Figure 3.

Conditional deletion of CB₁ receptors in GABAergic or glutamatergic neurons differentially alters the shift between freezing and active coping in fear conditioning. A, Total freezing of Glu-CB₁^−/− (n = 18), GABA-CB₁^−/− (n = 14), and WT (n = 13) littermates during the 8 min CS presentation. B, Total active coping of Glu-CB₁^−/−, GABA-CB₁^−/−, and WT littermates during the 8 min CS presentation. C, Time course of freezing and active coping of WT mice (note the presence of the three phases of behavior). D, Time course of freezing and active coping of Glu-CB₁^−/− mice (note the absence of Phase 3). E, Time course of freezing and active coping of GABA-CB₁^−/− mice (note the absence of Phase 1). F, Sum of individual freezing and active coping time scores as percentage of the total 8 min tone exposure (left) or percentage of 60 s bins (right). Data are mean ± SEM *p < 0.05; **p < 0.01; ***p < 0.001.