Timing-specific effects of single-session M1 anodal tDCS on motor sequence retention in healthy older adults

Anodal transcranial direct current stimulation (tDCS) may assist in counteracting age-related decline cognitive and motor functions. The study investigated the potential impact of anodal tDCS, timing its application, mitigating deficits sequence learning. Forty-eight healthy older adults received, over primary cortex (M1), tDCS – sham at least 1 week apart before, during or after an explicit sequence-learning task with electrophysiological measures corticospinal excitability (CSE) short-interval intracortical inhibition (SICI) also obtained. Bayesian analyses revealed no generalised benefit to acquisition immediate retention. Furthermore, there was not enough evidence support timing-specific differences on performance However, delayed retention measured 24 ​h worse (13.1%) than (17.6%) session for group receiving acquisition, but before (anodal: 18.4%; sham: 16.7%) 18.5%; 16.3%) it. No corresponding task-specific stimulation-based changes CSE SICI were observed. Thus, single-session M1 only proved ineffective facilitating also, when administered learning, detrimental Overall, these null negative results have implications use clinical rehabilitative settings, especially elderly.