INDIVIDUAL DIFFERENCES IN FRONTAL/BASAL-GANGLIA STRUCTURES AS PREDICTORS OF PERFORMANCE IN HEALTHY AGING: ON THE INTERPLAY BETWEEN MOTOR CONTROL AND COGNITION
Oron Levin – Movement Control and Neuroplasticity Research Group, Department of Kinesiology, Group Biomedical Sciences, KU Leuven, Heverlee, Belgium
Abstract: The associations between age-related differences in motor performance and individual changes in brainʼs structural integrity were examine in healthy older adults. Structural MRI (T1-weighted images) were collected from 35 young and 30 older adults who underwent a battery of motor tests, including multilimb reaction time task (MULRT) and perturbed balance control tests. With respect to performance on MULRT task (35 young, 30 old adults), observation revealed that: (i) inward deformation (i.e., local atrophy) of the nucleus accumbens and caudate were predictive of longer action selection times in complex conditions, but not in easy task conditions; but (ii) only local atrophy of the left nucleus accumbens predicted performance declines in elderly (Boisgontier et al., 2016). With respect to balance control (30 young, 28 old adults), observations showed that structural changes in regions of the brainstem were the strongest predictor of postural stability: (iii) lower brainstem volume predicted larger center of pressure deviation and higher odds of balance loss. On the contrary (iv), greater basal ganglia volume was associated with more unstable posture (Boisgontier et al., 2017). While the associations between morphological changes in basal ganglia and performance may not be generalized across all motor functions, results from the two studies suggest that the relevance of the nucleus accumbens for different aspects of motor control increases with age. It is proposed that damage to the bottleneck underlying interactions between different neurotransmitter systems in the nucleus accumbens seem to be a neurocorrelate of motor performance deficits in healthy aging. Finally, the observations from two studies raise a question about the role of dopaminergic circuitry in the interplay between cognition and motor control.