| Abstract: | The responses of the rabbit's visual cortical neurons to paired and rhythmic punctiform stimulation of their receptive fields were compared with responses to diffuse photic stimuli and the electric stimulation of the optic nerve. Diffuse photic and electric stimuli evoke a short-lasting initial activation of a neuron, followed by an inhibitory phase, during which the response to repetitive stimulation is suppressed. By contrast, localized stimulation of the neuron's receptive field with a spot of light produces an intensive and longer-lasting activation which is not followed by profound inhibition. Fusion of the responses to paired and rhythmic localized stimuli is therefore possible when the intervals between stimuli are brief enough. Rhythmic stimulation is capable of evoking sustained activation of a neuron during the entire duration of light flicker. During stimulation of a single point of the receptive field such prolonged activation can take place only within a limited range of stimulation frequencies (up to 15/sec), while higher frequencies evoke responses to the onset and offset of sequences of light flashes only. If, however, rhythmic stimuli alternate between the various points of a receptive field, prolonged neuronal activation is observed with any frequency of stimulation.A. N. Severtsov Institute of Evolutionary Morphology and Ecology of Animals, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 3, No. 3, pp. 252–259, May–June, 1971. |
