Ocular dominance in striate cortex is altered by neonatal section of the posterior corpus callosum in the cat

Abstract

In adult cats that had previously undergone surgical section of the posterior corpus callosum at 13-18 days after birth, the striate cortex was examined using extracellular single unit recordings. The receptive fields of the cells examined were located from the vertical meridian to 39 degrees peripherally, and ranged from above to below the horizontal meridian. Cells were classified according to type (simple, complex), ocular dominance, receptive field size and location. Callosum sectioned cats had 53% of striate cells activated monocularly as compared to 25% for control cats. This increase in monocularly activated units primarily occurred for receptive fields in the paracentral region of the visual field, from 4-39 degrees. The age at which the neonatal surgery had occurred was correlated with the individual cat's proportion of monocularly activated cells. Therefore, the increase in monocular activation of striate units occurred within a large portion of the normal binocular visual field. This physiological change was partially predicted by a previous behavioral study showing a substantial loss in the extent of the binocular visual field following neonatal corpus callosum section (Elberger 1979).