Event-related desynchronization (ERD) in the alpha frequency during development of implicit and explicit learning

To understand the role of the motor cortex in implicit and explicit learning, we studied alpha event-related desynchronization (ERD) while 13 right-handed individuals performed a variation of the serial reaction time task (SRTT). EEG signals were recorded simultaneously from 29 scalp locations and the ERD was computed. During data collection, all subjects developed implicit knowledge, demonstrated by shortening of the response time, and explicit knowledge of the test sequence. The average ERD maps of all 13 subjects demonstrated that during the initial learning, there was a decline in alpha band power that was maximal over the contralateral central region. The ERD reached a transient peak amplitude at a point when the subjects attained full explicit knowledge, and diminished subsequently. The transient peak in ERD was highly significant at C3. These electrophysiologic findings support previous studies which have demonstrated that motor activity changes as behavior changes over the course of learning.