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


Effects of early alternating defocus on the postnatal development of disparity sensitivity in monkey visual cortex



Conference Title

Society of Neuroscience Annual Meeting


Society of Neuroscience


New Orleans, Louisiana / November 4-9, 2000

Publication Date / Copyright Date



The postnatal development of functional binocular connections in the primary visual cortex (V1) is readily disrupted by interocularly discordant signals. In this study we determined whether early alternating defocus alters the disparity tuning functions of V1 neurons, and if so, whether the alterations are spatial-frequency dependent. A defocusing contact lens of –1.5D, -3D, or –6D was worn by macaque monkeys on alternate eyes on successive days between 3 weeks and 9 months of age. The monkeys' visual capacities were measured using behavioral testing methods prior to extracellular single-unit recording experiments in V1. Behaviorally the lens-reared monkeys showed reductions in disparity sensitivity that were spatial-frequency dependent and increased in severity with the power of the defocusing lens. The disparity sensitivity of V1 neurons in the lens-reared monkeys was reduced particularly for those units tuned to higher spatial frequencies. This effect was largest for a monkey reared with 6D defocus and smallest in a subject with 1.5D defocus. The data support the hypothesis that the disparity processing mechanisms are spatial-frequency dependent, and that sensory reductions in disparity sensitivity may reflect the constraints imposed by anomalies at the earliest stages of cortical processing for binocular signals.




binocular vision, anisometropia, stereopsis, primary visual cortex

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