Fig. 1

A Example picture of virus expression in dorsolateral (dl, top) and ventrolateral (vl, bottom) PAG. B Experimental design and optogenetic manipulation during fear conditioning as well as experimental groups. C Fear memory formation is reduced when dl/lPAG neurons are inhibited during the shock period of fear conditioning. Auditory CS-evoked behavioral freezing responses during 'Test' period following learning. GFP (n = 10), ‘Offset’ (n = 9) and ‘Overlap’ (n = 10) groups. A one way ANOVA revealed significant main effect of optogenetic manipulation [F(2, 26) = 7.93, p = 0.002] and post-hoc test showed that averaged CS-evoked freezing during all three CSs in the ‘Overlap’ group is significantly lower than that of the ‘GFP’ and ‘Offset’ control groups (*p < 0.05, **p < 0.01). D Optogenetic inhibition of vlPAG during the shock period of fear conditioning had no affect on the acquisition of fear memory formation [F(2, 32) = 1.35, p = 0.27]. GFP (n = 14), ‘Offset’ (n = 11) and ‘Overlap’ (n = 10) groups