title: Distinct mechanisms mediate the reinstatement and spontaneous recovery of extinguished fear in rats.
abstract: It is controversy whether the summation of new contextual conditioning with residual conditioned response contributes to the reinstatement phenomenon. Here, we examined the summation hypothesis in the auditory conditioned fear paradigm by comparing the freezing levels during pre-tone and tone presentation periods. Unexpectedly, we found that the onset of tone relieves fear during the reinstatement test, which is not predicted by the summation hypothesis; whereas the onset of tone enhances fear during the spontaneous recovery test and early extinction session. These results implicated that return of fear in two conventional assays after extinction, i.e., reinstatement assay and spontaneous recovery assay, are mediated by different mechanisms.
authors.affiliation: Neurobiology Laboratory and State Key Laboratory of Biomembrane and Membrane, Biotechnology, College of Life Sciences, Peking University, Beijing 100871, PR China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Ma
authors.forename: Yin-Yan
authors.initials: YY
authors.lastname: Ma
authors.forename: Long-Chuan
authors.initials: LC
authors.lastname: Yu
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D003214:Conditioning, Classical / Q000502:physiology*; D004597:Electroshock; D005108:Extinction, Psychological / Q000502:physiology*; D005121:Extremities; D005239:Fear / Q000502:physiology / Q000523:psychology*; D046352:Freezing Reaction, Cataleptic / Q000502:physiology; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley