Figure 5.

CS test. Percentage of immobility displayed by control (CTL, n = 10), paired (PA, n = 12), unpaired (UN, n = 12), and US exposure only (US, n = 8) mice during consecutive 1-min time intervals as assessed by latency 1st BI (A) and the continuous (B) and time-sampling (C) methods of hand scoring. The auditory CS was administered during the last 3 min (4th to 6th) of CS testing. Both hand-scored and latency 1st BI results indicated that during the 4th min of CS testing, PA mice showed increased levels of freezing behavior compared with UN, US, and CTL groups. *P < .005, **P < .0001 versus UN, US, and CTL mice at the same time point (Newman-Keuls post hoc test).