Fig. 4: Voluntary running reduced fear memory expression.

A Experimental paradigm. After fear conditioning, mice were divided into two groups. One group underwent four weeks of voluntary running, while the control group was housed normally in their cages. Fear recall tests were conducted weekly for both groups. B, G Mice exhibited similar levels of contextual fear memory (B, t (14) = 0.0508, p = 0.9602) and tone-cued fear memory (G, t (14) = 0.2272, p = 0.8235) before undergoing voluntary running. C–F In the control group, context fear memory persisted for at least four weeks; while voluntary running gradually reduced fear expression overtime: two-week running (D, t (14) = 4.034, p = 0.0012), three-week running (E, t (14) = 6.800, p < 0.0001), and four-week running (F, t (14) = 15.34, p < 0.0001) significantly decreased fear expression, but one-week running (C, t (14) = 0.2993, p = 0.7691) had no effect. H–K In the control group, tone-cued fear memory persisted for at least four weeks; while voluntary running gradually reduced fear expression overtime: two-week running (I, t (14) = 5.118, p = 0.0002), three-week running (J, t (14) = 10.11, p < 0.0001), and four-week running (K, t (14) = 14.61, p < 0.0001) significantly decreased fear memory expression, but one week running (H, t (14) = 0.1660, p = 0.8705) had no effect. B-K, unpaired two-tailed Student’s t-test, n = 8 mice for each group. The data are presented as the mean ± SEM, **p < 0.01, ***p < 0.001.