Orientation disparity and plasticity of cortical cells in kittens following surgical rotation of the eye.

We have studied the effect of surgically induced monocular rotation of the eye on cells in visual area 17 of normal kittens (N = 420 cells) and of kittens monocularly deprived (N = 296 cells) at early (1-1.5 months) or late (3 months) ages. The receptive fields of cortical neurons in monocularly deprived kittens of the early operated group were abnormal in shape, a condition which is reflected by the high proportions of cells missing orientation (46.9%) and direction (47.7%) specificity when driven through the rotated eye. In addition, many cells (46%) were visually inactive in these kittens. The proportions of the above cell groups were less pronounced in the operated kittens with binocular vision and in all late operated kittens, indicating a specific effect of the rotation itself. In the early operated kittens with binocular vision, the rotation resulted in 35.9% binocular cells in the hemisphere contralateral and 40.0% in the hemisphere ipsilateral to the rotated eye. The results for the monocularly deprived early operated kittens were 42.8% and 21.5% respectively. Thus, the rotation was effective in limiting the influence of the deprivation to only the contralateral hemisphere. The distribution of the cells in accordance with their receptive field orientations following correction for the surgical rotation shows a considerable disturbance to orientation specificity, as reflected by the wide range of angular disparities found for the binocular cells. While for three kittens (28 cells) a tendency toward the zero line was found, for four kittens (28 cells) we could not prove, it indicating that a compensation for the interocular difference surgically induced is not seen.