Download or read book Feedforward and Feedback Processes in Vision written by Hulusi Kafaligonul and published by Frontiers Media SA. This book was released on 2015-07-10 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Towards an Integrated Model of Feedforward feedback Processing in the Visual Cortex written by Ivaylo P. Riskov and published by . This book was released on 2008 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this work is to explore a potential improvement on a visual recognition system. The system is a biologically-plausible computational model of the feedforward part of the ventral stream in the visual cortex and successfully models human performance on visual recognition tasks for the first 50-100 milliseconds since the presentation of the visual stimulus. We make the first steps to a possible augmentation of the system that will account for both feedforward and feedback processes in the ventral stream. We explore the plausibility of Bayesian network models for feedback. Our results show that although the resulting system under performs the original, it has a better rate of improvement as more and more training examples are added to it.
Download or read book Webvision written by Helga Kolb and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Feedforward Contributions to Sensory Response Properties in the Early Visual System written by Bartlett Doe Moore and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The unique ecological utility provided by the complex sensory processing that occurs in the brains of visual animals cannot be over appreciated. Psychologists, physiologists, mathematicians, and philosophers, among others, have subjected vision in humans and non-human animals to intense scrutiny. Perhaps the most studied regions of the mammalian visual system are the early visual pathways: the retina, the dorsal lateral geniculate nucleus of the thalamus (LGN), and area 17 of the primary visual cortex (V1). This dissertation was conceived and conducted to elucidate some of the contributions of feedforward processes to sensory responses in the early visual system. Extracellular recordings were collected from individual neurons in the retina, visual thalamus, and primary visual cortex of cats, and the primary visual cortex of ferrets while controlling the sensory input to the system. These methods were used to characterize five distinct features of information processing: 1) the influence of stimulus temporal frequency on orientation tuning in V1 neurons, 2) the influence of stimulus temporal frequency on direction selectivity in V1 neurons, 3) the response properties of LGN neurons in the absence of On-center retinal input, 4) the orientation tuning in V1 neurons in the absence of On-center LGN input, and 5) the direction selectivity of V1 neurons in the absence of On-center LGN input. The results presented in the following chapters show that the paradigmatic feedforward model of processing in the early visual system and its contribution to neuronal response properties requires further refinement. The work presented in chapter 2 show that the direction selectivity--but not orientation tuning--of ferret V1 neurons is dependant on the temporal frequency of stimuli, suggesting that stability of orientation tuning is an important aspect of early visual processing. The work presented in chapter 3 suggest there is more frequent divergence of connections in the retinogeniculate pathway of the cat than previously recognized and that functionally silent, non-specific retinal inputs can undergo rapid plasticity when the On pathway is disrupted. The work presented in chapter 4 investigates the response properties of V1 neurons in the absence of On-center LGN activity. The results show that while orientation tuning is resilient to the reduction in feedforward input, direction selectivity behaves more erratically. The early visual system is the computational foundation upon which more complex features are detected in the visual environment. In order to understand how visual processing in later visual pathways is accomplished, it is critical that the feedforward contributions to response properties in the early visual pathways be understood.
Download or read book Vision and the Visual System written by Peter H. Schiller and published by Oxford University Press, USA. This book was released on 2015 with total page 441 pages. Available in PDF, EPUB and Kindle. Book excerpt: 'Vision and the Visual System' offers students, teachers and researchers a rigorous, yet accessible account of how the brain analyses the visual scene. Schiller and Tehovnik describe key aspects of visual perception such as colour, motion, pattern and depth while explaining the relationship between eye movements and neural structures in the brain.
Download or read book Understanding Vision written by Li Zhaoping and published by Oxford University Press, USA. This book was released on 2014 with total page 397 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vision science has grown hugely in the past decades, but there have been few books showing readers how to adopt a computional approach to understanding visual perception, along with the underlying mechanisms in the brain. This book explains the computational principles and models of biological visual processing, and in particular, primate vision.
Download or read book Colour and Form Perception Straddling the Boundary written by Galina V. Paramei and published by Frontiers Media SA. This book was released on 2016-05-31 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: Starting from psychophysics, over the last 50 years, most progress in unravelling the mechanisms of color vision has been made through the study of single cell responses, mainly in LGN and striate cortex. A similar development in the study of form perception may seem to be underway, centred on the study of temporal cortex. However, because of the combinatorial characteristics of form perception, we are also observing the opposite tendency: from single-cell activity to population coding, and from static receptive field structures to system dynamics and integration and, ultimately, a synthetic form of psychophysics of color and form perception. From single cells to system integration: it is this development the present Research Topic wishes to highlight and promote. How does this development affect our views on the various attributes of perception? In particular, we are interested in to what extent evolving knowledge in the field of color perception is relevant within a developing integrative framework of form perception. The goal of this Research Topic is to bring together experimental research encompassing both color and form perception. For this volume, we planned a broad scope of topics – on color in complex scenes, color and form, as well as dynamic aspects of form perception. We expect that the Research Topic will be attractive to the community of researchers whose work straddles the boundary between the two visual perception fields, as well as to the wider community interested in integrative/systems neuroscience.
Download or read book A Combined MRI and Histology Atlas of the Rhesus Monkey Brain in Stereotaxic Coordinates written by Kadharbatcha S. Saleem and published by Academic Press. This book was released on 2012-04-23 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Combined MRI and Histology Atlas of the Rhesus Monkey Brain in Stereotaxic Coordinates, Second Edition maps the detailed architectonic subdivisions of the cortical and subcortical areas in the macaque monkey brain using high-resolution magnetic resonance (MR) images and the corresponding histology sections in the same animal. This edition of the atlas is unlike anything else available as it includes the detailed cyto- and chemoarchitectonic delineations of the brain areas in all three planes of sections (horizontal, coronal, and sagittal) that are derived from the same animal. This is a significant progress because in functional imaging studies, such as fMRI, both the horizontal and sagittal planes of sections are often the preferred planes given that multiple functionally active regions can be visualized simultaneously in a single horizontal or sagittal section. This combined MRI and histology atlas is designed to provide an easy-to-use reference for anatomical and physiological studies in macaque monkeys, and in functional-imaging studies in human and non-human primates using fMRI and PET. The first rhesus monkey brain atlas with horizontal, coronal, and sagittal planes of sections, derived from the same animal Shows the first detailed delineations of the cortical and subcortical areas in horizontal, coronal, and sagittal plane of sections in the same animal using different staining methods Horizonal series illustrates the dorsoventral extent of the left hemisphere in 47 horizontal MRI and photomicrographic sections matched with 47 detailed diagrams (Chapter 3) Coronal series presents the full rostrocaudal extent of the right hemisphere in 76 coronal MRI and photomicrographic sections, with 76 corresponding drawings (Chapter 4) Sagittal series shows the complete mediolateral extent of the left hemisphere in 30 sagittal MRI sections, with 30 corresponding drawings (Chapter 5). The sagittal series also illustrates the location of different fiber tracts in the white matter Individual variability - provides selected cortical and subcortical areas in three-dimensional MRI (horizontal, coronal, and sagittal MRI planes). For comparison, it also provides similar areas in coronal MRI section in six other monkeys. (Chapter 6) Vasculature - indicates the corresponding location of all major blood vessels in horizontal, coronal, and sagittal series of sections Provides updated information on the cortical and subcortical areas, such as architectonic areas and nomenclature, with references, in chapter 2 Provides the sterotaxic grid derived from the in-vivo MR image
Download or read book Visual Masking written by Bruno Breitmeyer and published by Oxford University Press, USA. This book was released on 2006-04-20 with total page 383 pages. Available in PDF, EPUB and Kindle. Book excerpt: Where most current approaches to the study of visual consciousness adopt a 'steady-state' view, the approach presented in this book explores its dynamic properties down to a resolution in the millisecond range."--BOOK JACKET.
Download or read book Computational and Cognitive Neuroscience of Vision written by Qi Zhao and published by Springer. This book was released on 2016-10-03 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt: Despite a plethora of scientific literature devoted to vision research and the trend toward integrative research, the borders between disciplines remain a practical difficulty. To address this problem, this book provides a systematic and comprehensive overview of vision from various perspectives, ranging from neuroscience to cognition, and from computational principles to engineering developments. It is written by leading international researchers in the field, with an emphasis on linking multiple disciplines and the impact such synergy can lead to in terms of both scientific breakthroughs and technology innovations. It is aimed at active researchers and interested scientists and engineers in related fields.
Download or read book Visual Perception Part 1 written by Susana Martinez-Conde and published by Elsevier. This book was released on 2006-10-05 with total page 341 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a collection of articles reflecting state-of-the-art research in visual perception, specifically concentrating on neural correlates of perception. Each section addresses one of the main topics in vision research today. Volume 1 Fundamentals of Vision: Low and Mid-Level Processes in Perception covers topics from receptive field analyses to shape perception and eye movements. A variety of methodological approaches are represented, including single-neuron recordings, fMRI and optical imaging, psychophysics, eye movement characterization and computational modelling. The contributions will provide the reader with a valuable perspective on the current status of vision research, and more importantly, with critical insight into future research directions and the discoveries yet to come. · Provides a detailed breakdown of the neural and psychophysical bases of Perception · Presents never-before-published original discoveries · Includes multiple full-color illustrations
Download or read book Developing and Applying Biologically Inspired Vision Systems Interdisciplinary Concepts written by Pomplun, Marc and published by IGI Global. This book was released on 2012-11-30 with total page 447 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This book provides interdisciplinary research that evaluates the performance of machine visual models and systems in comparison to biological systems, blending the ideas of current scientific knowledge and biological vision"--
Download or read book Hierarchical Object Representations in the Visual Cortex and Computer Vision written by Antonio Rodríguez-Sánchez and published by Frontiers Media SA. This book was released on 2016-06-08 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past 40 years, neurobiology and computational neuroscience has proved that deeper understanding of visual processes in humans and non-human primates can lead to important advancements in computational perception theories and systems. One of the main difficulties that arises when designing automatic vision systems is developing a mechanism that can recognize - or simply find - an object when faced with all the possible variations that may occur in a natural scene, with the ease of the primate visual system. The area of the brain in primates that is dedicated at analyzing visual information is the visual cortex. The visual cortex performs a wide variety of complex tasks by means of simple operations. These seemingly simple operations are applied to several layers of neurons organized into a hierarchy, the layers representing increasingly complex, abstract intermediate processing stages. In this Research Topic we propose to bring together current efforts in neurophysiology and computer vision in order 1) To understand how the visual cortex encodes an object from a starting point where neurons respond to lines, bars or edges to the representation of an object at the top of the hierarchy that is invariant to illumination, size, location, viewpoint, rotation and robust to occlusions and clutter; and 2) How the design of automatic vision systems benefit from that knowledge to get closer to human accuracy, efficiency and robustness to variations.
Download or read book Twin Mechanisms Rapid Scene Recognition Involves Both Feedforward and Feedback Processing written by Xukun Zhang and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The low spatial frequency (LSF) component of visual stream rapidly conveyed coarse information for global perception, while the high spatial frequency (HSF) component delivered fine-grained information for detailed analyses. Early feedforward theorists deemed that a coarse-to-fine process was sufficient for a rapid scene recognition. However, some researchers discovered some early local recurrent processing in the primary visual cortex. Based on the response priming paradigm, the present study aimed to deeply explore how different spatial frequency interacted each other in the process of rapid scene recognition. Resulted from rapid recognition of prime scenes, Experiment 1 revealed a typical response priming effect. But in Experiment 2, when the HSF and the LSF components of the same pictures were presented in a rapid sequence, neither the LSF-to-HSF sequence nor the HSF-to-LSF sequence reproduced the response priming effect. These results demonstrated that LSF or HSF component alone was not sufficient for rapid scene recognition and, further, the integration of different spatial frequency needed some early feedback loops.
Download or read book Feedback Systems written by Karl Johan Åström and published by Princeton University Press. This book was released on 2021-02-02 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The essential introduction to the principles and applications of feedback systems—now fully revised and expanded This textbook covers the mathematics needed to model, analyze, and design feedback systems. Now more user-friendly than ever, this revised and expanded edition of Feedback Systems is a one-volume resource for students and researchers in mathematics and engineering. It has applications across a range of disciplines that utilize feedback in physical, biological, information, and economic systems. Karl Åström and Richard Murray use techniques from physics, computer science, and operations research to introduce control-oriented modeling. They begin with state space tools for analysis and design, including stability of solutions, Lyapunov functions, reachability, state feedback observability, and estimators. The matrix exponential plays a central role in the analysis of linear control systems, allowing a concise development of many of the key concepts for this class of models. Åström and Murray then develop and explain tools in the frequency domain, including transfer functions, Nyquist analysis, PID control, frequency domain design, and robustness. Features a new chapter on design principles and tools, illustrating the types of problems that can be solved using feedback Includes a new chapter on fundamental limits and new material on the Routh-Hurwitz criterion and root locus plots Provides exercises at the end of every chapter Comes with an electronic solutions manual An ideal textbook for undergraduate and graduate students Indispensable for researchers seeking a self-contained resource on control theory
Download or read book Vision From Neurons to Cognition written by C. Casanova and published by Gulf Professional Publishing. This book was released on 2001-10-25 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt: Internationally renowned researchers discuss how the various parts of the brain process and integrate visual signals, providing up to date original findings, reviews, and theoretical proposals on visual processing. This book addresses the basic mechanisms of visual perception as well as issues such as neuronal plasticity, functional reorganization and recovery, residual vision, and sensory substitution. Knowledge of the basic mechanisms by which our brain can analyze, reconstruct, and interpret images in the external world is of fundamental importance for our capacity to understand the nature and causes of visual deficits, such as those resulting from ischemia, abnormal development, neuro-degenerative disorders, and normal aging. It is also essential to our goal of developing better therapeutic strategies, such as early diagnosis, visual training, behavioral rehabilitation of visual functions, and visual implants.
Download or read book Looking and Acting written by Michael Land and published by Oxford University Press. This book was released on 2009-07-30 with total page 283 pages. Available in PDF, EPUB and Kindle. Book excerpt: How do our eyes process and communicate the data needed for us to negotiate the world around us? This book exploits recent technological advances in eye tracking systems to present a state-of-the-art account of human vision. It explores practical implications, for example in driving, playing sports, and ergonomics.
