[Dynamics of the receptive fields of visual cortex and lateral geniculate body neurons in the cat]

The dynamics of receptive fields of the visual cortex and lateral geniculate neurons were investigated in acute experiments on unanesthetized immobilized cats. For this purpose a computer presented small local flashes in a random order to 100 points of the receptive field and changes in three-dimensional relief of activity within the field were evaluated every 20 ms. Regular dynamic reorganizations of registered receptive fields of all investigated neurons were observed both after switching on and off the light stimulus. After the latency a small region of weak responses appeared in the centre of field. Later on the recorded field enlarged gradually, reaching maximal size at 60-100 ms, and after that began to narrow and disappeared or fell to pieces. The central inhibitory zone of the field had the same dynamics. If the neuron responded to stimulation by generating two bursts of spikes, during the second one the receptive field changed in the same way. The effect was revealed under various conditions of light stimulation. Functional significance of these effects for orientational information coding by visual cortex neurons is discussed.