Download or read book Human Neurophysiological Mechanisms of Contextual Modulation in Primary Visual Cortex written by Jennifer Frances Schumacher and published by . This book was released on 2010 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Exploring Mechanisms for Contextual Modulation in V1 written by Matthew P. Whitmire and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The brain can quickly take complex visual information in a scene and group together or distinguish relevant features, allowing us to seamlessly interpret and interact with the world around us. Evidence from recordings in visual cortex have shown that neurons not only responsive to stimuli within their receptive field, but also sensitive to stimuli in the surrounding area. This effect is referred to as contextual modulation. The primary visual cortex (V1) represents high resolution spatial information and stands as the bottleneck before all other visual processing in the cortex, making it a prime location to study complex mechanisms for sensory encoding, like contextual modulation. This dissertation investigates contextual modulation mechanisms present in V1 by: 1) testing if the large-scale population activity in V1 contributes to contour grouping while a monkey is engaged in a complex and difficult contour detection task, and 2) comparing how excitatory and inhibitory cell populations in V1 contribute to orientation tuning, size tuning, and surround modulation effects. First, I will show that we can train rhesus macaques to reliably perform a complex contour detection task with stimuli based on the statistics of contours found in natural scenes. Next, I will demonstrate that when recording voltage sensitive dye imaging signals during the contour detection task, V1 does not show evidence of participating in the contour grouping computation. This suggests V1 may only relay information from individual elements, which are then grouped together in subsequent visual areas. Continuing, I will present that inhibitory cells in macaque V1 show orientation tuning and orientation maps with broader tuning than excitatory cells. Then, I will demonstrate that inhibitory and excitatory size tuning and receptive field sizes do not differ substantially and that V1 surround modulation may be sensitive to general discontinuity, rather than only orientation difference. These results do not support key models of inhibition during size tuning effects and open the field to more work comparing contextual modulation effects across excitatory and inhibitory cells in macaque. Overall, this thesis challenges widely held models of contextual modulation in V1, both for contour grouping and how inhibition shapes surround modulation effects
Download or read book Vision and Movement written by and published by . This book was released on 1996 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Neurobiology of Attention written by Laurent Itti and published by Elsevier. This book was released on 2005-03-31 with total page 757 pages. Available in PDF, EPUB and Kindle. Book excerpt: A key property of neural processing in higher mammals is the ability to focus resources by selectively directing attention to relevant perceptions, thoughts or actions. Research into attention has grown rapidly over the past two decades, as new techniques have become available to study higher brain function in humans, non-human primates, and other mammals. Neurobiology of Attention is the first encyclopedic volume to summarize the latest developments in attention research.An authoritative collection of over 100 chapters organized into thematic sections provides both broad coverage and access to focused, up-to-date research findings. This book presents a state-of-the-art multidisciplinary perspective on psychological, physiological and computational approaches to understanding the neurobiology of attention. Ideal for students, as a reference handbook or for rapid browsing, the book has a wide appeal to anybody interested in attention research.* Contains numerous quick-reference articles covering the breadth of investigation into the subject of attention* Provides extensive introductory commentary to orient and guide the reader* Includes the most recent research results in this field of study
Download or read book Visual Cortex written by Stephane Molotchnikoff and published by BoD – Books on Demand. This book was released on 2012-09-26 with total page 427 pages. Available in PDF, EPUB and Kindle. Book excerpt: The neurosciences have experienced tremendous and wonderful progress in many areas, and the spectrum encompassing the neurosciences is expansive. Suffice it to mention a few classical fields: electrophysiology, genetics, physics, computer sciences, and more recently, social and marketing neurosciences. Of course, this large growth resulted in the production of many books. Perhaps the visual system and the visual cortex were in the vanguard because most animals do not produce their own light and offer thus the invaluable advantage of allowing investigators to conduct experiments in full control of the stimulus. In addition, the fascinating evolution of scientific techniques, the immense productivity of recent research, and the ensuing literature make it virtually impossible to publish in a single volume all worthwhile work accomplished throughout the scientific world. The days when a single individual, as Diderot, could undertake the production of an encyclopedia are gone forever. Indeed most approaches to studying the nervous system are valid and neuroscientists produce an almost astronomical number of interesting data accompanied by extremely worthy hypotheses which in turn generate new ventures in search of brain functions. Yet, it is fully justified to make an encore and to publish a book dedicated to visual cortex and beyond. Many reasons validate a book assembling chapters written by active researchers. Each has the opportunity to bind together data and explore original ideas whose fate will not fall into the hands of uncompromising reviewers of traditional journals. This book focuses on the cerebral cortex with a large emphasis on vision. Yet it offers the reader diverse approaches employed to investigate the brain, for instance, computer simulation, cellular responses, or rivalry between various targets and goal directed actions. This volume thus covers a large spectrum of research even though it is impossible to include all topics in the extremely diverse field of neurosciences.
Download or read book A Novel Circuit Model of Contextual Modulation and Normalization in Primary Visual Cortex written by Daniel Brett Rubin and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This same model also provides a biologically plausible mechanism for cortical normalization, an operation that has been shown to be ubiquitous in V1. Through a winner-take-all population response, we demonstrate how this network undergoes a strong reduction in trial-to-trial variability at stimulus onset. We also propose a novel mechanism for attentional modulation in visual cortex. We then go on to test several of the critical pre- dictions of the model using single unit electrophysiology. From these experiments, we find ample evidence for the spatially-periodic patterns of activity predicted by the model. Lastly, we show how this same circuit motif may underlie behavior in a higher cortical region, the lateral intraparietal area.
Download or read book Fitting the Mind to the World written by Colin W. G. Clifford and published by Oxford University Press. This book was released on 2005-05-05 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This book brings together a collection of studies from international researchers who demonstrate the brain's remarkable capacity to adapt its representation of the visual world in response to changes in its environment."--BOOK JACKET.
Download or read book Functional Organisation of the Human Visual Cortex written by Balazs Gulyas and published by Elsevier Health Sciences. This book was released on 1993-05-18 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt: Functional Organisation of the Human Visual Cortex
Download or read book Natural Image Statistics written by Aapo Hyvärinen and published by Springer Science & Business Media. This book was released on 2009-04-21 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aims and Scope This book is both an introductory textbook and a research monograph on modeling the statistical structure of natural images. In very simple terms, “natural images” are photographs of the typical environment where we live. In this book, their statistical structure is described using a number of statistical models whose parameters are estimated from image samples. Our main motivation for exploring natural image statistics is computational m- eling of biological visual systems. A theoretical framework which is gaining more and more support considers the properties of the visual system to be re?ections of the statistical structure of natural images because of evolutionary adaptation processes. Another motivation for natural image statistics research is in computer science and engineering, where it helps in development of better image processing and computer vision methods. While research on natural image statistics has been growing rapidly since the mid-1990s, no attempt has been made to cover the ?eld in a single book, providing a uni?ed view of the different models and approaches. This book attempts to do just that. Furthermore, our aim is to provide an accessible introduction to the ?eld for students in related disciplines.
Download or read book Multisensory Object Perception in the Primate Brain written by Marcus Johannes Naumer and published by Springer Science & Business Media. This book was released on 2010-07-03 with total page 383 pages. Available in PDF, EPUB and Kindle. Book excerpt: It should come as no surprise to those interested in sensory processes that its research history is among the longest and richest of the many systematic efforts to understand how our bodies function. The continuing obsession with sensory systems is as much a re?ection of the fundamental need to understand how we experience the physical world as it is to understand how we become who we are based on those very experiences. The senses function as both portal and teacher, and their individual and collective properties have fascinated scientists and philosophers for millennia. In this context, the attention directed toward specifying their properties on a sense-by-sense basis that dominated sensory research in the 20th century seems a prelude to our current preoccupation with how they function in concert. Nevertheless, it was the concentrated effort on the operational principles of in- vidual senses that provided the depth of understanding necessary to inform current efforts to reveal how they act cooperatively. We know that the information provided by any individual sensory modality is not always veridical, but is subject to a myriad of modality-speci?c distortions. Thus, the brain’s ability to compare across the senses and to integrate the information they provide is not only a way to examine the accuracy of any individual sensory channel but also a way to enhance the collective information they make available to the brain.
Download or read book From Attention to Goal Directed Behavior written by Francisco Aboitiz and published by Springer Science & Business Media. This book was released on 2008-11-21 with total page 335 pages. Available in PDF, EPUB and Kindle. Book excerpt: Attention is a key psychological construct in the understanding of human cognition, and the target of enormous efforts to elucidate its physiological mechanisms, as the wealth of literature—both primary and secondary—attests (for recent compilations see Itti, Rees, & Tsotsos, 2005; Paletta & Rome, 2008; Posner, 2004). But in addition to asking what attention actually is, decomposing and analyzing its varieties, or delimiting its neurobiological mechanisms and effects, in this volume we want to explore attention somewhat differently. We believe that a full-fledged theory of attention must consider its workings in the context of motivated, goal-directed, and environmentally constrained organisms. That attention is related to goal-directed behavior is not news. What the contri- tions to this volume do suggest, however, is the existence of fundamental links between attention and two key processes that are crucial for adapted conduct: go- directed behavior and cognitive control. Importantly, they show that these relations can be explored at multiple levels, including neurodynamical, neurochemical, evo- tionary, and clinical aspects, and that in doing so multiple methodological challenges arise that are worth considering and pursuing. The reader will find here, therefore, a selection of contributions that range from basic mechanisms of attention at the n- ronal level to developmental aspects of cognitive control and its impairments. Another trend that will become evident is that, in different ways, the authors stress the need to understand these issues as they unfold in natural behavior (both healthy and pathological), thus arguing for a more ecological approach to these questions.
Download or read book The New Cognitive Neurosciences written by Michael S. Gazzaniga and published by MIT Press. This book was released on 2000 with total page 1468 pages. Available in PDF, EPUB and Kindle. Book excerpt: This second edition reflects the many advances that have taken place in this field, particularly in imaging and recording techniques. The majority of the chapters in this edition of "The Cognitive Neurosciences" are new, and those from the first edition have been rewritten and updated.
Download or read book Neuronal Operations in the Visual Cortex written by Guy A. Orban and published by Springer. This book was released on 1984 with total page 406 pages. Available in PDF, EPUB and Kindle. Book excerpt: The invitation by the editors of the series "studies of brain function" to contribute a monograph on the visual cortex gives me the opportunity to present in a concentrated manner much of the work I have done on the visual cortical areas of cat and monkey. However, the field of visual cortical physi ology is so active and so diverse that the presentation of only my own work would have given a very incomplete view of visual cortical functioning. Therefore this monograph also reviews most of the studies carried out on the subject in the last two decades. Where possible I have tried not only to describe the cortical machinery but also its possible functional purpose regarding vision. In doing this I have expressed my personal views rather than just reviewing the experimental facts. Much of the work presented in this monograph has been supported by the National Research Council of Belgium and the Research Council of the Catholic University of Leuven. I express my gratitude to them. I have en joyed collaborating in these studies with P. O. Bishop, H. Kato, H. Kennedy, K. P. Hoffmann, H. Maes, J. Duysens, E. Vandenbussche, and H. van der Glas. I am much indebted to all those who have commented on earlier versions of this monograph: J. Allman, H. Barlow, J. BuBier, M. Callens, J. Duysens, O. J. Griisser, P. Heggelund, H. Kennedy, L. C. Orban and L. Palmer.
Download or read book Brain and Visual Perception written by David H. Hubel M.D. and published by Oxford University Press. This book was released on 2004-10-14 with total page 739 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the story of a hugely successful and enjoyable 25-year collaboration between two scientists who set out to learn how the brain deals with the signals it receives from the two eyes. Their work opened up a new area of brain research that led to their receiving the Nobel Prize in 1981. The book contains their major papers from 1959 to 1981, each preceded and followed by comments telling how and why the authors went about the study, how the work was received, and what has happened since. It begins with short autobiographies of both men, and describes the state of the field when they started. It is intended not only for neurobiologists, but for anyone interested in how the brain works-biologists, psychologists, philosophers, physicists, historians of science, and students at all levels from high school to graduate level.
Download or read book Channels in the Visual Nervous System written by Baruch Blum and published by . This book was released on 1991 with total page 518 pages. Available in PDF, EPUB and Kindle. Book excerpt: Published by Freund Publishing House Ltd. Suite 500, Chesham House, 150 Regent Street, London, W1R 5FA, England. Contains edited articles, mostly from the 12th European Conference on Visual Perception (ECVP) held at Zichron Yaacov, Israel in 1989. While the subject is the proceeding of visual information from the receptor up to the perceptual and the conceptual level, material is oriented towards the long lasting concept of "channels" in the visual nervous system. "Channels" are covered from all points of view, including those that find the concept useful as well a those that criticize it. Annotation copyrighted by Book News, Inc., Portland, OR
Download or read book Inhibitory Mechanisms in the Primary Visual Cortex written by Gary Allan Walker and published by . This book was released on 1998 with total page 524 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book How Animals See the World written by Olga F. Lazareva and published by Oxford University Press. This book was released on 2012-04-19 with total page 559 pages. Available in PDF, EPUB and Kindle. Book excerpt: The visual world of animals is highly diverse and often very different from that of humans. This book provides an extensive review of the latest behavioral and neurobiological research on animal vision, detailing fascinating species similarities and differences in visual processing.
