Variable decay of memory and its recovery in cycloheximide-treated mice.

Mice were trained in an automated visual-discrimination task. When injected with cycloheximide before training, mice showed: (a) some impairment of memory within minutes after the beginning of training, (b) gradual development of total amnesia in less than 3 hr or in more than 6 hr after training, depending on the extent of training, and (c) spontaneous recovery of memory within 3 days after training. The results are consistent with the operation of three processes of memory storage: (i) a short-term process that is independent of protein synthesis, (ii) a long-term that is dependent on protein synthesis, and (iii) a slow-developing memory storage that becomes apparent during the days after training.