Effects of visual cortex removal on receptive-field properties of neurons in lateral suprasylvian visual area of the cat

Abstract

The influence of inputs from visual cortex areas 17, 18 and 19 on receptive-field properties of cells in the cat''s lateral suprasylvian visual cortex (LS area) was investigated. Aspiration lesions were made in visual cortex, and single-cell recording was carried out in the LS area a few hours to 5 wk later. The effects of removing areas 17, 18 and 19 combined, only areas 18 and 19, only area 17 or only areas 17 and 18 were assessed in an effort to determine the specific contribution of each area. Bilateral removal of areas 17, 18 and 19 produced 3 main changes in the functional properties of LS area neurons: a reduction in the proportion of cells with direction selectivity (from 81% in normal cats to 7.5% following the lesion), an increase in the proportion of cells which responded as well or better to stationary flashing stimuli as to moving stimuli (from 5% in normal cats to 44.5% following the lesion), and a reduction in the proportion of cells driven by the ipsilateral eye and a corresponding increase in the porportion of cells driven exclusively by the contralateral eye (from 33% in normal cats to 86% following the lesion). Unilateral removal of areas 17, 18 and 19 had similar effects to bilateral removal on cells in LS cortex ipsilateral to the lesion. Cells in LS cortex contralateral to a unilateral lesion appeared normal. Bilateral removal of areas 18 and 19 had no apparent effect on the response properties of LS cortex cells. Removal of inputs from area 17 is necessary to produce the changes. Bilateral removal of area 17 alone produced effects on LS cortex cells that were similar to those following removal of areas 17, 18 and 19. Bilateral removal of areas 17 and 18 produced effects on LS cortex cells that were comparable in degree to those produced by combined removal areas 17, 18 and 19. Acute visual cortex lesions made only a few hours prior to recording produced changes in LS cortex that were similar to those produced by lesions made up to 5 wk prior to recording. LS cortex neurons receive functional information for direction selectivity, response to the ipsilateral eye and suppression of responses to stationary flashing stimuli from ipsilateral visual cortex areas 17 and 18. Some LS cortex cells appear to receive the relevant functional information from area 17 alone, whereas others receive the information independently from both areas 17 and 18. The remaining functional properties of LS cortex cells are provided by the thalamic inputs.