Download or read book Cortical Mechanisms Underlying Low level Motion Processing in the Visual System of Human and Non human Primates written by Roger Jacques Elisabeth Bours and published by . This book was released on 2010 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Primate Visual System written by Jon H. Kaas and published by CRC Press. This book was released on 2003-07-28 with total page 439 pages. Available in PDF, EPUB and Kindle. Book excerpt: The last 20 years of research have been marked by exceptional progress in understanding the organization and functions of the primate visual system. This understanding has been based on the wide application of traditional and newly emerging methods for identifying the functionally significant subdivisions of the system, their interconnections, the
Download or read book Visual Detection of Motion written by Andrew T. Smith and published by . This book was released on 1994 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt: The brain's ability to detect movement within the retinal image is crucial not only for determining the trajectories of moving objects, but also for identifying and interpreting image motion resulting from eye and head movements. This book summarizes our knowledge of how information about image motion is encoded in the brain. Key Features * Valuable reference source for those involved in the rapidly expanding area of motion perception * Strong emphasis on integration of physiological, computation, and psychophysical approaches * Topics include: * Principles of local motion detection * Inputs to local motion detectors * Integration of motion signals * Higher-order interpretation of motion * Motion detection and eye movements
Download or read book The Primate Visual System written by Jan Kremers and published by John Wiley & Sons. This book was released on 2005-12-13 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many recent developments in the field in recording, staining, genetic and stimulation techniques, in vivo, and in vitro have significantly increased the amount of available data on the primate visual system. Written with contributions from key neurobiologists in the field, The Primate Visual System will provide the reader with the latest developments, examining the structure, function and evolution of the primate visual system. The book takes a comparative approach as a basis for studying the physiological properties of primate vision and examines the phylogenetic relationship between the visual systems of different primate species. Taken from a neurobiologist’s perspective this book provides a unique approach to the study of primate vision as a basis for further study into the human visual system. Altogether an important overview of the structure, function and evolution of the primate visual system from a neurobiologist’s perspective, written specifically for higher level undergraduate and graduate students taking courses in neuroscience, physiology, optics/ visual science, as well as a valuable read to researchers new to the field.
Download or read book Neurophysiological Aspects of Color Vision in Primates written by E Zrenner and published by . This book was released on 1982-11-01 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development and Specification of Cortical Areas in the Non Human Primate written by Clarisse Pace and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primate cerebral cortex has undergone evolutionary expansion and complexification, which is reflected by an increase in the number of cortical areas and an enlargement of the supragranular neuron layers. The developmental mechanisms involved in cortical expansion and aerial specification in primates are considered to be key factors underlying functional dynamics of the primate cortex as well as the highly developed computational abilities of the human brain. This PhD thesis seeks to refine our understanding of non human primate (NHP) cortical specification through two parallel approaches. The first part focuses on the analysis of the development of a cortical area rarely studied, the frontal cortex. Using long term live imaging with two-photon time lapse video microscopy on organotypic slices of embryonic NHP cortex as well as immunostainings experiments, we have characterized the morphology and proliferative behavior of frontal cortex progenitors. While our results point to conserved characteristics of cortical development between caudal and rostral regions of the cortex, it also reveals a differential temporal regulation of the balance between proliferative and differentiative divisions between the visual and the frontal cortex. In the second part of this work, we aimed to assess the role of thalamocortical afferents (TCA) on areal identity, focusing on their influence on cortical progenitor proliferation in the visual cortex of the embryonic NHP. A first aim was to determine the relationship between the thalamocortical pathway and the germinal zones in the visual cortex, before assessing the influence of TCA on cell cycle kinetics. Tracing experiments show that the spatiotemporal features of embryonic TCA development provide the necessary circumstances for TCA to interact with and have an influence on progenitors during corticogenesis. We provide evidence of a temporally regulated and area-specific mitogenic effect by TCA on progenitors in the embryonic visual NHP cortex. Together, the results of this PhD thesis provide new insights on area specific features of NHP corticogenesis and on the mechanisms involved in areal specification.
Download or read book Visual Motion Processing in the Human Cortex written by Alexander Christopher Huk and published by . This book was released on 2001 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Research Awards Index written by and published by . This book was released on 1987 with total page 818 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Perceiving in Depth Volume 1 Basic Mechanisms written by Ian P. Howard and published by Oxford University Press. This book was released on 2012-01-27 with total page 671 pages. Available in PDF, EPUB and Kindle. Book excerpt: The three-volume work Perceiving in Depth is a sequel to Binocular Vision and Stereopsis and to Seeing in Depth, both by Ian P. Howard and Brian J. Rogers. This work is much broader in scope than the previous books and includes mechanisms of depth perception by all senses, including aural, electrosensory organs, and the somatosensory system. Volume 1 reviews sensory coding, psychophysical and analytic procedures, and basic visual mechanisms. Volume 2 reviews stereoscopic vision. Volume 3 reviews all mechanisms of depth perception other than stereoscopic vision. The three volumes are extensively illustrated and referenced and provide the most detailed review of all aspects of perceiving the three-dimensional world. Volume 1 starts with a review of the history of visual science from the ancient Greeks to the early 20th century with special attention devoted to the discovery of the principles of perspective and stereoscopic vision. The first chapter also contains an account of early visual display systems, such as panoramas and peepshows, and the development of stereoscopes and stereophotography. A chapter on the psychophysical and analytic procedures used in investigations of depth perception is followed by a chapter on sensory coding and the geometry of visual space. An account of the structure and physiology of the primate visual system proceeds from the eye through the LGN to the visual cortex and higher visual centers. This is followed by a review of the evolution of visual systems and of the development of the mammalian visual system in the embryonic and post-natal periods, with an emphasis on experience-dependent neural plasticity. An account of the development of perceptual functions, especially depth perception, is followed by a review of the effects of early visual deprivation during the critical period of neural plasticity on amblyopia and other defects in depth perception. Volume 1 ends with accounts of the accommodation mechanism of the human eye and vergence eye movements.
Download or read book Visual motion and self motion processing in the human brain MPI Series in Biological Cybernetics Bd 31 written by Elvira Fischer and published by Logos Verlag Berlin GmbH. This book was released on 2011 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: For the successful recognition of objective, `real' motion based on visual cues it is necessary to take self-induced motion signals into account, such as those induced by eye-movements. During a series of fMRI studies we measured responses of visual and parietal regions to motion cues derived from (a) retinal motion, (b) eyemovements (visual pursuit) and (c) objective, (real) motion. We show that the recently described cingulate sulcus visual area (CSv) is not, as implied before, primarily driven by 3D self-motion cues but favoured 2D translational coherent motion over 3D expanding flow fields. Further, we found that V3A is capable of integrating retinal motion with eye-movements, thus allowing V3A to respond to object motion independent of retinal motion. This allowed us to define a new functional localizer for area V3A. Finally, we showed that activity in the foveal representation of the early visual cortex is driven by a combination of retinal input and by error signals as hypothesized by of Rao and Ballard (1999) for predictive coding. Taken together, this work provides evidence that regions V3A and CSv are key regions concerning visual self-motion processing and that early visual regions might be modulated by feedback from higher motion processing regions.
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 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 Decoding Motor Intentions from Human Brain Activity written by Jason P. Gallivan and published by . This book was released on 2011 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt: You read my mind. Although this simple everyday expression implies 'knowledge or understanding' of another's thinking, true 'mind-reading' capabilities implicitly seem constrained to the domains of Hollywood and science-fiction. In the field of sensorimotor neuroscience, however, significant progress in this area has come from mapping characteristic changes in brain activity that occur prior to an action being initiated. For instance, invasive neural recordings in non-human primates have significantly increased our understanding of how highly cognitive and abstract processes like intentions and decisions are represented in the brain by showing that it is possible to decode or 'predict' upcoming sensorimotor behaviors (e.g., movements of the arm/eyes) based on preceding changes in the neuronal output of parieto-frontal cortex, a network of areas critical for motor planning. In the human brain, however, a successful counterpart for this predictive ability and a similar detailed understanding of intention-related signals in parieto-frontal cortex have remained largely unattainable due to the limitations of non-invasive brain mapping techniques like functional magnetic resonance imaging (fMRI). Knowing how and where in the human brain intentions or plans for action are coded is not only important for understanding the neuroanatomical organization and cortical mechanisms that govern goal-directed behaviours like reaching, grasping and looking - movements critical to our interactions with the world - but also for understanding homologies between human and non-human primate brain areas, allowing the transfer of neural findings between species. In the current thesis, I employed multi-voxel pattern analysis (MVPA), a new fMRI technique that has made it possible to examine the coding of neural information at a more fine-grained level than that previously available. I used fMRI MVPA to examine how and where movement intentions are coded in human parieto-frontal cortex and specifically asked the question: What types of predictive information about a subject's upcoming movement can be decoded from preceding changes in neural activity? Project 1 first used fMRI MVPA to determine, largely as a proof-of-concept, whether or not specific object-directed hand actions (grasps and reaches) could be predicted from intention-related brain activity patterns. Next, Project 2 examined whether effector-specific (arm vs. eye) movement plans along with their intended directions (left vs. right) could also be decoded prior to movement. Lastly, Project 3 examined exactly where in the human brain higher-level movement goals were represented independently from how those goals were to be implemented. To this aim, Project 3 had subjects either grasp or reach toward an object (two different motor goals) using either their hand or a novel tool (with kinematics opposite to those of the hand). In this way, the goal of the action (grasping vs. reaching) could be maintained across actions, but the way in which those actions were kinematically achieved changed in accordance with the effector (hand or tool). All three projects employed a similar event-related delayed-movement fMRI paradigm that separated in time planning and execution neural responses, allowing us to isolate the preparatory patterns of brain activity that form prior to movement. Project 1 found that the plan-related activity patterns in several parieto-frontal brain regions were predictive of different upcoming hand movements (grasps vs. reaches). Moreover, we found that several parieto-frontal brain regions, similar to that only previously demonstrated in non-human primates, could actually be characterized according to the types of movements they can decode. Project 2 found a variety of functional subdivisions: some parieto-frontal areas discriminated movement plans for the different reach directions, some for the different eye movement directions, and a few areas accurately predicted upcoming directional movements for both the hand and eye. This latter finding demonstrates -- similar to that shown previously in non-human primates -- that some brain areas code for the end motor goal (i.e., target location) independent of effector used. Project 3 identified regions that decoded upcoming hand actions only, upcoming tool actions only, and rather interestingly, areas that predicted actions with both effectors (hand and tool). Notably, some of these latter areas were found to represent the higher-level goals of the movement (grasping vs. reaching) instead of the specific lower-level kinematics (hand vs. tool) necessary to implement those goals. Taken together, these findings offer substantial new insights into the types of intention-related signals contained in human brain activity patterns and specify a hierarchical neural architecture spanning parieto-frontal cortex that guides the construction of complex object-directed behaviors.
Download or read book High level Motion Processing written by Takeo Watanabe and published by MIT Press. This book was released on 1998 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt: The contributors to this book focus on such key aspects of motion processing as interaction and integration between locally measured motion units, structure from motion, heading in an optical flow, and second-order motion. They also discuss the interaction of motion processing with other high-level visual functions such as surface representation and attention.
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 Chromatic Influences on Motion Processing in the Primate Visual System written by Karen R. Dobkins and published by . This book was released on 1992 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Contrast invariant Orientation Tuning and Efficient Selection in Human Visual Cortex written by Min Young Lee and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The visual system is a complex network of structures that work together to process and make sense of visual information derived from the surrounding environment. This dissertation explores the challenges faced by the visual system, both externally and internally, in achieving its goal of providing a coherent perception of the visual world. Chapter 2 focuses on contrast-invariant orientation tuning, a remarkable ability of the visual system to maintain stable perception regardless of changes in stimulus contrasts. While extensively studied in non-human primates, the existence of contrast-invariant orientation tuning in human visual cortex has been uncertain. I present evidence that orientation tuning in human visual cortex remains invariant to changes in stimulus contrast. Chapter 3 investigates the neural mechanism of selective attention and its impact on contrast-discrimination behavior. By employing different task designs with varying numbers of targets, the association between the number of targets and different attention mechanisms is examined. It is demonstrated that the efficient selection mechanism is utilized when multiple targets are present, while both the efficient selection and response gain mechanisms are associated with fewer targets. Also, the efficient selection model proves to be effective in explaining the behavior in attention tasks. In investigating these mechanisms, I utilize the steady-state visual evoked potential (SSVEP) frequency tagging technique involving multiple input stimuli, which is an effective tool for studying both sensory and cognitive processes. This dissertation contributes to our understanding of how the human visual system adapts to external changes and internal demands, shedding light on the mechanisms of contrast-invariant orientation tuning and selective attention.
