STUDIES OF AGING AND COGNITION IN NONHUMAN PRIMATES

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Our previous work has centered on characterizing the cognitive and brain changes that occur with aging in the rhesus monkey. We have thus identified changes in recognition memory, spatial working memory, and executive function which parallel closely the changes that occur in aging humans. We also determined that monoamine receptor binding density in the dorso-lateral pre-frontal cortex is related to aging and to performance on cognitive tasks which tap these cognitive domains. In this project period, we examined whether sex modulates cognitive performance as well as motor behavior. We found that males perform better than females on a task of spatial working memory, but that the sex difference disappears in aged animals. In addition, we demonstrated that young females can benefit from a simple training to obtain scores similar to that of young males. In the motor task, monkeys had to retrieve a Life Saver candy from rods of different complexity. We examined whether fine motor ability (1) is sexually dimorphic, (2) declines with age and (3) declines differently in males and females. In addition, we measured the whole brain volume, the volumes of the caudate, putamen, hippocampal formation and the area of the corpus callosum in a subset of the monkeys (n=15) for which magnetic resonance images of the brain were available. All monkeys performed similarly in the test with the simplest rod. In the test with complex rods, however, age-related slowing of motor function was evident in males, but not in females. Age-related decreases in the normalized caudate and putamen volumes were similar in males and in females. Motor speed was not significantly correlated to any of the neuroanatomical measures under study. Further studies are under way to examine the relationships between motor performance and more complex behaviors such as cognition.