The Aging Cerebellum: Cortico-Cerebeller Connectivity, Volume and the Impact on Behavior.

Healthy aging is associated with declines in both sensorimotor and cognitive performance. An understanding of the neural underpinnings of these behavioral declines is key to their mitigation and prevention. To date, the majority of the literature on aging has focused on the cerebral cortex. Thus, our current knowledge of aging is limited as there has been little work to investigate the cerebellum. Converging evidence indicates a potentially important role for the cerebellum in age-related performance declines, though it has yet to be studied in detail. Investigating cortico-cerebellar networks and volume in aging would provide insight into the variability of behavioral performance in older adults. We investigated resting state cortico-cerebellar networks in healthy young (Chapter 2) and older (Chapter 3) adults. Cerebellar volume was investigated in Chapter 4. In Chapters 2 and 3, we predicted that the cortico-cerebellar networks would be consistent with the known functional topography of the cerebellum. However, in the older adults, we hypothesized that these networks would exhibit reduced connectivity strength. We also predicted that reduced cortico-cerebellar connectivity would be correlated with behavioral performance in a manner consistent with the cerebellar functional topography. In Chapter 4 we hypothesized that there would be age differences in regional cerebellar volume. Again, we expected to see correlations between volume and behavior in a functionally specific topographical manner. Our findings in Chapters 2 and 3 support the predicted functionally distinct cortico-cerebellar networks. Additionally, in Chapter 3 we demonstrated widespread decreased cortico-cerebellar connectivity strength in older adults. Cortico-cerebellar connectivity was also associated with behavioral performance in older adults, but not in a topographical manner. Rather, we demonstrated the behavioral importance of cerebellar connectivity strength with the striatum and structures implicated in the default mode network. Finally, in Chapter 4 we found smaller cerebellar volume in older adults, though there were no regional differences in volume. However, our findings indicated that the posterior cerebellum is particularly important for sensorimotor behavioral performance. Regions of the cerebellum associated with cognitive function may be particularly important for sensorimotor task performance. Together, these results provide novel insight into the role of the cerebellum in aging.PHDPsychologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/96054/1/jessbern_1.pd