title: Patterned (single) alternation in infant rats after combined or separate lesions of hippocampus and amygdala.
abstract: The role of the developing hippocampus and the amygdala on patterned (single) alternation (PA) in the infant rat was investigated in 4 experiments. In Experiments 1 and 2, pups were given 2 bilateral electrolytic hippocampal lesions or sham surgeries at 10 or 11 days of age and were trained 6 days later in a straight runway. In Experiment 1, there were 120 trials in 1 day, with an 8-, a 15-, or a 30-s intertrial interval (ITI). PA learning occurred in lesion and sham pups at the 8- and 15-s ITIs, but it was reduced in both groups at the 30-s ITI. In Experiment 2, training was extended to 240 trials over 2 days, with a 30- or 60-s ITI. Sham and lesion pups showed PA at the 30-s ITI, but the emergence of PA was delayed in the lesion pups at the 60-s ITI. In Experiment 3, amygdaloid lesions had no effect on PA learning at the 8-s ITI. However, when pups with hippocampal and amygdaloid lesions were trained at the 8-s ITI, the emergence of PA was delayed, and its size was reduced (Experiment 4). The results of these experiments argue for a role of the hippocampus in PA learning at long ITIs and suggest that, even in 16-day-old pups exposed to an 8-s ITI, the combined hippocampal and amygdaloid lesion produces a deficit greater than either the hippocampal or the amygdaloid lesion. The results are discussed in relation to current theories that distinguish between 2 levels of memory function.
authors.affiliation: Department of Psychology, University of Texas, Austin 78712.
authors.forename: N J
authors.initials: NJ
authors.lastname: Lobaugh
authors.forename: P L
authors.initials: PL
authors.lastname: Greene
authors.forename: M
authors.initials: M
authors.lastname: Grant
authors.forename: T
authors.initials: T
authors.lastname: Nick
authors.forename: A
authors.initials: A
authors.lastname: Amsel
mesh_terms: D000679:Amygdala / Q000502:physiology*; D000818:Animals; D001143:Arousal / Q000502:physiology; D001288:Attention / Q000502:physiology; D001931:Brain Mapping; D003216:Conditioning, Operant / Q000502:physiology*; D004193:Discrimination Learning / Q000502:physiology*; D005260:Female; D006624:Hippocampus / Q000502:physiology*; D008297:Male; D008568:Memory / Q000502:physiology*; D008570:Memory, Short-Term / Q000502:physiology; D011939:Mental Recall / Q000502:physiology*; D009042:Motivation; D009949:Orientation / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D012055:Reinforcement Schedule