title: The role of the dorsal hippocampus in the acquisition and retrieval of context memory representations.
abstract: It is argued that the hippocampus contributes to contextual fear conditioning by supporting the acquisition of a conjunctive memory representation of context, which associates with shock. This function was examined by studying the context pre-exposure facilitation effect (CPFE). A rat that is shocked immediately after being placed into a context subsequently displays almost no fear of that context. However, if it is pre-exposed to the context the day before immediate shock, it displays significant freezing to that context. By using 5-aminomethyl-3-hydroxysoxazole to temporarily inactivate the dorsal hippocampus (DH) at three different phases of the procedure, which produces the CPFE, we show that the hippocampus is necessary for the following: (1) acquisition of the context memory, (2) retrieval of this memory at the time of immediate shock, and (3) retrieval of the context-shock memory at the time of testing. In contrast, inactivating the DH before a standard contextual shock experience had no effect on contextual fear conditioning. These results support the view that two processes can support contextual fear conditioning: (1) conditioning to the conjunctive representation, which depends on the hippocampus, and (2) conditioning to the features that make up the context, which does not.
authors.affiliation: Department of Psychology, Center for Neuroscience, University of Colorado, Boulder, Colorado 80309, USA.
authors.forename: Patricia
authors.initials: P
authors.lastname: Matus-Amat
authors.forename: Emily A
authors.initials: EA
authors.lastname: Higgins
authors.forename: Ruth M
authors.initials: RM
authors.lastname: Barrientos
authors.forename: Jerry W
authors.initials: JW
authors.lastname: Rudy
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D003213:Conditioning, Psychological / Q000187:drug effects / Q000502:physiology; D004597:Electroshock; D005239:Fear / Q000187:drug effects / Q000502:physiology*; D018755:GABA Agonists / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008568:Memory / Q000502:physiology*; D011939:Mental Recall / Q000502:physiology*; D008845:Microinjections; D009118:Muscimol / Q000494:pharmacology; D009433:Neural Inhibition / Q000187:drug effects; D051381:Rats; D020318:Rats, Long-Evans; D013037:Spatial Behavior / Q000187:drug effects / Q000502:physiology; D013997:Time Factors
chemical_list: D018755:GABA Agonists; D009118:Muscimol