Progress in Motor Control edition:VII location:Marseilles, FR date:July 23-25, 2009
The ability to use one’s hands in a coordinated fashion is essential for performing activities of daily living such as opening a box or cutting food with utensils. Based on behavioral work, it is well accepted that significant deficits exist in the bimanual abilities of elderly individuals. However, the neural correlates underlying such declines have yet to be determined and, thus, remain unknown. The purpose of the present study was to elucidate age-related neural activation differences associated with bimanual task performance. Participants included 16 old (mean age=68.3 yrs; 8 females) and 16 young (mean age=25.7 yrs; 8 females) healthy adults who performed, in an fMRI environment, bimanual coordination tasks that varied in complexity (i.e. in-phase, anti-phase) and movement frequency (i.e. 45, 60, 75, 90% of critical anti-phase speed) demands. Despite producing movements of similar accuracy/stability as young subjects, it was found that old individuals activated a larger, more extensive cohort of brain areas that included supplementary motor area, higher order feedback processing areas and regions typically ascribed to cognitive functions (e.g. memory, attention). Further, “overactivation” of the supplementary motor and left secondary somatosensory areas was positively correlated with elderly coordinative ability during the more complex anti-phase task. This result suggests a compensation mechanism similar to that described previously for cognitive and hand-foot coordination tasks. These novel findings extend previous work regarding movement-related brain activation in old individuals, showing that greater neural resources are required to match the level of performance seen in young subjects.