Figure 4. lOFC inactivation does not affect object recognition.
(A): Sample phase, where rats explored two identical objects and received JH60 injections. (B): First recognition test, where one familiar object was replaced by a novel one. (C):Second recognition test, where the previous familiar object was substituted by yet another novel object. (D and G): Rats in both groups explored the two objects for the same amount of time during sample (2-way ANOVA; O1 × O2: F1,17 = 1.833, P = 0.193; CTRL vs hM4d: F1,17 = 0.14, P = 0.712; interaction: F1,26 = 0.059, P = 0.809)(D) which was evident in the discrimination index (two-tailed unpaired t-test, P = 0.634)(G), demonstrating that lOFC inactivation does not affect exploratory behavior in this task. (E and H): Rats from both groups showed equally robust object recognition learning, evident in the increased exploration of the novel object (2-way ANOVA; Familiar × Novel: F1,17 = 13.53, P = 0.002**; CTRL vs hM4d: F1,17 = 0.045, P = 0.835; interaction: F1,26 = 0.025, P = 0.876) (E) and an increase in the discrimination index, which was identical between groups (two-tailed unpaired t-test; P = 0.882) (H), indicating that lOFC inactivation in sample did not affect recognition learning or memory retention, nor did it induce some form of context-dependent learning. (F and I): Again, rats in both the control and hM4d groups showed a similar level of preference for the novel object (2-way ANOVA; Familiar × Novel: F1,17 = 18.13, P = 0.0005***; CTRL vs hM4d: F1,17 = 3.085, P = 0.097; interaction: F1,26 = 0.053, P = 0.82) (F), as confirmed in the discrimination index (two-tailed unpaired t-test; P = 0.775)(I), confirming that learning under the effects of JH60 injections was similar to when no drug was injected. Asterisks in E and F indicate results of post-hoc multiple comparison tests. Data are represented as mean ± SEM. CTRL n= 9 and hM4d n=10 biologically independent animals. *P<0.05, **P<0.01.