title: Differential effects of fornix and caudate nucleus lesions on two radial maze tasks: evidence for multiple memory systems.
abstract: The present experiments were designed to examine the hypothesis that the mammalian brain contains anatomically distinct memory systems. Rats with bilateral lesions of caudate nucleus or fimbria-fornix and a control group were tested postoperatively on 1 of 2 versions of the radial maze task. In a standard win-shift version, each of the 8 arms of the maze was baited once, and the number of errors (revisits) in the first 8 choices of each trial was recorded. Fimbria-fornix rats were impaired in choice accuracy, while caudate animals were unimpaired relative to controls. Different groups of rats with similar lesions were tested on a newly developed win-stay version of the radial maze, in which the location of 4 randomly selected baited arms was signaled by a light at the entrance to each arm, and which required rats to revisit arms in which reinforcement had been previously acquired within a trial. Rats with fimbria-fornix lesions were superior to controls in choice accuracy on the win-stay radial maze task, while caudate animals were impaired relative to controls. The results demonstrate a double dissociation of the mnemonic functions of the hippocampus and caudate nucleus. Some implications of the presence of 2 memory systems in the mammalian brain are discussed.
authors.affiliation: Department of Psychology, McGill University, Montreal, Quebec, Canada.
authors.forename: M G
authors.initials: MG
authors.lastname: Packard
authors.forename: R
authors.initials: R
authors.lastname: Hirsh
authors.forename: N M
authors.initials: NM
authors.lastname: White
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D002421:Caudate Nucleus / Q000502:physiology*; D006624:Hippocampus / Q000502:physiology*; D007858:Learning / Q000502:physiology*; D008297:Male; D008568:Memory / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains