Cortical Plasticity as Revealed by Ocular Dominance Shift: Effects of Limited Visual Environments

摘要

Kittens were dark-reared until about 51/2 weeks of age, at which time each kitten was allowed one week of 12 hr/day monocular experience in a controlled visual environment. In most cases mean luminance of the sawdust in the conditioning cage was in the range 0.3 to 15 the mFL. In half the cases a large mobile rotated outside the cage, and spotlights were directed to illuminate the mobile. At the end of conditioning week, we recorded from cells in area 17, noting ocular dominance and other receptive field properties for each cell. Kittens which had their monocular experience alone had virtually no ocular dominance shift. If kittens were accompanied by a sibling, or a toy, or got to view their mother at a 50 cm distance, they had partial OD shifts. If the illumination were raised into the photopic realm, then socially isolated kittens also showed a partial shift. We think that the presence of the mother allows a kitten to have a greater experience of optic flow and reduces separation anxiety; these two factors are probably important for an environment in which developmental plasticity can occur in visual cortex.