NEURAL CORRELATES OF CONDITIONED RESPONSES STUDIED WITH MULTIPLE CHRONICALLY IMPLANTED MOVING MICROELECTRODES

Neuronal discharges and evoked potentials were studied in trained cats with multiple but movable microelectrodes implanted in the brain. Usually, average evoked responses to a visual stimulus closely resemble the poststimulus histograms of multiple-unit activity simultaneously recorded from the same electrode. Although different neuronal ensembles within extensive brain regions display great variability in their responses to single conditioned stimuli, they reveal striking similarity in average patterns of activity when correct behavioral performance subsequently ensues. Information about the stimulus may be represented by the stable average pattern of activity of a distributed aggregate of neurons. Different patterns of response are displayed to different stimuli. These patterns are markedly changed when animals fail to perform and are then characterized by decrease in amplitude or disappearance of a burst of neural discharge with a latency of about 40 msec. The retrieval of a memory about a stimulus may be related to this late component in the response of the neural ensemble. © 1969.