To investigate the short-term modulatory effects of cerebellar theta burst stimulation (TBS) on motor sequence learning ability and motor cortical excitability in healthy individuals.

Ten medical interns from the Department of Rehabilitation and Medicine at Ruijin Rehabilitation Hospital (March to June 2024) were enrolled in a single-group pretest-posttest study. Participants received a single session of continuous theta burst stimulation (cTBS) over the right cerebellum. Before and after stimulation, participants performed a serial reaction time task (SRTT) with their right hand, with reaction times (RTs) and accuracy rates recorded. Changes in corticospinal excitability were assessed by measuring motor evoked potential (MEP) amplitude, latency, resting motor threshold (RMT), intracortical inhibition (ICI), intracortical facilitation (ICF), and cortical silent period (CSP).

Post-cTBS, RTs for repeated sequences were prolonged (P<0.05), while RTs for random sequences shortened (P<0.05). Overall accuracy remained stable (P>0.05). In the left primary motor area (M1), MEP amplitude decreased (P<0.05), RMT increased (P<0.05), ICI inhibitory effect was enhanced (P<0.05), and CSP showed a trend toward prolongation (P>0.05). No significant changes were observed in ICF.

Cerebellar cTBS impairs the immediate performance of healthy participants during motor sequence learning, resulting in delayed responses, indicating that cerebellar cTBS may exert an adverse effect on immediate sequence consolidation. Concurrently, cerebellar cTBS reduces cortical excitability in the contralateral M1, consistent with the notion that the cerebellum exerts an inhibitory influence over cortical motor areas. These findings provide evidence for the specific role of cerebellar TBS in motor sequence learning.