Associations between pre-to-post TMS-evoked potential changes and motor sequence learning across retention intervals.

Motor sequence learning involves practice-related changes in behavior and neural activity, yet the neurophysiological markers associated with later retention remain unclear. TMS-evoked potentials (TEPs) provide a measure of cortical responses to stimulation and may help characterize physiological-behavioral relationships across different learning timescales. Whether these associations differ across retention intervals remains unclear. We examined whether baseline TMS-EEG measures or task-related changes in right primary motor cortex (M1) TEPs are associated with initial acquisition and subsequent performance change across short and long-term retention intervals during a non-dominant hand motor sequence task. Seventeen healthy right-handed adults performed a five-element finger-tapping sequence with the left hand across three sessions: Day 1 (acquisition), Day 2 (short-term retention), and Day 7 (long-term retention). Single-pulse TMS-EEG was acquired before and after task performance over right M1 at each session. Four TEP components (N45, N100, P180, and N280) were analyzed. Day 1 training was associated with increases in PR and ACC, together with improved accuracy-adjusted efficiency, and slope dynamics remained broadly stable across later test sessions. Acute pre-to-post right-M1 TEP changes were not associated with rapid within-session acquisition. Pre-to-post P180 TEP change showed a nominal association with subsequent efficiency change, with a stronger nominal pattern over the 24-h interval than over the 5-day interval. However, neither the P180 dTEP effect nor the Interval × dTEP interaction survived FDR correction, and both were sensitive to participant-level influence and bootstrap resampling. These findings suggest that right-M1 TEP measures showed different relationships with rapid within-session acquisition and between-session performance change. Late P180 changes may be related to performance change across different retention intervals, but whether they reflect time-dependent consolidation processes remains to be established.