Synaptic correlates of memory and menopause in the hippocampal dentate gyrus in rhesus monkeys

Yuko Hara, C. Sehwan Park, William G.M. Janssen, Mary T. Roberts, John Morrison, Peter R. Rapp

Research output: Contribution to journalArticle

40 Scopus citations

Abstract

Aged rhesus monkeys exhibit deficits in hippocampus-dependent memory, similar to aging humans. Here we explored the basis of cognitive decline by first testing young adult and aged monkeys on a standard recognition memory test (delayed nonmatching-to-sample test; DNMS). Next we quantified synaptic density and morphology in the hippocampal dentate gyrus (DG) outer (OML) and inner molecular layer (IML). Consistent with previous findings, aged monkeys were slow to learn DNMS initially, and they performed significantly worse than young subjects when challenged with longer retention intervals. Although OML and IML synaptic parameters failed to differ across the young and aged groups, the density of perforated synapses in the OML was coupled with recognition memory accuracy. Independent of chronological age, monkeys classified on the basis of menses data as peri- or post-menopausal scored worse on DNMS, and displayed lower OML perforated synapse density, than premenopausal monkeys. These results suggest that naturally occurring reproductive senescence potently influences synaptic connectivity in the DG OML, contributing to individual differences in the course of normal cognitive aging.

Original languageEnglish (US)
JournalNeurobiology of Aging
Volume33
Issue number2
DOIs
StatePublished - Feb 1 2012
Externally publishedYes

Keywords

  • Delayed nonmatching-to-sample
  • Disector method
  • Estrogen
  • Hippocampus
  • Menopause
  • Outer molecular layer
  • Perforated synapse
  • Postsynaptic density
  • Recognition memory

ASJC Scopus subject areas

  • Neuroscience(all)
  • Aging
  • Clinical Neurology
  • Developmental Biology
  • Geriatrics and Gerontology

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