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Feedforward and Feedback Processes in Vision

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889195947 Year: Pages: 151 DOI: 10.3389/978-2-88919-594-7 Language: English
Publisher: Frontiers Media SA
Subject: Psychology --- Science (General)
Added to DOAB on : 2016-03-10 08:14:32
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The visual system consists of hierarchically organized distinct anatomical areas functionally specialized for processing different aspects of a visual object (Felleman & Van Essen, 1991). These visual areas are interconnected through ascending feedforward projections, descending feedback projections, and projections from neural structures at the same hierarchical level (Lamme et al., 1998). Accumulating evidence from anatomical, functional and theoretical studies suggests that these three projections play fundamentally different roles in perception. However, their distinct functional roles in visual processing are still subject to debate (Lamme & Roelfsema, 2000). The focus of this Research Topic is the roles of feedforward and feedback projections in vision. Even though the notions of feedforward, feedback, and reentrant processing are widely accepted, it has been found difficult to distinguish their individual roles on the basis of a single criterion. We welcome empirical contributions, theoretical contributions and reviews that fit into any one (or a combination) of the following domains: 1) their functional roles for perception of specific features of a visual object 2) their contributions to the distinct modes of visual processing (e.g., pre-attentive vs. attentive, conscious vs. unconscious) 3) recent techniques/methodologies to identify distinct functional roles of feedforward and feedback projections and corresponding neural signatures. We believe that the current Research Topic will not only provide recent information about feedforward/feedback processes in vision but also contribute to the understanding fundamental principles of cortical processing in general.

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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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.

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.

Visible Light Communication and Positioning

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ISBN: 9783039214358 / 9783039214365 Year: Pages: 144 DOI: 10.3390/books978-3-03921-436-5 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Added to DOAB on : 2019-12-09 11:49:16
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In recent years, wireless communications have significantly evolved due to the advanced technology of smartphones;, portable devices; and the rapid growth of Internet of Things, e-Health, and intelligent transportation systems . Moreover, there is anare increasing need fors of emerging intelligent services like positioning and sensing in athe future intelligence society. Recent years have witnessed the growing research interests and activities in the communication and intelligencet services in the optical wireless spectrum, as a complementary technology to more

Power Quality in Microgrids Based on Distributed Generators

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ISBN: 9783039280063 / 9783039280070 Year: Pages: 194 DOI: 10.3390/books978-3-03928-007-0 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Technology (General) --- General and Civil Engineering
Added to DOAB on : 2020-01-07 09:08:26
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This book comprises ten articles covering different aspects of power quality issues in microgrids and distributed generation (DG) systems, including 1) Detection and estimation of power quality; 2) Modeling; 3) Harmonic control for DG systems and microgrids; 4) Stability improvements for microgrids. Different power quality phenomena and solution were studied in the included papers, such as harmonics, resonance, frequency deviation, voltage sag, and fluctuation. From a network point of view, some papers studied the harmonic and stability issues in standalone microgrids which are more likely to cause power quality problems. Other papers discussed the power quality problems in microgrids which are weakly interconnected with the main distribution grid. In view of the published papers, there is a trend that increasingly advanced modeling, analysis, and control schemes were applied in the studies. Moreover, the latest works focus not only on single-unit problems but also multiple units or network issues. Although some of the hot topics are not included, this book covers multiple aspects of the current power quality research frontier, and represents a particularly useful reference book for frontier researchers in this field.

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