Figure 1.

Diagram of experimental design and IA task. A) Rats were housed in a home cage but moved into the light box used for the task on the training day. A brief electrical foot-shock (2 s) was applied in the dark box in the shock cage. Brain slices were prepared at various time points of the training. B) Thirty minutes after the training, the rats consistently showed a longer latency before entering the dark side of the box. **P < 0.01 vs. training. Error bars indicate ± sem. The number of rats is shown at the bottom of each bar.