Increased prefrontal top-down control in older adults predicts motor performance and age-group association

Abstract

Bimanual motor control declines during healthy ageing, affecting the ability of older adults to maintain independence. Age-related changes in neural dynamics of movement preparation that underlie reduced bimanual motor control, however, remain largely elusive. Here, we assessed effective connectivity within a prefrontal-premotor network of 19 young and 20 older adults during the preparatory phase of complex bimanual movements using high-density electroencephalography and Dynamic Causal Modelling of evoked responses. We found that excitatory interhemispheric prefrontal to premotor coupling in older adults predicted age-group association and poor motor-performance. In contrast, excitatory intrahemispheric prefrontal to premotor coupling enabled older adults to maintain motor-performance at the cost of lower movement speed. Our results disentangle the complex interplay in the prefrontal-premotor network underlying reduced bimanual control and the well-known speed-accuracy trade-off seen in older adults. We anticipate these coupling patterns to be potential biomarkers for healthy ageing and a possible future target of non-invasive brain-stimulation.