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The sources of a thalamic input to different loci of the suprasylvian gyrus (SSG) of the porpoise (Phocaena phocaena) cortex were studied by means of the retrograde HRP and fluorescent tracing methods. After injections of HRP into the anterior part of the SSG most cells were labelled in the lateral part of the ventrobasal complex. Some cells were also labelled in the ventroposteroinferior nucleus, posterior nucleus and caudally in the ventral parvocellular medial geniculate (MG). After injections of bisbenzimide in the middle part of the SSG many labelled cells were found in the ventral parvocellular MG and in the inferior pulvinar. Less cells were labelled in the magnocellular MG, lateral pulvinar and posterior nucleus. After bisbenzimide injection into the posterior part of the SSG the similar distribution of labelled cells was found but a sheet of labelled cells was shifted more laterally.

The excitability cycles of neurons of the rabbit visual cortex in response to the optic nerve shock were compared with those in response to small light flashes. The pairs of stimuli consisted either of conditioned shock and testing light flash or of conditioned light flash and testing shock. The inhibitory phase of the response to the nerve shock was unable to depress a powerful reaction to adequate light stimulation. However, the profound inhibition of response to the optic nerve shock was obtained at the end of the response to the preceding light stimulation.