Figure 6.

Nonfearful odors or general arousal do not produce remapping. A, The effects of coyote urine (fearful; 46 cells from 7 animals), 2-MB (aversive but nonfearful; 51 cells from 3 animals), and water (no odor; 20 cells from 3 animals) were compared by examining the short-term remapping produced when the odor was introduced after the baseline session (baseline/odor), removed 1 h later (odor/1 h), and before and after odor exposure (baseline/1 h). Only the fearful odor (coyote urine) produced significant short-term remapping. B, Pixel-by-pixel cross-correlations showing similarity scores across sessions in two groups of control animals. In the 2-MB group (2 animals, 31 cells), animals were trained as the extinction group but exposed to 2-MB during the conditioning session. In the ABA group (2 animals, 27 cells), animals were conditioned and tested for retrieval in context A but received extinction in context B. Bars represent means ± SEM, *p < 0.05. C, D, Rate maps showing example cells trained in the 2-MB group. Note the stability of these cells during all short-term sessions (24 h, ext1, ext2, and ext3) but not 24 h postext. E, F, Rate maps showing example cells trained in the ABA group. Note the remapping between 24 h and ext1 interval, indicating that the cells responded to the change from context A to context B. However, similarly to the 2-MB group, cells remained stable in context B (e.g., maps formed during ext1, ext2, and ext3). Additional remapping is observed when animals are reintroduced to context A during the postext session. The map retrieved during the postext session resembles the one formed at 24 h, indicating that in the absence of extinction in the training context, spatial representations stabilize in the long term. Peak firing frequency is shown on top of each map.