title: Hippocampus, perirhinal cortex, and complex visual discriminations in rats and humans.
abstract: Structures in the medial temporal lobe, including the hippocampus and perirhinal cortex, are known to be essential for the formation of long-term memory. Recent animal and human studies have investigated whether perirhinal cortex might also be important for visual perception. In our study, using a simultaneous oddity discrimination task, rats with perirhinal lesions were impaired and did not exhibit the normal preference for exploring the odd object. Notably, rats with hippocampal lesions exhibited the same impairment. Thus, the deficit is unlikely to illuminate functions attributed specifically to perirhinal cortex. Both lesion groups were able to acquire visual discriminations involving the same objects used in the oddity task. Patients with hippocampal damage or larger medial temporal lobe lesions were intact in a similar oddity task that allowed participants to explore objects quickly using eye movements. We suggest that humans were able to rely on an intact working memory capacity to perform this task, whereas rats (who moved slowly among the objects) needed to rely on long-term memory.
authors.affiliation: Department of Psychiatry, University of California, San Diego, La Jolla, California 92093, USA Department of Neurosciences, University of California, San Diego, La Jolla, California 92093, USA.
authors.forename: Jena B
authors.initials: JB
authors.lastname: Hales
authors.affiliation: Department of Psychiatry, University of California, San Diego, La Jolla, California 92093, USA.
authors.forename: Nicola J
authors.initials: NJ
authors.lastname: Broadbent
authors.affiliation: Department of Neurosciences, University of California, San Diego, La Jolla, California 92093, USA.
authors.forename: Priya D
authors.initials: PD
authors.lastname: Velu
authors.affiliation: Department of Psychiatry, University of California, San Diego, La Jolla, California 92093, USA Department of Psychology, University of California, San Diego, La Jolla, California 92093, USA Department of Neurosciences, University of California, San Diego, La Jolla, California 92093, USA Veterans Affairs San Diego Healthcare System, San Diego, California 92161, USA reclark@ucsd.edu lsquire@ucsd.edu.
authors.forename: Larry R
authors.initials: LR
authors.lastname: Squire
authors.affiliation: Department of Psychiatry, University of California, San Diego, La Jolla, California 92093, USA Veterans Affairs San Diego Healthcare System, San Diego, California 92161, USA reclark@ucsd.edu lsquire@ucsd.edu.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Clark
mesh_terms: D000368:Aged; D000818:Animals; D004192:Discrimination, Psychological / Q000502:physiology; D005260:Female; D006624:Hippocampus / Q000473:pathology / Q000502:physiology*; D006801:Humans; D008297:Male; D057567:Memory, Long-Term / Q000502:physiology*; D008570:Memory, Short-Term / Q000502:physiology*; D008875:Middle Aged; D051381:Rats; D020318:Rats, Long-Evans; D013702:Temporal Lobe / Q000473:pathology / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*