Figure 2.

Short-term fasting before fear extinction improves extinction learning. (a) Following fear conditioning, mice were fasted for 16 h before and during extinction training. Extinction recall was tested 24 h later with food available ad libitum. (b) Following fear acquisition, mice were divided into two equal groups, one that was fasted and one with food available. (c) No difference in conditioned stimulus (CS) induced freezing was observed between fasted and non-fasted mice, (d) but facilitated fear extinction in mice that were fasted 16 h before and during fear extinction learning, and (e) reduced CS-induced freezing in extinction recall of mice that were fasted before and during extinction learning (repeated two-way analysis of variance (ANOVA) for acquisition and extinction learning, Student's t-test for CS-induced freezing and extinction recall testing, *P<0.05, **P<0.01; Food: n=10, fasting: n=10).