Supplementary Figure 4: Inhibition of insular cortex with muscimol reverses SAP test behavior.

In a pilot study, rats were implanted with insular cortex cannula for microinjection exactly as described in the online methods. After 7 days of recovery rats received SAP tests with either PN 30 (n = 9) or PN 50 (n = 10) conspecifics. SAP tests were as in Fig. 2: Habituation to arena on Day 1, Habituation with exposure to naïve conspecifics on Day 2, and SAP tests with one conspecific exposed to 2 footshocks prior to test on Day 3. Either Vehicle (0.9% saline) or muscimol (100 ng/side in saline) was injected to the insular cortex 60 minutes prior to SAP tests on day 3. This experiment was different in design from the others included in the main text because rats received only 1 SAP test precluding the more powerful within-subject comparisons of drug effect. SAP behavior is shown as the mean (+/− SEM) percent of time spent interacting with the stressed conspecific of the total time spent in social interaction during the SAP test. A 2-way between subjects ANOVA revealed a significant Age by Drug interaction, F(1, 34) = 16.27, p < 0.001. Post hoc comparisons between drug conditions within each age revealed a significant decrease in time spent interacting with the stressed PN 30 juvenile conspecific by muscimol (**p = 0.005, Sidak) and a significant increase in time spent interacting with the stressed PN 50 adult conspecific (*p = 0.043, Sidak).