College of Optometry Faculty Proceedings, Presentations, Posters, Speeches, Lectures, etc.

Title

Effects of brief unrestricted vision during early monocular form deprivation in macaque monkeys

Format

Poster

Conference Title

Society of Neuroscience Annual Meeting

Organization/Association/Group

Society of Neuroscience

Location

San Diego, California / October 23-27. 2004

Publication Date / Copyright Date

10-27-2004

Abstract

Monocular form deprivation early in life leads to a severe loss of visual sensitivity in the deprived eye (amblyopia). In this study we determined whether a few hours of unrestricted vision every day during the period of monocular form-deprivation prevents amblyopia and whether the behavioral outcome is associated with response alterations in V1 and/or V2. Seven infant macaque monkeys (Macaca mulatta) were reared with a monocular diffuser lens in front of the right eye and a clear plano lens in the left eye between 3 weeks and 4 months of age. The rearing regimen included daily unrestricted-vision for one, two or four hours. When the monkeys were about 18 months of age, spatial contrast sensitivity functions were measured for the deprived and non-deprived eyes using operant psychophysical methods. Following the behavioral testing, microelectrode-recording experiments were conducted. Monkeys that experienced 4 hours of daily unrestricted vision did not develop amblyopia, while one or two hours of unrestricted vision was less effective in preventing amblyopia. There were no significant interocular differences in the monocular spatial-filter properties of V1 or V2 neurons, even in those monkeys that exhibited the most severe amblyopia. However, in V2, but not in V1, we could not find neurons dominated by the behaviorally amblyopic eye of these severely amblyopic monkeys. In less amblyopic monkeys, there was a high prevalence of interocular suppression, which was generally stronger in neurons dominated by the amblyopic eye. These results suggest that a severe functional loss of V2 neurons dominated by the amblyopic eye is more closely associated with the neural mechanisms underlying the observed behaviorally demonstrated amblyopia than altered monocular response properties of V1 or V2 neurons.

Disciplines

Optometry

Keywords

visual cortex, development, electrophysiology, receptive field

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