Figure legends
Fig. 1. Schematic diagrams showing the location of brain regions in which Fos-immunoreactive cells were counted (open square). For simplicity, the locations are shown only on the right side. For an explanation of abbreviations, see the corresponding numbers in Table 3.
Fig. 2. Duration of freezing, duration of investigation, and frequency of walking during the test period of Experiment 1. Fear-conditioned subjects received an intraperitoneal administration of either haloperidol (Hal, n = 8), SR49059 (SR, n = 6), atosiban (Ato, n = 8), naloxone (Nal, n = 6), or saline (Sal, n = 6) and were tested in the presence of an associate (Social: open bars). Fear-conditioned subjects received an intraperitoneal administration of saline and were tested alone (Alo: filled bars, n = 7). *P < 0.05 as determined using MANOVA, followed by Dunnett’s post hoc test.
Fig. 3. Frequency of walking (mean ± SEM) in each 5-min bin in Experiment 2. The subjects received an intraperitoneal administration of either naloxone (Nal, n = 8) or saline (Sal, n = 8) and underwent the open-field test.
Fig. 4. Representative photomicrographs showing Fos-immunoreactive cells in the nucleus accumbens (NAc) shell, anterior cingulate cortex (ACC), insular cortex (IC), and paraventricular nucleus of the hypothalamus (PVN) of fear-conditioned subjects that received an intraperitoneal administration of saline (Sal) or naloxone (Nal) and were tested in the presence of an associate. Scale bars indicate 200 µm.