Fig. 2.

Mean activity levels (in responses per minute, RPM; +SEM) during the test with AX and BX (and AY and BY; Experiment 1; left panels), and A and B (Experiment 2; right panels). Rats in groups Sham (upper panels) and HPC (lower panels) had received exposure of AX and BY prior to trials on which X was followed by shock after a trace interval of 40 s and Y was not. Asterisks indicate p < 0.05.