Utilizing a dosage of
cycloheximide which was found to inhibit cerebral
protein synthesis by almost 90% after injection, separate groups of 13-day-old mice received either
cycloheximide or saline followed by 0 (control), 15, or 25 training trials in a discriminated
shock-escape T-maze. Twenty-four hr later, each mouse was treated with
cycloheximide or saline and tested for retention by an additional 25 trails in the T-maze. As reflected by correct choice-point turns, the results suggest that whereas salinetreated mice demonstrated reliable retention of prior learning,
cycloheximide treated mice exhibited memory impairment;
cycloheximide per se had no effect on performance during either original training or retest. A final experiment indicated that this memory impairment was not due to
cycloheximide's general debilitating side effects at the time of retention testing. Taken together, these data suggest that
protein synthesis inhibition during training impaired consolidation and/or retrieval processes involved in memory. The biochemical and behavioral effects following
cycloheximide injection in 13-14-day-old mice in the present study parallel those reported with adult animals and lend indirect support to the hypothesis that the 24-hr memory capacity exhibited by these young mice reflects the early functioning of those processes involved in adult long-term memory.