Photic evoked activity in the visual cortex of monocularly deprived cats

Abstract

Monocular eyelid closure during the first 2 months of life has previously been shown to cause a dramatic reduction in the number of neurons that can be activated by photic stimulation of the deprived eye. Those studies recorded single neuron responses to stimulation with discrete forms. In contrast, the author has previously shown that the initial components of the slow-wave response from one region of the cortex evoked by diffuse stimulation of the deprived eye are actually similar to these components when evoked from the nondeprived eye. The disparity in these findings may be due to the fact that the slow-wave data were recorded from only one region of the visual cortex and in response to diffuse photic stimulation. To resolve these differences the slow-wave response from areas 17, 18, and 19 and single-unit activity in response to diffuse photic stimulation were studied. The response evoked from the deprived eye was found to be reduced in area 17 but was sometimes actually larger in areas 18 and 19 than the response evoked from the good eye. Of 45 single units tested, 36 could be driven by stimulation of either eye. Evidently, photic stimulation of the deprived eye is capable of evoking neuronal discharge within the visual cortex. Indeed, the ability of neuronal transmission from the deprived eye to activate neurons within the visual cortex is in keeping with the evidence on behavioral recovery from monocular eyelid closure.