Theta oscillatory activity predicts motor learning chunk performance

Despite the long-standing tradition of motor sequence learning (MSL) research, cortical oscillatory dynamics that provide the basis for learning mechanisms require more evidence and linkage to cognitive control theories. We explore the functional role of event-related synchronisation/desynchronisation (ERD/S) that supports MSL and seek to understand their development from learning. Twenty-five participants performed a Go/NoGo version of the discrete sequence production task and learnt two different 6-key sequences over five learning blocks for each hand. During MSL, continuous 32-channel EEG were recorded across all trials. EEG was data was segmented into epochs matching the sequence execution phases: 1) motor preparation; 2) motor execution; 3) post-movement. ERD/S values were extracted from three separate bands: θ (4–8 Hz), α (8–12 Hz), and β (12–28Hz) in 100 ms time windows for the motor preparation, motor execution and post-movement epochs. During motor preparation, larger theta ERS over the fronto-motor areas were found post-learning compared to pre-training. Whilst executing a sequence, increased theta ERS positively correlated with the response times performance of concatenation. This suggest that theta activity over fronto-motor areas may facilitate working memory processes in the loading of subsequent motor chunks cued for execution. Although typical beta ERS was evident during the post phase, it was not correlated with MSL behavioural performance. Whilst behavioural performances show motor chunk boundaries through concatenation, mid-sequence theta ERS suggests working memory involvement in active retrieval and priming of subsequent motor chunks.