Fig. 1.

Short multimodal stress impairs learning and memory and area CA3 synaptic plasticity in select dendritic lamina. (A) Mice experiencing a 5-h combined psychological/physical stress failed to distinguish an object that they had seen before from a novel one. Control mice explored the novel object preferentially, whereas stressed mice spent almost equal time exploring an object they had encountered 6 h earlier and a novel one, suggesting they did not distinguish between them. *P < 0.05. (B) Stressed mice that were allowed a 90-min recovery period explored two objects for the same duration as control mice, eliminating the possibility that their apparent memory defects were a result of freezing or poor motivation. n = 10 mice per group. (C) Slices prepared from mice < 1 h after multimodal stress (red) exhibited deficient LTP magnitude at area CA3 C/A synapses as compared with controls (blue). Representative traces from baseline (thin lines) and 30-min postinduction (thick lines) are shown. Values in parentheses indicate numbers of slices. *P = 0.01 for minutes 30–40. (D) Mossy fiber potentiation tested in slices from the same animals as in C showed no effect of stress. Results are shown as means ± SEM. Values in parentheses indicate number of mice. [Scale bars in C and D: 1 mV (vertical bar) and 10 ms (horizontal bar).]