3.3 Experiment 3
The behavioral responses during the acclimation period were not significantly different between the groups (F 3,15= 3.08, P = 0.059) (Table 2). In contrast, the behavioral responses during the experimental period differed significantly between the groups (F 3,15 = 4.75, P = 0.016) (Table 2). A post hoc test revealed that the Nal group showed increased freezing (P = 0.0013) and decreased walking (P = 0.0031) and investigation (P = 0.015) as compared to the Sal group.
We analyzed Fos expression in 16 brain regions (Table 3). Statistical analyses revealed that the Nal group showed increased density of Fos-ir cells in the PVN (t 17 = −2.43, P = 0.026) and decreased density of Fos-ir cells in the NAc shell (t 17 = 2.76, P = 0.013), ACC (t 17 = 4.11, P = 0.0007), and IC (t 16 = 2.17, P = 0.045) compared to the Sal group (Fig. 4). In addition, the Nal group tended to show decreased density of Fos-ir cells in the NAc core (t 17 = 2.09, P = 0.052).