Training and task-related differences in retrograde amnesia thresholds determined by direct electrical stimulation of the cortex in rats

These experiments investigated the thresholds for producing retrograde amnesia (RA) by direct electrical stimulation of the cortex in rats. In different inhibitory (passive) avoidance tasks the degree of RA varied with the region of cortex (frontal or posterior) stimulated, as well as the motivational and training conditions used: water deprivation lowered the threshold for RA produced by frontal cortex stimulation; familiarization pretraining elevated the threshold for RA produced by posterior cortex stimulation. Brain seizure thresholds and patterns were not influenced by the variations in the motivational and pretraining conditions. These findings indicate that, in rats, the degree of RA produced by direct electrical stimulation of the cortex varies markedly with the training conditions.