FIG. 7.

Comparison of the effects of stimulant drugs administered during either the light or dark phase on hippocampal cell proliferation in the dentate gyrus of the rat. Data are expressed as a percentage of change from the respective vehicle control group. Values are means ± SEM. Drug abbreviations and number of animals per experimental group as in figure legend 5. * P < 0.05 vs. respective dark phase; by unpaired (two-tailed) t test. All three stimulants induced a larger suppression of cell proliferation when administered during the light phase, as compared to the dark phase.