title: Critical determinants of nonspatial working memory deficits in rats with conventional lesions of the hippocampus or fornix.
abstract: Rats with conventional lesions of the hippocampus or fornix were compared postoperatively with controls on nonspatial memory tasks. Neither lesion impaired delayed matching-to-sample (DMS) performance in a discrete-trial task involving "pseudo-trial-unique" complex stimuli. An impairment emerged if a single pair of complex stimuli was used throughout each day's session, and the greatest impairment was obtained with the use of a single pair of less complex stimuli throughout each day's test. Transfer to a continuous DMS task with no explicit intertrial interval produced a different pattern because both lesion and control levels of performance were depressed when two complex stimuli were used repeatedly. A final, separate discrimination learning experiment showed that hippocampectomized rats readily discriminated between the stimuli associated with the greatest lesion-induced DMS deficit. Hippocampal dysfunction thus produces clear deficits on non-spatial memory tasks under appropriate test conditions.
authors.affiliation: Department of Experimental Psychology, University of Oxford, England.
authors.forename: J N
authors.initials: JN
authors.lastname: Rawlins
authors.forename: G L
authors.initials: GL
authors.lastname: Lyford
authors.forename: A
authors.initials: A
authors.lastname: Seferiades
authors.forename: R M
authors.initials: RM
authors.lastname: Deacon
authors.forename: H J
authors.initials: HJ
authors.lastname: Cassaday
mesh_terms: D000818:Animals; D001070:Appetitive Behavior / Q000502:physiology; D001288:Attention / Q000502:physiology*; D001931:Brain Mapping; D004193:Discrimination Learning / Q000502:physiology*; D006624:Hippocampus / Q000502:physiology*; D008297:Male; D011939:Mental Recall / Q000502:physiology*; D009434:Neural Pathways / Q000502:physiology; D009949:Orientation / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology*; D011340:Problem Solving / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012153:Retention, Psychology / Q000502:physiology