Abstract
A central problem in the neurobiology of normal aging is why learning is preserved in some aged individuals yet impaired in others. To investigate this issue, we examined whether age-related deficits in spatial learning are associated with a reduction in postsynaptic density (PSD) area in hippocampal excitatory synapses (i.e., with a structural modification that is likely to have a deleterious effect on synaptic function). A hippocampus-dependent version of the Morris water maze task was used to separate Long-Evans male rats into young adult, aged learning-unimpaired, and equally aged learning-impaired groups. Axospinous synapses from the CA1 stratum radiatum were analyzed using systematic random sampling and serial section analyses. We report that aged learning-impaired rats exhibit a marked (∼30%) and significant reduction in PSD area, whereas aged learning-unimpaired rats do not. The observed structural alteration involves a substantial proportion of perforated synapses but is not observed in nonperforated synapses. These findings support the notion that many hippocampal perforated synapses become less efficient in aged learning-impaired rats, which may contribute to cognitive decline during normal aging.
Original language | English (US) |
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Pages (from-to) | 7648-7653 |
Number of pages | 6 |
Journal | Journal of Neuroscience |
Volume | 24 |
Issue number | 35 |
DOIs | |
State | Published - Sep 1 2004 |
Keywords
- CA1 stratum radiatum
- Hippocampus
- Learning deficits
- Normal aging
- Perforated synapses
- Rat
ASJC Scopus subject areas
- General Neuroscience