The Neural Mechanisms Underlying Visual Target Search
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The Neural Mechanisms Underlying Visual Target Search
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Author : Marino Pagan
language : en
Publisher:
Release Date : 2015
The Neural Mechanisms Underlying Visual Target Search written by Marino Pagan and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
The task of finding specific objects and switching between targets is ubiquitous in everyday life. Searching for a particular object requires our brains to activate and maintain a representation of the target (working memory), identify each encountered object (object recognition), and determine whether the currently viewed object matches the sought target (decision making). The comparison of working memory and visual information is thought to happen via feedback of target information from higher-order brain areas to the ventral visual pathway. However, what is exactly represented by these areas and how do they implement this comparison still remains unknown. To investigate these questions, we employed a combined approach involving electrophysiology experiments and computational modeling. In particular, we recorded neural responses in inferotemporal (IT) and perirhinal (PRH) cortex as monkeys performed a visual target search task, and we adopted population-based read-outs to measure the amount and format of information contained in these neural populations. In Chapter 2 we report that the total amount of target match information was matched in IT and PRH, but this information was contained in a more "explicit" (i.e. linearly separable) format in PRH. These results suggest that PRH implements an "untangling" computation to reformat its inputs from IT. Consistent with this hypothesis, a simple linear-nonlinear model was sufficient to capture the transformation between the two areas. In Chapter 3, we report that the untangling computation in PRH takes time to evolve. While this type of dynamic reformatting is normally attributed to complex recurrent circuits, here we demonstrated that this phenomenon could be accounted by the same instantaneous linear-nonlinear model presented in Chapter 2. This counterintuitive finding was due to the existence of non-stationarities in the IT neural representation. Finally, in Chapter 4 we completely describe a novel set of methods that we developed and applied in Chapters 2 and 3 to quantify the task-specific signals contained in the heterogeneous neural responses in IT and PRH, and to relate these signals to measures of task performance. Together, this body of work revealed a previously unknown untangling computation in PRH during visual search, and demonstrated that a feed-forward linear-nonlinear model is sufficient to describe this computation.
The Neural Mechanisms Underlying Invariant Object Search In V4 And Inferotemporal Cortex
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Author : Noam Roth
language : en
Publisher:
Release Date : 2018
The Neural Mechanisms Underlying Invariant Object Search In V4 And Inferotemporal Cortex written by Noam Roth and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with categories.
Finding a specific visual target, such as your car keys, requires the brain to combine visual information about objects in the currently viewed scene with working memory information about your target to determine whether your target is in view. This combination of context-specific signals with visual information is thought to happen via feedback of target information from higher brain areas to the ventral visual pathway. However, exactly where and how these signals are combined remains unknown. To investigate, we recorded neural responses in V4 and inferotemporal cortex (IT) while monkeys performed an invariant object search task, where targets could appear across variation in their size, position and background context. We applied two complementary approaches to this data to investigate the neural mechanisms underlying target search. The first approach (Chapter 2) is from a computational perspective: where and how are visual and target signals combined when searching for a target? Specifically, we found that while task-relevant modulations in V4 were large, they were larger in IT, suggesting that top-down context-specific modulations are integrated into the ventral visual pathway at multiple stages. In Chapter 3, we focused on the neural responses recorded from IT from the perspective of neural coding: we sought to understand how signal and noise combine to determine task performance. We found that while signals that report the solution for object search were much smaller than signals that act as noise for the task (nuisance modulations) in IT cortex, nuisance modulations had a small effect on task performance. This counterintuitive finding was due to large trial variability constrained by short, behaviorally relevant spike counting windows. Together, this body of work provides insight into where and how the brain combines context-specific signals with visual information during invariant object search.
Neural Mechanisms Of Bottom Up Selection During Visual Search
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Author :
language : en
Publisher:
Release Date : 2001
Neural Mechanisms Of Bottom Up Selection During Visual Search written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001 with categories.
Models of attention and saccade target selection propose that within the brain there is a topographic map of visual salience that selects, through a winner-take-all mechanism, locations for further processing. The results of a series of recent experiments in monkeys performing pop-out visual search tasks suggest that the frontal eye field (FEF) functions as a map of visual salience. FEF is located at the interface of sensory and motor processing and participates in the transformation of visual information into a command to move the eyes. Visually responsive neurons in FEF identify conspicuous objects in a search array regardless of the feature that renders conspicuousness. Furthermore, selection occurs at a constant interval following search array presentation and is dissociated from saccade production. The finding of a visual salience map in FEF validates models of visual selection and can serve to guide future empirical and theoretical investigations.
The Influence Of Attention Learning And Motivation On Visual Search
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Author : Michael D. Dodd
language : en
Publisher: Springer Science & Business Media
Release Date : 2012-12-09
The Influence Of Attention Learning And Motivation On Visual Search written by Michael D. Dodd and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-12-09 with Psychology categories.
The Influence of Attention, Learning, and Motivation on Visual Search will bring together distinguished authors who are conducting cutting edge research on the many factors that influence search behavior. These factors will include low-level feature detection; statistical learning; scene perception; neural mechanisms of attention; and applied research in real world settings.
Neural Mechanisms Of Top Down Selection During Visual Search
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Author :
language : en
Publisher:
Release Date : 2001
Neural Mechanisms Of Top Down Selection During Visual Search written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001 with categories.
The brain's representation of visual information depends greatly on the behavioral relevance of the viewed stimuli. While in some instances behavioral significance is derived from conspicuity, in many situations significance depends on top-down factors such as the viewer's goals and knowledge. Studies combining neural recordings and behavioral observations have begun to elucidate how the brain selects visual stimuli based on top-down information. While many visual areas of the brain that are selective for visual attributes participate in the selection process, the outcome of the selection process across these areas appears to be represented in structures like the frontal eye field, a key stage in the transformation of visual selection into a command to move the eyes. Evidence shows that the frontal eye field exhibits all the characteristics of a visual salience map in which the behavioral significance of stimuli derived from bottom-up and top-down influences is represented. The patterns of neural modulation in structures like the frontal eye field can be used to design more efficient machine-vision algorithms for target selection.
Visual Attention Mechanisms
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Author : Virginio Cantoni
language : en
Publisher: Springer Science & Business Media
Release Date : 2012-12-06
Visual Attention Mechanisms written by Virginio Cantoni and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-12-06 with Computers categories.
Proceedings of the Fifth International School on Neural Networks "E.R. Caianiello" on Visual Attention MechaProceedings of the Fifth International School on Neural Networks "E.R. Caianiello" on Visual Attention Mechanisms, held 23-28 October 2000 in Vietri sul Mare, Italy.nisms, held 23-28 October 2000 in Vietri sul Mare, Italy. The book covers a number of broad themes relevant to visual attention, ranging from computer vision to psychology and physiology of vision. The main theme of the book is the attention processes of vision systems and it aims to point out the analogies and the divergences of biological vision with the frameworks introduced by computer scientists in artificial vision.
Mechanisms Of Target Selection And Feature Binding In Visual Object Recognition
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Author : Bernd Schönwälder
language : en
Publisher:
Release Date : 2007
Mechanisms Of Target Selection And Feature Binding In Visual Object Recognition written by Bernd Schönwälder and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with categories.
It has become common knowledge that if there is a unifying principle that enables the human brain to realize its tremendous capabilities, then it is its highly parallel organisation of underlying processes. However, the mystery of integration of all these distributed processes into the single, coherent consciousness that we experience, also referred to as the "binding problem", is still one of the most controversial research topics in modern cognitive neuroscience. This thesis aims to contribute methodological as well empirical advances to the understanding of general, formalised properties of different types of integration mechanisms for visual featural information, which are supposed to be involvedin early as well as in late processing stages of the visual system. It focuses on developing mathematical methods that employ behavioural reaction time data to differentiate between different implementation variants of integrational mechanisms. These methods are developed with respect to their application in the visual search paradigm. A modified version of the visual search paradigm, which involves feature change asynchronies to temporally separate featural manipulations in the presentation of stimuli, is applied to investigate into current research topics of pre-attentive feature integration. In a series of experiments recent findings about the temporal organization of feature integration and binding processes are addressed. In the focus of this experimental investigation is the question in how far differences in processing delays between dimension-specific featural information, like color, motion or orientation information, can account for temporal misbindings as has been recently reported in the literature.
The Neuroscience Of Attention The Neuroscience Of Attention
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Author : George R. Mangun
language : en
Publisher: Oxford University Press
Release Date : 2012-02-16
The Neuroscience Of Attention The Neuroscience Of Attention written by George R. Mangun and has been published by Oxford University Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-02-16 with Medical categories.
This book will provide the reader with a solid overview of the mechanisms and models in the neuroscience of attentional control and selection from leading authorities working in humans and animals, and incorporating a array of neuroscience methods from single neuron recordings to functional brain imaging.
Cortical Mechanisms Of Vision
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Author : Michael Jenkin
language : en
Publisher: Cambridge University Press
Release Date : 2009-07-09
Cortical Mechanisms Of Vision written by Michael Jenkin and has been published by Cambridge University Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009-07-09 with Medical categories.
The advent of sensors capable of localizing portions of the brain involved in specific computations has provided significant insights into normal visual information processing and specific neurological conditions. Aided by devices such as fMRI, researchers are now able to construct highly detailed models of how the brain processes specific patterns of visual information. This book brings together some of the strongest thinkers in this field, to explore cortical visual information processing and its underlying mechanisms. It is an excellent resource for vision researchers with both biological and computational backgrounds, and is an essential guide for graduate students just starting out in the field.
The Role Of Selective Attention In The Perception Of Multiple Element Visual Arrays
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Author : Steven J. Luck
language : en
Publisher:
Release Date : 1993
The Role Of Selective Attention In The Perception Of Multiple Element Visual Arrays written by Steven J. Luck and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1993 with categories.