FIGURE 2.

Traced fear conditioning (FC) performance. (A) Experimental protocol. A repeated ANOVA was used to determine the significance of differences in freezing behavior between the two groups during the training phase (B,C) and trace FC phase (F,G). Group differences at certain time points were determined by the least significant difference (LSD) post hoc test. An independent t-test was used to detect group differences in the contextual FC phase (D,E). Data are expressed as the mean ± SEM. *P < 0.05, **P < 0.01 for needle group vs. tactile group. P24: n (tactile group) = 12, n (needle group) = 15; P87: n = 17. ITI, intertrial interval.