Journal
JOURNAL OF NEUROSCIENCE
Volume 38, Issue 49, Pages 10467-10478Publisher
SOC NEUROSCIENCE
DOI: 10.1523/JNEUROSCI.1234-18.2018
Keywords
aging; area 7a; dendritic spines; primate; thin spines; working memory
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Funding
- National Institute of Aging [NIA R01-AG006647, NIA R01-AG010606, NIA P01-AG016765, NIA T32-AG049688]
- Intramural Research Program of the National Institute on Aging
- NATIONAL INSTITUTE ON AGING [T32AG049688, R01AG010606, ZIAAG000352, R01AG006647, P01AG016765] Funding Source: NIH RePORTER
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Brodmann area 7a of the parietal cortex is active during working memory tasks in humans and nonhuman primates, but the composition and density of dendritic spines in area 7a and their relevance both to working memory and cognitive aging remain unexplored. Aged monkeys have impaired working memory, and we have previously shown that this age-induced cognitive impairment is partially mediated by a loss of thin spines in prefrontal cortex area 46, a critical area for working memory. Because area 46 is reciprocally connected with area 7a of the parietal cortex and 7a mediates visual attention integration, we hypothesized that thin spine density in area 7a would correlate with working memory performance as well. To investigate the synaptic profile of area 7a and its relevance to working memory and cognitive aging, we investigated differences in spine type and density in layer III pyramidal cells of area 7a in young and aged, male and female rhesus macaques (Macaca mulatta) that were cognitively assessed using the delayed response test of working memory. Area 7a shows age-related loss of thin spines, and thin spine density positively correlates with delayed response performance in aged monkeys. In contrast, these cells show no age-related changes in dendritic length or branching. These changes mirror age-related changes in area 46 but are distinct from other neocortical regions, such as VI. These findings support our hypothesis that cognitive aging is driven primarily by synaptic changes, and more specifically by changes in thin spines, in key association areas.
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