INTEROCULAR CONTROL OF NEURONAL RESPONSIVENESS IN CAT VISUAL-CORTEX

NEURONS in the cat primary visual cortex are selective for particular contourorientations' but their responsiveness can vary under certain c onditions. After prolonged stimulation (adaptation), the contrast sens itivity of cortical cells is reduced(2-5) and the 'gain' (the strength of response as a function of contrast) falls(5-6). The response to an optimal contour is also reduced when,a different stimulus is superimp osed on the receptive field in the same eye(7-9). Here we report that the sudden appearance of aninappropriate stimulus in one eye can inter ocularly suppress the activity of cortical neurons if they are already responding to an optimally oriented stimulus in the other eye. In str abismic cats, whose cortical neurons lack binocular facilitation, even contours of similar orientation shown to the two eyes trigger such su ppression. This interocular control of cortical responsiveness could s erve to veto signals from one eye under conditions that would otherwis e cause double vision and perceptual confusion.