.
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Martel, Marie. "Body representations in action : development and plasticity in the sensory guidance of prehension." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1288.
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Planifier, exécuter un mouvement fait appel à des représentations mentales de l'action. Ces dernières ont été formalisées par les sciences computationnelles sous le terme de modèles internes du contrôle moteur. Outre l'environnement, les informations concernant la posture, les dimensions de l'effecteur sont également cruciales et doivent être mises à jour fréquemment. Etonnamment, les modèles actuels de l‘action n'attribuent pas aux représentations du corps un rôle majeur. La mise à jour de ces représentations de l'action et du corps doit intervenir dès l'enfance, néanmoins leur développement reste méconnu. En premier lieu, je me suis attachée au développement des représentations de l'action chez les enfants de 5 à 10 ans, au développement typique d'une part et lors de Troubles des Acquisitions et de la Coordination (TAC) d'autre part. A travers la cinématique, j'ai cherché à comprendre comment les enfants développent leur capacité à anticiper et adapter leurs mouvements. Dans un deuxième temps, l'utilisation d'un outil qui allonge fonctionnellement le bras m'a permis d'examiner les inputs sensoriels (vision, proprioception) nécessaires à la plasticité des représentations du corps chez l'adulte. Enfin, j'ai interrogé ces mécanismes de plasticité des représentations de l'effecteur au cours de la croissance de l'individu alors que les dimensions corporelles changent progressivement. Dans ce but, j'ai étudié la plasticité induite par l'outil chez des enfants et adolescents au développement typique. Finalement, je discuterai des liens entre représentations du corps et contrôle moteur, deux notions indispensables à la cognition motrice<br>To prepare and perform movements efficiently, accurate action representations are necessary, formalized by computational science as “internal models”. Actions representations do not require exclusively the representation of object properties, information about the body and particularly the effector such as its posture and dimension are also crucial. Thus, effector representations need to be updated to account for postural changes, yet, they do not play a prominent role in the actual models of motor control. In addition, updates settings of both action and body representation are presumably established ontogenetically, but little is known on their developmental path. First, I investigated the maturation of action representation in children from 5 to 10 years of age, as well as the potential differences in children with Developmental Coordination Disorder (DCD). Through kinematics analyses, I sought to understand how children develop their ability to control their movements. Second, using a tool functionally extending arm length, I questioned the sensory inputs for body representation plasticity in adults, such as proprioception and vision. Third, I probed rapid body representations plasticity during the slowly changing dimensions of the body during growth. To this aim I investigated in typically developing children and adolescents tool-induced plasticity of the upper-limb representation. Finally, I discuss the relationship between body representations and motor control in adults and children, as despite being both related they have often times walked parallel ways
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Chakrabarty, Arnab. "Role of sensory input in structural plasticity of dendrites in adult neuronal networks." Diss., lmu, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-155241.
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Norris, Andrew J. "Sensory modalities, plasticity and prey choice in three sympatric species of whiting (Pisces:Sillaginidae) /." St. Lucia, Qld, 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17866.pdf.
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LeBlanc, Jocelyn Jacqueline. "Critical period plasticity and sensory function in a neuroligin-3 model of autism." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:10820.
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Extensive experience-dependent refinement of cortical circuits is restricted to critical periods of plasticity early in life. The timing of these critical periods is tightly regulated by the relative levels of excitatory and inhibitory (E/I) neurotransmission during development. Genetic disruption of synaptic proteins that normally maintain E/I balance can result in severe behavioral dysfunction in neurodevelopmental disorders like autism, but the mechanisms are unclear. We propose that abnormal critical periods of sensory circuit refinement could represent a key link between E/I imbalance and the cognitive and behavioral problems in autism.
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Heron, James, N. W. Roach, David J. Whitaker, and James Vincent Michael Hanson. "Attention regulates the plasticity of multisensory timing." Wiley, 2010. http://hdl.handle.net/10454/4548.
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Evidence suggests that human time perception is likely to reflect an ensemble of recent temporal experience. For example, prolonged exposure to consistent temporal patterns can adaptively realign the perception of event order, both within and between sensory modalities (e.g. Fujisaki et al., 2004 Nat. Neurosci., 7, 773-778). In addition, the observation that 'a watched pot never boils' serves to illustrate the fact that dynamic shifts in our attentional state can also produce marked distortions in our temporal estimates. In the current study we provide evidence for a hitherto unknown link between adaptation, temporal perception and our attentional state. We show that our ability to use recent sensory history as a perceptual baseline for ongoing temporal judgments is subject to striking top-down modulation via shifts in the observer's selective attention. Specifically, attending to the temporal structure of asynchronous auditory and visual adapting stimuli generates a substantial increase in the temporal recalibration induced by these stimuli. We propose a conceptual framework accounting for our findings whereby attention modulates the perceived salience of temporal patterns. This heightened salience allows the formation of audiovisual perceptual 'objects', defined solely by their temporal structure. Repeated exposure to these objects induces high-level pattern adaptation effects, akin to those found in visual and auditory domains (e.g. Leopold & Bondar (2005) Fitting the Mind to the World: Adaptation and Aftereffects in High-Level Vision. Oxford University Press, Oxford, 189-211; Schweinberger et al. (2008) Curr. Biol., 18, 684-688).<br>Wellcome Trust, College of Optometrists
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Gunner, Georgia. "Sensory Deprivation Induces Microglial Synapse Engulfment." eScholarship@UMMS, 2021. https://escholarship.umassmed.edu/gsbs_diss/1148.
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Synaptic connectivity is highly plastic in early development and undergoes extensive remodeling in response to changes in neuronal activity and sensory experience. Microglia, the resident central nervous system macrophages, participate in shaping mature neuronal circuits by dynamically surveying the brain parenchyma and pruning away less active synaptic connections. However, it is unknown how changes in neuronal activity regulates microglial pruning within circuits and whether this activity-dependent pruning is necessary to achieve plasticity. Using the rodent somatosensory circuit, I identified that microglia engulf and eliminate synapses in the cortex following early postnatal (P4) unilateral removal of mouse whiskers. I found this early life microglial synaptic remodeling requires specific chemokine signaling between neurons and microglia. Mice that lack expression of either the neuronal chemokine CX3CL1 (fractalkine), or its microglial receptor CX3CR1, have significantly reduced microglial synapse engulfment and fail to eliminate synapses following whisker removal. To gain more insight into how this signaling is regulated, I performed both single-cell RNA sequencing of the primary somatosensory cortex as well as microglia-specific Translating Ribosome Affinity Purification (TRAP) sequencing. I identified that the majority of central nervous system (CNS) cell populations in the somatosensory cortex, including microglia, undergo transcriptional changes following whisker removal. Further, the transcriptional changes in microglia after whisker cauterization require expression of the receptor CX3CR1. Importantly, I also found that Adam10, a gene encoding the metalloprotease known to post-translationally cleave CX3CL1 into a soluble chemokine, is upregulated in the deprived cortex after whisker ablation. Pharmacological inhibition of ADAM10 inhibits microglia-mediated removal of synapses in the deprived cortex. These data support a mechanism by which cleavage of membrane-bound CX3CL1 by ADAM10 is necessary for neuronal signaling to microglia via CX3CR1 to induce transcriptional changes within microglia upstream of synaptic engulfment and elimination following sensory deprivation.
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Bogdanov, Sergei, and Sergei Bogdanov. "Effects of Hand Transplantation on Cortical Organization." Thesis, University of Oregon, 2012. http://hdl.handle.net/1794/12378.
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Amputation induces substantial reorganization of the body part somatotopy in primary sensory cortex (S1), and these effects of deafferentation increase with time. Determining whether these changes are reversible is critical for understanding the potential to recover from deafferenting injuries. Here, we report evidence that the representation of a transplanted hand and digits can actually recapture the pre-amputation S1 hand territory in two transplant patients. With limited sensation 4 months post operation, one of the patient's (D.S.) palmar tactile stimulation evoked contralateral S1 responses that were indistinguishable in location and amplitude from those detected in healthy matched controls. The other patient (M.S.) demonstrated not only much improved sensation but also recovered ability to localize tactile stimuli 120+ months after the operation. The results described suggest that even decades after complete deafferentation, restoring afferent input to S1 leads to re-establishment of the gross hand and digits representations within their original territory.
Stimulation of the deafferented cortical maps may play an important role in
maintaining their viability until the afferent input is restored. Motor imagery and creation of virtual visual feedback of the absent hand with a mirror have been proposed as stimuli. We used fMRI to record neural activity while 11 unilateral hand amputees and matched controls performed aurally-paced thumb-finger sequencing movements with their intact hand (matching hand in case of controls) under visual guidance during four conditions: 1) intact hand (ME), 2) ME with motor imagery of the amputated hand, 3) ME with virtual visual feedback of the amputated hand, and 4) ME with motor imagery and the virtual visual feedback of the amputated hand. In contrast to controls, amputees showed increases in activity during all four conditions within the former functionally-defined sensorimotor hand territory. Movements of the intact hand likely increase activity in the former hand territory as a result of decreased interhemispheric inhibition. This stimulation may maintain deafferented hand representations that can recover soon after the afferent input is restored by hand transplantation.
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Chen, Simon. "Molecular mechanisms underlying sensory-driven structural and functional plasticity in the awake developing brain." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/42763.
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During early brain development, formation of functional neural circuits requires correct neuronal morphological growth and formation of appropriate synaptic connections. In addition, sensory experience and neural activity impart lasting effects on morphological and functional complexity by directing synapse formation and synaptic plasticity. Errors in these events may result in the creation of dysfunctional circuits underlying common neurodevelopmental disorders, including Autism Spectrum Disorder (ASDs), schizophrenia, and epilepsy. Therefore, to understand the normal development and the pathophysiology of these disorders, we must decipher the molecular mechanisms regulating developmental neural circuit structural and functional plasticity. This dissertation discusses work on the molecular mechanisms underlying structural and functional plasticity in the developing brain, ranging from cell adhesion molecules involved with initial synapse formation to transcription factors regulating sensory experience-driven functional plasticity. In the first half of the dissertation, using two-photon time-lapse imaging of individual growing neurons within intact and awake embryonic Xenopus brains, I found that the cell adhesion molecules, neurexin (NRX) and neuroligin-1 (NLG1), confer stabilization to labile dendritic filopodia, supporting their transition into longer and persistent branches through an activity-dependent multistep process. Disrupting NRX-NLG1 function destabilizes filopodia and culminates in reduced dendritic arbor complexity as neurons mature over days. These findings suggest that abnormalities in brain neuron structural development may contribute to ASDs. In the second half of the dissertation, I used in vivo two-photon calcium imaging of visual network activity and rapid time-lapse imaging of individual growing brain neurons to identify morphological correlates of experience-driven functional potentiation and depression during critical periods of neural circuit formation. Further, I identified the transcription factor MEF2A/2D as a major regulator of neuronal response to plasticity-inducing stimuli directing both structural and functional changes. Unpatterned sensory stimuli that change plasticity thresholds induce rapid degradation of MEF2A/2D through a classical apoptotic pathway requiring NMDA receptors and caspases-9, 3 and 7, demonstrating natural sensory experience fine-tunes the plasticity thresholds of neurons during neural circuit formation. Together, work in this dissertation provides new insights into the molecular and cellular mechanisms of how sensory experience and synapse formation direct structural and functional plasticity in the embryonic developing brain.
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Chery, Romain. "Plasticité de la dynamique spatiale et temporelle de la représentation d’une odeur dans le bulbe olfactif de souris." Thesis, Paris 11, 2012. http://www.theses.fr/2012PA11T102.
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La représentation corticale des informations sensorielles est fondamentale dans la perception, la reconnaissance et la mémorisation des différents objets de l’environnement. Les mécanismes de codage d’un stimulus sensoriel au niveau d’une population neuronale prennent place dans le temps et l’espace, deux composantes que nous avons étudiées successivement dans ce travail de thèse. Dans le bulbe olfactif, la dynamique des activités neuronales se traduit par de larges oscillations du potentiel de champ local. Plusieurs études indiquent que ces activités oscillatoires varient en fonction de l’environnement olfactif ou de l’expérience de l’animal. Toutefois peu d’études ont comparé les réponses oscillatoires aux odeurs entre les états d’éveil et d’anesthésie. La composante spatiale du traitement olfactif dans le bulbe se manifeste par l’activation d’unités fonctionnelles, les glomérules. Visualisées par des techniques d’imagerie fonctionnelle, ces activités distribuées à la surface du bulbe olfactif forment une topographie lâche des molécules olfactive reconnues en périphérie par les neurorécepteurs olfactifs. L’existence d’une plasticité de ces cartes spatiales, un aspect crucial du codage de la représentation de l’information dans d’autres modalités sensorielles, est débattue dans le bulbe olfactif. Dans ce cadre, les travaux présentés dans cette thèse s’articulent autour de deux questions : quel est l’impact de l’état d’éveil de l’animal sur les oscillations du potentiel de champ local enregistré dans le bulbe olfactif ? Existe-t-il une plasticité des cartes glomérulaires suite à un apprentissage associatif ? Par l’enregistrement, chez les mêmes souris, des régimes oscillatoires en condition éveillée et anesthésiée (par un mélange de kétamine-xylazine ou kétamine-médétomidine), nous montrons que les profils de réponses oscillatoires évoquées par l’odeur sont similaires dans les deux conditions, et que l’activité spontanée est modulée différemment selon le régime anesthésique. Pour étudier le codage spatial nous avons en premier lieu visualisé et décrit les variations des cartes glomérulaires évoquées par les odeurs en enregistrant par imagerie optique deux types de signaux basés sur l’activité métabolique, le signal intrinsèque et l’autofluorescence des flavoprotéines. Suite au développement d’une fenêtre optique dans le bulbe olfactif en chronique, nous avons pu comparer les cartes spatiales obtenues avant et après un apprentissage olfactif. Nous avons mis en évidence un impact différentiel de deux types de conditionnement sur la représentation spatiale de l’odeur<br>The cortical representation of sensory information is fundamental for perception, recognition and storage of different objects in the environment. Sensory coding by neuronal population has two components, time and space, that we studied successively in this thesis. In the olfactory bulb, the rhythmic and transient’s dynamic of the extracellular activities are represented as large oscillations of the local field potential. Several studies indicate that these oscillatory activities vary with the olfactory environment or the experience of the animal. However, very few studies have compared oscillatory profiles evoked by odors between awake and anesthetized animals. The spatial component of sensory processing in the olfactory bulb is characterized by the activation of functional units, the glomeruli, which can be visualized by functional imaging techniques. These distributed activities at the surface of the olfactory bulb form a coarse topography of the olfactory molecules that bind on peripheral olfactory neuroreceptors. However, the fact that these spatial maps are plastic, a crucial aspect of encoding the representation of information in other sensory modalities, is still debated in the olfactory bulb. In this context, the work presented in this thesis is driven by two questions: what is the impact of the level of arousal on the oscillations of local field potential recorded in the olfactory bulb? Are glomerular maps plastic after associative learning? In the same mice, we recorded oscillatory activities in awake and anesthetized conditions (using ketamine-xylazine or ketamine-medetomidine mixtures). We show that the profiles of oscillatory responses evoked by odor stimulations are similar in the two conditions, and that spontaneous activity is differentially modulated according to the anesthetic regime. To study odor spatial coding, we used optical imaging to record odor-evoked glomerular maps using two types of metabolic signals, the intrinsic signal and flavoproteins autofluorescence. We developed chronic optical window on the olfactory bulb that allowed us to compare the spatial maps obtained before and after olfactory learning. We have shown that two types of conditioning exerted a differential impact on the spatial representation of the odor
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Min, Lia. "Experience-Dependent Loss of Cross-Modal Plasticity in Mouse Visual Cortex." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10643.
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We perceive the world through sensory experience. Sensory information is registered and processed by our brain in a modality specific fashion. Interestingly, studies have shown that the visual cortex of early but not late blind subjects is able to respond to touch or sound (Sadato et al., 1996; Buchel et al., 1998; Weeks et al., 2000; Gougoux et al., 2009). Here, we investigated whether sensory parcellation in adult cortex is innate or is acquired during early postnatal life in an experience-dependent manner. Furthermore, we studied the anatomical substrates and molecular pathways possibly involved in cross-modal activation and its plasticity. First, mice were reared from birth in total darkness until adulthood (DR) to replicate the human blind condition. Cross-modal activity and the underlying circuitry were analyzed. We found that DR visual cortex was strongly activated by sound stimulation using functional imaging, single-unit recording, and c-Fos immunohistochemistry. Functional analysis was followed by anatomical tracing studies, which showed ectopic projections from the auditory thalamus and auditory cortex into the secondary visual area in DR animals. The second half of our study looked at how visual experience affects cross-modal plasticity. We found that cross-modal activity and ectopic connectivity is present in normally reared young mice (25 postnatal days: P25). Normal sensory experience through the first two months of postnatal life was sufficient to decrease the number of ectopic inputs. Interestingly, exposing DR mice to visual experience as adults established transient functional sensory specificity in the visual cortex without eliminating the ectopic anatomical inputs. Lastly, we tested several molecular pathways that can potentially regulate cross-modal plasticity. We found that myelin signaling and cholinergic modulation controls the duration of cross-modal plasticity and consolidates sensory modularization. Overall, our work proposes a model of how cross-modal inputs into early sensory areas are pruned or retained depending on early life experience. This study provides insight into how the cortex develops functional specificity, and help approach disorders that exhibit abnormal sensory integration and disrupted neuronal connectivity such as Autism Spectrum Disorder.
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Amcoff, Mirjam. "Fishing for Females : Sensory Exploitation in the Swordtail Characin." Doctoral thesis, Uppsala universitet, Zooekologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-207334.
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Mate choice plays an important role in sexual selection and speciation. The evolution of mate choice is intriguing in cases where choosy individuals gain little except for genetic material from the mate and where the trait used as a criterion for the choice is costly to its bearer. The sensory exploitation hypothesis is an interesting idea that applies to such cases because it suggests that sexual preferences may arise as side-effects of preferences that are under selection in other contexts. The role of mate choice in speciation is strong but is debated because the reasons for population divergence in mate preferences and sexual traits are sometimes hard to explain. Also in this context sensory exploitation offers a potential explanation in that a link between natural and sexual selection may result in divergence in sexual selection whenever populations differ in natural selection. In this thesis, I test several aspects of this hypothesis in a species of fish, the swordtail characin (Corynopoma riisei). In this species males display a flag-like ornament that grows from the operculum. Because females respond to this ornament by biting at it, it has been proposed to act as a food-mimic. By manipulating female food type and quantity, and testing the resulting female preference for the male ornament, I find support for the theory that the preference has evolved through sensory exploitation and that females indeed appear to relate the ornament to a food item. Furthermore, I show that sensory exploitation can lead to morphological divergence among natural populations in this species. Apart from the flag-ornament, other courtship signals are also investigated. The results show that the relative importance of different signals may vary depending on receiver motivation. This suggests that various aspects of both male courtship signals and the conditions during which they are being signalled should be considered to gain a full understanding of mate choice and its role in sexual selection and speciation.
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Maalouf, Marwan. "Functions of the cerebral cortex and cholinergic systems in synaptic plasticity induced by sensory preconditioning." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0028/NQ51962.pdf.
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Philipp, Sebastian Thomas. "Information integration and neural plasticity in sensory processing investigated at the levels of single neurons, networks, and perception." Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-161996.
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In this doctoral thesis, several aspects of information integration and learning in neural systems are investigated at the levels of single neurons, networks, and perception.
In the first study presented here, we asked the question of how contextual, multiplicative interactions can be mediated in single neurons by the physiological mechanisms available in the brain. Multiplicative interactions are omnipresent in the nervous system and although a wealth of possible mechanisms were proposed over the last decades, the physiological origin of multiplicative interactions in the brain remains an open question. We investigated permissive gating as a possible multiplication mechanism. We proposed an integrate-and-fire model neuron that incorporates a permissive gating mechanism and investigated the model analytically and numerically due to its abilities to realize multiplication between two input streams. The applied gating mechanism realizes multiplicative interactions of firing rates on a wide range of parameters and thus provides a feasible model for the realization of multiplicative interactions on the single neuron level.
In the second study we asked the question of how gaze-invariant representations of visual space can develop in a self-organizing network that incorporates the gating model neuron presented in the first study. To achieve a stable representation of our visual environment our brain needs to transform the representation of visual stimuli from a retina-centered coordinate system to a frame of reference that is independent of changes in gaze direction. In the network presented here, receptive fields and gain fields organized in overlayed topographic maps that reflected the spatio-temporal statistics of the training input stream. Topographic maps supported a gaze-invariant representation in an output layer when the network was trained with natural input statistics. Our results show that gaze-invariant representations of visual space can be learned in an unsupervised way by a biologically plausible network based on the spatio-temporal statistics of visual stimulation and eye position signals under natural viewing conditions.
In the third study we investigated psychophysically the effect of a three day meditative Zen retreat on tactile abilities of the finger tips. Here, meditators strongly altered the statistics of their attentional focus by focussing sustained attention on their right index finger for hours. Our data shows that sustained sensory focussing on a particular body part, here the right index finger, significantly affects tactile acuity indicating that merely changing the statistics of the attentional focus without external stimulation or training can improve tactile acuity.
In the view of activity-dependent plasticity that is outlined in this thesis, the main driving force for development and alterations of neural representations is nothing more than neural activity itself. Patterns of neural activity shape our brains during development and significant changes in the patterns of neural activity inevitably change mature neural representations. At the same time, the patterns of neural activity are formed by environmental sensory inputs as well as by contextual, multiplicative inputs like gaze-direction or by internally generated signals like the attentional focus. In this way, our environments as well as our inner mental states shape our neural representations and our perception at any time.
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Chakrabarty, Arnab [Verfasser], and Tobias [Akademischer Betreuer] Bonhoeffer. "Role of sensory input in structural plasticity of dendrites in adult neuronal networks / Arnab Chakrabarty. Betreuer: Tobias Bonhoeffer." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2013. http://d-nb.info/103286267X/34.
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Balu, Ramani. "Intrinsic and Synaptic Properties of Olfactory Bulb Neurons and Their Relation to Olfactory Sensory Processing." Case Western Reserve University School of Graduate Studies / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=case1173540900.
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Carlsson, Josefine. "The affects of exercise and brain plasticity, discussed in relation to Functional oriented Music Therapy; a theoretical study." Thesis, University of Skövde, School of Humanities and Informatics, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-68.
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<p>Abstract</p><p>This essay examines which role functional oriented music therapy, which is supposed to help sensorimotor development, can have in schools and in health care. To find this out, research about what kinds of effects exercise can have on academic achievements and in recovery from brain injuries has been brought up. The research concerning academic achievements was conducted with school children; some children without difficulties, some with sensory integration problems, and some with motor skill difficulties. In addition to this, research about the brain structure superior colliculus, which lies behind sensory integration, is also brought up.</p><p>The results showed that children who were given more exercise had significantly better scores in academic skills than the children with normal academic education. Thus, it might be reasonable to practise functional oriented music therapy in schools, both as helping general development, but also for children with different types of difficulties.</p><p>The research concerning exercise and injuries has made clear that the adult brain can change via neurogenesis, plasticity and cortical reorganization. These three aspects are important when practicing a skill or when recovering from an injury. Exercise has been shown to affect these three aspects positively and can therefore also aid the recovery from injuries.</p><p>Thus, there seems to be many theoretical aspects supporting the FMT- method. However, the question is if the results of one treatment form can generalize over such a wide range of injuries and defects that the FMT –adepts usually have. It is therefore also discussed if further experiments on the FMT-method could help make it a more effective tool for rehabilitation.</p>
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Heiss, Leah Rose Laurel, and leah heiss@rmit edu au. "Empathy and the space between: investigating the role of digitally enhanced apparel in promoting remote empathetic connection." RMIT University. Architecture and Design, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20070112.101632.
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This body of work is the culmination of a two year investigation into the role of electronically enhanced apparel and artefacts in providing empathetic linkage between people who do not share physical space. The research draws from the diverse fields of philosophy, communications theory, neuropsychology, presence technologies and technologically advanced textiles, and proposes that a nexus of these disciplines may provide significant opportunities for enhancing the user interactivity of garments and artefacts. Remote emotional connection is investigated through the creation of sensor embedded garments and artefacts that have been developed in collaboration with a fashion designer and an electronics engineer. The prototypes encourage remote empathetic connection through the real-time transference of heartbeat. The exegesis is structured into five chapters which consider remote presence, flexible consciousness, the architecture of empathy, plasticity in sense perception and the development of prototypes. The project chapter focuses in the development of and testing of a rnage of garments and artefacts thatt conduct presence information between remotely located people. The garments sense, process, transmit and receive the heartbeat signal (ECG). They are enabled with ECG sensors, signal processing equipment, small vibration motors and radio transceivers which allow users to 'feel' the heartbeat of a remote friend/lover/relative as vibration through their garment. The prototypes aim to enrich the remote communications experience through reintroducing an embodied, tactile dimension that is present in face-to-face communication. A range of user testing trials are discussed in the thesis which have been undertaken to assess the impact of the garments at a conscious and a non-conscious level. Conscious experiences were gauged through qualitative testing by way of interviews and unsolicited written reactions. Non-conscious physiological ractions were assessed by recording ECG throughout user-testing periods. This data has been processed by using HRV (heart rate variability) analysis software, running on MatLab.
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André, Marion Agnès Emma [Verfasser], Denise [Gutachter] Manahan-Vaughan, and Hanns [Gutachter] Hatt. "Sensory information processing in hippocampal synaptic plasticity, spatial and extinction learning / Marion Agnès Emma André ; Gutachter: Denise Manahan-Vaughan, Hanns Hatt." Bochum : Ruhr-Universität Bochum, 2016. http://d-nb.info/1119447380/34.
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Dietz, Birte Elsabeth [Verfasser], Denise [Gutachter] Manahan-Vaughan, and Stefan [Gutachter] Herlitze. "Sensory integration by hippocampal synaptic plasticity and place cells / Birte Elsabeth Dietz ; Gutachter: Denise Manahan-Vaughan, Stefan Herlitze ; International Graduate School of Neuroscience." Bochum : Ruhr-Universität Bochum, 2018. http://d-nb.info/1167505387/34.
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Erlandson, Melissa. "Investigating the plasticity of sensory cortical circuits in the context of learning in the wild-type mouse and a conditional mouse model of fragile X syndrome." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0342.
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L'objectif de ce projet est l’étude de la plasticité des circuits corticaux dans le contexte de l'apprentissage des souris « sauvages » et modèles du syndrome de l’X fragile. Des études sur l'efficacité de la combinaison d'enregistrement des potentiels de champ locaux extracellulaires avec la stimulation laser UV (LSPS) pour cartographier les réseaux ont été réalisées. Nous avons trouvé des enregistrements de champs extracellulaires qui pourraient être utilisés pour détecter les réponses synaptiques évoquées par LSPS. Nos résultats indiquent une méthode alternative pour obtenir des cartes complètes de réseaux intracorticaux excitateurs. Ensuite, nous avons développé un paradigme d'apprentissage associatif sensoriel et étudié ses effets sur les réseaux intracorticaux excitateurs du cortex baril. Ex vivo un affaiblissement des projections excitatrices entre les couches 4 et 2/3 qui dans les colonnes de vibrisses C a été observée. Enfin, nous avons utilisé ces mêmes approches dans une souris modèle du syndrome de l'X fragile (FXS). Pour étudier les liens entre les déficits sensoriels, l'apprentissage associatif et les altérations fonctionnelles des réseaux sensoriels, nous avons utilisé un modèle de souris mutantes dans lequel la pathologie FXS était ciblée sur la couche 4 du cortex somatosensoriel. Il a été constaté que les souris WT présentaient une dépression similaire, alors qu'elle était absente FXS. En conclusion, les études sur les mutants sensoriels de type sauvage ont mis en lumière les conséquences de l'apprentissage sur les réseaux corticaux sensoriels et les liens entre la plasticité des réseaux corticaux sensoriels et les capacités cognitives<br>The aim of this project is to study the plasticity of the cortical circuits in the context of the learning of wild type mice and models of Fragile X Syndrome. First, investigations into the efficacy of recording combination of extracellular local field potentials with UV laser stimulation (LSPS) to map networks were performed. We found extracellular field records could be used to detect the synaptic responses evoked by LSPS. Our results indicate an alternative method for obtaining complete maps of excitatory intracortical networks. Next, we developed a sensory associative learning paradigm and studied its effects on excitatory intracortical networks the barrel cortex. Ex vivo a weakening of the excitatory projections between layers 4 and 2/3 which in the columns of vibrissae C was observed and declined function of the speed of the behavioural response. Finally, we used these same approaches in a Fragile X Syndrome (FXS) model mouse. To study the links between sensory deficits, associative learning, and functional alterations of sensory networks, we used a model of mutant mice in which the FXS pathology was targeted to the layer 4 of the somatosensory cortex. Our hypotheses were that behavioural conditioning would change the cortical sensory circuits of the FXS sensory mutant and that the abnormal plasticity of these circuits would in turn affect the performance. It was found the WT mice exhibited a similar depression, whereas it was absent FXS. In conclusion, wild type mouse and FXS sensory mutant studies shed light on the consequences of learning on sensory cortical networks and on the links between plasticity of sensory cortical networks and cognitive abilities
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Philipp, Sebastian Thomas [Verfasser], and Thomas [Akademischer Betreuer] Wachtler. "Information integration and neural plasticity in sensory processing investigated at the levels of single neurons, networks, and perception / Sebastian Thomas Philipp. Betreuer: Thomas Wachtler." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2013. http://d-nb.info/1043906517/34.
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Bradley, Claire. "The first steps of cortical somatosensory and nociceptive processing in humans : anatomical generators, functional plasticity, contribution to sensory memory and modulation by cortical stimulation." Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10213.
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Les sensations en provenance de notre corps se combinent pour donner lieu à des perceptions extrêmement variées, pouvant aller de la brûlure douloureuse au toucher agréable. Ces deux types d'informations dites nociceptives et non nociceptive sont traitées au sein du système nerveux somatosensoriel. Dans ce travail de thèse, nous avons modélisé et caractérisé l'activité électrique du cortex operculo-insulaire au sein des réseaux somatosensoriels non-douloureux et nociceptif, grâce à des enregistrements non-invasifs chez l'Homme. La validité du modèle en réponse à un stimulus nociceptif a été évaluée par comparaison avec des enregistrements intra-corticaux réalisés chez des patients épileptiques. Nous avons ensuite utilisé ce modèle pour déterminer si la stimulation corticale non invasive classiquement utilisée pour soulager les douleurs neuropathiques (stimulation magnétique du cortex moteur) permettait de modifier les réponses nociceptives chez des participants sains. Nous avons montré que cette intervention n'est pas plus efficace qu'une stimulation factice (placebo) sur le plan du blocage nociceptif. Finalement, nous avons tenté de stimuler directement le cortex operculo-insulaire, par trois méthodes différentes : par stimulation électrique locale, intracrânienne et par stimulations non-invasives magnétique (rTMS) et électrique (tDCS). Dans l'ensemble, les travaux présentés ici montrent comment une approche non-invasive chez l'Homme permet de caractériser et de moduler l'activité du cortex operculo-insulaire, qui pourrait être une cible intéressante pour le traitement des douleurs réfractaires<br>The somatosensory system participates in both non-nociceptive and nociceptive information Processing. In this thesis work, we model and characterize the electrical activity of the operculo-insular cortex within non-painful and nociceptive networks, using non-invasive electrophysiological recordings in humans. Validity of the modeled response to a nociceptive stimulus was evaluated by comparing it to intra-cranial recordings in epileptic patients, revealing excellent concordance. We went on to use this model to determine whether a technique of non-invasive cortical stimulation currently used to relieve neuropathic pain (motor cortex magnetic stimulation) was able to modulate acute nociceptive processing in healthy participants. We show that this intervention is not more efficacious than placebo stimulation in blocking nociception. This raises questions regarding the mechanisms of action of this technique in patients, which might implicate a modulation of pain perception at a higher level of processing. Finally, we attempted to stimulate the operculo-insular cortex directly, using three different methods. Low-frequency intra-cortical stimulation in epileptic, transcranial magnetic stimulation (TMS) of the same region in healthy participants and multipolar transcranial electrical stimulation (tDCS).Altogether, the studies presented here show how a non-invasive approach in humans allows characterising and modulating the activity of the operculo-insular cortex. While this region might be an interesting target for future treatment of drug-resistant pain, its stimulation in patients would require further investigation of parameters and procedures
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Chappell, Tyson. "The long-term teratogenic effect of prenatal alcohol exposure on the somatosensory and motor cortex of rats." View the abstract Download the full-text PDF version, 2007. http://etd.utmem.edu/ABSTRACTS/2007-013-Chappell-index.htm.
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Thesis (Ph.D.)--University of Tennessee Health Science Center, 2007.<br>Title from title page screen (viewed on February 29, 2008). Research advisor: Robert S. Waters, Ph.D. Document formatted into pages (xix, 179 p. : ill.). Vita. Abstract. Includes bibliographical references (p. 152-178).
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Triner, Joceline Clare. "Defining neurochemical properties and functions of primary sensory neurons in the rat trigeminal ganglion." Thesis, University of Plymouth, 2013. http://hdl.handle.net/10026.1/1585.
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The trigeminal ganglion (TG) is a complex sensory structure and multiple lines of evidence suggest that significant differences exist in anatomical, neurochemical and physiological properties between it and its equivalent structure in the somatosensory system, the dorsal root ganglion (DRG). This is likely to be a reflection, first on the unique areas of tissue innervation of the TG and second, on the unusual responses to injury which give rise to distinct pain symptoms such as toothache, migraine and temporomandibular joint disorders. In an attempt to address this disparity in knowledge, we have carried out an in-depth in vivo study investigating neurochemical populations and cell size distributions of sensory neurons within the rat TG. We have performed a detailed analysis of expression patterns for receptor components of important inflammatory mediators, NGF (TrkA), TNFα (p55) and IL-6 (gp130), along with the thermo-transducers TRPV1 and TRPM8. For each analysis we have compared our findings with those of the rat DRG. We have shown a significantly larger population of NF200+ neurons within the TG (51%) compared to the DRG (40%), and most interestingly, the majority of NF200+ neurons in the TG were within the small to medium cell size range, conferring a nociceptive phenotype. We have for the first time, determined expression of p55 and gp130 protein levels within neurochemically defined subpopulations of the TG. We show that a large proportion (33%) of TG neurons, in particular 27% of NF200+ neurons co-express p55, and thereby have the potential to respond directly to TNFα. Furthermore, we have observed gp130 protein expression to be ubiquitous within the TG, suggesting all neurons, including non-nociceptors, could respond to IL-6. In addition, we have utilised biochemical and electrophysiological techniques in vitro to measure the functional outcome of exposure of TG neurons to IL-6. We have demonstrated that IL-6 activates the JAK/STAT signalling pathway, preferentially within NF200+ neurons. Furthermore, we have shown that IL-6 sensitises the response of TG neurons to the TRPV1 agonist capsaicin, altering the gating properties and prolonging the opening time of the channel. Taken together, our findings support the emerging picture of a complex combinatorial pattern of co-expression of sensory neurochemicals, transducers and receptor components that help to define TG neuronal modality and function. We would advocate caution in making generalisations across sensory ganglia in particular in extrapolating data from the DRG to the trigeminal ganglion.
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Le, Fur Iris. "La plasticité sonore : la création visuelle et sonore, une interaction sensorielle, émotionnelle et sémantique." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0101.
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Sur la base d’une pratique artistique explorant le phénomène vibratoire de la matière, cette thèse propose une réflexion sur les interactions entre matières sonores et matières visuelles au sein d’une même production plastique. Il s’agit d’analyser l’acte de création composé d’un agencement sensible de divers éléments auditifs et visuels réagissant de manière réciproque et provoquant une mutation de leur perception sensorielle, émotionnelle et sémantique. Un tour d’horizon de certains grands acteurs de l’histoire des pratiques sonores au XX° et XXI° siècle permettra d’aborder la question de l’interaction entre l’ouïe et la vue dans une production artistique. Seront abordées les notions de plasticité sonore, de mouvement vibratoire par l’altération, ainsi que du métissage plastique issu du métissage culturel. Dans un second temps, mon étude portera sur le processus de création d’une installation sonore par mode vibratoire, à travers l’écoute, le processus d’écriture sonore et les caractéristiques des espaces publics en tant que lieu d’accueil d’une œuvre. En dernier lieu, l’étude de la spécificité de la vibration sonore à générer des émotions, mettant en relief les mécanismes cérébraux sollicités par la perception bi-sensorielle aussi bien au niveau du corps de l’artiste créant, que ceux du public expérimentant l’œuvre<br>On the basis of an artistic practice exploring the vibratory phenomenon of matter, this thesis proposes a reflection on the interactions between sound and visual materials within the same plastic production. It is a matter of analyzing the act of creation comprising a sensoriel arrangement of various auditory and ocular elements reacting reciprocally and causing a mutation of their sensory, emotional and semantic perception. A survey of some of the major 20th and 21st century players in the history of sonic cultural practices will address the issue of the interaction between hearing and sight in an artistic production. The notions of sound plasticity, of vibratory movement through alteration, as well as that of plastic mixing resulting from cultural intermingling will be discussed. secondly, my study will focus on the process of creating a sound installation by vibratory mode, through listening, the process of sound writing and the characteristics of public spaces as an artwork. Finally, the study of the specificity of sound vibration to generate emotions, highlighting the cerebral mechanisms required by bi-sensory perception both in the body of the creative artist and those of the public experiencing the 'artwork
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Souza, Gabriela Valiengo de. "Potenciais evocados auditivos de longa latência em adultos pré e pós adaptação do AASI." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/5/5170/tde-27102017-085811/.
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Introdução: Plasticidade auditiva refere-se a mudanças que ocorrem no sistema sensorial responsável pela transmissão da informação acústica. A plasticidade do sistema nervoso auditivo central está relacionada a capacidade de adaptação através da reintrodução de estímulos por meio de aparelhos de amplificação sonora ou implante coclear. Essas mudanças são observadas a partir do desempenho de pacientes com o uso do aparelho de amplificação sonora, e podem ser verificadas por meio dos potenciais evocados auditivos de longa latência. Objetivo: caracterizar os Potenciais Evocados Auditivos de Longa Latência (PEALL) em adultos e idosos com perda auditiva neurossensorial, verificando os efeitos da estimulação auditiva por meio da comparação destes potenciais pré e pós adaptação do Aparelho de Amplificação Sonora Individual (AASI). Metodologia: Participaram deste estudo 15 indivíduos adultos e idosos, de ambos os gêneros, de 55 a 85 anos de idade, com perda auditiva neurossensorial de grau leve a moderado com simetria entre as orelhas, sem experiência prévia com qualquer tipo de dispositivo de amplificação sonora. Os indivíduos foram encaminhados pelas empresas de aparelho auditivo WIDEX, Audibel e o Espaço Reouvir, tratando-se de novos usuários de AASI. Os PEALL foram realizados nas condições com e sem AASI, a 60 e 75 dBnNA em campo sonoro, em dois momentos: primeira avaliação realizada até uma semana após a adaptação do AASI e a segunda avaliação realizada após 6 meses da adaptação do AASI. Resultados: Na comparação da primeira avaliação com a segunda avaliação, na condição sem AASI a 60 dBnNA, observou-se diferença estatisticamente significante na latência do componente P1 (p-valor= 0,034). Na condição sem AASI a 75 dBnNA, observou-se diferença estatisticamente significante para a latência do componente P300 (p-valor 0,031) e para a amplitude P2N2 (p-valor 0,024), com diminuição da latência e aumento da amplitude na segunda avaliação. Por sua vez, na comparação da primeira avaliação com a segunda avaliação, na condição com AASI a 75 dBnNA, obteve-se uma diferença estatisticamente significante na latência do componente N2 (p-valor 0,009) e na amplitude P2N2 (p-valor 0,024), com aumento da amplitude na segunda avaliação. Evidenciou-se, também, diferença significante na amplitude P1N1 (p-valor 0,024) na condição com AASI a 60 dBnNA. Conclusão: Os PEALL com estímulo de fala demonstraram ser um importante procedimento para ser utilizado na prática clínica, visando monitorar a plasticidade neuronal do Sistema Nervoso Auditivo Central frente à estimulação auditiva (uso de AASI), em adultos e idosos com perda auditiva neurossensorial de grau leve a moderado<br>Introduction: Auditory plasticity refers to changes that occur in the sensory system responsible for the transmission of acoustic information. The plasticity of the central auditory nervous system is related to the capacity of adaptation through the reintroduction of stimuli of sound amplification devices or cochlear implants. These changes are observed from the performance of patients with the use of the sound amplification apparatus, and can be verified by long-latency auditory evoked potentials. Purpose: To characterize long latency auditory evoked potentials (LLAEP) in adults with sensorineural hearing loss, verifying the effects of auditory stimulation by comparing these before and after adaptation potentials of the Individual Sound Amplification (AASI). Methodology: Fifteen adult and elderly individuals of both genders, aged 55 to 85 years, with mild to moderate sensorineural hearing loss with symmetry between the ears, without prior experience with any type of sound amplification device. The subjects were referred by hearing aid companies WIDEX, Audibel and Espaço Reouvir, in the case of new hearing aids users. The LLAEP were performed in the conditions with and without AASI, at 60 and 75 dBnNA in sound field, in two moments: first evaluation performed up to one week after AASI adaptation and the second evaluation performed after 6 months of AASI adaptation. Results: In the comparison of the first evaluation with the second evaluation, in the condition without AASI at 60 dBnNA, a statistically significant difference was observed in the latency of the P1 component (p-value = 0.034). In the condition without AASI at 75 dBnNA, a statistically significant difference was observed for the latency of the P300 component (p-value 0.031) and for the P2N2 amplitude (p-value 0.024), with latency decrease and amplitude increase in the second evaluation. In the comparison of the first evaluation with the second evaluation, in the condition with AASI at 75 dBnNA, there was a statistically significant difference in the latency of the N2 component (p-value 0.009) and in the P2N2 amplitude (p-value 0.024) , With amplitude increase in the second evaluation. There was also a significant difference in P1N1 amplitude (p-value 0.024) in the condition with AASI at 60 dBnNA. Conclusion: The LLAEP was an important procedure to be used in clinical practice, aiming to monitor the neural plasticity of the Central Auditory Nervous System in front of auditory stimulation (hearing aids use) in adults and elderly patients with mild to moderate sensorineural hearing loss of amplification and the importance of neural plasticity of the Central Auditory Nervous System
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Bol, Kieran G. "Redundant Input Cancellation by a Bursting Neural Network." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20061.
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One of the most powerful and important applications that the brain accomplishes is solving the sensory "cocktail party problem:" to adaptively suppress extraneous signals in an environment. Theoretical studies suggest that the solution to the problem involves an adaptive filter, which learns to remove the redundant noise. However, neural learning is also in its infancy and there are still many questions about the stability and application of synaptic learning rules for neural computation.
In this thesis, the implementation of an adaptive filter in the brain of a weakly electric fish, A. Leptorhynchus, was studied. It was found to require a cerebellar architecture that could supply independent frequency channels of delayed feedback and multiple burst learning rules that could shape this feedback. This unifies two ideas about the function of the cerebellum that were previously separate: the cerebellum as an adaptive filter and as a generator of precise temporal inputs.
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Figueiredo, Sabrina Suellen Rolim. "Potencial Evocado Auditivo de Longa Latência em crianças usuárias de implante coclear." Pontifícia Universidade Católica de São Paulo, 2015. https://tede2.pucsp.br/handle/handle/12013.
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Previous issue date: 2015-03-10<br>The use of amplification and implantable devices is an alternative to minimize the effects of sensory deprivation, imposed by hearing loss. The effects of sensory deprivation in the central auditory system have been studied by recording the latencies of Long Latency Auditory Evoked Potential (LLAEP) as a cortical maturation indicator. The assessment of auditory cortical development of the child user of cochlear implant (CI) can provide important data on the conditions of the upper ways, and the effectiveness of the strategy used after the intervention, through the use of hearing aids or CI. OBJECTIVE: To study the LLAEP in children with bilateral sensorineural hearing loss, severe and/or profound cochlear implant users. METHOD: This study is qualitative/quantitative, descriptive, using the LLAEP in children with sensorineural severe and/or profound hearing with cochlear implant. The participants were 8 children using unilateral cochlear implant, age ranging between 3 and 5 years old. Data were collected regarding the etiology, hearing age, chronological age at implantation, mean values of free field audiometry with CI, and the record of LLAEP in the free field as a transducer with the speech stimulus /ba/, in the intensity of 75 dBSPL, with the use of CI. The eye movement was recorded to control the generated artifact. RESULTS: The values of LLAEP latency were statistically analyzed and described according to the study variables. It was possible to identify the component P1 in all volunteers in the study. Regarding the N1 component, 50% of the patients showed responses allowing the registry. None of the participants presented the P2 component. There is a statistically significant correlation founded between the latency value of the N1 component and the time in which the participant had no use of hearing aids, waiting for the diagnosis. CONCLUSION: LLEAP may be useful in routine clinical audiology to monitor the central auditory development in children with cochlear implants. The effects of central auditory deprivation and changes in central auditory processing can be monitored by recording LLAEP and monitoring of other factors that influence the user's IC auditory performance<br>O uso de dispositivos de amplificação e dispositivos implantáveis é uma alternativa para minimizar os efeitos da privação sensorial, imposta pela deficiência auditiva. Os efeitos da privação sensorial no sistema auditivo central têm sido estudados por meio do registro das latências do Potencial Evocado Auditivo de Longa Latência (PEALL) como um indicador de maturação cortical. A avaliação do desenvolvimento cortical auditivo da criança usuária de Implante Coclear (IC) pode fornecer dados importantes sobre as condições das vias superiores, e a efetividade da estratégia utilizada, após a intervenção, por meio da adaptação de AASI ou de IC. OBJETIVO: Estudar o PEALL em crianças usuárias de Implante Coclear. MÉTODO: O estudo é do tipo quali/quantitativo, descritivo, por meio da realização do PEALL em crianças com deficiência auditiva sensorioneural de grau severo e/ou profundo adaptadas ao Implante Coclear. Participaram da pesquisa 8 crianças usuárias de Implante Coclear unilateral, com idades entre 3 a 5 anos. Foram coletados dados referentes à etiologia, idade auditiva, idade cronológica na ativação, valores médios da audiometria em campo livre com IC, e o registro dos PEALL, com o estímulo de fala /ba/ na intensidade de 75 dBNPS. O registro do movimento ocular foi realizado para melhor controle do artefato gerado. RESULTADOS: Os valores de latência dos PEALL foram analisados estatisticamente e descritos de acordo com as variáveis do estudo. Foi possível identificar o componente P1 em todos os voluntários do estudo. Com relação ao componente N1, metade da amostra apresentou respostas possibilitando o registro. Nenhum dos participantes apresentou o componente P2. Foi encontrada correlação estatisticamente significante entre o valor de latência do componente N1 e o tempo em que o participante ficou sem uso de AASI, aguardando o diagnóstico. CONCLUSÃO: O registro dos PEALL é viável e útil na rotina da clínica fonoaudiológica para o acompanhamento do desenvolvimento auditivo central em crianças com implantes cocleares. Os efeitos da privação auditiva central e as mudanças no processamento auditivo central podem ser monitoradas pelo registro dos PEALL e pelo acompanhamento dos demais fatores que influenciam a performance do usuário de IC
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Furucho, Mariana Antonia Aguiar. "Modelo neurocomputacional dos estágios iniciais da doença de Alzheimer." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/47/47135/tde-06022018-092738/.
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Há evidências convincentes de que o início da doença de Alzheimer é precedido por uma redução de estímulos sensoriais, como ocorre durante a aposentadoria, catarata, surdez e degeneração macular, em um cérebro idoso que apresenta deficiência de receptores tipo GABAA. Neste trabalho foi utilizado um modelo computacional fenomenológico do koniocortex, que é a primeira camada cortical que recebe estímulos sensoriais, adaptado para simular as fases iniciais da doença de Alzheimer. A arquitetura e as propriedades dos neurônios do modelo computacional do koniocortex se assemelham as do cérebro, sendo também capaz de aprender, permitindo com isso que a memória de curto prazo seja testada em qualquer momento. Usando o modelo computacional é possível também analisar as fases iniciais da doença de Alzheimer simulando o \"envelhecimento\" do koniocortex artificial através de um conjunto de parâmetros referentes à plasticidade intrínseca, à acetilcolina, aos estímulos sensoriais, ao pruning sináptico, entre outros. O modelo computacional revela que, quando o envelhecimento afeta os neurônios que expressam receptores GABA-A ocorrendo na sequência uma redução dos estímulos sensoriais, o resultado dessa cascata de eventos leva ao hipermetabolismo e ao início da fase de deposição excessiva das placas -amiloide<br>There is compelling evidence that Alzheimers disease onset is preceded by a reduction of sensory stimuli like during job retirement, cataract, deafness or even macular degeneration, over an aged brain with impaired GABA-A receptor inhibitions. In this paper, was adapted a phenomenological computational model of the koniocortex which is the first cortical layer that receives sensory stimuli to simulate the initial phases of Alzheimers disease. The architecture and neurons properties of the modeled koniocortex resemble those of the brain, so that the model is also able to learn, thereby allowing the assessment of short-term memory at any moment. By using the computational model, it is possible to analyze the initial phases of Alzheimers disease by aging the artificial koniocortex through a set of parameters related to intrinsic plasticity, acetylcholine, sensory stimuli, synaptic pruning, among others. The computational model shows that when aging occurs in such way that GABA-A receptor expressing neurons are affected, and, in the sequence, a reduction of sensory stimuli takes place, the result of this cascade of events leads to hypermetabolism and to the initial phase excessive deposition of beta-amyloid plaques
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Collins, Thérèse. "Conséquences perceptives de la plasticité sensori-motrice du système visuel." Paris 5, 2007. http://www.theses.fr/2007PA05H047.
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La transformation d'une information visuelle en une commande motrice appropriée est essentielle pour la réalisation d'une action précise et adaptée sur les objets de l'environnement. Dans le système visuel, il s'agit de transformer les coordonnées sensorielles d'un objet visuel en coordonnées motrices susceptibles de'diriger un mouvement oculaire vers cet objet. La transformation sensori-motrice est sujette à la plasticité : il est possible de dissocier les coordonnées motrices de la saccade oculaire des coordonnées visuelles de la cible grâce au phénomène d'adaptation saccadique. Dans un premier temps, les connaissances sur l'adaptation saccadique ont été approfondies en précisant la spécificité de l'adaptation à l'intentionnalité de la saccade (saccades réactives versus volontaires), la structure de l'étendue spatiale de l'adaptation accadique, et son influence sur la dynamique de la saccade. L'adaptation saccadique a été exploitée pour examiner la contribution de chaque système de coordonnées - motrices et visuelles - sur la perception. Deux aspects de la perception ont été étudiées : l'orientation de l'attention visuo-spatiale et la perception de l'espace. Les résultats montrent que lorsque les coordonnées motrices sont modifiées par adaptation saccadique, l'orientation de l'attention visuo-spatiale subit une modification analogue. Ainsi, la répartition des capacités perceptives à travers le champ visuel dépendrait de l'action en cours de préparation. Les coordonnées motrices organisent également la perception de l'espace. Quand ces coordonnées sont modifiées par adaptation, la perception de la localisation des objets dans l'espace subit une modification proportionnelle. Ainsi, la perception de l'espace dépendrait du potentiel à agir dans cet espace. Ces résultats suggèrent que l'action et l'intention d'agir joueraient un rôle important dans la perception du monde visuel<br>The transformation of visual information about an object into an appropriate motor command is essential to precise and adapted action in the environment. In the visual system, the sensory coordinates of a visual object must be transformed into motor coordinates appropriate to acquiring that object with a saccadic eye movement. Sensory-motor transformation is subject to plasticity, as shown by saccadic adaptation which introduces a discrepancy between the motor coordinates of the saccade and the visual coordinates of the target. The characteristics of saccadic adaptation were studied by examining the selectivity of adaptation to mtentionality (reactive versus volitional saccades), the structure of the spatial extent of saccadic adaptation, and the effect on saccade dynamics. Saccadic adaptation was exploited to examine the contribution of the two coordinate systems - motor and visual - to perception. Two aspects of visual perception were studied: the orientation of visuo-spatial attention, and the perception of visual space. The results show that when the motor coordinates are adaptively modified, the orientation of visuo-spatial attention is modified in an analogous manner. The distribution of perceptual capacities throughout the visual field depends on the action being prepared. Motor coordinates also organize the perception of visual space. When they are adaptively modified, the perceived localization of objects is proportionally affected: the perception of space depends on the potential to act within that space. Taken together, these results suggest an important role of action and action intention in the perception of the visual world
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Duffau, Hugues. "Plasticite corticale sensori-motrice a court terme chez l'homme etude par stimulation electrique per-operatoire." Paris 6, 2000. http://www.theses.fr/2000PA066563.
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La plasticite cerebrale (reorganisation neurono-synaptique continue optimisant le fonctionnement des reseaux) a pu etre objectivee in vivo, initialement chez l'animal (plasticites naturelle et post-lesionnelle) et plus recemment chez l'homme grace aux methodes d'imagerie neurofonctionnelle et de stimulations transcraniennes (plasticites naturelle a court et long terme, et post-lesionnelle a long terme seule). Dans notre travail, nous avons utilise la technique des stimulations electriques directes per-operatoires afin d'etudier chez l'homme les processus de plasticite corticale sensorimotrice post-lesionnelle a court terme, durant la resection chirurgicale de lesions cerebrales de la region centrale (cette cartographie fonctionnelle representant un benefice direct pour le patient). Les resultats ont montre : dans 3 cas une reorganisation rapide de la carte fonctionnelle au sein de l'aire motrice primaire, avec demasquage de sites moteurs redondants (plasticite locale) ; dans un autre cas, une redistribution immediate des cartes sensorimotrices, avec demasquage de redondances motrices de part et d'autre du sillon central (plasticite regionale). Les processus physiopathologiques sous-tendant ces phenomenes sont discutes, sur la base de la probable existence de circuits paralleles potentiellement compensateurs les uns pour les autres, et possiblement hierarchises. Secondairement, nous envisageons l'application de ce potentiel plastique (sensorimoteur voire concernant les fonctions cognitives) en therapeutique, notamment neurochirurgicale. Nous avons ainsi pratique dans un but oncologique, une resection premierement de l'aire somatosensorielle primaire chez 6 patients, deuxiemement de zones du langage redistribuees a la suite d'une premiere intervention (1 patient), dans tous les cas avec recuperation post-operatoire. Enfin, nous proposons comme perspective une etude visant a tenter d'induire la plasticite cerebrale de facon controlee (notamment par l'acte operatoire).
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Le, Ray Didier. "Modulations phasiques et plasticité à long terme d'un réseau sensori-moteur : étude dans le système nerveux locomoteur de l'écrevisse." Aix-Marseille 2, 1997. http://www.theses.fr/1997AIX22097.
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Une des grandes questions de la neurobiologie des mouvements est de comprendre comment au cours d'un mouvement le message sensoriel interagit avec la commande centrale afin de construire la commande motrice finale. Dans cette perspective, nous avons analyse au sein du reseau sensori-moteur implique dans le controle des mouvements d'une articulation d'une patte locomotrice chez l'ecrevisse, les mecanismes d'integration (et leur modulation) des informations proprioceptives dans le programme moteur produit par un generateur central. Nous avons tout d'abord realise une etude in vitro complete des proprietes de ce reseau : codage sensoriel multiple, differentes formes de reponse reflexe monosynaptique des motoneurones, cablage des connexions sensori-motrices et, par simulation informatique, fonctionnement des synapses sensori-motrices. Ce reseau sensori-moteur est le lieu de modulations importantes, capables de transformer son activite de facon transitoire ou a long terme. En fonction de l'activite centrale, il peut se produire une inversion phasique du reflexe de resistance en reflexe d'assistance : nous avons demontre que ce phenomene depend du poids relatif de trois interneurones specialises. Ce reseau presente aussi un phenomene de potentiation a long terme des synapses sensori-motrices : d'origine purement postsynaptique, il met en jeu le glutamate (neurotransmetteur des motoneurones chez l'ecrevisse) et se traduit par l'augmentation de liberation de neurotransmetteur par l'afference presynaptique. Nos resultats demontrent la complexite des integrations sensori-motrices et la finesse de leurs mecanismes de controle, conferant ainsi aux interactions entre afferences et cpg un role essentiel dans l'elaboration des mouvements.
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Dinomais, Mickaël. "Etude du cortex sensori-moteur en imagerie par Résonance Magnétique Fonctionnelle : du sujet sain à l'enfant avec paralysie cérébrale." Angers, 2013. http://tel.archives-ouvertes.fr/tel-01021084.
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La paralysie cérébrale (PC) est définie comme un trouble du mouvement secondaire à une lésion cérébrale précoce non progressive. C'est la première cause de handicap moteur de l'enfant. La médecine physique et de réadaptation a donc un intérêt particulier à l'étude du contrôle centrale de la motricité (motricité-cérébrale) aussi bien en termes d'organisation que de réorganisation après lésion, et ce, afin de proposer de nouvelles méthodes de rééducation motrice. Après avoir montré, chez le sujet sain, que la motricité-cérébrale pouvait être étudiée, en imagerie par résonance magnétique fonctionnelle (IRMf), par l'observation du mouvement et le mouvement passif, nous démontrons que l'IRMf " de repos " peut étudier la connectivité fonctionnelle du réseau sensori-moteur chez l'enfant avec PC. D'autre part, dans cette population, l'observation d'une main parétique active le réseau sensori-moteur comme attendu chez le sujet sain, avec une prédominance d'activation dans le cortex moteur primaire lésé. Aussi, lorsque l'on combine cette tâche d'observation du mouvement à un mouvement passif congruent de la main parétique, on observe une activation plus importante des aires sensori-motrices, notamment des aires de " haut niveau ". Cette tâche de mouvement vidéo-guidé nous semble pouvoir constituer une tâche de rééducation motrice dont l'efficience sera à tester ultérieurement. Enfin, nous exposons l'accident vasculaire néonatal comme modèle d'étude de la plasticité postlésionnelle, notamment pour différencier la plasticité " mal-adaptative " de la plasticité efficiente<br>Cerebral palsy (CP) is a non-progressive injury to the developing central nervous system resulting in permanent disorders of the development of movement and posture, causing activity limitation. Therefore physical and rehabilitation medicine has a particular interest in the study of organization and reorganization of the sensorimotor cortex following early brain injury in order to propose new methods for motor rehabilitation. We first showed that motor cortex could be analyzed in functional magnetic resonance imaging (fMRI) using action-observation and passive movement tasks. We then demonstrated in patients with unilateral CP that resting state analysis could study functional connectivity in sensorimotor system. Moreover, our work showed that observing hand movement produced, in CP patients, large bilateral activations in temporo-parieto-fronto-occipital network, comprising most of the nodes of the well described action-observation network. For either side, observing hand movements recruits the primary motor cortex, contralateral to the viewed hand, as would be expected in healthy persons. In addition, we showed that the combination of observation of congruent hand movement simultaneously to passive movement of the paretic hand recruits more motor areas, giving neuronal substrate to propose video-guided passive movement of paretic hand in CP rehabilitation. Finally we present the perinatal stroke as a well suited model to analyze the postlesional neural plasticity notably the "mal-adaptive" plasticity
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Bensmail, Boughediri Soraya. "Modélisation neuromimétique du contrôle sensori-moteur des mouvements du membre supérieur : cas du pointage et de la saisie." Versailles-St Quentin en Yvelines, 2005. http://www.theses.fr/2005VERS0032.
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Les avancés dans le domaine du contrôle moteur attirent les scientifiques de disciplines autres que la neurophysiologie. Les roboticiens adhèrent également à ces programmes pour élaborer de nouvelles lois de commandes neuromimétiques basées sur la simulation du SNC exécutant une action motrice. Un modèle de contrôle sensorimoteur est développé pour l'apprentissage des mouvements visuo-guidés. Nous avons réunis dans ce schéma de contrôle des hypothèses fondées sur des principes "computationnels" relatifs à l'organisation en colonnes du cortex cérébral et la théorie de Marr-Albus-Ito du cervelet. Ces principes décrivent plusieurs mécanismes de plasticités synaptiques situées dans différents sites du SNC : cortex cérébral et cervelet. Cette approche connexioniste est appliquée pour simuler l'apprentissage de mouvements visuo-guidés par le "bras et avant-bras" et la prise "pouce-index". Le modèle est constitué de deux niveaux hiérarchiques : le niveau supra-spinal qui génère les commandes motrices pour activer les muscles, le niveau spinal provoquant les déplacements de la structure musculo-squelettique. Pour transformer les ordres moteurs en déplacement, les forces musculaires sont générées suivant la théorie du Point d'Équilibre. La simulation du formalisme montre que les processus adaptatifs prenant place dans différents sites du modèle global coopèrent sans s'interférer. Pour le mouvement de pince "pouce-index", nous proposons que le modèle de contrôle soit étendu en considérant deux structures. Cela correspond à deux régions au niveau du réseau cortical contrôlant deux points de travail et un seul réseau cérébelleux coordonnant le mouvement global<br>The advanced ones in motor control research attract the scientists of disciplines other than the neurophysiology. Thus, the robotics researchers also adhere to these programs. Their aim is to elaborate new neuromimetic command rules inspired from the SNC executiong motor action. A model of sensorimotor control is developed for visuo-guided movements learning. This model is developed based on several prerequisites about "computational" principles of brain structures : the columnar organization of the cerebral cortex and the Marr-Albus-Ito theory of cerebellar learning. The adaptive rules incorporeted in the model simulate the synaptic plasticities localised in various sites of the CNS : cerebral cortex and cerebellum. This connexionist approach is applied to simulate learning of the "arm" visuo-guided movements and the "thumb-index" pinch. The neural network model consists of two hierarchical levels : the high level which generates motor orders to muscles activation and the spinal level producing musculo-skeletal structure displacements. Thus, muscular forces are generated according to the Equilibrium-Point-Hypothesis. The simulation of the non linear formalism shows that adaptive processes taking place in different sites of the total neural network model cooperate without interferer. For the movement of "thumb-index" grip , we propose that the neural network model is deployed by considering two fingers structure. So the cortical level is presented by two pathways controlling two working points and only one cerebellar network may be able to coordinate the global pinch movement
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Le, Bon-Jego Morgane. "Modifications à long terme du fonctionnement d'un réseau sensori-moteur : neuromodulation sérotoninergique et plasticité post-lésionnelle du réseau contrôlant l'articulation coxo-basale chez l'écrevisse." Bordeaux 1, 2003. http://www.theses.fr/2003BOR12740.
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Nous avons étudiés, sur une préparation in vitro du réseau neuronal contrôlant l'articulation coxobasale de la patte chez l'écrevisse, deux mécanismes modifiant le fonctionnement du réflexe de résistance. Ce réflexe est un élément clé du maintien postural chez l'animal. En utilisant une combinaison d'approches anatomique, électrophysiologique, pharmacologique et de simulation numérique, nous avons, dans un premier temps, précisé l'organisation des voies sensori-motrices impliquées dans ce réflexe. Puis, nous avons étudié les modifications fonctionnelles de ce réseau dans deux contextes : 1)Nous avons montré que la 5HT induit une augmentation du gain du réflexe de résistance. La réponse réflexe des motoneurones augmente jusqu'à 300 %, par une multiplicité d'effets coopératifs sur différentes cibles. Les motoneurones, légèrement dépolarisés présentent une augmentation notable de leur résistance d'entrée. Cependant, l'effet majeur de la 5HT se porte sur les interneurones du circuit réflexe dont l'excitabilité et la transmission synaptique vers les motoneurones sont accrues. 2)Dans un contexte très différent, nous avons analysé la plasticité post-lésionnelle des voies sensori-motrices après section du nerf sensoriel. Nous avons montré que les neurones privés de leur corps cellulaire ne dégénèrent pas mais, en l'absence d'activité, le fonctionnement de leurs synapses est modifié. Si, fonctionnellement, les connexions monosynaptiques disparaissent 20 jours après la perte du propriocepteur, les voies polysynaptiques persistent encore jusqu'à six mois. Lorsque toutes les connexions sont devenues inefficaces, il est possible de les restaurer par un protocole de stimulation électrique du nerf sensoriel. En conclusion, ces données suggèrent que l'étage interneuronale joue un rôle capital dans le réglage du fonctionnement de ce réseau, tant en ce qui concerne la neuromodulation sérotoninergique que la maintien de la fonctionnalité des voies sensorimotrices.
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Zhao, Cong Jian [Verfasser]. "Expression and Regulation of the Neuronal Calcium Sensor Protein VILIP-1 and Effect on the α4β2 nAChR in Rat Hippocampal Neurons and Cell lines: Implications for Synaptic Plasticity / CongJian Zhao". Berlin : Freie Universität Berlin, 2008. http://d-nb.info/1022646818/34.
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Santos, Gabriela Lopes dos. "Senso de posição articular está bilateralmente reduzido para abdução e flexão do ombro em indivíduos hemiparéticos crônicos." Universidade Federal de São Carlos, 2014. https://repositorio.ufscar.br/handle/ufscar/5323.
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Previous issue date: 2014-02-19<br>Financiadora de Estudos e Projetos<br>Background: The stroke is the leading cause of adult disability in the world. One of the main complaints of individuals post-stroke refers to the loss of function of the upper limb, as evidenced during the performance of activities of daily living. This difficulty may be related to an important component of sensorimotor control, joint position sense, a submodality of proprioception. The relationship of sense of joint and the difficulties of upper limb movements are not clear in the literature. Objectives: To investigate whether the joint position sense of both shoulders of chronic hemiparetic is altered during the abduction and flexion, and whether there is any correlation between joint position sense and sensorimotor performance in these subjects. Methods: The study included 13 subjects with chronic hemiparesis due to ischemic stroke and 13 healthy subjects matched for gender and age. The proprioception was assessed using an isokinetic dynamometer and by joint sense position. The variable calculated was absolute error for shoulder abduction and flexion at the 30° and 60°. The motor performance was assessed by the upper extremity of the Fugl-Meyer Motor Assessment Scale. For the comparison between paretic, nonparetic and control limbs was utilized Kruskal Wallis test following post-hoc of Mann-Whitney with Bonferroni adjustment. For the correlation were used the Spearman. Results: No difference was found between the paretic and non-paretic limbs in both movements at 30o and 60o (p>0.05). But higher values of absolute error for both paretic and nonparetic limbs compared to control were observed during abduction at 30o (p <0.01) and at 60o (p=0.03 and p=0.04, respectively). During flexion, higher values of absolute error was observed in paretic limbs compared to control at 30o (p=0.01) and also at 60o (p=0.02). Non paretic limbs presented higher values of absolute error only at 30o, when compared to control (p=0.01). Total absolute error was inversely correlated to sensibility and proprioception Fugl-Meyer Motor Assessment Subscales (EFM). Absolute error also was directly correlated right hemisphere injury. Furthermore, absolute error was to shoulder´s subluxation during abduction. Conclusion: The joint position sense is affected in both shoulders of chronic post-stroke ischemic hemiparetic subjects during flexion and abduction. These proprioceptive deficits of the paretic limb are correlated to subscale score of proprioception and sensibility EFM, shoulder´s subluxation and damaged hemisphere.<br>O Acidente Vascular Cerebral (AVC) é a principal causa de incapacidade em adultos no mundo. Uma das principais queixas de indivíduos pós- AVC refere-se à perda da função do membro superior, evidenciado durante a realização de atividades da vida diária. Essa pode estar relacionada a um componente importante do controle sensório-motor, o senso de posição articular, uma submodalidade da propriocepção. A relação do senso de articular e as dificuldades de movimentos do membro superior ainda não estão claras na literatura. Objetivos: Investigar se o senso de posição articular de ambos os ombros de hemiparéticos crônicos está alterada durante a abdução e flexão, e se há correlação entre o senso de posição articular, o desempenho sensório-motor e o lado de lesão. Métodos: O estudo incluiu 13 indivíduos com hemiparesia crônica decorrente de AVC isquêmico e 13 indivíduos saudáveis pareados por sexo e idade. A propriocepção foi avaliada através do senso de posição articular em um dinamômetro. A variável calculada foi erro absoluto para abdução e flexão do ombro a 30° e 60°. O desempenho motor foi avaliado Escala de Avaliação de Fugl-Meyer (EFM) para membros superiores. Para a comparação entre o membro parético, não parético e controle foi utilizado o teste de Kruskal Wallis seguinte post-hoc de Mann-Whitney com ajuste de Bonferroni. Para a correlação foi utilizado a Correlação de Spearman. Resultados: Não foi encontrada diferença entre os membros parético e não parético em ambos os movimentos, a 30o e 60o (p>0,05). Mas, foram observados altos valores de erro absoluto para ambos os membros, parético e não parético, comparado ao controle durante a abdução a 30o (p<0,01) e a 60o (p=0,03 e p=0,04, respectivamente). Durante a flexão, foram constatados altos valores absolutos no membro parético comparado ao controle a 30° (p=0,01) e também a 60° (p=0,02). O membro não parético apresentou altos valores de erro absoluto somente a 30°, comparado ao controle (p=0,01). O erro absoluto do membro parético foi inversamente correlacionado com a pontuação da subescala de sensibilidade e propriocepção da EFM. O erro absoluto foi diretamente correlacionado com a lesão do hemisfério direito. Além disso, o erro absoluto do membro parético durante a abdução foi correlacionado com a subluxação do ombro. Conclusão: O senso de posição articular está alterado em ambos os ombros de indivíduos hemiparéticos crônicos pós-AVC isquêmico durante a flexão e abdução. Esses déficits proprioceptivos do membro parético estão correlacionados com a pontuação da subescala de propriocepção e sensibilidade da EFM, lesão do hemisfério e subluxação do ombro.
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Dinomais, Mickael. "Etude du cortex sensori-moteur en Imagerie par Résonance Magnétique Fonctionnelle : du sujet sain à l'enfant avec paralysie cérébrale." Phd thesis, Université d'Angers, 2013. http://tel.archives-ouvertes.fr/tel-01021084.
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La paralysie cérébrale (PC) est définie comme un trouble du mouvement secondaire à une lésion cérébrale précoce non progressive. C'est la première cause de handicap moteur de l'enfant. La médecine physique et de réadaptation a donc un intérêt particulier à l'étude du contrôle centrale de la motricité (motricité-cérébrale) aussi bien en termes d'organisation que de réorganisation après lésion, et ce, afin de proposer de nouvelles méthodes de rééducation motrice. Après avoir montré, chez le sujet sain, que la motricité-cérébrale pouvait être étudiée, en imagerie par résonance magnétique fonctionnelle (IRMf), par l'observation du mouvement et le mouvement passif, nous démontrons que l'IRMf " de repos " peut étudier la connectivité fonctionnelle du réseau sensori-moteur chez l'enfant avec PC. D'autre part, dans cette population, l'observation d'une main parétique active le réseau sensori-moteur comme attendu chez le sujet sain, avec une prédominance d'activation dans le cortex moteur primaire lésé. Aussi, lorsque l'on combine cette tâche d'observation du mouvement à un mouvement passif congruent de la main parétique, on observe une activation plus importante des aires sensori-motrices, notamment des aires de " haut niveau ". Cette tâche de mouvement vidéo-guidé nous semble pouvoir constituer une tâche de rééducation motrice dont l'efficience sera à tester ultérieurement. Enfin, nous exposons l'accident vasculaire néonatal comme modèle d'étude de la plasticité postlésionnelle, notamment pour différencier la plasticité " mal-adaptative " de la plasticité efficiente.
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Sarout, Bruna Nunes Marsiglio. "Behavioural circadian rhythms : a novel approach to monitor sheep in extensive systems and study the differences between beef steers for methane emission, feed efficiency and growth." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/164375.
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As tecnologias baseadas em sensores estão cada vez mais disponíveis e podem ser usadas para coletar informações detalhadas sobre o comportamento animal. Com esta informação é possível avaliar o ritmo circadiano de variáveis comportamentais e monitorar sua resposta. A identificação de variações na resposta deste ritmo tem o potencial de detectar problemas de saúde e questões de bem-estar animal. O objetivo deste trabalho foi estudar os ritmos circadianos comportamentais como uma nova abordagem para monitorar ovelhas em sistemas extensivos e estudar a emissão de metano, eficiência alimentar e crescimento de novilhos de corte. Este trabalho foi composto por dois experimentos (ovinos e bovinos). Foram utilizados cochos automatizados e sensores de atividade baseados em acelerômetro para coletar informações detalhadas do comportamento ingestivo (bovinos) e do comportamento de atividade (ovinos e bovinos), juntamente com as características de desempenho animal. Estes dados foram utilizados para calcular a percentagem de comportamento cíclico harmônico/sincronizado a cada período de 24 h. Essa porcentagem é chamada de grau de acoplamento funcional (DFC) e é calculada com uso de um período móvel de sete dias. No experimento com ovinos, um total de 29 ovelhas Scottish Blackface foram monitoradas por quatro semanas em cada estação do ano, em sistema extensivo nas terras altas da Escócia. Dados meteorológicos foram coletados diariamente. Modelos estatísticos de regressão com efeito aleatório foram utilizados para avaliar a variação da resposta entre indivíduos. Houve uma forte dinâmica criada pelas estações do ano e pelo ciclo produtivo/fisiológico das ovelhas. Durante a primavera e o verão, o desvio padrão do DFC foi um melhor estimador do ganho de peso quando comparado ao índice de moção. A combinação da análise do DFC e o agrupamento de indivíduos com base em sua resposta às variáveis ambientais oferece potencial para obter informações relevantes para o manejo do rebanho. O experimento de bovinos foi conduzido com duas dietas contrastantes (volumoso: concentrado 8:92 e 50:50) e duas raças (40 mestiços Charolês e 40 Luing). Os padrões diurnos de ingestão e atividade foram altamente sincronizados. O ritmo circadiano da atividade foi importante para explicar as diferentes emissões de metano entre indivíduos, independente da raça ou dieta, e também teve ligação com a eficiência alimentar e o crescimento dos novilhos. Este trabalho mostra a importância dos ritmos circadianos comportamentais e como essas abordagens podem melhorar a qualidade e o significado dos dados provenientes de sensores automatizados.<br>Sensor-based technologies are becoming increasingly available and can be used to gather detailed information about animal behaviour. With this information it is possible to assess animal behavioural circadian rhythm and monitor its response. Identifying breakdowns of this rhythm has the potential to detect health problems and animal welfare issues. The aim of this work was to study the behavioural circadian rhythms as a novel approach to monitor sheep in extensive systems and to study the differences between beef steers production traits, in methane emission, feed efficiency and growth. This work consisted of two experiments, one dealing with sheep in an extensive system and the other with housed beef steers. Automated feed intake equipment and accelerometer-based activity sensors were used to collect detailed information on feed intake (for cattle) and activity behaviour (for sheep and cattle), alongside animal performance characteristics. These data were used to calculate the percentage of cyclic behaviour that is harmonic/synchronized to each 24 h period as Degree of Functional Coupling (DFC) shown within rolling seven day periods. In the sheep experiment, in total twenty-nine Scottish Blackface ewes were monitored for four consecutive weeks in each season across a full year, in an extensive system on Scottish upland pastures. Weather data were collected daily. Random regression statistical models were used to assess between-individual variation in response to the weather. There was a strong dynamic created by the seasons and by the production and physiological cycle in sheep in these high latitude systems. Over the spring and summer period, the variation in the response of DFC was a better estimator of BWG (Body Weight Gain) than the use of a simple motion index. The combination of circadian rhythm analysis and the clustering of individuals into groups based around their regression response to environmental variables provides considerable potential to glean information relevant for group and individual animal management. The cattle experiment was conducted with two contrasting diets (concentrate-based and mixed diet) and two breeds (40 crossbred Charolais and 40 purebred Luing). The diurnal patterns of feeding and activity behaviours were strong and highly synchronised. Activity rhythmicity was well suited to show up differences between individual methane emissions independent of breed or diet, and it was also well related to important production traits as feed efficiency and growth of beef steers. This work shows the importance of the behavioural circadian rhythms and that these approaches may enhance the quality and meaningfulness of data coming from automated sensors.