Dynamic Spatial Organization of Receptive Fields of Neurons in the 21a Cortical Area

We studied changes in the spatial parameters of receptive fields (RFs) of visually sensitive neurons in the associative area 21a of the cat cortex under conditions of presentation of moving visual stimuli. The results of experiments demonstrated that these parameters are dynamic and depend, from many aspects, on the pattern of the stimulus used for their estimation. Angular lengths of the horizontal and vertical axes of the RFs measured in the case of movement of the visual stimuli exceeded many times those determined by presentation of stationary blinking stimuli. As is supposed, a visual stimulus, when moving along the field of vision, activates a certain number of the neurons synaptically connected with the examined cell and possessing RFs localized along the movement trajectory. As a result, such integrated activity of the neuronal group can change the excitation threshold and discharge frequency of the studied neuron. It seems probable that correlated directed activation of the neuronal groups represents a significant neurophysiological mechanism providing dynamic modifications of the RF parameters of visually sensitive neurons in the course of processes of visual perception and identification of moving objects within the field of vision.