Neuroplastic and motor behavioral changes after intermanual transfer training of non-dominant hand: A prospective fMRI study.

BACKGROUND: Intermanual transfer of learning is an important movement basis for a keyboard and instrument playing movement. However, the issue of where neural plastic mechanism occurs in the brain after intermanual transfer training remains both controversial and unresolved.

OBJECTIVE: The aim of present study is to investigate the neuroplastic mechanism associated with the interlimb transfer learning from non-dominant hand to dominant hand.

METHODS: Twenty healthy right-handed adults were classified into either the control group (no-training) or the experimental group (training serial button-press motor task, SPMT), 5 days a week for two consecutive weeks. SPMT involved pressing the numbers 1, 2, 3, and 4 in a random sequence, which was presented in the monitor screen. Outcome measures included movement accuracy (MA), movement time (MT), and the fMRI data using a 3T MRI scanner. Repeated measures of analysis of variance (ANOVA) and non-parametric tests were used at p <0.05.

RESULTS: Motor performances in the MA and MT were significantly more improved in the experimental group than in the control group (p <0.05). Neuroimaging data revealed a distributed subcortical and cortical motor network including the SMA-thalamus (VL/VL)-basal ganglia-cerebellum loop, suggesting a differential and time-dependent neural network utilized during intermanual transfer learning.

CONCLUSION: Pre-training intermanual transfer learning involved a form of declarative (or explicit) motor learning, which was primarily mediated by the cortical motor network, whereas post-training involved a form of procedural knowledge, which activated subcortical and cortical motor network regions, including the SMA-thalamus (VL/VL)-basal ganglia-cerebellum loop.