In experiments on alert and non-immobilized rabbits, slow potentials and reactions of the visual area neurones were recorded in the course of elaboration of conditioned inhibition and of a defensive conditioned reflex to rhythmic light flashes of various frequencies without isochronous pain reinforcement. Analysis of the data obtained showed that the ability of the neurones to follow the light rhythm is due not so much to the properties of the cells themselves as to the morphofunctional properties of the system in which they are included and to the interaction between excitatory and inhibitory influences. Pain stimulation at all its frequencies weakens the inhibitory, hyperpolarization processes in the cortical visual area. At the same time under the influence of pain the first phase of activation in response to light flashes is fragmented in a number of neurones. Judging by the authors' and published data, such modulation of neuronal responses in the visual area under pain effect reflects a convergence of modality-specific and of activating modality-non-specific afferentations of the visual analyser. The result of such convergence is reproduced in a conditioned way.