Figure 2

ACC stimulation induces long-term fear memory. (a) Three pairings of 30 s tone and 10 s electrical train stimulation were delivered in the paired group on the conditioning day; (b,c) Percentage freezing to the tone (b) and the conditioning context (c) measured at 1 hr, 1 day and 3 days after paired training. After paired training, long-lasting fear memory was detected in most of the mice (n = 16 mice, filled circles), while some other mice showed no freezing across the test periods (n = 5, data not shown). After unpaired training of tone and ACC stimulation, mice showed no freezing to the tone (n = 6, open squares) but clear memory to the training environment; * P < 0.05 compared with the unpaired group;(d) Stimulating sites in ACC on the schematic representation of coronal section 0.62 mm anterior to the Bregma. Filled circles, effect sites of ACC paired group; open circles, no effect sites of ACC paired group; open squares, ACC unpaired group.