Fig. 2.
Electrical stimulation of ACC during observational fear learning. (A) Diagram of the apparatus and treatment used for observational fear conditioning. (B) Representative photograph indicating the location of the electrode used for electrical stimulation in the right ACC. (C and D) Electrical stimulation of the right ACC (n = 18) increased both the observational freezing behavior (F1,29 = 25.122, P < 0.001; C) and the 24-h memory recall (F1,29 = 7.385, P = 0.011; D) compared with the nonstimulated controls (n = 16). Electrical stimulation into the left ACC (n = 21) had no effect on observational fear learning (F1,33 = 1.008, P = 0.323; C) and 24-h contextual memory recall (F1,33 = 0.041, P = 0.841; D) compared with nonstimulated controls. (E and F) Total freezing time showed an enhanced effect on right electrical stimulation into the right ACC in observational fear learning (E) and 24-h contextual memory recall (F) compared with nonstimulated controls or mice with stimulation into the left ACC. Trains were delivered every 1 s for 4 min during training in observational fear conditioning. Error bars represent SEM. *P < 0.05, **P < 0.01.