Age-related changes of the functional architecture of the cortico-basal ganglia circuitry during motor task execution

Normal human aging is associated with declining motor control and function. It is thought that dysfunction of the cortico-basal ganglia circuitry may contribute to age-related sensorimotor impairment, however the underlying mechanisms are poorly characterized. The aim of this study was to enhance our understanding of age-related changes in the functional architecture of these circuits. Fifty-nine subjects, consisting of a young, middle and old group, were studied using functional MRI and a motor activation paradigm. Functional connectivity analyses and examination of correlations of connectivity strength with performance on the activation task as well as neurocognitive tasks completed outside of magnet were conducted. Results indicated that increasing age is associated with changes in the functional architecture of the cortico-basal ganglia circuitry. Connectivity strength increased between subcortical nuclei and cortical motor and sensory regions but no changes were found between subcortical components of the circuitry. Further, increased connectivity was correlated with poorer performance on a neurocognitive task independently of age. This result suggests that increased connectivity reflects a decline in brain function rather than a compensatory process. These findings advance our understanding of the normal aging process. Further, the methods employed will likely be useful for future studies aimed at disambiguating age-related versus illness progression changes associated with neuropsychiatric disorders that involve the cortico-basal ganglia circuitry.