Introduction: Visual cortex performs an extensive series of computations. Some of the basic features of cortical vision have been worked out on monkey models, and we expect these to generalize to human. In the monkey the visual portion of cortex can be subdivided into more than 30 distinct visual areas. These visual areas are identified by their different patterns of inputs and outputs, as well as by general features of how the neurons within these areas respond to visual stimuli. Lesions of certain visual areas are devastating to visual function, while lesions of other areas result in very modest visual deficits, as if their function can be taken over by the remaining parts of the brain Methods: A study of the color sensitivity in one of the largest and most extensive visuals areas, primary visual cortex was made. The main significance of the color results is that it is possible to make quantitative measurements of how specific areas in human cortex respond to visual stimuli. This expands the scope of fMRI from one of localizing activity to measuring the level of the activity A new set of studies were initiated on the question of plasticity in human visual cortex. We have received funding to study the cortical response of amblyopes, these are individuals whose eyeball is intact and functioning, but who have very poor vision due to degraded cortical function. Amblyopia is a failure of visual plasticity: during childhood the signals from one eye do not properly reach visual cortex either because of strabismus (lazy eye) or anisotropia (poor optics). If the failure of these signals to reach cortex is not corrected during childhood, then quality of the visual input is out of the compliance range during the years of normal development and causes reduced visual sensitivity of cortical origin. Conclusion: We have initiated a set of studies on the cortical response in amblyopes, and we have found diminished signals from the amblyopic eye. We are now analyzing the effect of these diminished signals on the cortical organization of amblyopic observers.
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