QUANTITATIVE STUDIES OF CENTRAL VISUAL DEVELOPMENT

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The goal of this research is to uncover the neuronal mechanisms that limit the development of visual performance in primates. Recent advances in visual psychophysics and theory have made it possible to formulate questions about visual development in the same terms used to analyze adult vision, and we are conducting experiments to explore the neurobiology of development in these functional terms. To establish the critical underlying mechanisms, we recorded from neurons in LGN (the first brain nucleus that receives visual information from the eye) and primary visual cortex (V1) in newborns. We found that the degree of improvement in sensitivity and resolution of neurons in LGN was not substantial enough to account for the behaviorally measured changes. Our recordings in V1 are as yet quite preliminary, but we expect to find a greater degree of maturation in V1 than we found at the level of the LGN. We have found one potentially important immaturity in visual cortex of new borns the organization of local influences (surround influences) on V1 cells is less specific than in adults. We are working to characterize the nature and extent of this immaturity. In addition to these studies, we are studying the development of sensitivity to visual motion in primates. We find that the development of motion sensitivity is not independent of the development of spatial resolution; therefore, these functions, which were thought to be dependent on different brain mechanisms, may have shared components. FUNDING NIH grants EY02017 and RR00166. Carandini, M., Movshon, J.A., and Ferster, D. Pattern adaptation and cross-orientation interactions in the primary visual cortex. Neuropharmacology 37 501-511, 1998. Kiorpes, L., Kiper, D.C., O'Keefe, L.P., Cavanaugh, J.R., and Movshon, J.A. Neuronal correlates of amblyopia in the visual cortex of macaque monkeys with experimental strabismus and anisometropia. J. Neurosci. 18 6411-6424, 1998. Kiorpes, L. and Movshon, J.A. Peripheral and central factors limiting the development of contrast sensitivity in macaque monkeys. Vision Res. 38 61-70, 1998. Murphy, K.M., Jones, D.J., Fenstemaker, S.B., Pegado, V.D., Kiorpes, L., and Movshon, J.A. Spacing of cytochrome oxidase blobs in visual cortex of normal and strabismic monkeys. Cerebral Cortex 8 237-244, 1998. O'Keefe, L.P. and Movshon, J.A. Processing of first- and second-order motion signals by neurons in area MT of the macaque monkey. Vis. Neurosci. 15 305-317, 1998. Bair, W., Cavanaugh, J.R., and Movson, J.A. Temporal dynamics of direction selective neurons in areas MT and V1. Soc. Neurosci. Abstr. 24 1745, 1998. Cavanaugh, J.R., Bair, W., and Movshon, J.A. Signals setting contrast gain arise from iso-oriented domains aligned with the receptive field axis of macaque striate cortex neurons. Soc. Neurosci. Abstr. 24 1875, 1998. Kiorpes, L., Tang, C., and Movshon, J.A. Visual efficiency in amblyopic macaque monkeys. Perception (Suppl) 27 21, 1998. Movshon, J.A., Kiper, D.C., O'Keefe, L.P., Cavanaugh, J.R., and Kiorpes, L. Neuronal correlates ofo amblyopia in the visual cortex of macaques with experimental strabismus and anisometropia. Perception (Suppl) 27:16, 1998. O'Keefe, L.P. and Movshon, J.A. The "window of visibility" and direction tuning of STS neurons in alert macaque monkeys. Soc. Neurosci. Abstr. 24 1745, 1998. Priebe, N.J., Bair, W., Cavanaugh, J.R., Movshon, J.A., and Lisberger, S.G. Direction and speed selectivity of gain control in single neurons in macaque visual area MT. Soc. Neurosci. Abstr. 24 648, 1998. Tang, C., Kiorpes, L., and Movshon, J.A. Motion detection in amblyopic macaque monkeys. Invest. Ophthalmol. Vis. Sci. 39 S329, 1998.