Multiple-unit activity of the rabbit cerebral cortex in single-session avoidance conditioning

In overtraining, an analysis of four consecutive 50-msec post-CS-onset periods revealed a decline in multiple-unit activity over periods within motor-sensory cortex, whereas dorsal limbic cortex showed a more sustained unit response over the four periods.

Abstract

Multiple-unit neuronal activity was recorded from three "nonspecific" polysensory regions of the cerebral cortex of rabbit during single-session discrete-trial avoidance acquisition and during asymptotic conditioned response (CR) performance (overtraining). The CS was a pure tone, and the UCS was a shock delivered through the grid floor of the rotating-wheel conditioning apparatus. The CS did not evoke unit activity in any of the areas on the initial conditioning trials. Two of the cortical areas (motor-sensory cortex and dorsal limbic cortex) showed significant increases in CS-evoked multiple-unit activity over stages of acquisition, paralleling the development of behavioral CRs. The same two areas also yielded substantial CS-evoked unit activity during overtraining. In overtraining, an analysis of four consecutive 50-msec post-CS-onset periods revealed a decline in multiple-unit activity over periods within motor-sensory cortex, whereas dorsal limbic cortex showed a more sustained unit response over the four periods. A third nonspecific cortical area (posterior limbic cortex) yielded no systematic acquisition-related unit response alterations.