Responses of cerebral cortex to diffuse monocular and binocular stimulation.

Surface potentials and single unit potentials in the cat9s cerebral cortex have been recorded in response to diffuse visual stimulation. Surface responses produced by stimulation of the contralateral eye are larger in amplitude than those produced by stimulation of the ipsilateral eye, while those produced by binocular stimulation are larger still. The amplitude of the surface responses increases to a maximum with increasing intensity of stimulation. For any given single cell, there is a constant ratio between the average number of unit discharges in response to contralateral, ipsilateral and binocular stimulation. At different stimulus intensities this ratio is constant, although the absolute numbers of discharges may be different. It has been possible to divide the cells into functional groups according to a ) which eye produces the larger number of discharges, i.e. which eye is ‘dominant’ and b ) whether binocular stimulation produces more, fewer, or as many discharges as stimulation of the dominant eye alone. All the functionally different types of neurones may be found in all the cellular layers of the cortex. The latency of the unit responses is shorter with binocular than with monocular stimulation, and is shorter when brighter stimuli are used.