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Neuro-motor control and feed-forward models of locomotion in humans

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889196142 Year: Pages: 190 DOI: 10.3389/978-2-88919-614-2 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Neurology
Added to DOAB on : 2016-08-16 10:34:25
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Abstract

Locomotion involves many different muscles and the need of controlling several degrees of freedom. Despite the Central Nervous System can finely control the contraction of individual muscles, emerging evidences indicate that strategies for the reduction of the complexity of movement and for compensating the sensorimotor delays may be adopted. Experimental evidences in animal and lately human model led to the concept of a central pattern generator (CPG) which suggests that circuitry within the distal part of CNS, i.e. spinal cord, can generate the basic locomotor patterns, even in the absence of sensory information. Different studies pointed out the role of CPG in the control of locomotion as well as others investigated the neuroplasticity of CPG allowing for gait recovery after spinal cord lesion. Literature was also focused on muscle synergies, i.e. the combination of (locomotor) functional modules, implemented in neuronal networks of the spinal cord, generating specific motor output by imposing a specific timing structure and appropriate weightings to muscle activations. Despite the great interest that this approach generated in the last years in the Scientific Community, large areas of investigations remain available for further improvement (e.g. the influence of afferent feedback and environmental constrains) for both experimental and simulated models. However, also supraspinal structures are involved during locomotion, and it has been shown that they are responsible for initiating and modifying the features of this basic rhythm, for stabilising the upright walking, and for coordinating movements in a dynamic changing environment. Furthermore, specific damages into spinal and supraspinal structures result in specific alterations of human locomotion, as evident in subjects with brain injuries such as stroke, brain trauma, or people with cerebral palsy, in people with death of dopaminergic neurons in the substantia nigra due to Parkinson’s disease, or in subjects with cerebellar dysfunctions, such as patients with ataxia. The role of cerebellum during locomotion has been shown to be related to coordination and adaptation of movements. Cerebellum is the structure of CNS where are conceivably located the internal models, that are neural representations miming meaningful aspects of our body, such as input/output characteristics of sensorimotor system. Internal model control has been shown to be at the basis of motor strategies for compensating delays or lacks in sensorimotor feedbacks, and some aspects of locomotion need predictive internal control, especially for improving gait dynamic stability, for avoiding obstacles or when sensory feedback is altered or lacking. Furthermore, despite internal model concepts are widespread in neuroscience and neurocognitive science, neurorehabilitation paid far too little attention to the potential role of internal model control on gait recovery. Many important scientists have contributed to this Research Topic with original studies, computational studies, and review articles focused on neural circuits and internal models involved in the control of human locomotion, aiming at understanding the role played in control of locomotion of different neural circuits located at brain, cerebellum, and spinal cord levels.

Distributed Networks: New Outlooks on Cerebellar Function

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889196265 Year: Pages: 211 DOI: 10.3389/978-2-88919-626-5 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Neurology
Added to DOAB on : 2016-08-16 10:34:25
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Accumulating evidence suggests that the cerebellum subserves functions beyond the sensorimotor realm. This possibility has received considerable attention during the past quarter century, with recent findings revealing putative cerebellar roles in cognition, emotion and spatial navigation. These functions are potentially underpinned by the behaviour-dependent formation of functional networks in which the cerebellum forms one node of distributed circuits spanning thalamic, limbic and neocortical regions. However, these views are not universally accepted. Therefore, the over-arching aim of this Research Topic was to provide a forum through which the debate on the role of cerebellar interactions with motor and "non-motor" structures can be pursued in a rigorous manner. In particular, we aimed to bring together findings from the clinical, animal, theoretical and neuroimaging fields.

Information Theory in Neuroscience

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ISBN: 9783038976646 Year: Pages: 280 DOI: 10.3390/books978-3-03897-665-3 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Mathematics --- Science (General)
Added to DOAB on : 2019-03-21 15:50:41
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As the ultimate information processing device, the brain naturally lends itself to being studied with information theory. The application of information theory to neuroscience has spurred the development of principled theories of brain function, and has led to advances in the study of consciousness, as well as to the development of analytical techniques to crack the neural code—that is, to unveil the language used by neurons to encode and process information. In particular, advances in experimental techniques enabling the precise recording and manipulation of neural activity on a large scale now enable for the first time the precise formulation and the quantitative testing of hypotheses about how the brain encodes and transmits the information used for specific functions across areas. This Special Issue presents twelve original contributions on novel approaches in neuroscience using information theory, and on the development of new information theoretic results inspired by problems in neuroscience.

Power Electronics in Renewable Energy Systems

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ISBN: 9783039210442 / 9783039210459 Year: Pages: 604 DOI: 10.3390/books978-3-03921-045-9 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Technology (General) --- General and Civil Engineering
Added to DOAB on : 2019-06-26 08:44:06
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This book offers a collection of 30 scientific papers which address the problems associated with the use of power electronic converters in renewable energy source-based systems. Relevant problems associated with the use of power electronic converters to integrate renewable energy systems to the power grid are presented. Some of the covered topics relate to the integration of photovoltaic and wind energy generators into the rest of the system, and to the use of energy storage to mitigate power fluctuations, which are a characteristic of renewable energy systems. The book provides a good overview of the abovementioned topics.

Keywords

modular multilevel converter --- battery energy storage system --- state-of-charge balancing --- second-life battery --- multi-energy complementary --- microgrid --- demand response --- operation optimization --- electricity price --- peak-current-mode control --- dynamic modeling --- duty-ratio constraints --- discontinuous conduction mode --- FACTS devices --- active power filter --- static compensator --- control strategies --- grid-connected converter --- SPWM --- SVM --- maximum power point tracking --- open circuit voltage --- perturb and observe --- thermoelectric generator --- two-stage photovoltaic power --- virtual synchronous generator --- adaptive-MPPT (maximum power point tracking) --- improved-VSG (virtual synchronous generator) --- power matching --- failure zone --- governor --- frequency regulation --- inverter --- voltage-type control --- static frequency characteristics --- grid-connected converter --- adaptive resonant controller --- PLL --- impedance analysis --- distorted grid --- digital signal processor (DSP) TMS320F28335 --- grid-connected inverter --- internal model --- linear quadratic regulator --- LCL filter --- photovoltaic systems --- multilevel power converter --- soft switching --- selective harmonic mitigation --- phase shifted --- voltage cancellation --- adaptive control --- sliding mode control --- speed control --- wind energy system --- microgrid (MG) --- droop control --- washout filter --- hardware in the loop (HIL) --- active front-end converter --- back-to-back converter --- permanent magnet synchronous generator (PMSG) --- THD --- type-4 wind turbine --- wind energy system --- Opal-RT Technologies® --- synchronization --- adaptive notch filter (ANF) --- phase-locked loop (PLL) --- wind power prediction --- phase space reconstruction --- multivariate linear regression --- cloud computing --- time series --- multiple VSGs --- oscillation mitigation --- coordinated control --- small-signal and transient stability --- coordination control --- energy storage --- grid support function --- inertia --- photovoltaic --- virtual synchronous generator --- weak grid --- parallel inverters --- oscillation suppression --- notch filter --- impedance reshaping --- boost converter --- peak-current-mode control --- dynamic modeling --- discontinuous operation mode --- doubly-fed induction generator --- short-circuit fault --- frequency regulation --- variable power tracking control --- improved additional frequency control --- variable coefficient regulation --- inertia and damping characteristics --- generator speed control --- electrical power generation --- turbine and generator --- grid-connected converter --- organic Rankine cycle --- renewable energy --- multiport converter (MPC) --- single ended primary inductor converter (SEPIC) --- multi-input single output (MISO) --- renewable power system --- coupled oscillators --- virtual impedance --- synchronization --- power converters --- droop control --- virtual admittance --- distributed generation --- energy --- renewable energy --- microgrids --- Energy Internet --- energy router --- microgrid --- electric vehicle --- PV --- battery-energy storage --- DC-AC power converters --- impedance emulation --- stability analysis --- power-hardware-in- the-loop --- photovoltaic generators --- maximum power point tracking --- step size --- perturbation frequency --- source and load impedance --- transient dynamics --- stability --- grid synchronization --- power electronics --- power grid --- inverter --- grid-connected --- microgrid --- experiment --- modules --- synchronverter --- power ripple elimination --- resonant controller --- unbalanced power grid --- ROCOF --- PLL --- error --- low inertia --- VSC --- n/a

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