Interocular suppression in cat striate cortex is not orientation selective.

For the majority of neurones in cat striate cortex, the response to an optimal stimulus presented to one eye is suppressed when a stimulus of substantially different orientation is presented to the other eye. In order to determine the true orientational tuning of the underlying inhibitory interactions in the absence of binocular facilitation for matched stimuli, we tested how the response of such cells to an optimal grating in one eye is affected by gratings in the other eye of spatial frequencies too high or low to elicit an excitatory response through either eye: the vast majority of cells displayed suppression that was essentially independent of orientation. Our results indicate that interocular inhibition derives from cells representing all orientations, but is swamped by interocular facilitation for stimuli matched in orientation and spatial frequency.