CEREBELLAR OVER-RECRUITMENT AND REDUCED MEDIAL FRONTAL ENGAGEMENT WITH INCREASING BIMANUAL TASK COMPLEXITY IN HEALTHY OLDER ADULTS

Bimanual coordination declines with age, but the neural mechanisms underlying these changes remain unclear. Age-related differences in brain activity have been interpreted either as compensatory over-recruitment of frontal regions or as a shift toward feedback-mediated control. To investigate these alternatives, we examined brain activity using fMRI in twenty-three younger and twenty-three older adults performing a dynamic visuomotor bimanual pinch-force task.
Behaviorally, older adults showed lower accuracy than younger adults, particularly when task demands increased. Neuroimaging results revealed age-dependent overactivation of posterior cerebellar lobules VI–VII, regions implicated in online error correction and internal model updating. Activity in these regions was negatively associated with performance across participants. Anterior cerebellar lobules IV–V showed increased activation in relation to higher performance demands, and older adults exhibited reduced activity in the medial frontal pole (BA9/10) during more demanding movements. No consistent age-related overactivation was observed in parieto-frontal regions.
These findings indicate that age-related differences in dynamic bimanual coordination are most pronounced in the cerebellum, with posterior and anterior regions showing distinct patterns related to performance and task demands. Together, the results are consistent with a shift toward feedback- and error-driven control strategies in older adults, rather than compensatory frontal over-recruitment.