Fig. 1.

Effects of three different doses of VPA on the judgment bias of rats in the ambiguous-cue interpretation test. a The mean ± SEM optimism index of the control (white bar) and VPA 100 mg/kg (light grey bar), 200 mg/kg (grey bar), and 400 mg/kg (black bar) treated rats. The mean ± SEM proportion of b positive, c negative, and d omitted responses to the trained and ambiguous tones in the control (white circle) and VPA 100 mg/kg (white square), 200 mg/kg (white triangle), and 400 mg/kg (white diamond) treated rats. N = 16/group