Binocular interactions in area 21a of the cat.

We investigated binocular suppression in area 21a cells of the anaesthetized cat using drifting sinusoidal gratings presented simultaneously to each eye. The grating presented to the dominant eye was always oriented optimally and the grating presented to the non-dominant eye was either at the same orientation, but at the least effective relative spatial phase, or orthogonal. The binocular response of approximately 80% of cells was less than the monocular dominant eye response when there was a mismatch in orientation or spatial location between stimuli. Response suppression in the two binocular stimulus conditions had a correlation coefficient (r) of 0.55. We propose a parsimonious model to account for the response facilitation and suppression by binocular stimulation of area 21a neurons.