The locus coeruleus: its possible role in memory consolidation.

Three experiments were done looking at the effects on memory of discrete electrolytic lesions in the locus coeruleus of mice. In Experiment 1 mice received electrolytic lesions of the locus coeruleus immediately following training on the 1 trial inhibitory avoidance step-through task. Retention of this response, measured 48 hr later was normal, suggesting that locus coeruleus lesions per se do not interfere with the performance of this rather simple response. In Experiments 2 and 3 mice were treated exactly as in Experiment 1 except that a transcorneal ECS was administered 40 hr or 7 days after initial training and locus coeruleus lesions. Mice with locus coeruleus lesions were amnesic following a 40 hr delayed ECS treatment when tested either 8 hr or 24 hr after ECS. Mice with locus coeruleus lesions were not amnesic following a 7 day delayed ECS. These data are interpreted to suggest that the locus coeruleus is normally involved in the temporal delineation of the susceptibility period of newly formed memory. A malfunction of the locus coeruleus can result in a profound extension of the normal susceptibility period of newly formed memory to ECS produced amnesia.