Neurophysiological correlates of age-related changes in human motor function

TLDR

Age‑related motor deficits are linked to structural and chemical changes in the aging brain. The study aims to map age‑related physiological changes in brain systems underlying simple motor behavior. Using 1.5‑T fMRI, 22 right‑handed participants (10 young, 12 elderly) performed a paced button‑press task while brain activity was recorded. Elderly participants showed slower reaction times and greater activation in multiple motor and cerebellar regions, suggesting compensatory recruitment of additional cortical and subcortical networks.

Abstract

<b><i>Background:</i></b> There are well-defined and characteristic age-related deficits in motor abilities that may reflect structural and chemical changes in the aging brain. <b><i>Objective:</i></b> To delineate age-related changes in the physiology of brain systems subserving simple motor behavior. <b><i>Methods:</i></b> Ten strongly right-handed young (&lt;35 years of age) and 12 strongly right-handed elderly (&gt;50 years of age) subjects with no evidence of cognitive or motor deficits participated in the study. Whole-brain functional imaging was performed on a 1.5-T MRI scanner using a spiral pulse sequence while the subjects performed a visually paced “button-press” motor task with their dominant right hand alternating with a rest state. <b><i>Results:</i></b> Although the groups did not differ in accuracy, there was an increase in reaction time in the elderly subjects (mean score ± SD, young subjects = 547 ± 97 ms, elderly subjects = 794 ± 280 ms, <i>p</i> &lt; 0.03). There was a greater extent of activation in the contralateral sensorimotor cortex, lateral premotor area, supplementary motor area, and ipsilateral cerebellum in the elderly subjects relative to the young subjects (<i>p</i> &lt; 0.001). Additional areas of activation, absent in the young subjects, were seen in the ipsilateral sensorimotor cortex, putamen (left &gt; right), and contralateral cerebellum of the elderly subjects. <b><i>Conclusions:</i></b> The results of this study show that elderly subjects recruit additional cortical and subcortical areas even for the performance of a simple motor task. These changes may represent compensatory mechanisms invoked by the aging brain, such as reorganization and redistribution of functional networks to compensate for age-related structural and neurochemical changes.