Visual and somatosensory cortical unit activity at different stages of goal-directed behavior.

Abstract

1. Neurons of the visual and somatosensory areas of the cortex can participate in the formation of either all or only some stages of a behavioral act. Under these circumstances, neurons changing their activity at two or more stages of instrumental behavior predominate in the visual cortex. 2. Of all visual and somatosensory cortical neurons tested, statistically significant correlation between spike discharge and sensory modality of the trigger conditioned stimulus can be observed in neurons of the visual cortex at the time of its activation. At all subsequent stages of the behavioral act the dynamics of discharge activity of the visual and somatosensory cortical neurons is independent of the sensory modality of the conditioned stimulus. 3. At the stage of performance of an instrumental action, most neurons of the visual and somatosensory areas of the cortex increased their spike activity; the total number of responding neurons was the same in both regions studied. 4. In the final stages of the behavioral act, spike activity of neurons of the visual and somatosensory areas of the cortex differed in direction; in the “period of anticipation” of reinforcement most responding visual cortical neurons increased their discharge frequency, whereas most somatosensory cortical neurons reduced their discharge frequency. Meanwhile, at the stage of obtaining the final useful result (lapping milk) spike activity decreased in most visual cortical neurons and either increased or decreased in neurons in the somatosensory area.