RESUMEN
Significant surround modulation was reported in the cortical areas corresponding to the periphery of the visual field, whereas no clear surround modulation was reported in the center. To understand the neural bases underlying the differences of the functions between the cortical areas corresponding to the center and periphery of the visual field, responses of the cells in the cat early visual cortex with their receptive fields in the center and periphery of the visual field were recorded by using multichannel electrodes, and cross-correlations of the spikes in the responses to the full-field stimuli, and the center-surround stimuli, which contained a grating in a central patch and a surround grating, were analyzed. Percentages of the cell pairs showing significant cross-correlation were larger in the cortical areas corresponding to the periphery than the center. In the center of the visual field, the percentages of the cell pairs showing significant cross-correlation significantly decreased as the separation of the recording points increased, and the time lags of the peaks of the cross-correlogram distributed around zero. In the periphery of the visual field, the time lags of the peaks of the cross-correlogram distributed more widely and increased as the separation of the recording points increased. In the responses to the center-surround stimuli in the preferred orientation of each cell, percentages of the cell pairs showing significant cross-correlation were larger in the periphery than the center. These results suggest that more lateral interactions occur in the cortical areas corresponding to the periphery than the center of the visual field.