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1
LODI, MATTEO. "Analisi e sintesi di Central Pattern Generator." Doctoral thesis, Università degli studi di Genova, 2019. http://hdl.handle.net/11567/944845.
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Negli esseri viventi, un Central Pattern Generator (CPG) è una rete di neuroni
relativamente piccola, in grado di produrre pattern ritmici anche in assenza di
feedback sensoriali o di segnali provenienti dal sistema nervoso centrale. Queste
reti hanno un ruolo fondamentale nella regolazione di molte attività ritmiche,
come per esempio la nuotata, la respirazione, la masticazione e la locomozione.
Lo studio di queste reti è di interesse per diverse discipline, non solo per la loro
valenza biologica, ma anche per le loro possibili applicazioni alla riabilitazione e
al controllo di robot biologicamente ispirati. In questa tesi sono proposti alcuni
strumenti per l'analisi, la riduzione, la sintesi e l'emulazione circuitale di tali reti
neuronali. In particolare, i tool proposti sono stati applicati ad un caso di studio
in cui ci si è concentrati sul CPG responsabile della locomozione dei topi.
2
Straub, Volko A. "In vitro study of a central pattern generator." Thesis, University of Sussex, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285209.
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Atoofi, Payam, Fred H. Hamker, and John Nassour. "Learning of Central Pattern Generator Coordination in Robot Drawing." Frontiers Media S.A, 2018. https://monarch.qucosa.de/id/qucosa%3A31530.
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How do robots learn to perform motor tasks in a specific condition and apply what they have learned in a new condition? This paper proposes a framework for motor coordination acquisition of a robot drawing straight lines within a part of the workspace. Then, it addresses transferring the acquired coordination into another area of the workspace while performing the same task. Motor patterns are generated by a Central Pattern Generator (CPG) model. The motor coordination for a given task is acquired by using a multi-objective optimization method that adjusts the CPGs' parameters involved in the coordination. To transfer the acquired motor coordination to the whole workspace we employed (1) a Self-Organizing Map that represents the end-effector coordination in the Cartesian space, and (2) an estimation method based on Inverse Distance Weighting that estimates the motor program parameters for each SOM neuron. After learning, the robot generalizes the acquired motor program along the SOM network. It is able therefore to draw lines from any point in the 2D workspace and with different orientations. Aside from the obvious distinctiveness of the proposed framework from those based on inverse kinematics typically leading to a point-to-point drawing, our approach also permits of transferring the motor program throughout the workspace.
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Brooks, Matthew Bryan. "Multistability in bursting patterns in a model of a multifunctional central pattern generator." Atlanta, Ga. : Georgia State University, 2009. http://digitalarchive.gsu.edu/math_theses/73/.
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Thesis (M.S.)--Georgia State University, 2009.Title from title page (Digital Archive@GSU, viewed July 20, 2010) Andrey Shilnikov, Robert Clewley, Gennady Cymbalyuk, committee co-chairs; Igor Belykh, Vladimir Bondarenko, Mukesh Dhamala, Michael Stewart, committee members. Includes bibliographical references (p. 65-67).
5
Plavac, Nick. "Analysis of the central pattern generator for peristalsis in a caterpillar." Diss., Online access via UMI:, 2007.
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Thesis (M.S.)--State University of New York at Binghamton, Department of Systems Science and Industrial Engineering, Thomas J. Watson School of Engineering and Applied Science, 2007.Includes bibliographical references.
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Hellgren, Kotaleski Jeanette. "Modeling of bursting mechanisms and coordination in a spinal central pattern generator /." Stockholm : Tekniska högsk, 1998. http://www.lib.kth.se/abs98/hell0616.pdf.
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Vavoulis, Dimitris V. "Computational modelling of the feeding central pattern generator in the pond snail, lymnaea stagnalis." Thesis, University of Sussex, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444346.
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Ockert, Waldemar. "The modulation of locomotor central pattern generators by octopamine and Tyramine indrosophila larvae." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/the-modulation-of-locomotorcentral-pattern-generators-byoctopamine-and-tyramine-indrosophila-larvae(b2d5df6c-23ca-4bdd-9f52-14cf8423c979).html.
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Movement is controlled by neuronal central pattern generator (CPG) networks that are segmentally organised in organisms across the animal kingdom. The precise role of neuromodulators in the function, development and, particularly, the maintenance of these circuits is currently unresolved. This study investigates the effects of chronically altered signalling of tyramine and/or octopamine, two well established neuromodulators, in Drosophila larval locomotion. It shows that tyramine reduces crawling speed in larvae, whereas octopamine increases speed up to a physiological maximum. Changes in crawling speed are mediated by modulating stride duration, whilst stride length remains constant. These two neuromodulators also affect segmental muscle contraction and relaxation rates, indicative that the effects on crawling speed are likely to be at least partially due to modulatory effects on muscle physiology. Muscle recordings from muscle M6 in two adjacent segments, during fictive forward locomotion show that stride duration is influenced by a variable time delay between segmental CPG outputs. Frequency and duration of individual segmental outputs, by contrast, remains constant. The behavioural and electrophysiological data suggest, therefore, that the segmental locomotor CPG outputs remain constant in response to chronically altered neuromodulatory signalling. This study also identified a close spatial proximity of motor neuronal dendritic branches and putatively octopaminergic and/or tyraminergic synaptic terminal varicosities in the ventral nerve cord (VNC) neuropil. Moreover, manipulation of a putatively octopaminergic and/or tyraminergic subpopulation of interneurons, located in anterior brain regions, is sufficient to induce a similar, albeit smaller, larval crawling deficit. This indicates that the effects of locomotion may be induced in the central nervous system. This is confirmed in identified motor neurons as chronic changes in octopaminergic and/or tyraminergic signalling increase the frequency of bursting of action potential firing. In addition, the synaptic current amplitudes are substantially reduced in both ventral and dorsal muscle- innervating motor neurons, indicative of an effect to presynaptic excitation. In contrast, the function of neuromuscular junction remains largely unchanged. Taken together, this data shows that neuromodulation is sufficient to alter the output of a relatively small group of neurons, that comprise the locomotor CPG. The site of action of these modulators is, however, likely to be diverse.
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Zhao, Le. "Adaptive neurocomputation with spiking semiconductor neurons." Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.675688.
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In this thesis, we study the neurocomputation by implementing two different neuron models. One is a semi magnetic micro p-n wire that emulates nerve fibres and supports the electrical propagation and regeneration. The other is a silicon neuron based on Hodgkin-Huxley conductance model that can generate spatiotemporal spiking patterns. The former model focuses on the spatial propagation of electrical pulses along a transmission line and presents the thesis that action potentials may be represented by solitary waves. The later model focuses on the dynamical properties such as how the output patterns of the active networks adapt to external stimulus. To demonstrate the dynamical properties of spiking networks, we present a central pattern generator (CPG) network with winnerless competition architecture. The CPG consists of three silicon neurons which are connected via reciprocally inhibitory synapses. The network of three neurons was stimulated with current steps possessing different time delays and that the voltage oscillations of the three neurons were recorded as a function of the strengths of inhibitory synaptic interconnections and internal parameters of neurons, such as voltage thresholds, time delays, etc. The architecture of the network is robust and sensitively depends on the stimulus. Stimulus dependent rhythms can be generated by the CPG network. The stimulus-dependent sequential switching between collective modes of oscillations in the network can explain the fundamental contradiction between sensitivity and robustness to external stimulus and the mechanism of pattern memorization. We successfully apply the CPG in modulating the heart rate of animal models (rats). The CPG was stimulated with respiratory signals and generated tri-phasic patterns corresponding to the respiratory cycles. The tri-phasic stimulus from the CPG was used to synchronize the heart rate with respiration. In this way, we artificially induce the respiratory sinus arrhythmia (RSA), which refers to the heart rate fluctuation in synchrony with respiration. RSA is lost in heart failure. Our CPG paves to way to novel medical devices that can provide a therapy for heart failure.
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Venugopal, Sharmila. "Role of inhibition and hyperpolarization-activated membrane properties in a lick/gape central pattern generator." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1218566830.
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Vierk, Ricardo [Verfasser]. "Postembryonic maturation and putative modulation of the central pattern generator for flight in Manduca sexta / Ricardo Vierk." Berlin : Freie Universität Berlin, 2010. http://d-nb.info/1024103439/34.
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Taccola, Giuliano. "Modulation of the activity of the locomotor central pattern generator in the rat spinal cord in vitro." Doctoral thesis, SISSA, 2005. http://hdl.handle.net/20.500.11767/4307.
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The present study has investigated the rhythmic properties of spinal networks in the neonatal rat spinal cord in vitro, by means of intracellular recordings from single motoneurons (MNs) and extracellular recordings from ventral and dorsal roots (VRs;DRs). Distinct subclasses of metabotropic glutamate receptors (mGluRs) on rat spinal neurons mediated complex facilitatory and inhibitory effects. The class I agonist DHPG evoked MN depolarization (via the mGluR1 subtype) mostly at network level and generated sustained, network-dependent oscillations (via the mGluR5 subtype). DHPG also decreased the amplitude of reflex responses induced by DR stimuli, an effect unrelated to depolarization but dependent on glycinergic transmission. Single reflex responses were insensitive to group I mGluRs antagonists, suggesting no phasic activation of group I receptors during this process. Finally, DHPG depressed the glycinergic recurrent IPSP, perhaps by impairing the cholinergic input to Renshaw cells. Thus, the cellular distribution of those mGluRs at strategic circuit connections may determine the functional outcome of the network in terms of excitation or inhibition. Activation of class II or III mGluRs had no direct action on MNs although it strongly blocked evoked synaptic transmission, presumably acting at presynaptic level. To extend our understanding of the network-based properties, which enable a neuronal circuit to produce sustained electrical oscillations, we explored the potential contribution of mGluRs to generate rhythmic discharges. During cumulative depolarization or fictive locomotion, spinal mGluRs were minimally activated by endogenous glutamate, although they could potently modulate these responses once activated by exogenously applied mGluR agonists. Disinhibited bursting was associated with the activation of mGluR1 receptors (facilitating network excitability) and of group II mGluRs (depressing it). We investigated if the K+ channel blocker 4-aminopyridine (4-AP) could facilitate spinal locomotor networks in addition to its well-known effect on motor nerve conduction. 4-AP produced synchronous VR oscillations, which did not develop into fictive locomotion. These oscillations had network origin, required intact glutamatergic transmission and were probably amplified via electrotonic coupling. 4-AP slightly increased input resistance of lumbar MNs, without affecting their action or resting potentials. DR evoked synaptic responses were enhanced by 4-AP without changes in axon conduction. 4-AP accelerated chemically or electrically induced fictive locomotion and facilitated the onset of fictive locomotion in the presence of subthreshold stimuli, that were previously insufficient to activate locomotor patterns. Thus, although 4-AP per se could not directly activate the locomotor network of the spinal cord, it could strongly facilitate the locomotor program initiated by neurochemicals or electrical stimuli. On DRs, 4-AP induced sustained synchronous oscillations smaller than electrically evoked synaptic potentials, persistent after sectioning off the ventral region and preserved in an isolated dorsal quadrant, indicating their dorsal horn origin. 4-AP oscillations were network mediated via glutamatergic, glycinergic and GABAergic transmission. Isolated ventral horn areas could not generate 4-AP oscillations, although their intrinsic, disinhibited bursting was accelerated by the substance. Activation of fictive locomotion by either application of neurochmicals or stimulus trains to a single DR reversibly suppressed DR oscillations induced by 4-AP. The present electrophysiological investigation also examined whether the broad spectrum potassium channel blocker tetraethylammonium (TEA) could generate locomotor-like patterns. Low concentrations of TEA induced irregular, synchronous discharges incompatible with locomotion. Higher concentrations evoked alternating discharges between flexor and extensor motor pools, plus a large depolarization of MNs with spike broadening. The alternating discharges were superimposed on slow, shallow waves of synchronous depolarization. Rhythmic alternating patterns were suppressed by blockers of glutamate, GABAA and glycine receptors, disclosing a background of depolarizing bursts inhibited by antagonism of group I mGluRs. Furthermore, TEA also evoked irregular discharges on DRs. The rhythmic alternating patterns elicited by TEA on VRs were relatively stereotypic, had limited synergy with the fictive locomotion induced by DR stimuli, and were not accelerated by 4-AP.
Horizontal section of the spinal cord preserved irregular VR discharges and DR discharges, demonstrating that the action of TEA on spinal networks was fundamentally different from that of 4-AP.
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Garcia, Paul Anthony. "Modeling the Intersegmental Coordination of Heart Motor Neurons in the Medicinal Leech." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5064.
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We constructed a model of the coordination of segmental heart motor neurons driving blood circulation in leeches. The heart motor neuron models were conductance-based; conductances of voltage-gated and synaptic currents were adjusted to match the firing pattern of heart motor neurons from the living system. Each motor neuron receives a specific pattern of inhibitory input from rhythmic premotor heart interneurons and translates this spatiotemporal pattern into the fictive heartbeat motor pattern. The temporal pattern of synaptic input to the model was derived from extracellularly recorded spikes of the premotor heart interneurons. We focused on determining the components necessary to produce side-to-side asymmetry in the motor pattern: motor neurons on one side fire nearly in synchrony (synchronous coordination), while on the other they fire in a rear-to-front progression (peristaltic coordination). The model reproduces the general trends in phasing and was used to investigate the effective contribution of several synaptic and cellular properties of the motor neurons. The spatial and temporal pattern of premotor synaptic input, the electrical coupling between the segmental motor neurons, intra-burst, short-term synaptic plasticity of the synaptic inputs, and the axonal conduction delays all were integrated with the intrinsic membrane properties to influence intersegmental phasing.
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Anderson, JoAnna Todd. "Characterization of a sacral dorsal column pathway activating autonomic and hindlimb motor pattern generation." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42849.
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Spinal cord injuries (SCI) sever communication between supraspinal centers and the central pattern generator (CPG) responsible for locomotion. Because the CPG is intact and retains the ability to initiate locomotor activity, it can be accessed electrically and pharmacologically. The goal of this thesis was to identify and characterize a novel spinal cord surface site along the sacral dorsal column (sDC) for electrically evoking locomotor-like activity in the neonatal rat spinal cord. Stimulation of the sDC robustly activated rhythmic left-right alternation in flexor-related ventral roots that was dependent on the activation of high-threshold C fiber afferents. The C fibers synapsed onto spinal neurons, which project to the lumbar segments as part of a pathway dependent on purinergic, adrenergic, and cholinergic receptor activation. In ventral roots containing only somatic efferents, rhythmic activity was rarely recruited. However, in ventral roots containing both autonomic and somatic efferents, sacral dorsal column stimulation recruited autonomic efferent rhythms, which subsequently recruited somatic efferent motor rhythms. The efferent rhythms revealed a half-center organization with very low stimulation frequencies, and the evoked alternating bursts entrained to the stimuli. Similar entrainment was seen when sDC stimuli were applied during ongoing neurochemically-induced locomotor rhythms. The rhythmic patterns evoked by sDC stimulation operated over a limited frequency range, with a discrete burst structure of fast-onset, frequency-independent peaks. In comparison, neurochemically-induced locomotor bursts operated over a wide frequency range and had slower time to peaks that varied with burst frequency. The overall findings support the discovery of an autonomic efferent pattern generator that is recruited by sacral visceral C fiber afferents. It is hoped that this research will advance the understanding of afferent activation of the lumbar central pattern generator and potentially provide insight useful for future development and design of neuroprosthetic devices.
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Snell, Lewis Casbeer. "Sensorimotor Integration And The Role Of The Cercal System In The Reproductive Behavior Of The Cricket, Acheta Domesticus." Oxford, Ohio : Miami University, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1122917477.
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Wojcik, Jeremy J. "Neural Cartography: Computer Assisted Poincare Return Mappings for Biological Oscillations." Digital Archive @ GSU, 2012. http://digitalarchive.gsu.edu/math_diss/10.
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This dissertation creates practical methods for Poincaré return mappings of individual and networked neuron models. Elliptic bursting models are found in numerous biological systems, including the external Globus Pallidus (GPe) section of the brain; the focus for studies of epileptic seizures and Parkinson's disease. However, the bifurcation structure for changes in dynamics remains incomplete. This dissertation develops computer-assisted Poincaré ́maps for mathematical and biologically relevant elliptic bursting neuron models and central pattern generators (CPGs). The first method, used for individual neurons, offers the advantage of an entire family of computationally smooth and complete mappings, which can explain all of the systems dynamical transitions. A complete bifurcation analysis was performed detailing the mechanisms for the transitions from tonic spiking to quiescence in elliptic bursters. A previously unknown, unstable torus bifurcation was found to give rise to small amplitude oscillations. The focus of the dissertation shifts from individual neuron models to small networks of neuron models, particularly 3-cell CPGs. A CPG is a small network which is able to produce specific phasic relationships between the cells. The output rhythms represent a number of biologically observable actions, i.e. walking or running gates. A 2-dimensional map is derived from the CPGs phase-lags. The cells are endogenously bursting neuron models mutually coupled with reciprocal inhibitory connections using the fast threshold synaptic paradigm. The mappings generate clear explanations for rhythmic outcomes, as well as basins of attraction for specific rhythms and possible mechanisms for switching between rhythms.
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Klein, Theresa Jean. "A Neurorobotic Model of Humanoid Walking." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/203434.
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In this dissertation, we describe the development of a humanoid bipedal robot that fully physically models the human walking system, including the biomechanics of the leg, the sensory feedback pathways available in the body, and the neural structure of the central pattern generator (CPG). Using two different models of the CPG, we explore several issues in the neurobiology and robotics literature, including the role of reflexes in locomotion, the role of load reception and positive force feedback in generating the gait, and the degree to which central or peripheral control plays in human walking. We show that the walking pattern can be generated by a combination of a half-center CPG and reflex interactions phase modulated by the CPG, and that load receptors in the muscles can play a substantial role in generating the gait, using positive force feedback. We compare the gait of the robot to human subjects and show that this architecture produces human-like stepping. Varying the degree of direct central control of lower limb muscles by the CPG, we show that the most human-like gait is generated with a relatively weak central control signal, which modulates reflex responses that generate most of the muscle activation. These results allow us to conceive of locomotion as a series of nested loops, with a central CPG or rhythm generator modulating lower level reflex interactions, while higher centers modulate the CPG. Since locomotion is a primary mechanism by which animals interact with the world, this research is relevant to artificial intelligence researchers. Recent understanding of cognition holds that minds are embodied, situated relative to a set of goals, and exist in a feedback loop of interaction with the environment. In our robot, we model the dynamics of the body, the neural architecture and the sensory feedback channels in a complete dynamical feedback loop, and show that the robot entrains to the the natural dynamics of the world. We propose the concept of nested loops with descending phase modulation as a conceptual paradigm for a more general understanding of nervous system organization.
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Perry, Sharn. "Deciphering the Locomotor Network : The Role of Spinal Cord Interneurons." Doctoral thesis, Uppsala universitet, Institutionen för neurovetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-305601.
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In the spinal cord, an intricate neural network generates and coordinates the patterning of limb movements during locomotion. This network, known as the locomotor central pattern generator (CPG), comprises of various cell populations that together orchestrate the output of motor neurons. Identification of CPG neurons through their specific gene expression is a valuable tool that can provide considerable insight to the character, intrinsic properties and role of a population, which represents a step toward understanding locomotor circuit function and correlating neural activity to behaviour. We selectively targeted two inhibitory CPG populations to investigate their molecular characteristics, circuitry and functional role; Renshaw cells (RCs) marked by their specific expression of the cholinergic nicotinic receptor α2 (Chrna2) and a subset of the dI6 population derived by their selective expression of the Doublesex and mab-3 related transcription factor 3 (Dmrt3). We found that RCs have hyperpolarisation-activated cation (Ih) and small calcium-activated potassium (ISK) modulatory currents that differentially regulate their excitation and firing properties, which influence the instantaneous feedback to motor neurons through the recurrent inhibition circuit. Due to previous difficulties isolating RCs from the surrounding locomotor circuits, their functional role remains poorly defined. For the first time, we selectively silenced RC inhibition and found that all aspects of motor behaviour, including coordination and gait were normal. The deletion of RC signalling instead altered the electrical and synaptic properties of the recurrent inhibitory circuit, suggesting that developmental plasticity compensates for the loss of RC inhibition. We reveal Dmrt3 neurons comprise a population of glycinergic inhibitory, spike-frequency adapting commissural interneurons active during locomotion. Conditional silencing of the Dmrt3 population resulted in considerable gait abnormalities in the neonatal and adult mouse. This manifested as an uncoordinated CPG output in vitro, impaired limb coordination in pups and increased fore- and hindlimb synchrony in adults that was exacerbated at faster locomotor speeds. Dmrt3 mediated inhibition subsequently impacts locomotion and suggests the Dmrt3 population contribute to coordinating speed dependent left-right limb alternation. This thesis provides cellular, circuit and behavioural insights into the Renshaw cell and Dmrt3 populations and enhances our knowledge regarding their probable function within the locomotor CPG.
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Rubeo, Scott Edward. "Control of Simulated Cockroach Using Synthetic Nervous Systems." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1495555770825904.
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Shaw, Kendrick Matthew. "Dynamical Architectures for Controlling Feeding in Aplysia californica." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1382998904.
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Gaspar, Roberta Caveiro. "Respostas motoras durante a marcha com suspensão parcial de peso na esteira em indivíduos com lesão medular completa e incompleta." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/39/39136/tde-18062018-151435/.
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Introdução: A Locomoção tem como uma das características básicas a ritmicidade. Entre os mecanismos que envolvem seu controle destaca-se o conceito de um gerador de padrão central (GPC) capaz de gerar atividades neurais e musculares rítmicas. A técnica de treino locomotor com suspensão de peso na esteira (TLSP) utiliza esse conceito e emerge como uma estratégia terapêutica efetiva após a lesão medular (LM) em humanos em função do alto nível de automatismo do sistema nervoso, podendo ser esperadas diferentes respostas em lesões completas e incompletas. Portanto, uma análise detalhada das respostas biomecânicas obtidas durante o TLSP pode servir como base para compreensão do controle neural da locomoção humana. Objetivos: Caracterizar, a partir de parâmetros biomecânicos, a marcha com suspensão parcial de peso e assistência manual em indivíduos com lesões medulares completas e incompletas. Método: 40 indivíduos (20 com LM e 20 sem lesão) foram divididos em quatro grupos: Lesão Medular ASIA A (GLA), Lesão Medular ASIA B (GLB), Lesão Medular ASIA C e D (GLC) e Grupo Controle (GC) composto por sujeitos sem lesão. Durante o TLSP, ambos os grupos foram submetidos ao mesmo protocolo, com suspensão do peso corporal, duração total do treino e velocidades pré-definidas. Foram coletados dados de eletromiografia de superfície e a análise cinemática foi realizada por meio de 7 centrais inerciais. As análises foram realizadas por meio de análise de variância múltipla (MANOVA) Resultados: Em relação às variáveis cinemáticas o GC apresentou menor tempo de apoio em relação ao GLA não havendo diferenças entre os outros grupos com lesão medular. Quanto à ativação muscular o GLA e GLB apresentaram maior atividade de músculos proximais com co-contrações, GLC atividade proximal similar à GLA, GLB e distal similar ao GC que apresentou níveis mais baixos de atividade muscular com maior atividade distal em relação a proximal. Para o momento do pico de atividade, o GC apresentou momento antecipado para músculos proximais, atrasado para músculos distais em relação aos grupos com LM. Conclusão: Quando comparados ao GC, os grupos com LM apresentaram maiores amplitudes de sinal eletromiográfico, provavelmente pelo fato de o GC realizar a tarefa de forma mais eficiente com menor demanda de ativação muscular. Não foi possível reconhecer padrões rítmicos de ativação nos grupos com LMIntroduction: The locomotion has a characteristic the rhythmicity. Concerning the understanding of the mechanisms involving its control, the concept of a central pattern generator (GPC) capable of generating neural and muscular rhythmic activities stands out. The body weight support treadmill training (BWSTT) technique uses this concept and emerges as an effective therapeutic strategy after spinal cord injury (LM) in humans due to the high level of automatism of the nervous system, and different responses can be expected in complete and incomplete injuries. Therefore, a detailed analysis of the biomechanical responses obtained during BWSTT may serve as a basis for understanding the neural control of human locomotion. Objectives: To characterize, from biomechanical parameters, treadmill gait with body weight support in individuals with complete and incomplete spinal cord injury. Method: 40 individuals (20 with LM and 20 without lesion) were divided into four groups: ASIA A (GLA), ASIA B (GLB), ASIA C and D (GLC) and Control Group (GC) composed of subjects without injury. During BWSTT, both groups were submitted to the same protocol, with pre-defined body weight suspension, total training duration and speeds. Surface electromyography data were collected and kinematic analysis was performed by means of 7 inertial power plants. The analyzes were performed through multiple variance analysis (MANOVA). Results: In the kinematic variables, the CG presented less support time in relation to the GLA and there were no differences between the other groups with spinal cord injury. As for muscle activation, GLA and GLB presented higher activity of proximal muscles with co-contractions, GLC presented similar proximal activity similar to GLA, GLB and distal similar to GC, which presented lower levels of muscular activity with greater distal activity in relation to proximal muscles. For the moment of peak activity, the GC presented early moment for proximal muscles, delayed to distal muscles in relation to the groups with LM. Conclusion: When compared to CG, the groups with LM presented higher amplitudes of electromyographic signal, probably because the CG performed the task more efficiently with less demand for muscle activation. It was not possible to recognize rhythmic patterns of activation in the LM groups
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Clark, Merry Christine. "MonoAminergic Receptors in the Stomatogastric Nervous System: Characterization and Localization in Panulirus Interruptus." Digital Archive @ GSU, 2008. http://digitalarchive.gsu.edu/biology_diss/36.
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Neural circuit flexibility is fundamental to the production of adaptable behaviors. Invertebrate models offer relatively simple networks consisting of large, identifiable neurons that are useful for investigating the electrophysiological properties that contribute to circuit output. In particular, central pattern generating circuits within the crustacean stomatogastric nervous system have been well characterized with regard to their synaptic connectivities, cellular properties, and response to modulatory influences. Monoaminergic modulation is essential for the production of adaptable circuit output in most species. Monoamines, such as dopamine and serotonin, signal via metabotropic receptors, which activate intracellular signaling cascades. Many of the neuronal and network targets of monoaminergic modulation in the crustacean stomatogastric nervous system are known, but nothing is known of the signal transduction cascades that mediate the biophysical response. This work represents a thorough characterization of monoaminergic receptors in the crustacean stomatogastric nervous system. We took advantage of the close phylogenetic relationship between crustaceans and insects to clone monoaminergic receptors from the spiny lobster. Using a novel database mining strategy, we were able to identify several uncharacterized monoaminergic receptors in the Panulirus interruptus genome. We cloned one serotonin (5-HT2βPan) and three dopamine receptors (D1αPan, D1βPan, and D2αPan), and characterized them with regard to G protein coupling and signal transduction cascades. We used a heterologous expression system to show that G protein couplings and signaling properties of monoaminergic receptors are strongly conserved among vertebrate and invertebrate species. This work further shows that DAR-G protein couplings in the stomatogastric nervous system are unique for a given receptor subtype, and receptors can couple to multiple signaling pathways, similar to their mammalian homologs. Custom made antibodies were used to localize monoamine receptors in the stomatogastric ganglion, and in identified neurons. Pyloric neurons show unique receptor expression profiles, which supports the idea of receptor expression as an underlying mechanism for cell-type specific effects of a given modulator. Receptors are localized to the synaptic neuropil, but are not expressed in the membrane of large diameter processes or the soma. The localization of dopamine receptors in identified pyloric neurons suggests that they may respond to synaptic, paracrine or neurohormonal dopamine signals. This work also supports the idea that different types of signals can be generated by a single receptor.
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Merrison-Hort, Robert. "Computational study of the mechanisms underlying oscillation in neuronal locomotor circuits." Thesis, University of Plymouth, 2014. http://hdl.handle.net/10026.1/3107.
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In this thesis we model two very different movement-related neuronal circuits, both of which produce oscillatory patterns of activity. In one case we study oscillatory activity in the basal ganglia under both normal and Parkinsonian conditions. First, we used a detailed Hodgkin-Huxley type spiking model to investigate the activity patterns that arise when oscillatory cortical input is transmitted to the globus pallidus via the subthalamic nucleus. Our model reproduced a result from rodent studies which shows that two anti-phase oscillatory groups of pallidal neurons appear under Parkinsonian conditions. Secondly, we used a population model of the basal ganglia to study whether oscillations could be locally generated. The basal ganglia are thought to be organised into multiple parallel channels. In our model, isolated channels could not generate oscillations, but if the lateral inhibition between channels is sufficiently strong then the network can act as a rhythm-generating ``pacemaker'' circuit. This was particularly true when we used a set of connection strength parameters that represent the basal ganglia under Parkinsonian conditions. Since many things are not known about the anatomy and electrophysiology of the basal ganglia, we also studied oscillatory activity in another, much simpler, movement-related neuronal system: the spinal cord of the Xenopus tadpole. We built a computational model of the spinal cord containing approximately 1,500 biologically realistic Hodgkin-Huxley neurons, with synaptic connectivity derived from a computational model of axon growth. The model produced physiological swimming behaviour and was used to investigate which aspects of axon growth and neuron dynamics are behaviourally important. We found that the oscillatory attractor associated with swimming was remarkably stable, which suggests that, surprisingly, many features of axonal growth and synapse formation are not necessary for swimming to emerge. We also studied how the same spinal cord network can generate a different oscillatory pattern in which neurons on both sides of the body fire synchronously. Our results here suggest that under normal conditions the synchronous state is unstable or weakly stable, but that even small increases in spike transmission delays act to stabilise it. Finally, we found that although the basal ganglia and the tadpole spinal cord are very different systems, the underlying mechanism by which they can produce oscillations may be remarkably similar. Insights from the tadpole model allow us to predict how the basal ganglia model may be capable of producing multiple patterns of oscillatory activity.
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Hayes, Heather Brant. "Biomechanics and electrophysiology of sensory regulation during locomotion in a novel in vitro spinal cord-hindlimb preparation." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/42797.
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The purpose of this dissertation was to gain insight into spinal sensory regulation during locomotion. To this end, I developed a novel in vitro spinal cord-hindlimb preparation (SCHP) composed of the isolated in vitro neonatal rat spinal cord oriented dorsal-up with intact hindlimbs locomoting on a custom-built treadmill or instrumented force platforms. The SCHP combines the neural and pharmacological accessibility of classic in vitro spinal cord preparations with intact sensory feedback from physiological hindlimb movements. thereby expanding our ability to study spinal sensory function. I then validated the efficacy of the SCHP for studying behaviorally-relevant, sensory-modulated locomotion by showing the impact of sensory feedback on in vitro locomotion. When locomotion was activated by serotonin and N-methyl D-aspartate, the SCHP produced kinematics and muscle activation patterns similar to the intact rat. The mechanosensory environment could significantly alter SCHP kinematics and muscle activitation patterns, showing that sensory feedback regulates in vitro spinal function. I further demonstrated that sensory feedback could reinforce or initiate SCHP locomotion.
Using the SCHP custom-designed force platform system, I then investigated how presynaptic inhibition dynamically regulates sensory feedback during locomotion and how hindlimb mechanics influence this regulation. I hypothesized that contralateral limb mechanics would modulate presynaptic inhibition on the ipsilateral limb. My results indicate that contralateral limb stance-phase loading regulates ipsilateral swing-phase sensory inflow. As contralateral stance-phase force increases, contralateral afferents act via a GABAergic pathway to increase ipsilateral presynaptic inhibition, thereby inhibiting sensory feedback entering the spinal cord. Such force-sensitive contralateral presynaptic inhibition may help preserve swing, coordinate the limbs during locomotion, and adjust the sensorimotor strategy for task-specific demands.
This work has important implications for sensorimotor rehabilitation. After spinal cord injury, sensory feedback is one of the few remaining inputs available for accessing spinal locomotor circuitry. Therefore, understanding how sensory feedback regulates and reinforces spinally-generated locomotion is vital for designing effective rehabilitation strategies. Further, sensory regulation is degraded by many neural insults, including spinal cord injury, Parkinson's disease, and stroke, resulting in spasticity and impaired locomotor function. This work suggests that contralateral limb loading may be an important variable for restoring appropriate sensory regulation during locomotion.
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Shachykov, Andrii. "Neural modeling of human motor coordination inspired by biological signals aiming for parkinsonian gaits." Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0291.
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Cette thèse présente une plate-forme de simulation neuro-musculo-squelettique du système locomoteur humain pour reproduire des allures de marche saines ou altérées par la maladie de Parkinson, ou par d’autres troubles locomoteurs. Le premier chapitre s’intéresse aux grands principes du système locomoteur en se focalisant sur les structures neuronales du cerveau qui sont le siège des troubles parkinsoniens. La transmission à la moelle épinière des signaux de contrôle de l'activité musculaire au travers de plusieurs boucles fermées est décrite. Différents modèles neuronaux des troubles parkinsoniens issus de la littérature sont présentés. Le second chapitre présente le contrôleur neuronal implémenté dans la plate-forme. Il utilise un modèle original de «central pattern generators» (CPG) inspiré du réseau locomoteur spinal. Ce CPG peut générer des signaux rythmiques variables selon ses paramètres neuronaux contrôlés par des signaux descendants du cerveau. Les signaux des motoneurones du CPG sont appliqués en tant qu'excitation au modèle de muscles flexeur/extenseur. Le chapitre trois présente les simulateurs musculo-squelettiques GAIT2DE et OpenSim utilisés ainsi que les modifications apportées pour simuler, en boucle fermée, le système locomoteur marchant sur le sol et les retours proprioceptifs et extéroceptifs exploités par les CPGs. Le chapitre quatre concerne l'analyse du cycle de la marche et l'optimisation des paramètres du contrôleur. Le cycle de marche permet de comparer des données de simulation avec des paramètres de marche réelle, et d’optimiser le contrôleur à partir d'une analyse comparative utilisant la corrélation croisée. Le chapitre cinq présente les résultats obtenus avec les deux simulateurs en intégrant une circuiterie complète à base des CPGs et d’un réflexe du contrôle d’équilibre. Les résultats montrent qu’on peut générer différentes démarches plus ou moins coordonnées selon les paramètres neuronaux reproduisant ainsi les allures observées pour la maladie de Parkinson ou d’autres troubles connus en médecine. Le dernier chapitre conclu et propose certaines améliorations de la plate-forme dans son ensemble pour simuler des démarches dues à d’autres maladies neurodégénératives ou à l’impact de prothèses ou suite à des interventions chirurgicalesMy thesis aims to simulate the impact of motor disorders on the human gait to help non-invasive diagnosis of neurodegenerative diseases such as Parkinson's disease. Indeed, the simulation of the human locomotor system helps to deepen our understanding of the functioning of the human body by providing biological, biomechanical and kinematic data that would be difficult to collect otherwise and by helping to evaluate the coordination of a patient's movements to predict its condition after surgery. The goal of my thesis is, more specifically, to create a new platform for neuro-musculoskeletal simulation of the human locomotor system to reproduce healthy or altered walking gaits by Parkinson's disease or by disorders of the musculoskeletal system or locomotor disorders. The work presented includes several matters. Firstly, the main principles of the nervous system that control human locomotion are reviewed, by focusing on neural structures located in the brain and which are the sources of parkinsonian disorders. The neural controller of the simulation platform is based on an original model of central pattern generator (CPG) inspired by the spinal locomotor network and developed at LORIA in recent years. The musculoskeletal simulators are used in this thesis to obtain a closed-loop physical simulation of the locomotor system walking on the ground and whose proprioceptive and exteroceptive sensory feedback is used by the CPGs. The musculoskeletal simulator GAIT2DE was used with the OpenSim simulator which is more realistic and more used in Biomechanics field. The simulated gait analysis and controller parameter optimization are concerned followed by the results obtained with the simulators. These results show that it is possible to generate different walking patterns that are relatively stable and coordinated by modifying the neuronal parameters of GPCs. The simulation platform will allow to simulate abnormal gait due to different causes such as neurodegenerative diseases or the impact of the addition of artificial limbs (prostheses) and surgical interventions
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Harischandra, Nalin. "Computer Simulation of the Neural Control of Locomotion in the Cat and the Salamander." Doctoral thesis, KTH, Beräkningsbiologi, CB, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-47362.
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Locomotion is an integral part of a whole range of animal behaviours. The basic rhythm for locomotion in vertebrates has been shown to arise from local networks residing in the spinal cord and these networks are known as central pattern generators (CPG). However, during the locomotion, these centres are constantly interacting with the sensory feedback signals coming from muscles, joints and peripheral skin receptors in order to adapt the stepping or swimming to varying environmental conditions. Conceptual models of vertebrate locomotion have been constructed using mathematical models of locomotor subsystems based on the neurophysiological evidence obtained primarily in the cat and the salamander, an amphibian with a sprawling posture. Such models provide opportunity for studying the key elements in the transition from aquatic to terrestrial locomotion. Several aspects of locomotor control using the cat or the salamander as an animal model have been investigated employing computer simulations and here we use the same approach to address a number of questions or/and hypotheses related to rhythmic locomotion in quadrupeds. Some of the involved questions are, the role of mechanical linkage during deafferented walking, finding inherent stabilities/instabilities of muscle-joint interactions during normal walking and estimating phase dependent controlability of muscle action over joints. Also we investigate limb and body coordination for different gaits, use of side-stepping in front limbs for turning and the role of sensory feedback in gait generation and transitions in salamanders. This thesis presents the basics of the biologically realistic models of cat and salamander locomotion and summarizes computational methods in modeling quadruped locomotor subsystems such as CPG, limb muscles and sensory pathways. In the case of cat hind limb, we conclude that the mechanical linkages between the legs play a major role in producing the alternating gait. In another experiment we use the model to identify open-loop linear transfer functions between muscle activations and joint angles while ongoing locomotion. We hypothesize that the musculo-skeletal system for locomotion in animals, at least in cats, operates under critically damped condition. The 3D model of the salamander is successfully used to mimic locomotion on level ground and in water. We compare the walking gait with the trotting gait in simulations. We also found that for turning, the use of side-stepping alone or in combination with trunk bending is more effective than the use of trunk bending alone. The same model together with a more realistic CPG composed of spiking neurons was used to investigate the role of sensory feedback in gait generation and transition. We found that the proprioceptive sensory inputs are essential in obtaining the walking gait, whereas the trotting gait is more under central (CPG) influence compared to that of the peripheral or sensory feedback. This thesis work sheds light on understanding the neural control mechanisms behind vertebrate locomotion. Additionally, both neuro-mechanical models can be used for further investigations in finding new control algorithms which give robust, adaptive, efficient and realistic stepping in each leg, which would be advantageous since it can be implemented on a controller of a quadruped-robotic device.This work is Funded by Swedish International Development cooperation Agency (SIDA). QC 20111110
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Fujiki, Soichirou. "Studies on underlying mechanism of interlimb coordination of legged robots using nonlinear oscillators." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/199270.
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Larhammar, Martin. "Neuronal Networks of Movement : Slc10a4 as a Modulator & Dmrt3 as a Gait-keeper." Doctoral thesis, Uppsala universitet, Genetisk utvecklingsbiologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-230425.
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Nerve cells are organized into complex networks that comprise the building blocks of our nervous system. Neurons communicate by transmitting messenger molecules released from synaptic vesicles. Alterations in neuronal circuitry and synaptic signaling contribute to a wide range of neurological conditions, often with consequences for movement. Intrinsic neuronal networks in the spinal cord serve to coordinate vital rhythmic motor functions. In spite of extensive efforts to address the organization of these neural circuits, much remains to be revealed regarding the identity and function of specific interneuron cell types and how neuromodulation tune network activity. In this thesis, two novel genes initially identified as markers for spinal neuronal populations were investigated: Slc10a4 and Dmrt3. The orphan transporter SLC10A4 was found to be expressed on synaptic vesicles of the cholinergic system, including motor neurons, as well as in the monoaminergic system, including dopaminergic, serotonergic and noradrenergic nuclei. Thus, it constitutes a novel molecular denominator shared by these classic neuromodulatory systems. SLC10A4 was found to influence vesicular transport of dopamine and affect neuronal release and reuptake efficiency in the striatum. Mice lacking Slc10a4 displayed impaired monoamine homeostasis and were hypersensitive to the drugs amphetamine and tranylcypromine. These findings demonstrate that SLC10A4 is capable of modulating the modulatory systems of the brain with potential clinical relevance for neurological and mental disorders. The transcription factor encoded by Dmrt3 was found to be expressed in a population of inhibitory commissural interneurons originating from the dorsal interneuron 6 (dI6) domain in the spinal cord. In parallel, a genome-wide association study revealed that a non-sense mutation in horse DMRT3 is permissive for the ability to perform pace among other alternate gaits. Further analysis of Dmrt3 null mutant mice showed that Dmrt3 has a central role for spinal neuronal network development with consequences for locomotor behavior. The dI6 class has been suggested to take part in motor circuits but remains one of the least studied classes due to lack of molecular markers. To further investigate the Dmrt3-derived neurons, and the dI6 population in general, a Dmrt3Cre mouse line was generated which allowed for characterization on the molecular, cellular and behavioral level. It was found that Dmrt3 neurons synapse onto motor neurons, receive extensive synaptic inputs from various neuronal sources and are rhythmically active during fictive locomotion. Furthermore, silencing of Dmrt3 neurons in Dmrt3Cre;Viaatlx/lx mice led to impaired motor coordination and alterations in gait, together demonstrating the importance of this neuronal population in the control of movement.
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藤木, 聡一朗. "非線形振動子を用いた脚ロボットの肢間協調メカニズムに関する研究." Kyoto University, 2015. http://hdl.handle.net/2433/199503.
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Paiva, Rafael Cortes de. "Utilização de CPGs e técnicas de inteligência computacional na geração de marcha em robôs humanóides." reponame:Repositório Institucional da UnB, 2014. http://repositorio.unb.br/handle/10482/17048.
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Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, 2014.Submitted by Ana Cristina Barbosa da Silva (annabds@hotmail.com) on 2014-11-25T17:23:31Z No. of bitstreams: 1 2014_RafaelCortesdePaiva.pdf: 7660330 bytes, checksum: eaad53db8e1c76edec638a3e30ee5f3e (MD5)
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Nesse trabalho foi realizado o estudo de técnicas bio-inspiradas para gerar a marcha de um robô bípede. Foi utilizado o conceito de CPG, Central Pattern Generator (CPG), que é uma rede neural capaz de produzir respostas rítmicas. Elas foram modeladas como osciladores acoplados chamados de osciladores neurais. Para tanto foram utilizados alguns modelos de osciladores, o modelo de Matsuoka, o modelo de Kuramoto e o modelo de Kuramoto com acoplamento entre a dinâmica do oscilador e a dinâmica da marcha. Foram usados dois modelos de robôs, o Bioloid e o NAO. Para otimizar os parâmetros dos osciladores foram utilizados o Algoritmo Genético (AG), o Particle Swarm Optimization (PSO) e o Nondominated sorting Genetic Algorithm II (NSGA-II). Foi utilizada uma função de custo que através de determinadas condições tem como objetivo obter uma marcha eficiente. No NSGA-II, além dessa função de custo, foi utilizada outra função de custo que considera o trabalho realizado pelo robô. Além disso, também foi utilizada a aprendizagem por reforço para treinar um controlador que corrige a postura do robô durante a marcha. Foi possível propor um framework para obter os parâmetros dos osciladores e através dele obter uma marcha estável em ambas as plataformas. Também foi possível propor um framework utilizando aprendizagem por reforço para treinar um controlador para corrigir a postura do robô com a marcha sendo gerado pelo oscilador de Kuramoto com acoplamento. O objetivo do algoritmo foi minimizar a velocidade do ângulo de arfagem do corpo do robô, dessa forma, a variação do ângulo de arfagem também foi minimizada consequentemente. Além disso, o robô andou mais “cautelosamente” para poder manter a postura e dessa forma percorreu uma distância menor do que se estivesse sem o controlador. ______________________________________________________________________________ ABSTRACT
This document describes computational optimized bipedal robot gait generators. Thegaits are applied by a neural oscillator, composed of coupled central pattern generators(CPG), which are neural networks capable of producing rhythmic output. The models ofthe oscillators used were the Matsuoka model, Kuramoto model and Kura moto model withcoupling between the dynamics of the oscillator and dynamics of the gait. Two bipedalrobots, a NAO and a Bioloid, were used. The neural oscillators were optimized with threealgorithms, a Genetic Algorithm (GA), Particle Swarm Optimization (PSO) and Nondominatedsorting Genetic Algorithm II (NSGA-II). It was used a fitness function that has theobjective to obtain an efficient gait through some conditions. In NSGA-II, besides this fitnessfunction, another one was used that has the objective to minimize the work done by therobot. Additionally, reinforcement learning techniques were used to train a controller thatcorrects the robots gait posture. It was proposed a framework to obtain the parameters of theoscillators used and obtain efficient gaits in both robots. Also, it was proposed a frameworkusing reinforcement learning to train a controller to correct the robots gait posture. The objective of the algorithm was to minimize the pitch angular velocity, consequently the pitchangle standard deviation was minimized. Additionally, the robot moved with more “caution” and walked less compared with the walk without the posture controller.
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Chen, Zhixiong. "Brainstem Mechanisms Underlying Ingestion and Rejection." The Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1041523002.
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Lakshmanan, Subashini. "ROLE OF MULTIUNIT ACTIVITY IN RYTHMOGENESIS: INSIGHTS FROM DELETIONS." Master's thesis, Temple University Libraries, 2015. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/357746.
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BioengineeringM.S.
The rhythmic activity of locomotion is most frequently modeled as a periodic oscillation coordinated by a spinal Central Pattern Generator (CPG) controlling reciprocal activation of flexor and extensor muscles. Expression of locomotion errors in the form of spontaneous deletions in the motor output has been critical in formulating models of CPG network structure governing locomotion in mammals (Lafreniere-Roula et al 2005, Duysens 2006). Deletions are defined as the disappearance of either antagonist or agonist muscles’ activity along with the simultaneous tonic/rhythmic activity of the corresponding agonist or antagonist muscles. The formulation of a two-layer model of the CPG (Rhythm Generator (RG) layer & Pattern Formation (PF) layer) by Rybak et al (2006) stems from observations of such deletions in the fictive locomotion of the decerebrated cat. The RG functions as a clock controlling the temporal activity of the PF layer which controls the firing pattern of motor neuron pools that activate muscles. The deletion episodes are said to be “resetting” if the EMG activity after the deletion does not return after an integer value of the pre-deletion average period. If the motoneuron activity returns in phase with the pre-deletion “clock”, the deletion period is considered to be “non-resetting”. Multiunit Activity (MUA) recorded from a spinalised air-stepping cat was analyzed against its corresponding EMG activity to investigate the role of MUA in rhythmogenicity, specifically whether or not MUA activity may represent the RG layer of the Central Pattern Generator (CPG) model. This hypothesis would predict that MUA activity should be disrupted in phase or amplitude when and only when deletions episodes are re-setting.. Alternatively, MUA activity may reflect PF layer activity. In this case MUA activity should be disrupted in phase or amplitude during each of the deletions episodes. MUA’s spatio-temporal characteristics were compared to that of the EMG activity during the deletion periods for analysis. From the analysis performed, there was a significant proportion (average more than 25%) of the MUA (collected from the lumbar region of the spinal cord of spinalized cat) that were disrupted in phase or amplitude during non-resetting deletions or undisrupted during resetting episodes, indicating that MUA activity is unlikely to represent the RG layer activity during . In addition, MUA oscillation during the period of deletions was unchanged (amplitude or phase) for more than 25% of the deletion episodes, ruling out the possibility that MUA represents the activity of the PF layer. So although MUA has been found to be highly synchronized throughout the lumbar extent during locomotor activity, it does not appear to act as a “clocking” mechanism for the locomotor rhythm.
Temple University--Theses
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Nascimento, Filipe. "Cholinergic modulation of spinal motoneurons and locomotor control networks in mice." Thesis, University of St Andrews, 2018. http://hdl.handle.net/10023/16141.
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Locomotion is an innate behaviour that is controlled by different areas of the central nervous system, which allow for effectiveness of movement. The spinal cord is an important centre involved in the generation and maintenance of rhythmic patterns of locomotor activity such as walking and running. Interneurons throughout the ventral horn of the spinal cord form the locomotor central pattern generator (CPG) circuit, which produces rhythmic activity responsible for hindlimb movement. Motoneurons within the lumbar region of the spinal cord innervate the leg muscles to convey rhythmic CPG output to drive appropriate muscle contractions. Intrinsic modulators, such as acetylcholine acting via M2 and M3 muscarinic receptors, regulate CPG circuitry to allow for flexibility of motor output. Using electrophysiology and genetic techniques, this work characterized the receptors involved in cholinergic modulation of locomotor networks and the role and mechanism of action of a subpopulation of genetically identified cholinergic interneurons in the lumbar region of the neonatal mouse spinal cord. Firstly, the effects of M2 and M3 muscarinic receptors on the output of the lumbar locomotor network were characterised. Experiments in which fictive locomotor output was recorded from the ventral roots of isolated spinal cord preparations revealed that M3 muscarinic receptors are important in stabilizing the locomotor rhythm while M2 muscarinic receptor activation seems to increase the irregularity of the locomotor frequency whilst increasing the strength of the motor output. This work then explored the cellular mechanisms through which M2 and M3 muscarinic receptors modulate motoneuron output. M2 and M3 receptor activation exhibited contrasting effects on motoneuron function suggesting that there is a fine balance between the activation of these two receptor subtypes. M2 receptor activation induces an outward current and decreases synaptic drive to motoneurons while M3 receptors are responsible for an inward current and increase in synaptic inputs to motoneurons. Despite the different effects of M2 and M3 receptor activation on synaptic drive and subthreshold properties of MNs, both M2 and M3 receptors are required for muscarine-induced increase in motoneuron output. CPG networks therefore appear to be subject to balanced cholinergic modulation mediated by M2 and M3 receptors, with the M2 subtype also being important for regulating the intensity of motor output. Next, using Designer Receptor Exclusively Activated by Designer Drug (DREADD) technology, the impact of the activation or inhibition of a genetically identified group of cholinergic spinal interneurons that express the Paired-like homeodomain 2 (Pitx2) transcription factor was explored. Stimulation of these interneurons increased motoneuron output through the activation of M2 muscarinic receptors and subsequent modulation of Kv2.1 channels. Inhibition of Pitx2+ interneurons during fictive locomotion decreased the amplitude of locomotor bursting. Genetic ablation of these cells confirmed that Pitx2+ interneurons increase the strength of locomotor output by activating M2 muscarinic receptors. Overall, this work provides new insights into the receptors and mechanisms involved in intraspinal cholinergic modulation. Furthermore, this study provides direct evidence of the mechanism through which Pitx2+ interneurons regulate motor output. This work is not only important for advancing understanding of locomotor networks that control hindlimb locomotion, but also for dysfunction and diseases where the cholinergic system is impaired such as Spinal Cord Injury and Amyotrophic Lateral Sclerosis.
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Harischandra, Nalin. "Computer Simulation of the Neural Control of Locomotion in the Cat." Licentiate thesis, Stockholm : Numerisk analys och datalogi, Numerical Analysis and Computer Science, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4692.
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Hudson, Amber Elise. "Neuronal mechanisms for the maintenance of consistent behavior in the stomatogastric ganglion of Cancer borealis." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47654.
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Each neuron needs to maintain a careful balance between the changes implicit in experience, and the demands of stability required by its function. This balance tips depending on the neuronal system, but in any role, disease or neural disorders can develop when the regulatory mechanisms involved in neuronal stability fail. The objective of this thesis was to characterize mechanisms underlying neuronal stability and activity maintenance, in the hopes that further understanding of these processes might someday lead to novel interventions for neurological disorders.
The pyloric circuit of decapod crustaceans controls the rhythmic contractions of the foregut musculature, and has long been recognized as an excellent model system in which to study neuronal network stability. Recent experimental evidence has shown that each neuronal cell type of this circuit exhibits a unique set of positive linear correlations between ionic membrane conductances, which suggests that coordinated expression of ion channels plays a role in constraining neuronal electrical activity. In Aim 1, we hypothesized a causal relationship between expressed conductance correlations and features of cellular identity, namely electrical activity type. We partitioned an existing database of conductance-based model neurons based on various measures of intrinsic activity to approximate distinctions between biological cell types. We then tested individual conductance pairs for linear dependence to identify correlations. Similar to experimental results, each activity type investigated had a unique combination of correlated conductances. Furthermore, we found that populations of models that conform to a specific conductance correlation have a higher likelihood of exhibiting a particular feature of electrical activity. We conclude that regulating conductance ratios can support proper electrical activity of a wide range of cell types, particularly when the identity of the cell is well-defined by one or two features of its activity.
The phenomenon of pyloric network recovery after removal of top-down neuromodulatory input--a process termed decentralization--is seen as a classic model of homeostatic change after injury. After decentralization, the pyloric central pattern generator briefly loses its characteristic rhythmic activity, but the same activity profile is recovered 3-5 days later via poorly understood homeostatic changes. This re-emergence of the pyloric rhythm occurs without the full pre-decentralization set of fixed conductance ratios. If conductance ratios stabilize pyloric activity before decentralization as we showed in Aim 1, then other mechanisms must account for the return of the pyloric rhythm after network recovery. Based on vertebrate studies demonstrating a role for the extracellular matrix (ECM) in activity regulation, we hypothesized in Aim 2 that the ECM was participating in activity maintenance in the stomatogastric nervous system. We used the enzyme chondroitinase ABC (chABC) to degrade extracellular chondroitin sulfate (CS) in the stomatogastric ganglion while in organ culture. Our results are the first to demonstrate the presence of CS in the crustacean nervous system via immunochemistry. Furthermore, we show that while ongoing activity is not disrupted by chABC treatment, recovery of pyloric activity after decentralization was significantly delayed without intact extracellular CS. Our results are the first to show that CS has a role in neuronal activity maintenance in crustaceans, and suggest that CS may be involved in initiating or directing activity maintenance needed in times of neuronal stress.
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Guzulaitis, Robertas. "The organisation principles of spinal neural network: temporal integration of somatosensory input and distribution of network activity." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2013. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2013~D_20130925_093153-76748.
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Spinal cord integrates somatosensory information and generates coordinated motor responses. Temporal integration can be used for discrimination of important stimuli from noise. Here it is shown that temporal integration of somatosensory inputs in sub second time scale is possible without changes of intrinsic properties of motoneurons. The activity of premotor neurons increases during temporal integration and can be a mechanism for short term information storage in spinal cord. Suppression of motor activity after painful somatosensory stimulus is called cutaneous silent period. This motor suppression is well described in humans and used for diagnostics. However it is not known if the suppression of motor activity is due to inhibition of motoneurons or reduction of excitatory drive from premotor neurons. Here it is shown that motoneurons are inhibited during cutaneous silent period. Neural networks of spinal cord not only process somatosensory information but generate locomotion and reflexes too. It is accepted that neural networks controlling front and hind limb movements are located in cervical and lumbar enlargements respectfully. Here it is shown that thoracic segments of spinal cord contribute to hind limb movements as well. It means that neural network generating movements is much more widely distributed than previously thought.Nugaros smegenys gauna somatosensorinę informaciją, ją integruoja ir generuoja motorinius atsakus. Disertacijoje parodoma, kad somatosensorinių įėjimų viršsekundinė laikinė integracija nugaros smegenų neuronų tinkle vyksta ne dėl motorinių neuronų vidinių savybių kitimo. Laikinės integracijos metu padidėja priešmotorinių neuronų aktyvumas ir tai gali lemti informacijos apie somatosensorinį įėjimą saugojimą. Somatosensorinis tylos periodas – tai motorinio aktyvumo slopinimas po skausmingo stimulo. Jis plačiai aprašytas žmonėse, bei taikomas diagnostikoje. Nepaisant plataus taikymo, somatosensorinio tylos periodo mechanizmai nėra ištirti – nebuvo žinoma ar šis motorinio aktyvumo slopinimas vyksta slopinant motorinius neuronus, ar eliminuojant motorinių neuronų žadinimą. Disertacijoje parodoma, kad somatosensorinio tylos periodo metu motoriniai neuronai yra slopinami. Be somatosensorinės informacijos apdorojimo nugaros smegenų neuronų tinklai užtikrina judėjimo ir refleksų valdymą. Yra priimta, kad priekines ir užpakalines galūnes valdantys neuronų tinklai išsidėstę atitinkamai nugaros smegenų kaklinės ir strėnų sričių išplatėjimuose. Disertacijoje parodoma, kad ir krūtininiai nugaros smegenų segmentai prisideda prie užpakalinių galūnių motorinio aktyvumo generavimo. Tai leidžia manyti, kad neuronų tinklas generuojantis judesius yra išplitęs labiau, nei manyta iki šiol.
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Guzulaitis, Robertas. "Nugaros smegenų neuronų tinklo veikimo principai: somatosensorinės informacijos integracija ir aktyvumo išplitimas." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2013. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2013~D_20130925_093406-59707.
Full textAbstract:
Nugaros smegenys gauna somatosensorinę informaciją, ją integruoja ir generuoja motorinius atsakus. Disertacijoje parodoma, kad somatosensorinių įėjimų viršsekundinė laikinė integracija nugaros smegenų neuronų tinkle vyksta ne dėl motorinių neuronų vidinių savybių kitimo. Laikinės integracijos metu padidėja priešmotorinių neuronų aktyvumas ir tai gali lemti informacijos apie somatosensorinį įėjimą saugojimą. Somatosensorinis tylos periodas – tai motorinio aktyvumo slopinimas po skausmingo stimulo. Jis plačiai aprašytas žmonėse, bei taikomas diagnostikoje. Nepaisant plataus taikymo, somatosensorinio tylos periodo mechanizmai nėra ištirti – nebuvo žinoma ar šis motorinio aktyvumo slopinimas vyksta slopinant motorinius neuronus, ar eliminuojant motorinių neuronų žadinimą. Disertacijoje parodoma, kad somatosensorinio tylos periodo metu motoriniai neuronai yra slopinami. Be somatosensorinės informacijos apdorojimo nugaros smegenų neuronų tinklai užtikrina judėjimo ir refleksų valdymą. Yra priimta, kad priekines ir užpakalines galūnes valdantys neuronų tinklai išsidėstę atitinkamai nugaros smegenų kaklinės ir strėnų sričių išplatėjimuose. Disertacijoje parodoma, kad ir krūtininiai nugaros smegenų segmentai prisideda prie užpakalinių galūnių motorinio aktyvumo generavimo. Tai leidžia manyti, kad neuronų tinklas generuojantis judesius yra išplitęs labiau, nei manyta iki šiol.Spinal cord integrates somatosensory information and generates coordinated motor responses. Temporal integration can be used for discrimination of important stimuli from noise. Here it is shown that temporal integration of somatosensory inputs in sub second time scale is possible without changes of intrinsic properties of motoneurons. The activity of premotor neurons increases during temporal integration and can be a mechanism for short term information storage in spinal cord. Suppression of motor activity after painful somatosensory stimulus is called cutaneous silent period. This motor suppression is well described in humans and used for diagnostics. However it is not known if the suppression of motor activity is due to inhibition of motoneurons or reduction of excitatory drive from premotor neurons. Here it is shown that motoneurons are inhibited during cutaneous silent period. Neural networks of spinal cord not only process somatosensory information but generate locomotion and reflexes too. It is accepted that neural networks controlling front and hind limb movements are located in cervical and lumbar enlargements respectfully. Here it is shown that thoracic segments of spinal cord contribute to hind limb movements as well. It means that neural network generating movements is much more widely distributed than previously thought.
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Hurteau, Marie-France. "Effet d’une stimulation cutanée tonique de la région lombaire sur l’activité locomotrice du chat adulte ayant une lésion complète de la moelle épinière." Mémoire, Université de Sherbrooke, 2015. http://hdl.handle.net/11143/6749.
Full textAbstract:
Résumé : Suite à une lésion de la moelle épinière, divers comportements moteurs invalidants, tels des spasmes peuvent apparaître. Les traitements actuels pour la spasticité causent divers effets secondaires, dont une réduction de la capacité locomotrice des patients. La recherche de traitements non invasifs et non pharmacologiques permettant de réduire la spasticité sans affecter la récupération fonctionnelle du patient s’avère donc un enjeu prioritaire. Par ailleurs, une réduction des spasmes rythmiques peut être observée lorsque la peau lombosacrée est pincée. Ce potentiel inhibiteur d’une stimulation cutanée tonique est également perçu chez l’animal comme le lapin et le chat suite à une perte des voies supraspinales. Par contre, bien que ce type de stimulation semble efficace pour réduire la spasticité, son effet sur la capacité locomotrice n’a toujours pas été évalué. L’objectif du projet était de déterminer l’effet d’un pincement de la peau à divers niveaux lombaires sur la locomotion du chat ayant une lésion de la moelle épinière. Six chats implantés chroniquement pour l’électromyographie (EMG) ont subi une lésion complète de la moelle épinière au niveau thoracique et ont été entraînés sur tapis roulant pour récupérer une fonction locomotrice des pattes postérieures. L’effet d’une stimulation de 6 sites cutanés sur la ligne médiane au niveau des vertèbres lombaires L2 à L7 a été évalué lors de marche à 0.4 m/s via des analyses cinématiques et EMG. Les résultats obtenus démontrent que la zone cutanée perturbant le plus l’activité locomotrice se trouve sur la ligne médiane au niveau lombaire L4. À ce niveau, une diminution de l’activité des extenseurs et des fléchisseurs est perçue au niveau de l’EMG. De plus, des modifications du patron locomoteur comme un positionnement plus caudal de la patte lors de son contact et de son décollage sont également visibles, tout comme une perte du support de poids (force de réaction au sol). La coordination spatiale entre les pattes postérieures est également perturbée. Ces résultats suggèrent que bien que la stimulation cutanée puisse être une alternative intéressante pour le traitement non pharmacologique de la spasticité, celle-ci altère la capacité locomotrice. || Abstract : After a spinal cord injury, multiple abnormal motor activities can occur, such as rhythmic
spasms. These activities can be invalidating and are treated with different drugs that cause
various side effects, including a reduction of locomotor ability in patients. Therefore, there is a
need for novel non-invasive and non-pharmacological treatments for spasticity that will not
affect the functional recovery of patients. A reduction of rhythmic spasms can be observed
when the lumbosacral skin is pinched in a spinal cord-injured patient. This inhibition of
rhythmic activity by a tonic cutaneous stimulation is also present in cats and rabbits after the
loss of supraspinal input. Although this stimulation seems effective to reduce spasticity, its
effects on real locomotion have not been evaluated. The goal of this project was to determine
the effect of stimulating the skin at different lumbar levels on hindlimb locomotion of the
spinal cord-transected (spinalized) cat. Six cats chronically implanted for electromyography
(EMG) recording were spinalized at low thoracic levels and trained to recover hindlimb
locomotion on a treadmill. The effect of stimulating the skin over the midline of lumbar
vertebrae was evaluated during locomotion at 0.4 m/s and compared to control trials (without
stimulation) with kinematic, kinetic and EMG analyses. Stimulating the lumbar skin disrupted
hindlimb locomotion, with the largest effects observed at mid-lumbar levels. Cutaneous
stimulation reduced extensor and flexor EMG activity. Moreover, position of the paw at
contact and lift-off was more caudal and there was a loss of body weight support with
cutaneous stimulation. Spatial coordination between the hindlimb was also perturbed by the
cutaneous stimulation. Thus, results suggest that despite the fact that cutaneous stimulation
appears to be an interesting approach to diminish rhythmic spasms in spinal cord-injured
patients, it disrupts spinal-mediated locomotor capacity.
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Wolf, Sébastien. "The neural substrate of goal-directed locomotion in zebrafish and whole-brain functional imaging with two-photon light-sheet microscopy." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066468/document.
Full textAbstract:
La première partie de cette thèse présente une revue historique sur les méthodes d'enregistrements d'activité neuronale, suivie par une étude sur une nouvelle technique d'imagerie pour le poisson zèbre : la microscopie par nappe laser 2 photon. En combinant, les avantages de la microscopie 2 photon et l'imagerie par nappe de lumière, le microscope par nappe laser 2 photon garantie des enregistrements à haute vitesse avec un faible taux de lésions photoniques et permet d'éviter l'une des principales limitations du microscope à nappe laser 1 photon: la perturbation du système visuel. La deuxième partie de cette thèse traite de la navigation dirigée. Après une revue exhaustive sur la chemotaxis, la phototaxis et la thermotaxis, nous présentons des résultats qui révèlent les bases neuronales de la phototaxis chez le poisson zèbre. Grace à des expériences de comportement en réalité-virtuelle, des enregistrements d'activité neuronale, des méthodes optogénétiques et des approches théoriques, ce travail montre qu'une population auto-oscillante située dans le rhombencéphale appelée l'oscillateur du cerveau postérieur (HBO) fonctionne comme un pacemaker des saccades oculaires et contrôle l'orientation des mouvements de nage du poisson zèbre. Ce HBO répond à la lumière en fonction du contexte moteur, biaisant ainsi la trajectoire du poisson zèbre vers les zones les plus lumineuses de son environnement (phototaxis). La troisième partie propose une discussion sur les bases neuronales des saccades oculaires chez les vertébrés. Nous concluons ce manuscrit avec des résultats préliminaires suggérant que chez le poisson zèbre, le même HBO est impliqué dans les processus de thermotaxisThe first part of this thesis presents an historical overview of neural recording techniques, followed by a study on the development of a new imaging method for zebrafish neural recording: two-photon light sheet microscopy. Combining the advantages of two-photon point scanning microscopy and light sheet techniques, the two-photon light sheet microscope warrants a high acquisition speed with low photodamage and allows to circumvent the main limitation of one-photon light sheet microscopy: the disturbance of the visual system. The second part of the thesis is focused on goal-directed navigation in zebrafish larvae. After an exhaustive review on chemotaxis, phototaxis and thermotaxis in various animal models, we report a study that reveals the neural computation underlying phototaxis in zebrafish. Combining virtual-reality behavioral assays, volumetric calcium recordings, optogenetic stimulation, and circuit modeling, this work shows that a self-oscillating hindbrain population called the hindbrain oscillator (HBO) acts as a pacemaker for ocular saccades, controls the orientation of successive swim-bouts during zebrafish larva navigation, and is responsive to light in a state-dependent manner such that its response to visual inputs varies with the motor context. This peculiar response to visual inputs biases the fish trajectory towards brighter regions (phototaxis). The third part provides a discussion on the neural basis of ocular saccades in vertebrates. We conclude with some recent preliminary results on heat perception in zebrafish suggesting that the same hindbrain circuit may be at play in thermotaxis as well
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Tazerart, Sabrina. "Le courant sodique persistant dans le réseau locomoteur du rat nouveau-né : sa contribution dans l'émergence des activités pacemakers et du rythme locomoteur." Thesis, Aix-Marseille 2, 2011. http://www.theses.fr/2011AIX20653.
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La locomotion se définit par des mouvements répétés et coordonnés des membres droits et gauches et des muscles antagonistes d’une même articulation. L’activité locomotrice des rongeurs est générée par des groupes de neurones localisés dans la partie antérieure de l’élargissement lombaire; ce réseau de cellules est appelé Central Pattern Generator (CPG). Au cours de cette thèse, les études entreprises chez le rat nouveau-né ont eu pour but d’étudier les mécanismes cellulaires impliqués dans la genèse du rythme locomoteur. Le courant sodique persistant (INaP) joue un rôle important dans la genèse d’activités rythmiques de plusieurs structures supraspinales et notamment celles impliquées dans la mastication et la respiration. Curieusement, son existence et son implication dans la genèse d’activités rythmiques dans les structures du CPG locomoteur spinal n’ont jamais été abordées. A l’aide d’études électrophysiologiques, la thèse démontre l’existence de INaP et le caractérise pour la première fois au sein du CPG locomoteur. Ce courant est indispensable à la genèse du rythme locomoteur et joue un rôle fondamental dans l’émergence d’activités pacemakers au sein du CPG. Ces activités pacemakers émergent dans un contexte physiologique où des fluctuations dans la composition ionique du milieu extracellulaire interviennent au cours d’une activité locomotrice. L’ensemble de ces données suggère que le « cœur » du générateur de rythme pourrait être composé d’interneurones présentant une activité pacemaker dépendante de INaP dont la modulation pourrait être un élément fondamental à la fois dans le déclenchement et la modulation de l’activité locomotriceIdentification of the cellular mechanisms underlying the generation of the locomotor rhythm is of longstanding interest to physiologists. Hindlimb locomotor movements are generated by lumbar neuronal networks, referred to as central pattern generators (CPG). Although rhythm generation mechanisms within the CNS can vary, the activation of a subthreshold depolarizing conductance is always needed to start the firing of individual neurons. Among various subthreshold membrane conductances, the persistent sodium current (INaP) is involved in rhythmic activity of numerous supraspinal neurons such as those involved in the generation of masticatory and respiratory rhythm. The thesis was aimed at identifying and characterizing INaP in the neonatal rodent locomotor CPG, determining its importance in shaping neuronal firing properties and its role in the operation of the locomotor circuitry. Using electrophysiological studies the thesis has characterized INaP for the first time in the locomotor CPG. This current is essential to the generation of the locomotor rhythm and plays a fundamental role in the emergence of pacemaker activity within the CPG. These pacemaker activities emerge in a physiological context in which fluctuations in the ionic composition of the extracellular environment occur during locomotion. This study provides evidence that INaP generates pacemaker activities in CPG interneurons and new insights into the operation of the locomotor network with a critical implication of INaP in stabilizing the locomotor pattern
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Porter, Nicola J. "Muscarinic actions in Xenopus laevis tadpole swimming." Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/4286.
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Muscarinic acetylcholine receptors (mAChRs) mediate effects of acetylcholine (ACh) in many systems, including those involved in locomotion. In the stage 37/38 Xenopus laevis tadpole, a well-understood model system of vertebrate locomotion, mAChRs have been found to be located on motor neurons with evidence suggesting that mAChRs are involved in swimming behaviour. The current study aimed to further investigate the role of mAChR-mediated cholinergic transmission by employing extracellular and whole-cell patch clamp recordings to examine the effects of mAChR activation on the properties of different types of neurons in the Xenopus laevis tadpole swimming circuit. It was found that mAChR activation can increase the threshold for initiating swimming by skin stimulation and can lead to the generation of spontaneous motor output in the absence of physical stimuli. These effects were found to be a result of direct inhibition of dorsolateral sensory interneurons of the mechanosensory pathway, direct inhibition of glycinergic inhibitory interneurons in the CPG and a decrease in CPG neuron firing reliability during swimming. The data presented here comprise the first whole-cell patch-clamp investigation into mAChR-mediated cholinergic transmission in the Xenopus laevis tadpole swimming circuit and provide novel evidence that mAChRs modulate the properties of mechanosensory pathway and CPG neurons in this model system of vertebrate locomotion.
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Babski, Hélène. "Implication des neurones TJ-positifs dans le comportement locomoteur de la larve de Drosophile." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTT021/document.
Full textAbstract:
Les CPGs (Central Pattern Generators) sont des circuits neuronaux capables de générer de façon autonome des comportements rythmiques essentiels à la vie tels que la respiration ou la locomotion. Chez la larve de Drosophile, le CPG locomoteur est composé de motoneurones (MNs) et d’une grande diversité d’interneurones (INs). Combien d’entre eux sont nécessaires pour former une CPG fonctionnel et comment ils interagissent reste un mystère. Au cours de mon doctorat, j’ai étudié une population neuronale restreinte caractérisée par son expression du facteur de transcription (FT) de la famille des Maf, Traffic Jam (TJ). En utilisant une technique d’intersection génétique et grâce à une lignée TJ-Flp générée au cours de mon doctorat, j’ai démontré pour la première fois que différentes sous-populations de neurones TJ+ ont des fonctions distinctes dans le comportement locomoteur de la larve de Drosophile. Au travers de cette sous-division fonctionnelle, j’ai finalement identifié 3 neurones TJ+ per+ GABAergic par segment qui régulent la vitesse de locomotion des larves. Une caractérisation moléculaire poussée de ces cellules a permis de confirmer qu’elles appartiennent au groupe connu des « midline cells », et plus particulièrement des mnb progeny, dont la fonction était jusqu’à maintenant inconnue. Par ailleurs, le code combinatoire de FTs trouvé chez ces mnb progeny rappelle celui exprimé par les V2b, une population d’interneurones qui régulerait également la vitesse de locomotion chez les vertébrés. Ces similarités entre mnb progeny et V2b laissent à penser que cette population de neurones pourrait être conservée au cours de l’évolution. En outre, des résultats préliminaires suggèrent que les interneurones TJ+ ont également un rôle chez la mouche adulteCPGs (Central Pattern Generators) are neural networks able to autonomously generate essential rhythmic behaviours such as walking or breathing. In Drosophila larvae, the locomotor CPG is made up of motoneurons (MNs) and a huge variety of interneurons (INs). How many are actually necessary to constitute a functional CPG and how they interact is not known. During the course of this PhD, I studied a discrete neuronal population singled out by its expression of the Maf transcription factor (TF) Traffic Jam (TJ). Thanks to an intersectional genetics approach and a TJ-Flp line generated during my PhD, I showed for the first time that TJ+ neurons subpopulations have distinct functions in Drosophila larva locomotion. Functional subdivision of TJ+ population eventually led to the identification of 3 TJ+ per+ GABAergic neurons that regulate the speed of locomotion. Thorough molecular characterization of this population permitted to identify them as mnb progeny neurons, a well studied subgroup of midline cells whose function had never been described before. The TF combinatorial code expressed by these cells is highly reminiscent of the one found in V2b INs, a population in vertebrates thought to regulate the speed of locomotion as well in vertebrates; this opens the possibility of a functional conservation across evolution. Preliminary results furthermore suggest that TJ+ INs would have functional roles in the adult fly
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Park, Youngmin. "Infinitesimal Phase Response Curves for Piecewise Smooth Dynamical Systems." Case Western Reserve University School of Graduate Studies / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=case1370643724.
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Barnett, William Halbert. "Duty Cycle Maintenance in an Artificial Neuron." Digital Archive @ GSU, 2009. http://digitalarchive.gsu.edu/phy_astr_theses/7.
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Neuroprosthetics is at the intersection of neuroscience, biomedical engineering, and physics. A biocompatible neuroprosthesis contains artificial neurons exhibiting biophysically plausible dynamics. Hybrid systems analysis could be used to prototype such artificial neurons. Biohybrid systems are composed of artificial and living neurons coupled via real-time computing and dynamic clamp. Model neurons must be thoroughly tested before coupled with a living cell. We use bifurcation theory to identify hazardous regimes of activity that may compromise biocompatibility and to identify control strategies for regimes of activity desirable for functional behavior. We construct real-time artificial neurons for the analysis of hybrid systems and demonstrate a mechanism through which an artificial neuron could maintain duty cycle independent of variations in period.
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Soofi, Wafa Ahmed. "Regulation of rhythmic activity in the stomatogastric ganglion of decapod crustaceans." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53440.
Full textAbstract:
Neuronal networks produce reliable functional output throughout the lifespan of an animal despite ceaseless molecular turnover and a constantly changing environment. The cellular and molecular mechanisms underlying the ability of these networks to maintain functional stability remain poorly understood. Central pattern generating circuits produce a stable, predictable rhythm, making them ideal candidates for studying mechanisms of activity maintenance. By identifying and characterizing the regulators of activity in small neuronal circuits, we not only obtain a clearer understanding of how neural activity is generated, but also arm ourselves with knowledge that may eventually be used to improve medical care for patients whose normal nervous system activity has been disrupted through trauma or disease. We utilize the pattern-generating pyloric circuit in the crustacean stomatogastric nervous system to investigate the general scientific question: How are specific aspects of rhythmic activity regulated in a small neuronal network?
The first aim of this thesis poses this question in the context of a single neuron. We used a single-compartment model neuron database to investigate whether co-regulation of ionic conductances supports the maintenance of spike phase in rhythmically bursting “pacemaker” neurons. The second aim of the project extends the question to a network context. Through a combination of computational and electrophysiology studies, we investigated how the intrinsic membrane conductances of the pacemaker neuron influence its response to synaptic input within the framework of the Phase Resetting Curve (PRC). The third aim of the project further extends the question to a systems-level context. We examined how ambient temperatures affect the stability of the pyloric rhythm in the intact, behaving animal. The results of this work have furthered our understanding of the principles underlying the long-term stability of neuronal network function.
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Motyčková, Paulína. "Simulační modelování a řízení hadům podobných robotů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-442848.
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This paper deals with the design of a robotic snake, its assembly, simulation using CoppeliaSim, and the testing of various methods for the control of robotic snakes (Serpentinoid, CPG). For individual control methods, the influence of selected parameters on the signals controlling the motorized joints of the robotic snake is observed, and their influence on the speed and energy consumption of the given mechanism is described.
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Newcomb, James M. "Homologous Neurons and their Locomotor Functions in Nudibranch Molluscs." Digital Archive @ GSU, 2006. http://digitalarchive.gsu.edu/biology_diss/15.
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These studies compare neurotransmitter localization and the behavioral functions of homologous neurons in nudibranch molluscs to determine the types of changes that might underlie the evolution of species-specific behaviors. Serotonin (5-HT) immunohistochemistry in eleven nudibranch species indicated that certain groups of 5 HT-immunoreactive neurons, such as the Cerebral Serotonergic Posterior (CeSP) cluster, are present in all species. However, the locations and numbers of many other 5 HT-immunoreactive neurons were variable. Thus, particular parts of the serotonergic system have changed during the evolution of nudibranchs. To test whether the functions of homologous neurons are phylogenetically variable, comparisons were made in species with divergent behaviors. In Tritonia diomedea, which crawls and also swims via dorsal-ventral body flexions, the CeSP cluster includes the Dorsal Swim Interneurons (DSIs). It was previously shown that the DSIs are members of the swim central pattern generator (CPG); they are rhythmically active during swimming and, along with their neurotransmitter 5-HT, are necessary and sufficient for swimming. It was also known that the DSIs excite efferent neurons used in crawling. DSI homologues, the CeSP-A neurons, were identified in six species that do not exhibit dorsal-ventral swimming. Many physiological characteristics, including excitation of putative crawling neurons were conserved, but the CeSP A neurons were not rhythmically active in any of the six species. In the lateral flexion swimmer, Melibe leonina, the CeSP-A neurons and 5-HT, were sufficient, but not necessary, for swimming. Thus, homologous neurons, and their neurotransmitter, have functionally diverged in species with different behaviors. Homologous neurons in species with similar behaviors also exhibited functional divergence. Like Melibe, Dendronotus iris is a lateral flexion swimmer. Swim interneuron 1 (Si1) is in the Melibe swim CPG. However, its putative homologue in Dendronotus, the Cerebral Posterior ipsilateral Pedal (CPiP) neuron, was not rhythmically active during swim-like motor patterns, but could initiate such a motor pattern. Together, these studies suggest that neurons have changed their functional relationships to neural circuits during the evolution of species-specific behaviors and have functionally diverged even in species that exhibit similar behaviors.
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Boothe, David L. "Natural variation in biological and simulated central pattern generators." College Park, Md. : University of Maryland, 2007. http://hdl.handle.net/1903/7264.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2007.Thesis research directed by: Neuroscience and Cognitive Science. 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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Bay, John S. "Coupled nonlinear oscillators as central pattern generators for rhythmic locomotion." Connect to resource, 1985. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1157054630.
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Athanassiadis, Tuija. "Neural circuits engaged in mastication and orofacial nociception." Doctoral thesis, Umeå : Department of Integrative Medical Biology, Umeå university, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-26342.
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