This timely new volume presents broad-based and wide-ranging contributions on all aspects of vision. The material is grouped for presentation in a logical fashion in five main themes: peripheral processing; sensory integration in superior colliculus; organization of visual projections; development and plasticity; and neuronal encoding and visually guided behavior. The material spans from molecules to cognition, including overt behavior, and synaptic and membrane levels of analysis. The species studied also range over diverse phyla, while contributors too form a diverse group representing Europe, North America, and Asia. The Visually Responsive Neuron is an exciting and informative addition to the well known Progress in Brain Research series.

This timely new volume presents broad-based and wide-ranging contributions on all aspects of vision. The material is grouped for presentation in a logical fashion in five main themes: peripheral processing; sensory integration in superior colliculus; organization of visual projections; development and plasticity; and neuronal encoding and visually guided behavior.The material spans from molecules to cognition, including overt behavior, and synaptic and membrane levels of analysis. The species studied also range over diverse phyla, while contributors too form a diverse group representing Europe, North America, and Asia. The Visually Responsive Neuron is an exciting and informative addition to the well known Progress in Brain Research series.

The present volume covers the physiology of the visual system beyond the optic nerve. It is a continuation of the two preceding parts on the photochemistry and the physiology of the eye, and forms a bridge from them to the fourth part on visual psychophysics. These fields have all developed as independent speciali ties and need integrating with each other. The processing of visual information in the brain cannot be understood without some knowledge of the preceding mechanisms in the photoreceptor organs. There are two fundamental reasons, ontogenetic and functional, why this is so: 1) the retina of the vertebrate eye has developed from a specialized part of the brain; 2) in processing their data the eyes follow physiological principles similar to the visual brain centres. Peripheral and central functions should also be discussed in context with their final synthesis in subjective experience, i. e. visual perception. Microphysiology and ultramicroscopy have brought new insights into the neuronal basis of vision. These investigations began in the periphery: HARTLINE'S pioneering experiments on single visual elements of Limulus in 1932 started a successful period of neuronal recordings which ascended from the retina to the highest centres in the visual brain. In the last two decades modern electron microscopic techniques and photochemical investigations of single photoreceptors further contributed to vision research.

The invitation by the editors of the series "studies of brain function" to contribute a monograph on the visual cortex gives me the opportunity to present in a concentrated manner much of the work I have done on the visual cortical areas of cat and monkey. However, the field of visual cortical physi ology is so active and so diverse that the presentation of only my own work would have given a very incomplete view of visual cortical functioning. Therefore this monograph also reviews most of the studies carried out on the subject in the last two decades. Where possible I have tried not only to describe the cortical machinery but also its possible functional purpose regarding vision. In doing this I have expressed my personal views rather than just reviewing the experimental facts. Much of the work presented in this monograph has been supported by the National Research Council of Belgium and the Research Council of the Catholic University of Leuven. I express my gratitude to them. I have en joyed collaborating in these studies with P. O. Bishop, H. Kato, H. Kennedy, K. P. Hoffmann, H. Maes, J. Duysens, E. Vandenbussche, and H. van der Glas. I am much indebted to all those who have commented on earlier versions of this monograph: J. Allman, H. Barlow, J. BuBier, M. Callens, J. Duysens, O. J. Griisser, P. Heggelund, H. Kennedy, L. C. Orban and L. Palmer.

The brain is constantly bombarded with sensory stimuli. In order to process and perceive such diverse information streams simultaneously, the brain prioritizes information relevant to an animal's current behavioral needs. In this thesis, I investigate the neural mechanisms that enable the brain to increase or decrease visual signals depending on an animal's behavioral state. In chapter 1, I illustrate a novel mechanism, 3-5 Hz membrane potential (Vm) oscillations, that decreases the responsiveness of neurons in the primary visual cortex (V1) of mice. Using 2-photon guided whole-cell recordings as mice passive viewed and actively engaged drifting sine-wave gratings, I discovered that these visually-evoked phenomena were not influenced by changes in arousal or animal movement, but their timing was influenced by an animal's behavioral state. In addition to uncovering a novel mechanism for reducing the responsiveness of neurons in the brain, this chapter substantially furthers the field's knowledge of how behavior and arousal affect the membrane potential of neurons in the cerebral cortex. In chapter 2, I develop a method to train animals how to perform a visual attention task. I describe the hardware and software tools used to actuate the task and the method used to train the animals. Using the method outlined in this chapter, I was able to routinely train animals to perform a multimodal attention task with approximately one month of training. In chapter 3, I employed this new attention model and, using 2-photon guided whole-cell recordings in behaving animals, I discovered that attention boosts the depolarization associated with visual stimulation in layer 2/3 V1 neurons, illustrating a potential mechanism that causes neurons to be more responsive to visual cues during attention. Finally, using 128 channel silicon nanoprobes chronically implanted in V1, I verified that the attention task increased the responsiveness of V1 neurons and desynchronized the local network in mice, replicating results previously obtained in non-human primate models and setting the groundwork for future study. As a result, my thesis details novel neural mechanisms for enhancing or dampening visual signals and expands our knowledge of how the brain prioritizes information according to an animal's behavioral context.

The brain ... There is no other part of the human anatomy that is so intriguing. How does it develop and function and why does it sometimes, tragically, degenerate? The answers are complex. In Discovering the Brain, science writer Sandra Ackerman cuts through the complexity to bring this vital topic to the public. The 1990s were declared the "Decade of the Brain" by former President Bush, and the neuroscience community responded with a host of new investigations and conferences. Discovering the Brain is based on the Institute of Medicine conference, Decade of the Brain: Frontiers in Neuroscience and Brain Research. Discovering the Brain is a "field guide" to the brainâ€"an easy-to-read discussion of the brain's physical structure and where functions such as language and music appreciation lie. Ackerman examines: How electrical and chemical signals are conveyed in the brain. The mechanisms by which we see, hear, think, and pay attentionâ€"and how a "gut feeling" actually originates in the brain. Learning and memory retention, including parallels to computer memory and what they might tell us about our own mental capacity. Development of the brain throughout the life span, with a look at the aging brain. Ackerman provides an enlightening chapter on the connection between the brain's physical condition and various mental disorders and notes what progress can realistically be made toward the prevention and treatment of stroke and other ailments. Finally, she explores the potential for major advances during the "Decade of the Brain," with a look at medical imaging techniquesâ€"what various technologies can and cannot tell usâ€"and how the public and private sectors can contribute to continued advances in neuroscience. This highly readable volume will provide the public and policymakersâ€"and many scientists as wellâ€"with a helpful guide to understanding the many discoveries that are sure to be announced throughout the "Decade of the Brain."