Contextual Interactions In Cortical Motion And Surface Perception
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Contextual Interactions In Cortical Motion And Surface Perception
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Author : Julia Berzhanskaya
language : en
Publisher:
Release Date : 2005
Contextual Interactions In Cortical Motion And Surface Perception written by Julia Berzhanskaya and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with categories.
Abstract: This dissertation describes neural modeling and psychophysical experiments that clarify how ambiguous visual signals can be disambiguated by contextual interactions. A neural model of the V1-V2-MT-MST areas of the visual cortex is developed to explain how context can influence motion percepts. Psychophysical experiments clarify how context can influence the perception of gloss on a 3D surface and support earlier model predictions about perceptual surface formation. To process object motion in cluttered environments, the brain has to solve multiple problems. One concerns aperture ambiguity. If a featureless line is observed through an aperture in an occluding surface, the perceived direction of motion is perpendicular to the line and may differ from the real motion direction. Integration of motion across apertures helps to determine the true direction of motion. If multiple moving objects overlap, motion segmentation and motion separation in depth help to limit the areas of motion integration. Figure-ground constraints also help to disambiguate the object to which a moving feature belongs. Thus, both form and motion information are combined in the current 3D FORMOTION model to accurately determine object motion. The model simulates effects of visible and invisible occluders on segregation of motion signals within and across depth, and how object shape and nearby objects can influence motion percepts. The psychophysical experiments clarify how percepts of gloss in an image can change as a function distance on the depicted surface rather than of distance in the image plane. Data suggest that the perception of gloss depends on a spatially local filling-in process, or gloss propagation, that is triggered by distinctive highlight features in the context of a 3D surface representation. Space-variant gloss ratings can be explained by generalizing previous models of brightness perception.
Perceptual Consequences Of Surround Suppression And Plasticity In Visual Motion Processing
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Author : Liu Liu
language : en
Publisher:
Release Date : 2017
Perceptual Consequences Of Surround Suppression And Plasticity In Visual Motion Processing written by Liu Liu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
"The visual nervous system transforms the input from the visual scene into electrical signals. The electrical signals are in turn read out by other areas of the brain to form perceptual decisions. The relationship between neuronal responses evoked by sensory stimuli and their perceptual correlates is an important research question in modern computational and systems neuroscience. Previous studies of this relationship focused on correlating the response of single neurons to stimuli in their receptive field (RF), defined as a region of the visual space where selective stimuli can evoke a response. However, single neurons are part of a local circuitry that controls their selectivity and modulates their response. The local circuitry is composed of many neurons that encode surrounding regions of the visual space. The neurons in the circuit can interact via excitatory or inhibitory connections. The interactions are crucial for contextual modulation of single neuron response, since any stimulus on the RF of a neuron is part of a larger visual context. Aside from the contextual modulation of neuronal responses, another part of the sensory-to-decision transformation is how the responses of neurons are read out from a population. Correlations in the responses of neurons can have a large impact in the amount of information in a population, and this correlation should be quantified when considering a population readout.Another level of complexity is that downstream areas must use this sensory code flexibly in perceptual decision making. Many neurons and areas can contain the information about the sensory stimulus, and the readout should correspond to the experience of the animal. This thesis investigates these issues in order. In chapter 2, I determine the neural basis for a type of contextual modulation in our motion perception, the worsening of motion perception at large stimulus size. Large stimuli suppress the firing rate of neurons in a form of contextual modulation known as surround suppression. I simultaneously record from multiple neurons in the middle temporal visual area (MT), and I perform a simulation of the recorded responses and the correlation structure. I find surround suppression improves the population sensitivity for small stimuli at the expense of weaker sensitivity for large stimuli. In chapter 3, I examine the underlying circuitry mechanisms for surround suppression. Recent work suggests that the cortex operates in a theoretical network where excitation alone is strong enough to induce instability but inhibition maintains the stability. I pharmacologically manipulate the efficacy of inhibitory processes and find that the neuronal dynamics are consistent with the predictions. I then perform additional experiments to confirm that this network mechanism can be generalized to different stimulus dimensions in MT. In chapter 4, I examine the flexibility of the readout of sensory information. The readout of sensory evidence for visual perception is plastic and depends on recent training experience. I use reversible inactivation and microstimulation to probe the causal relationship between MT neuronal response and perception. I find the causal contribution of MT to visual motion perception depends on training the animals on a specific task of motion integration. This thesis has implications in the broader context of neural coding in health and diseases. Previous work shows that natural aging or disease processes can lead to deficits in our sensory perception, and the reduction of inhibition efficacy has been implicated. Therefore, an understanding of the inhibitory interactions in local cortical circuitry may lead to future treatments and interventions." --
The Visual Cortical Interactions Underlying The Perception Of Motion
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Author : Agnes Patricia Funk
language : en
Publisher:
Release Date : 2002
The Visual Cortical Interactions Underlying The Perception Of Motion written by Agnes Patricia Funk and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002 with Motion perception (Vision) categories.
Encyclopedia Of Neuroscience Volume 1
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Author : Larry R. Squire
language : en
Publisher: Academic Press
Release Date : 2009-06-12
Encyclopedia Of Neuroscience Volume 1 written by Larry R. Squire and has been published by Academic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009-06-12 with Medical categories.
The Encyclopedia of the Neuroscience explores all areas of the discipline in its focused entries on a wide variety of topics in neurology, neurosurgery, psychiatry and other related areas of neuroscience. Each article is written by an expert in that specific domain and peer reviewed by the advisory board before acceptance into the encyclopedia. Each article contains a glossary, introduction, a reference section, and cross-references to other related encyclopedia articles. Written at a level suitable for university undergraduates, the breadth and depth of coverage will appeal beyond undergraduates to professionals and academics in related fields.
Reciprocal Interactions Between Motion And Form Perception
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Author : P. Sinha
language : en
Publisher:
Release Date : 1994
Reciprocal Interactions Between Motion And Form Perception written by P. Sinha and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1994 with categories.
Lateral Interactions In The Primary Visual Cortex And Their Role In Perception
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Author : Mitesh K. Kapadia
language : en
Publisher:
Release Date : 1999
Lateral Interactions In The Primary Visual Cortex And Their Role In Perception written by Mitesh K. Kapadia and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1999 with categories.
On Perceived Motion And Figural Organization
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Author : Max Wertheimer
language : en
Publisher: MIT Press
Release Date : 2012-07-27
On Perceived Motion And Figural Organization written by Max Wertheimer and has been published by MIT Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-07-27 with Psychology categories.
Two seminal articles by a founder of the Gestalt school of psychology, newly translated and accompanied by essays that connect his work to current research. There are few articles in science that remain relevant over a span of 100 years; Max Wertheimer's pioneering experimental studies on apparent motion and figural organization are notable exceptions. Wertheimer's 1912 account of motion perception started a revolution and established the Gestalt school of psychology. It also paved the way for further investigations of apparent motion perception, including subsequent research by Oliver Braddick, Stuart Anstis, Vilaynur Ramachandran, and others. Wertheimer's 1923 article on figural organization (known as the "dot study" for its numerous examples of dot patterns) helped define grouping as a principle of figure-ground perception. This book provides contemporary readers and researchers with Wertheimer's two pivotal articles, newly translated into English and each accompanied by a synopsis, and two essays on apparent motion and figural organization that describe the long-term impact of Wertheimer's work. The translation of the original German into readable English prose allows English-language readers for the first time to appreciate Wertheimer's visionary ideas. The accompanying essays tie Wertheimer's phenomenological descriptions to the underlying neuronal mechanisms, bridging the years between the articles' first publication and modern research.
Dissertation Abstracts International
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Author :
language : en
Publisher:
Release Date : 2006
Dissertation Abstracts International written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with Dissertations, Academic categories.
Contextual Modulations Of Visual Perception And Visual Cortex Activity In Humans
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Author : B. de Haas
language : en
Publisher:
Release Date : 2014
Contextual Modulations Of Visual Perception And Visual Cortex Activity In Humans written by B. de Haas and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
Coding Of Multivariate Stimuli And Contextual Interactions In The Visual Cortex
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Author : Sander Wessel Keemink
language : en
Publisher:
Release Date : 2017
Coding Of Multivariate Stimuli And Contextual Interactions In The Visual Cortex written by Sander Wessel Keemink and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.