Receptive field surround stimulation modulates responses of neurons in visual area 21a of the cat

The response of most neurons in area 21a to stimulation of the classical receptive field (CRF) with a grating patch is suppressed by the simultaneous presentation of a grating surrounding the CRF, similar to many neurons in area 17 (1-4). However, the extent of response suppression in area 21a is independent of the orientation and direction of movement of the surround stimulus, which is not the case for neurons in area 17. This suggests that the surround suppression apparent in area 21a neurons is due to local interactions rather than simply reflecting the surround suppression in area 17.