Spectral and temporal electroencephalography measures reveal distinct neural networks for the acquisition, consolidation, and interlimb transfer of motor skills in healthy young adults.

OBJECTIVE: Plasticity of the central nervous system likely underlies motor learning. It is however unclear, whether plasticity in cortical motor networks is motor learning stage-, activity-, or connectivity-dependent. METHODS: From electroencephalography (EEG) data, we quantified effective connectivity by the phase slope index (PSI), neuronal activity by event-related desynchronization, and sensorimotor integration by N30 during the stages of visuomotor skill acquisition, consolidation, and interlimb transfer. RESULTS: Although N30 amplitudes and event-related desynchronization in parietal electrodes increased with skill acquisition, changes in PSI correlated most with motor performance in all stages of motor learning. Specifically, changes in PSI between the premotor, supplementary motor, and primary motor cortex (M1) electrodes correlated with skill acquisition, whereas changes in PSI between electrodes representing M1 and the parietal and primary sensory cortex (S1) correlated with skill consolidation. The magnitude of consolidated interlimb transfer correlated with PSI between bilateral M1s and between S1 and M1 in the non-practiced hemisphere. CONCLUSIONS: Spectral and temporal EEG measures but especially PSI correlated with improvements in complex motor behavior and revealed distinct neural networks in the acquisition, consolidation, and interlimb transfer of motor skills. SIGNIFICANCE: A complete understanding of the neuronal mechanisms underlying motor learning can contribute to optimizing rehabilitation protocols.