Fig. 3.

Age and timepoint impact time spent in close social contact during unconstrained free interaction. A) Schematic of behavioral timeline where opposite sex voles were allowed to interact in an open arena the day after each partner preference test at the short term and long term timepoints and following 4 wks separation. PPT: partner preference test, FI: free interaction. B) 18-month animals tended to spend the most time in close social contact, regardless of timepoint. Meanwhile, across ages, pairs spent less time in close social contact after 4 wks separation. C) Time spent in close social contact was then separated into 15-min time bins and analyzed within each age group. There was a main effect of time bin in 6- and 12-month pairs such that time spent in close social contact increased over the course of the 3-h task. There was an additional main effect of timepoint in 12-month pairs, where animals spent less time in close social contact after 4 wks separation. An interaction effect between timepoint and time bin was also apparent for 12-month pairs, and statistics for these comparisons can be found in Supplemental Table 1. There were no effects of time bin, timepoint, or their interaction on the time spent in close social contact during unconstrained free interaction in 18-month pairs. N = 5–10 pairs per group; **p < 0.01, ***p < 0.0001, ****p < 0.0001.