title: Role of the hippocampus in contextual memory after classical aversive conditioning in pigeons (C. livia).
abstract: We investigated the effects of hippocampal lesions with ibotenic acid (IBO) on the memory of the sound-context-shock association during reexposure to the conditioning context. Twenty-nine adult pigeons were assigned to a non-lesioned control group (CG, N = 7), a sham-lesioned group (SG, N = 7), a hippocampus-lesioned experimental group (EG, N = 7), and to an unpaired nonlesioned group (tone-alone exposure) (NG, N = 8). All pigeons were submitted to a 20-min session in the conditioning chamber with three associations of sound (1000 Hz, 85 dB, 1 s) and shock (10 mA, 1 s). Experimental and sham lesions were performed 24 h later (EG and SG) when EG birds received three bilateral injections (anteroposterior (A), 4.5, 5.25 and 7.0) of IBO (1 microl and 1 microg/microl) and SG received one bilateral injection (A, 5.25) of PBS. The animals were reexposed to the training context 5 days after the lesion. Behavior was videotaped for 20 min and analyzed at 30-s intervals. A significantly higher percent rating of immobility was observed for CG (median, 95.1; range, 79.2 to 100.0) and SG (median, 90.0; range, 69.6 to 95.0) compared to EG (median, 11.62; range, 3.83 to 50.1) and NG (median, 7.33; range, 6.2 to 28.1) (P<0.001) in the training context. These results suggest impairment of contextual fear in birds who received lesions one day after conditioning and a role for the hippocampus in the modulation of emotional aversive memories in pigeons.
authors.affiliation: Laboratório de Sistemas Neurais e Comportamento, Departamento de Biofísica e Fisiologia, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP, Brasil.
authors.forename: F
authors.initials: F
authors.lastname: Reis
authors.forename: A A
authors.initials: AA
authors.lastname: Schenka
authors.forename: L L
authors.initials: LL
authors.lastname: Melo
authors.forename: E A
authors.initials: EA
authors.lastname: Ferrari
mesh_terms: D000818:Animals; D001921:Brain / Q000166:cytology; D010856:Columbidae; D003463:Cues; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology*; D005239:Fear / Q000502:physiology*; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects* / Q000293:injuries* / Q000502:physiology; D007051:Ibotenic Acid / Q000494:pharmacology*; D007858:Learning / Q000502:physiology*; D008297:Male; D008568:Memory / Q000502:physiology*
chemical_list: D018690:Excitatory Amino Acid Agonists; D007051:Ibotenic Acid