Selective sparing after lesions of visual cortex in newborn kittens.

Abstract

Previous findings are discordant regarding the effects of perinatal lesions of Cortical Areas 17 and 18 on visual discrimination learning in cats. Three potential determinants of such sparing were investigated: age at lesion (4 or 181 days), age at testing (3 or 9 months), and stimulus complexity. Age at testing was not significant, but performance varied with stimulus complexity and cortical damage, and there was an interaction between stimulus complexity and age at lesion. Both operated groups were transiently impaired in discriminating objects and subsequently learned to discriminate simple 2-dimensional patterns as well as done by controls, but the lesion groups were permanently impaired in discriminating similar patterns circumscribed by irrelevant lines. The age-at-lesion groups differed, however, in discriminating patterns masked by superimposed lines. The group lesioned at 181 days was severely impaired at both acquisition and subsequent intercurrent performance; the group lesioned at 4 days was impaired only at intercurrent performance. This study suggests that sparing after early postnatal damage of Areas 17 and 18 occurs only under limited circumstances.

Learning and recall of form discriminations during reversible cooling deactivation of ventral-posterior suprasylvian cortex in the cat.

“…A two-choice Pennsylvania General Testing Apparatus (PGTA) was used for all discrimination training and testing (7,8). Detailed procedures for apparatus acclimation and training are described elsewhere (7).…”

Learning to see the trees before the forest: Reversible deactivation of the superior colliculus during learning of local and global visual features

“…For more details and an illustration, see figure 2 of Lomber et al (10). Before the initiation of these experiments all six cats were conditioned to perform discriminations in the Pennsylvania General Testing Apparatus as described in Cornwell et al (11,12), had learned and recalled more than 100 pattern or object discriminations, and performed within the normal range.…”

Vision After Early-Onset Lesions of the Occipital Cortex:II. Physiological Studies

“…Cortical lesions sustained early in life are generally believed to be better compensated than are similar lesions sustained in adulthood (see for example, Cornwell et al, 1989;Webster et al, 28 M.G. KNYAZEVA ET AI,. iii) The third is the functional recovery of extrageniculate pathways to the extrastriate visual areas (Hovda & Villablanca, 1990).…”