Figure 1: Opposite influence of LHL and LHF on spatial memory in mice.

(a) Experimental protocol. Mice were exposed to inescapable foot shocks or with simultaneous avoidance training for 6 days in different contextures, and then the learned helplessness (LHL) or learned helpfulness (LHF) was evaluated by forced swimming (FS) and spatial learning and memory were tested by Morris water maze (MWM; Ctrl, n=12; LHL, n=10; LHF, n=10) or Barns maze (BM; Ctrl, n=9; LHL, n=15; LHF, n=12). The Ctrl was exposed to the contextures without shock or training. (b) Number of shocks received during each training trial and mean number of shocks (rectangles, 30 times in total) was delivered randomly each day to the simply shocked group. (c,d) The immobility time in FS was videotaped and the LHL was defined as the immobility time >2 s.d. of the Ctrl (one-way analysis of variance (ANOVA) and Tukey’s multiple comparisons test). (e) Head swings were recorded during FS, which can distinguish LHF from the Ctrl (one-way ANOVA and Bonferroni’s multiple comparison test). (f–h) MWM data show spatial learning (f) and memory (g, h) deficits in the LHL group and the potentiation in the LHF (two-way ANOVA and Bonferroni’s post hoc test). (j–l) BM data show spatial learning (j) and memory (k,l) deficits in the LHL group and the potentiation in the LHF (two-way ANOVA, Bonferroni’s post hoc test). (i,m) Swimming speed in MWM test and the distance moved in BM test. (n) Representative searching paths during probe trial on BM. Data were presented as mean±s.e.m. *P<0.05, **P<0.01 versus Ctrl; ##P<0.01 versus LHL. Ctrl, control.