Figure 3.

Training increases the number of PSA-NCAM-labeled cells in the dentate gyrus 24 h after contextual fear conditioning. Left, Quantitative analysis of polysialylated cell number in the DG of two independent groups of animals, both of them trained in the contextual fear conditioning (1 mA), but one of them also tested 24 h later (Training + Test 24 h) and the other left undisturbed after training (Only training). Both groups of animals were perfused 24 h after training. Right, The same experimental protocol was followed to check independently the effects of training and retrieval in the tone fear-conditioning protocol on the number of hippocampal PSA-NCAM-labeled cells. Data represent mean ± SEM. Thickest horizontal discontinuous line represents mean values of the naive group, and thinner ones represent SEM values of this group. *p < 0.05 versus naive.