Download or read book Encoding Visual Features by Parallel Ganglion Cell Initiated Pathways in the Healthy Diseased and Artificial Retina written by Béla Völgyi and published by Frontiers Media SA. This book was released on 2019-10-16 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: Photons are sensed by retinal photoreceptors whose matrix-like distribution underlies the transformation of illumination patterns of the visual scene into photoreceptor activity patterns in a visuotopic fashion. Activity of neighboring photoreceptors then are compared by secondary bipolar cells to decipher information regarding luminosity- and color-contrast. Bipolar cells achieve this by comparing signals received directly from their center receptive field with those come from spatially offset surrounding receptive field areas mediated by inhibitory, sign-inverting horizontal cells. This information is ultimately sent to retinal ganglion cells, the output neurons of the retina. In addition to the excitatory bipolar cell inputs, spatial and temporal features of ganglion cell activation are robustly modified by inner retinal amacrine cells through inhibitory chemical and/or excitatory electrical synaptic inputs. Ganglion cells sample various bipolar cell subtypes in their dendritic field and utilize collected inputs to generate a spike output code on luminosity-contrast, color-contrast, object motion, background motion, motion direction, changes in background illumination in a subtype specific manner. Ganglion cells in each subtype cover the retinal surface economically, thus collective information across the population provide a feature pattern and through time a feature movie to the brain. Some of these movies are utilized for image perception, whereas others are sent to accessory visual brain centers to control eye-movement, pupil contraction or circadian entrainment. A large body of information has been revealed in the past decade regarding this field, however much of the details still remain unknown or even enigmatic, including: (i) the precise description of neural circuits that serve each ganglion cell subtype to generate a specific feature movie; (ii) the estimation of the number of various ganglion cell subtypes that partake in image forming and non-image forming signaling towards the brain; (iii) the description of changes in the inputs, morphology and signaling of retinal ganglion cells when the tissue is under stress or undergoes disease related degenerative processes; (iv) the comparison of ganglion cell classes with those of the human retina and finally, (v) the practical use of all the above information to establish retina inspired visual algorithms to suit computer, drone and/or robotic vision. Therefore, research articles in this issue were collected to touch upon each of these topics and highlight recent advances of the related field.
Download or read book Parallel Processing in the Visual System written by Jonathan Stone and published by Springer Science & Business Media. This book was released on 2013-03-08 with total page 439 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the mid-sixties, John Robson and Christina Enroth-Cugell, without realizing what they were doing, set off a virtual revolution in the study of the visual system. They were trying to apply the methods of linear systems analysis (which were already being used to describe the optics of the eye and the psychophysical performance of the human visual system) to the properties of retinal ganglion cells in the cat. Their idea was to stimulate the retina with patterns of stripes and to look at the way that the signals from the center and the antagonistic surround of the respective field of each ganglion cell (first described by Stephen Kuffier) interact to generate the cell's responses. Many of the ganglion cells behaved themselves very nicely and John and Christina got into the habit (they now say) of calling them I (interesting) cells. However. to their annoyance, the majority of neurons they recorded had nasty, nonlinear properties that couldn't be predicted on the basis of simple summ4tion of light within the center and the surround. These uncoop erative ganglion cells, which Enroth-Cugell and Robson at first called D (dull) cells, produced transient bursts of impulses every time the distribution of light falling on the receptive field was changed, even if the total light flux was unaltered.
Download or read book Understanding Modulatory Computations in Neural Pathways of the Retina written by Neda Nategh and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The retina performs multiple simultaneous processing operations on the visual scene using a network of only five basic cell types, but more than fifty subtypes. Like many higher order sensory neurons, retinal ganglion cells integrate input through multiple parallel pathways that are influenced by diverse populations of inhibitory interneurons, nearly all of which have unknown function. Understanding the specific contributions of interneuron pathways is difficult because it requires a quantitative model that includes both the interneuron's input, its output, and its effects on other sensory inputs. Here we present an experimental and computational approach to discover all of these relationships together. We studied the visual computations performed by amacrine cells, a class of inhibitory interneuron. Like inhibitory interneurons in other neural circuits, amacrine cells are highly diverse in their physiology and occupy distinct anatomical layers. To measure how the signals transmitted through individual sustained amacrine cells contribute to retinal output, we presented white noise visual stimuli to the intact, isolated salamander retina. We recorded intracellularly from and injected current into single amacrine cells while recording spiking activity from the ganglion cell population of the salamander retina using a multielectrode array. In this way, many simultaneous paired recordings were performed. To characterize the contribution of the amacrine cell, we first characterized the amacrine cell preferred stimulus feature. Then using the method of Spike-Triggered Covariance (STC), we measured the response of ganglion cells to the subspace of stimuli that was different from the amacrine preferred feature. Using this method, we were able to characterize both modulatory and additive effects of the amacrine pathway on other features encoded by the ganglion cell. We found great diversity in functional effects of amacrine cells, consisting of the linear effect in which amacrine pathway contributes in building the receptive field of the ganglion cell, and nonlinear effects in which amacrine pathway modulates the ganglion cell's response function for other visual features. Our analysis indicates that the amacrine cell population defines a context that modulates the multiple features conveyed by the ganglion cell. Because modulation occurs throughout the nervous system, our approach provides a general strategy to understand the functional contributions of specific neurons to computations in a complex circuit.
Download or read book Circuit Mechanisms Underlying the Encoding of Ethologically Relevant Visual Stimuli in the Retina written by Maxwell H. Turner and published by . This book was released on 2017 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the human retina, the axons of roughly 106 retinal ganglion cells (RGCs) carry all of the information underlying visual perception and visually guided behavior. RGC computation is the last processing step before the imposition of this sensory bottleneck. Because of the importance of RGC computation for visual function and because of the accessibility of the retina to physiological investigation, RGCs are among the best studied class of early sensory neurons. Many decades of investigation using artificial visual stimuli (e.g. spots, gratings, white noise etc.) has revealed a great deal about the physiology of RGCs, the computations they can perform, and the circuitry underlying these computations. What is lacking, however, is an understanding of RGC computation and encoding during natural visual stimulation. A complete understanding of RGC function requires extending what we have learned using artificial, mostly static visual stimuli to the dynamic and spatially structured conditions that characterize natural vision. A major focus of the thesis presented here is to begin to bridge this gap. In Chapter 2 I will review some of what is known about how neural circuits in the early visual system encode naturalistic visual inputs. In Chapters 3 & 4 I will present work that connects a ubiquitous concept in early visual processing - the receptive field - to the encoding of natural visual stimuli in the retina. Classical models of the retinal ganglion cell (RGC) receptive field assume linear integration across visual space, and this assumption guides most modern day models that aim to predict RGC responses to visual stimulation. I show that spatial nonlinearities can be important for encoding spatial contrast within a natural scene. Furthermore, we can use what we know about nonlinear receptive field structure to improve models of RGCs. Finally, I show that spatial contrast encoding by RGCs can be modulated by visual context. Regardless of the stimulus being encoded, a fundamental limit to the fidelity with which sensory information can be encoded is the variability of neural responses. Repeated presentations of the same stimulus will elicit variable responses from a single neuron. Noise is a feature of neural population responses as well, and in practice it is often found that this noise is correlated within a population. In Chapter 5, I will present a strategy used by retinal circuits to minimize the effect of noise on the encoding of a behaviorally-relevant feature of the visual world - namely an object's direction of motion.
Download or read book Visual Encoding in the Human Retina written by Katja Reinhard and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Lista de corresponsales written by and published by . This book was released on 1925 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Visual System of Fish written by Ron Douglas and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 531 pages. Available in PDF, EPUB and Kindle. Book excerpt: A question often asked of those of us who work in the seemingly esoteric field of fish vision is, why? To some of us the answer seems obvious - how many other visual scientists get to dive in a tropical lagoon in the name of science and then are able to eat their subjects for dinner? However, there are better, or at least scientifically more acceptable, reasons for working on the visual system of fish. First, in terms of numbers, fish are by far the most important of all vertebrate classes, probably accounting for over half (c. 22 000 species) of all recognized vertebrate species (Nelson, 1984). Furthermore, many of these are of commercial importance. Secondly, if one of the research aims is to understand the human visual system, animals such as fish can tell us a great deal, since in many ways their visual systems, and specifically their eyes, are similar to our own. This is fortunate, since there are several techniques, such as intracellular retinal recording, which are vital to our understanding of the visual process, that cannot be performed routinely on primates. The cold blooded fish, on the other hand, is an ideal subject for such studies and much of what we know about, for example, the fundamentals of information processing in the retina is based on work carried out on fish (e. g. Svaetichin, 1953).
Download or read book Cell Based Therapy for Degenerative Retinal Disease written by Marco A. Zarbin and published by Springer. This book was released on 2019-03-01 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses why specific diseases are being targeted for cell-based retinal therapy, what evidence exists that justifies optimism for this approach, and what challenges must be managed in order to bring this technology from the laboratory into routine clinical practice. There are a number of unanswered questions (e.g., surgical approach to cell delivery, management of immune response, optimum cell type to transplant) that very likely are not going to be answered until human trials are undertaken, but there is a certain amount of “de-risking” that can be done with preclinical experimentation. This book is essential reading for scientists, clinicians, and advanced students in stem cell research, cell biology, and ophthalmology.
Download or read book Biophysics and Neurophysiology of the Sixth Sense written by Nima Rezaei and published by Springer. This book was released on 2019-04-26 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multiple senses, like multiple intelligences, are a key to brain variability and therefore human evolution. Besides the traditional five senses (vision, olfaction, gustation, audition, and somatosensory), humans can also perceive the body’s own position (the sense of proprioception) and movement (the vestibular sense). Interoception is the feeling one has about the internal physiological conditions of the entire body. Additionally there is a sense of intuition, also known as the sixth sense. Despite their best efforts, researchers are still unable to concur in specifying the nature of the sixth sense; some consider the sense of proprioception as the sixth sense, whereas others prefer to consider that as a part of interoception. This book will provide a scientific system for the human sixth sense using relevant biophysical and neurophysiological evidence. The power of “sixth sense” seems to be underestimated, due to difficulties in defining the concept clearly. According to socioeconomics and neural physics, the sixth sense is that which permits humans to create perception or to enhance the quality of their perception of events. Roughly speaking, the sixth sense engages a metacognitive process through which prior knowledge and the information received from other sensory modalities are synergized. It is not restricted to specific arrow of time and type of mind or to the observer’s body, but it considers all arrows of time (past, present, future), types of mind (conscious and unconscious), and physical bodies (self and other). However it is expected that the observer has specific biases towards what happens now or would happen in the future and its relation to himself. Particularly, humans appeal to the sixth sense on the road to achieving success in social competitions and to reduce uncertainty in complex decision making processes. In addition to evidence linking genetic components to the sixth sense submodalities, there have been developed strategies for increasing the quality of perceptions provided by the sixth sense. Meditation, through which individuals try to be detached from the world, increases gamma-band activity and that increased gamma-band activity is found following top-down processing. Therefore it can be inferred that the detachment from the environment may enhance synchronization of the wave functions in favor of strengthening the sixth sense. It can serve as the mechanism of enhancement of the sixth sense in those whose sensory systems are intact, it can also serve as the mechanism of compensation in those who have sensory deficiencies. In the latter case, it in fact encourages creativity in the use of relatively strong senses. This justifies Beethoven's deafness and his great musical creativity or Bramblitt's blindness and his enormous capability to paint and many other similar examples. In summary, the present book is divided into five parts. Part 1 (chapters 1-6) provides information about the system of proprioception and its neurophysiology and biophysics. Part 2 (chapters 7-10) examines the system of interoception. The information provided in these two parts would enable us to move towards the next three parts of the story, aimed at developing a scientific system of the sixth sense. The first chapter of part 3 begins with concepts and uses them to arrive at reasonable conclusion that there must be a sense that requires multistep information processing and that is separate from the sense of proprioception and the sense of interoception. Such sense is commonly known as the sixth sense. However it should be re-numbered because the sense of proprioception is already known as the sixth sense. The second chapter of this part is to draw neurocircuitry that innervates the sixth sense in the mind of a man, while the third chapter would address the questions whether the sixth sense system requires an optimal competence or consciousness of mind to function properly and if so which is the optimal state: conscious or unconscious and competence or incompetence. In the fourth chapter of this part, we will focus on the self-other mergence as a pivotal step of the sixth sense system. The next chapter would be of great interest to neurobiologists. It talks about that the human sixth sense of the unseen world, either the unseen arrow of time or the unseen events, requires creativity and therefore the human sixth sense should be considered a source of creativity, variability and thus evolution. In the sixth chapter, the sixth sense is viewed as an economic activity stimulated by social environments. This chapter arisen from the fact that humans are full of enthusiasm to heighten their sixth sense and its accuracy and that they owe their enthusiasm largely to achieving the best possible profit and in other words to wining intense competitions in their life holds mainly on the concept of elasticity. Finally this part is finished by an amazing discussion on the art of the sixth sense. The first chapter of part 4 discusses physical theories that support the existence of sixth sense in the universe. The next chapter is to apply the Bayes’ theory to the sixth sense, leading to the conclusion that the sixth sense improves multisensory integration through optimizing uncertainty of information received from other sensory modalities. Chapter three in this part would address whether relative timing is applicable to the sixth sense like other senses. The last part of book aimed at directly discussing the sixth sense into the context of human health and behavior is organized into four chapters. The first chapter is to discuss neurodevelopmental changes in the sixth sense, while the second and third ones will discuss that in relation to psychiatric and neurological disorders. The most striking question how much power the sixth sense the sixth sense have over human health and behavior is addressed in the fourth chapter of this part and final chapter of book, which will be prepared using neural network models and sophisticated portraits possible for the system of sixth sense.
Download or read book Astrocytes in Patho Physiology of the Nervous System written by Vladimir Parpura and published by Springer Science & Business Media. This book was released on 2008-12-11 with total page 701 pages. Available in PDF, EPUB and Kindle. Book excerpt: Astrocytes were the original neuroglia that Ramón y Cajal visualized in 1913 using a gold sublimate stain. This stain targeted intermediate filaments that we now know consist mainly of glial fibrillary acidic protein, a protein used today as an astrocytic marker. Cajal described the morphological diversity of these cells with some ast- cytes surrounding neurons, while the others are intimately associated with vasculature. We start the book by discussing the heterogeneity of astrocytes using contemporary tools and by calling into question the assumption by classical neuroscience that neurons and glia are derived from distinct pools of progenitor cells. Astrocytes have long been neglected as active participants in intercellular communication and information processing in the central nervous system, in part due to their lack of electrical excitability. The follow up chapters review the “nuts and bolts” of ast- cytic physiology; astrocytes possess a diverse assortment of ion channels, neu- transmitter receptors, and transport mechanisms that enable the astrocytes to respond to many of the same signals that act on neurons. Since astrocytes can detect chemical transmitters that are released from neurons and can release their own extracellular signals there is an increasing awareness that they play physiological roles in regulating neuronal activity and synaptic transmission. In addition to these physiological roles, it is becoming increasingly recognized that astrocytes play critical roles during pathophysiological states of the nervous system; these states include gliomas, Alexander disease, and epilepsy to mention a few.
Download or read book Recent Advances In Retinal Degeneration written by Robert E. Anderson and published by Springer Science & Business Media. This book was released on 2007-12-03 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt: The product of perhaps the most important research meeting in the field, this essential text outlines all the latest research in retinal degeneration. Culled from the proceedings of the International Symposium on the subject, the topics in this volume explore the etiology, cellular mechanisms, epidemiology, models and potential therapeutic measures for the blinding diseases of retinitis pigmentosa and age-related macular degeneration. A must-read for researchers in the field.
Download or read book Artificial Intelligence in Medical Imaging written by Erik R. Ranschaert and published by Springer. This book was released on 2019-01-29 with total page 373 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a thorough overview of the ongoing evolution in the application of artificial intelligence (AI) within healthcare and radiology, enabling readers to gain a deeper insight into the technological background of AI and the impacts of new and emerging technologies on medical imaging. After an introduction on game changers in radiology, such as deep learning technology, the technological evolution of AI in computing science and medical image computing is described, with explanation of basic principles and the types and subtypes of AI. Subsequent sections address the use of imaging biomarkers, the development and validation of AI applications, and various aspects and issues relating to the growing role of big data in radiology. Diverse real-life clinical applications of AI are then outlined for different body parts, demonstrating their ability to add value to daily radiology practices. The concluding section focuses on the impact of AI on radiology and the implications for radiologists, for example with respect to training. Written by radiologists and IT professionals, the book will be of high value for radiologists, medical/clinical physicists, IT specialists, and imaging informatics professionals.
Download or read book Guide to Research Techniques in Neuroscience written by Matt Carter and published by Academic Press. This book was released on 2022-03-26 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modern neuroscience research is inherently multidisciplinary, with a wide variety of cutting edge new techniques to explore multiple levels of investigation. This Third Edition of Guide to Research Techniques in Neuroscience provides a comprehensive overview of classical and cutting edge methods including their utility, limitations, and how data are presented in the literature. This book can be used as an introduction to neuroscience techniques for anyone new to the field or as a reference for any neuroscientist while reading papers or attending talks. Nearly 200 updated full-color illustrations to clearly convey the theory and practice of neuroscience methods Expands on techniques from previous editions and covers many new techniques including in vivo calcium imaging, fiber photometry, RNA-Seq, brain spheroids, CRISPR-Cas9 genome editing, and more Clear, straightforward explanations of each technique for anyone new to the field A broad scope of methods, from noninvasive brain imaging in human subjects, to electrophysiology in animal models, to recombinant DNA technology in test tubes, to transfection of neurons in cell culture Detailed recommendations on where to find protocols and other resources for specific techniques "Walk-through" boxes that guide readers through experiments step-by-step
Download or read book Generation of Neurons and Their Integration in Pre Existing Circuits in the Postnatal Brain Signalling in Physiological and Regenerative Contexts written by Helena Mira and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contact.
Download or read book Retinal Degenerations written by Matthew M. LaVail and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 458 pages. Available in PDF, EPUB and Kindle. Book excerpt: The topics in this volume explore the etiology, cellular mechanisms, epidemiology, genetics, models and potential therapeutic measures for the blinding diseases of retinitis pigmentosa and age-related macular degeneration. Special focus is highlighted in the areas of Mechanisms of Photoreceptor Degeneration and Cell Death (extremely important because very little is known how or why photoreceptors die in these diseases, despite an abundance of genetic information), Age-Related Macular Degeneration (with several novel approaches to its analysis), Usher Syndrome (the most severe form of retinitis pigmentosa, which includes an early or congenital loss of hearing along with blindness), and Gene Therapy. In addition, the section on Basic Science Related to Retinal Degeneration is particularly strong with several laboratories reporting on new discoveries in the area of outer segment phagocytosis, a key component of photoreceptor-retinal pigment epithelial cell interactions in normal and degenerating retinas.
Download or read book A Guide to Human Gene Therapy written by Roland W. Herzog and published by World Scientific. This book was released on 2010 with total page 415 pages. Available in PDF, EPUB and Kindle. Book excerpt: 1. Non-viral gene therapy / Sean M. Sullivan -- 2. Adenoviral vectors / Stuart A. Nicklin and Andrew H. Baker -- 3. Retroviral vectors and integration analysis / Cynthia C. Bartholomae [und weitere] -- 4. Lentiviral vectors / Janka Matrai, Marinee K.L. Chuah and Thierry VandenDriessche -- 5. Herpes simplex virus vectors / William F. Goins [und weitere] -- 6. Adeno-Associated Viral (AAV) vectors / Nicholas Muzyczka -- 7. Regulatory RNA in gene therapy / Alfred. S. Lewin -- 8. DNA integrating vectors (Transposon, Integrase) / Lauren E. Woodard and Michele P. Calos -- 9. Homologous recombination and targeted gene modification for gene therapy / Matthew Porteus -- 10. Gene switches for pre-clinical studies in gene therapy / Caroline Le Guiner [und weitere] -- 11. Gene therapy for central nervous system disorders / Deborah Young and Patricia A. Lawlor -- 12. Gene therapy of hemoglobinopathies / Angela E. Rivers and Arun Srivastava -- 13. Gene therapy for primary immunodeficiencies / Aisha Sauer, Barbara Cassani and Alessandro Aiuti -- 14. Gene therapy for hemophilia / David Markusic, Babak Moghimi and Roland Herzog -- 15. Gene therapy for obesity and diabetes / Sergei Zolotukhin and Clive H. Wasserfall -- 16. Gene therapy for Duchenne muscular dystrophy / Takashi Okada and Shin'ichi Takeda -- 17. Cancer gene therapy / Kirsten A.K. Weigel-Van Aken -- 18. Gene therapy for autoimmune disorders / Daniel F. Gaddy, Melanie A. Ruffner and Paul D. Robbins -- 19. Gene therapy for inherited metabolic storage diseases / Cathryn Mah -- 20. Retinal diseases / Shannon E. Boye, Sanford L. Boye and William W. Hauswirth -- 21. A brief guide to gene therapy treatments for pulmonary diseases / Ashley T. Martino, Christian Mueller and Terence R. Flotte -- 22. Cardiovascular disease / Darin J. Falk, Cathryn S. Mah and Barry J. Byrne
Download or read book The Structure of the Retina written by Santiago Ramón y Cajal and published by . This book was released on 1972 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt:
