title: Hippocampal volume is preserved and fails to predict recognition memory impairment in aged rhesus monkeys (Macaca mulatta).
abstract: Aged monkeys exhibit deficits in memory mediated by the medial temporal lobe system, similar to the effects of normal aging in humans. The contribution of structural deterioration to age-associated memory loss was explored using magnetic resonance imaging techniques. We quantified hippocampal, cerebral and ventricular volumes in young (n = 6, 9-12 years) and aged (n = 6, 24-29 years) rhesus monkeys. Eleven subjects were tested on a recognition memory task, delayed non-matching-to-sample (DNMS). Compared to young animals, aged monkeys exhibited robust learning deficits and significant memory impairments when challenged with longer retention intervals. Hippocampal volume was statistically equivalent across age groups, differing by less than 6%, and there was no correlation between this measure and DNMS performance. Variability in cerebral volume was greater in the aged compared to young monkeys and this parameter was marginally correlated with DNMS performance with a 10-min delay. These findings confirm and extend the conclusion of recent post-mortem histological analyses demonstrating that normal cognitive aging occurs independently of gross structural deterioration in the primate hippocampus.
authors.affiliation: Department of Neuroscience and Kastor Neurobiology of Aging Laboratories, Mt. Sinai School of Medicine, One Gustave, L. Levy Place, Box 1065, NY 10029-6574, USA.
authors.forename: Jul Lea T
authors.initials: JL
authors.lastname: Shamy
authors.forename: Michael H
authors.initials: MH
authors.lastname: Buonocore
authors.forename: Leah M
authors.initials: LM
authors.lastname: Makaron
authors.forename: David G
authors.initials: DG
authors.lastname: Amaral
authors.forename: Carol A
authors.initials: CA
authors.lastname: Barnes
authors.forename: Peter R
authors.initials: PR
authors.lastname: Rapp
mesh_terms: D000375:Aging / Q000473:pathology*; D000818:Animals; D005260:Female; D006624:Hippocampus / Q000473:pathology* / Q000503:physiopathology*; D008253:Macaca mulatta; D008279:Magnetic Resonance Imaging; D008297:Male; D008569:Memory Disorders / Q000473:pathology* / Q000503:physiopathology*; D009929:Organ Size; D010364:Pattern Recognition, Visual; D021641:Recognition, Psychology; D013223:Statistics as Topic; D013647:Task Performance and Analysis