Figure 2.

Single-cue extinction training reduced the expression of the conditioned fear responses in a cue-specific manner. (a) Rats were conditioned with three different environmental cues-electric tail shock pairing. One week later, they were received extinction trials with repetitive tone cue re-exposure. Memory retention was tested 3 days later. (b–d) The conditioned rats with extinction training showed a significant reduction in both freezing behaviors and motivation of avoidance to tone cue-paired compartment (n=7 for all experimental groups). (e–g) The conditioned rats with extinction training displayed aversive behaviors to the conditioned odor cue-paired object and a robust increase in the plasma corticosterone levels after re-exposure to the odor cue (n=7 for all experimental groups). (h–j) The conditioned rats with extinction training displayed an increase in aggressive behaviors and the plasma corticosterone levels after re-visiting the conditioned chamber (n=7 for all experimental groups). All data represent group mean values±SEM. ^*p<0.05. N.S., not significant.