Our research programs involving awake behaving nonhuman primates are based at the NIH Animal Center (NIHAC) in Poolesville, MD, approximately 90 minutes from most of the NIA laboratories in Baltimore. The NIHAC provides outstanding infrastructure for animal housing, conditioning and quarantine, servicing much of the larger NIH community. The facility is less ideally configured in support of investigator research programs, however, and given the relatively remote location of the Center, opportunities for recruiting and retaining scientific staff can be challenging. Although project start-up has been protracted as a consequence, we have recently recruited a Biologist with significant experience at the NIHAC who we anticipate will substantially facilitate progress. Key project infrastructure has also been established, including custom-designed operant chambers for computer-aided, touch screen based neuropsychological testing, and we continue to retain off-site computer programming expertise in support of this element of the project. Although accessing the outstanding in vivo brain imaging facilities on NIH main campus presents a number of logistical hurdles and administrative issues surrounding reimbursement, we are actively pursuing options for continuing and extending this component of our nonhuman primate research program. Progress from imaging we conducted elsewhere includes a recent study testing whether age-related decline in spatiotemporal and recognition memory is coupled with atrophy of memory-related brain regions in rhesus monkeys (Shamy et al., 2011). Key findings were that, in contrast to expectations derived from lesion and electrophysiological studies in young subjects, the volume of selected prefrontal cortex (PFC) areas was coupled with the status of memory that is typically considered an exemplar of medial temporal lobe function. Hippocampal volume, by comparison, predicted performance on a classic test of PFC integrity (the delayed response task). Together, the results provide novel support for the view that cognitive aging in primates arises from region-specific morphometric alterations that are distributed across multiple memory-related brain systems, prominently including subdivisions of the PFC (Shamy et al, 2011). Complementing the overall project aims, collaborative studies have also examined individual differences in the neurocognitive outcome of aging in rhesus monkeys in relation to naturally occurring ovarian hormone decline. In two recently published reports, for example, brain material from behaviorally characterized young and aged subjects was used to evaluate synaptic density and morphology in the hippocampal dentate gyrus by quantitative electron microscopy (Hara et al., 2010;2011). These findings, together with observations from our related studies of surgical menopause and hormone treatment in monkeys, make the important point that the aged primate hippocampus remains sensitive to ovarian hormone status, and that the influence of reproductive senescence on circuit-specific synaptic subtypes may contribute to the effects of aging on hippocampal memory function. Progress in this area of research is surveyed in a number of recent reviews (e.g., Hara et al., 2011;Dumitriu et al., 2010).
Showing the most recent 10 out of 15 publications
