[Striate receptive fields mapped with single and bipartite stimuli].

In 22 acute experiments with anesthetized and immobilized adult cats, 364 maps of receptive fields (RF) of 47 striate neurons were obtained by means of single local stimuli flashed at different parts of the visual field, or with additional asynchronous activation of the RF excitatory center with oscillating bar of the optimal orientation. Under bipartite stimulation, considerable and significant decrease in the square and weight of the central excitatory RF zone was revealed in more then 75% of the studied cells. Additional excitatory zones appeared in 54% of cases, or the square and weight of the excitatory zones substantially increased, and inhibitory zones developed in 90% of cases. These effects were correlated with the degree of increase in the background firing during transition from the mode of mapping with single stimulation to that with bipartite stimulation. The mechanism and possible functional role of cooperative excitatory and inhibitory intracortical interactions in organization of receptive fields and detection of features of a visual image are discussed.