Download or read book Analysis of Spatial Overlap Between ON and Off Areas in Neurons of the Primary Visual Cortex of Macaques written by Mario Luis Mata and published by . This book was released on 2005 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analysis of Spatial Overlap Between on and Off Areas in Neurons of the Primary Visual Cortex written by Mario Luis Mata and published by . This book was released on 2006 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Functional Anatomy of Visual Processing in the Cerebral Cortex of the Macaque written by Koen Nelissen and published by Leuven University Press. This book was released on 2006 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, we examined the monkey cortical regions involved in processing of color, visual motion information, and the recognition of actions done by others. The aim was to gain better insight in the functional organization of the monkey visual cortex using in-house developed functional imaging techniques. Two different functional imaging techniques were used in these studies, the double-label deoxyglucose technique (DG) and functional magnetic resonance imaging (fMRI) in the awake monkey (Chapter 2). Both techniques allow to obtain an overview of stimulus-related neural activity throughout the whole brain, integrated over a limited amount of time. The results of the color experiments (Chapter 3) clearly showed that color related information is processed within a group of areas belonging to the ventral stream, which is involved in the perception of objects. Color-related metabolic activity was observed in visual areas V1, V2, V3, V4 and inferotemporal cortex (area TEO and TE). These findings set to rest the longstanding controversial claims that color would be processed almost selectively in one extrastriate visual area (V4) (Zeki SM, Brain Res 1973 53: 422-427). These results also show the usefulness of whole brain functional mapping techniques, as a complimentary approach to single cell measurements. In Chapter 4, we investigated which regions in the superior temporal sulcus (STS) of the monkey are involved in the analysis of motion. While the caudal part of the STS has been studied extensively, including area MT/V5 and MST, little is known about motion sensitivity in more anterior-ventral STS regions. Using fMRI, we were able to localize and delineate six different motion sensitive regions in the STS. One of these regions, that we termed 1st (lower superior temporal), had not been described so far. We were able to further characterize the six motion sensitive regions, using a wide variety of motion-sensitivity tests. The results of the latter tests suggested that motion related information might be processed along a second pathway within the STS, in addition to the MT-MST path (which is involved in the perception of heading). This second pathway, which includes the more rostral motion sensitive STS regions (FST, 1st and STPm) is possibly involved in the visual processing of biological movements (movements of animate objects) and actions. Finally, we investigated how and where in the monkey brain visual information about actions done is processed (Chapter 5 and 6). We found (Chapter 5) that, in agreement with earlier single unit results, the observation of grasping movements activates several regions in the premotor cortex of the monkey. Remarkable is that these premotor regions predominantly have a motor function, coding different types of higher order motor acts (for instance grasping of an object). These results are in agreement with earlier suggestions that we are able to understand actions done by others, because observation of a particular motor act activates our own motor representation of the same act. Furthermore, these studies suggested that within the frontal cortex of the monkey, there is a distinction between context-dependent (a person grasping) and more abstract (a hand grasping) action representations. In Chapter 6 we studied two other regions which are involved in the processing of visual information of actions done by others, the superior temporal sulcus (STS) and the parietal cortex. In the parietal cortex, we found a similar distinction between context-dependent and more abstract action representations as observed in prefrontal cortex. These results suggest that the parietal cortex is not only involved in the visual control of action planning, but also in the visual processing of actions performed by others. Based upon anatomical connections between the STS, parietal and frontal regions and motion-, form- and action-related functional properties of the former regions, we tentatively suggest how information about actions done by others might be sent from the STS to the frontal cortex along three different pathways. The latter working hypothesis will be tested in the future by additional fMRI control experiments and by combining fMRI, inactivation and microstimulation experiments while monkeys perform grasping tasks and/or view actions performed by others.
Download or read book The Role of Macaque V1 Neurons in Spatiochromatic Processing and Behavior written by Abhishek De and published by . This book was released on 2020 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vision is critical for survival. We can easily identify objects, guide actions, and avoid collisions if our eyes are open but these abilities are severely impaired if our eyes are closed. This tremendous feat of vision appears simplistic but is implemented by complex biological processes performed by the eye and brain. Therefore, a central goal in visual neuroscience is to understand how neurons in the brain represent scenes, and how the neural activity in turn helps guide behavior. Scenes are composed of spatial and chromatic variations, herein referred to as spatiochromatic variations. In the primary visual cortex (V1) of macaque monkeys, some neurons jointly analyze edges and color, making them an ideal substrate for understanding human spatiochromatic vision. Double-opponent (DO) cells in V1 respond strongly to adjacently placed lights of opposite color and weakly to spatially uniform light of one color. These properties make them well suited for processing of color across space. However, we do not know precisely what information DO cells represent and how. Understanding how DO cells function will advance the field of visual neuroscience in three ways. First, it will help us understand how DO cells are connected to other neurons, thereby shedding light on the organization of cells in V1. Second, it will help link the neuronal responses to behavioral phenomena in color vision. Third, it will advance mathematical models of visual processing that will guide research in other fields. How information about scenes is used for behavior is incomplete without understanding the link between neural activity and behavior. A mechanistic understanding of how V1 neural activity impacts visual perception will be important for understanding the role of V1 in diseases and designing brain-machine interfaces. Using a combination of electrophysiological measurements, monkey behavior and state-of-the-art techniques, I investigated the role of V1 DO cells in the spatiochromatic processing of light, and the role of V1 neural activity in visual perception. I compared my findings about DO cells to simple cells--the best understood functional cell type in V1 that represent oriented luminance edges in scenes, and integrate signals across space roughly linearly. I pursued my research in the form of three different projects, and I report the key findings from each of the projects below. In project 1, I investigated the representation of edges by DO cells. I found that DO cells represent chromatic edges the same way as simple cells represent luminance edges. In project 2, I investigated how DO cells integrate color signals across space. I found that DO cells integrate spatial signals as linearly as simple cells meaning that both these classes of neurons simply weigh and sum the incoming light to generate a spiking response. In interpreting this result, it is important to realize that linearity is not the default mode of visual neurons but rather implies a specialized wiring. My results suggest that the specialized wiring creates linear luminance edge detectors and chromatic edge detectors in V1. Together, the results from project 1 and project 2 suggest that DO cells are similar to simple cells in many ways, and these classes of neurons have a similar mechanism of processing edges than previously thought. This property has major implications in understanding the neural circuitry of these cell classes and their contributions to image processing, which I discuss in Chapters 2 & 3. In project 3, I investigated the impact of silencing neural activity on behavior by pioneering a fast and powerful neural inactivation technique in monkey cortex. The advantage of this technique is that the neural inactivation can be reversed on a trial-by-trial basis, which was difficult to achieve previously. Inactivation of V1 led to reduced sensitivity for visual detection by monkeys suggesting that V1 neural activity impacts visual perception. This result opens doors for possible therapeutic treatments of visual impairments and investigations of many outstanding questions in the domain of perception, action and cognition, which I discuss in Chapter 4. Collectively, my research has made important strides in the field of visual neuroscience by advancing our understanding of spatiochromatic processing by DO cells, and the impact of V1 neural activity on visual perception.
Download or read book Brain Warping written by Arthur W. Toga and published by Elsevier. This book was released on 1998-11-17 with total page 401 pages. Available in PDF, EPUB and Kindle. Book excerpt: Brain Warping is the premier book in the field of brain mapping to cover the mathematics, physics, computer science, and neurobiological issues related to brain spatial transformation and deformation correction. All chapters are organized in a similar fashion, covering the history, theory, and implementation of the specific approach discussed for ease of reading. Each chapter also discusses the computer science implementations, including descriptions of the programs and computer codes used in its execution. Readers of Brain Warping will be able to understand all of the approaches currently used in brain mapping, incorporating multimodality, and multisubject comparisons.Key Features* The only book of its kind* Subject matter is the fastest growing area in the field of brain mapping* Presents geometrically-based approaches to the field of brain mapping* Discusses intensity-based approaches to the field of brain mapping
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 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 Specificity and Diversity of Local Connections in Macaque Primary Visual Cortex written by Atomu Sawatari and published by . This book was released on 1999 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Chromatic and Form Processing in Macaque Primary Visual Cortex written by Sylvia David Elfar and published by . This book was released on 2002 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spatiotemporal Tuning and Contrast Adaptation in Mouse Primary Visual Cortex written by Emily Elizabeth LeDue and published by . This book was released on 2012 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Mice have emerged as a popular model of cortical visual processing due to their genetic manipulability. Compared to traditional animal models of visual processing there is less research describing the visual system of mice. Before we can use the genetic techniques available in mice, we must examine the similarity between their visual processing, and that of common animal models used in vision research. One useful method to characterize the way information about form and motion is processed is to examine the interaction between selectivity for spatial and temporal frequency of sine-wave gratings in a given visual area. In experiment 1, we investigated spatiotemporal tuning in neurons of mouse primary visual cortex (V1). Tuning for stimulus speed can readily be extracted from the spatiotemporal profile of a neuron, and we were interested in whether recently described differences in the degree of speed tuning in mouse V1 and macaque V1 were due to methodology. We confirm that speed tuning is rare in mouse V1, demonstrating a difference between motion processing in the striate cortex of mice and macaques. In experiment 2, we examined the spatiotemporal dependence of contrast adaptation in mouse V1 neurons. Little is known about the underlying cellular mechanisms of contrast adaptation, so the mouse provides an attractive model in which to study this phenomenon. We characterized the spatial and temporal frequency dependence of contrast adaptation in mouse V1 neurons simultaneously using a dynamic contrast ramp. We found that for most mouse V1 neurons there was often a difference between the grating that elicited maximal firing, and the grating where adaptation was most pronounced, such that adaptation was usually stronger at higher spatial frequencies.
Download or read book Local Circuitry and Function of Deep Layer Neurons in Monkey Primary Visual Cortex written by Farran Briggs and published by . This book was released on 2003 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Understanding the Dynamics of Spatial Frequency Tuning in Macaque VI written by Christine Elizabeth Bredfeldt and published by . This book was released on 2003 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2006 with total page 848 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Neuronal Coding of Orientation in the Primary Visual Cortex of the Macaque Monkey written by Or Mendels and published by . This book was released on 2013 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Representation and Spatial Organization of Color and Orientation in Primate Primary Visual Cortex written by Anupam Kumar Garg and published by . This book was released on 2019 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: Under the longstanding model of the primate primary visual cortex (V1), color and form are processed by distinct neurons that are clustered according to cytochrome oxidase (CO) expression. Previous studies have demonstrated that there is not strict spatial segregation but have continued to support the model at single neuron level; previous studies have failed to identify neurons selective for both orientation and color that respond much more strongly to their preferred color (on an equiluminant background) than to achromatic stimuli. But previous studies have been limited in their spatial resolution and sampling of stimulus space, leaving several outstanding questions. We overcame limitations of previous studies by utilizing GCaMP6f 2-photon calcium imaging, which enabled long-term recording from large populations of neurons with single neuron resolution. We displayed a variety of stimuli, including equiluminant colored gratings and luminance-modulated achromatic gratings at a variety of orientations and spatial frequencies. We also conducted reverse correlation using cone-isolating gratings to map the cone inputs individual neurons. Finally, we aligned our calcium imaging results with intrinsic signal imaging (ISI) and postmortem histology to relate the responses of individual neurons to functional and anatomical markers, such as CO blobs. We reveal that nearly half (46.4%) of neurons in V1's superficial (cortico-cortical output) layers prefer colored to achromatic stimuli and nearly one-fifth (19.1%) respond more than twice as strongly to colored stimuli. Amongst these strongly color-preferring cells, the majority (11.6% of all cells) are also strongly orientation selective and located far from CO blobs, while the remaining color-preferring cells (7.5% of all cells) are poorly tuned for orientation and located close to CO blobs. We also reveal that cells are spatially organized according to preferred color and the sign of their dominant cone inputs. These findings demonstrate that color and form are jointly processed by a previously unreported population of neurons located predominantly in the interblobs of primate V1, indicating that early and integrated processing contributes to perception of visual objects. Observations that both cone inputs and preferred hues are systematically mapped within V1 are likely to reflect underlying organization of thalamic inputs and local circuits within V1.
Download or read book The Visual Neurosciences written by John Simon Werner and published by MIT Press. This book was released on 2004 with total page 975 pages. Available in PDF, EPUB and Kindle. Book excerpt: An essential reference book for visual science.
Download or read book The Auditory Cortex written by Jeffery A. Winer and published by Springer Science & Business Media. This book was released on 2010-12-02 with total page 711 pages. Available in PDF, EPUB and Kindle. Book excerpt: There has been substantial progress in understanding the contributions of the auditory forebrain to hearing, sound localization, communication, emotive behavior, and cognition. The Auditory Cortex covers the latest knowledge about the auditory forebrain, including the auditory cortex as well as the medial geniculate body in the thalamus. This book will cover all important aspects of the auditory forebrain organization and function, integrating the auditory thalamus and cortex into a smooth, coherent whole. Volume One covers basic auditory neuroscience. It complements The Auditory Cortex, Volume 2: Integrative Neuroscience, which takes a more applied/clinical perspective.
