Figure 1.

The learned helplessness procedure induces behavioral changes and mPFC neuronal activation. A, A group of 110 FosGFP mice were subjected to the learned helplessness procedure, and their performance was analyzed by k-means (k = 2) clustering, using the number of failures and escape latency as classification parameters. Mice were classified as being either resilient (R) or learned helpless (LH) (see Materials and Methods). Among these 110 mice, 23 (red circles) belong to the LH group, and the rest (black circles) to the R group. Red and black stars represent the centroids for the learned helpless and the resilient group, respectively. B, Representative images of c-Fos expression in the mPFC of a FosGFP mouse killed 3.5 h after the learned helplessness testing session. Left, Expression of FosGFP was detected on the basis of GFP intrinsic fluorescence. Middle, c-Fos expression was detected using an antibody recognizing c-Fos. Right, Overlay, Bottom panels: higher-magnification images of the boxed area in PL (prelimbic cortex).