Effects of pretraining on subsequent cycloheximide induced amnesia

In the first experiment, mice were trained on a passive avoidance (PA) task, given one extinction trial, and then were injected with cycloheximide or saline shortly before retraining on the PA task. On a subsequent test trial, the performance of the cycloheximide group was inferior to the saline group, but superior to a cycloheximide group not given the pretraining experience. In the second experiment, one group of mice was given cycloheximide before each of two training sessions while another group received cycloheximide before the first training session and saline before the second. The group given cycloheximide before each training session was amnesic for both sessions to an equal degree, while the other group was amnesic for only the first session. The final test performance of the latter group was similar to that of a saline group not given any pretraining experience. These data seem to indicate that pretraining has limited effect on subsequent cycloheximide induced amnesia, and that such amnesia is the result of impaired memory formation rather than impaired memory retrieval.