Implicit and explicit learning in an auditory serial reaction time task

Objective - To explore the role of the motor cortex during implicit and explicit learning. Materials and methods - EEG signals were recorded from 30 channels by measuring task-related desynchronization (TRD) when 10 right-handed naive volunteers performed a variation of the serial reaction task. Stimuli, consisting of 4 pure tones of 500, 1000, 1500, and 2000 HZ, lasting 200 ms, were presented binaurally through a pair of tubephones at 60 dB with a 2-s constant interstimulus interval. A series of 10 repetitive tones represented the test sequence; the random sequence was the control. Results - All subjects developed implicit and explicit knowledge reflected by decreased response time, increased accuracy, and the ability to generate the sequence. Six of 10 subjects demonstrated implicit learning without explicit learning during the first 3 blocks. When subjects acquired full explicit learning, 10 Hz TRD at C3 reached a peak amplitude, declining thereafter. Conclusions - Properties of the sensorimotor cortex change during learning and these changes are independent of stimulus modality.