title: Intact renewal after extinction of conditioned suppression with lesions of either the retrosplenial cortex or dorsal hippocampus.
abstract: Extinction of fear to a Pavlovian conditioned stimulus (CS) is known to be context-specific. When the CS is tested outside the context of extinction, fear returns, or renews. Several studies have demonstrated that renewal depends upon the hippocampus, although there are also studies where renewal was not impacted by hippocampal damage, suggesting that under some conditions context encoding and/or retrieval of extinction depends upon other regions. One candidate region is the retrosplenial cortex (RSC), which is known to contribute to contextual and spatial learning and memory. Using a conditioned-suppression paradigm, Experiment 1 tested the impact of pre-training RSC lesions on renewal of extinguished fear. Consistent with previous studies, lesions of the RSC did not impact acquisition or extinction of conditioned fear to the CS. Further, there was no evidence that RSC lesions impaired renewal, indicating that contextual encoding and/or retrieval of extinction does not depend upon the RSC. In Experiment 2, post-extinction lesions of either the RSC or dorsal hippocampus (DH) also had no impact on renewal. However, in Experiment 3, both RSC and DH lesions did impair performance in an object-in-place procedure, an index of place memory. RSC and DH contributions to extinction and renewal are discussed.
authors.affiliation: Department of Psychological and Brain Sciences, Dartmouth College, Hanover, NH, United States. Electronic address: travispetertodd@gmail.com.
authors.forename: Travis P
authors.initials: TP
authors.lastname: Todd
authors.affiliation: Department of Psychological and Brain Sciences, Dartmouth College, Hanover, NH, United States.
authors.forename: Matthew Y
authors.initials: MY
authors.lastname: Jiang
authors.affiliation: Department of Psychological and Brain Sciences, Dartmouth College, Hanover, NH, United States.
authors.forename: Nicole E
authors.initials: NE
authors.lastname: DeAngeli
authors.affiliation: Department of Psychological and Brain Sciences, Dartmouth College, Hanover, NH, United States.
authors.forename: David J
authors.initials: DJ
authors.lastname: Bucci
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002540:Cerebral Cortex / Q000293:injuries / Q000502:physiology*; D003214:Conditioning, Classical / Q000502:physiology*; D005108:Extinction, Psychological / Q000502:physiology*; D005239:Fear / Q000523:psychology; D006624:Hippocampus / Q000293:injuries / Q000502:physiology*; D007266:Inhibition, Psychological; D008297:Male; D011597:Psychomotor Performance; D020318:Rats, Long-Evans
keywords: Conditioned suppression; Fear extinction; Hippocampus; Renewal; Retrosplenial