Abstract:

Procedural motor learning includes sequence learning and random learning. Neuroimaging studies have shown that the dorsolateral prefrontal cortex (DLPFC) and primary motor cortex (M1) play significant roles in procedural motor learning; however, the connectivity between the DLPFC and M1 and its relationship with different procedural motor learning are still unclear.
In this study, the serial response time task (SRTT) and transcranial magnetic stimulation (TMS) were used to explore the differences in left DLPFC-M1 connectivity between the different types of procedural motor learning. In experiment 1, dual-site paired-pulse TMS was used to detect the optimal interval from the DLPFC to the M1. In experiment 2, the participants were divided into two groups that underwent sequence learning or random learning. Behavioral data, motor evoked potentials from the M1 and electrophysiological data of DLPFC-M1 connectivity were assessed before and after learning.
The behavioral results showed that the learning effect of the sequence learning group was better. The electrophysiological results showed that motor evoked potentials from the M1 were the same before and after learning in both groups. At the optimal interval and appropriate stimulation intensity, the DLPFC-M1 connectivity in the sequence learning group was changed, and it was related to learning performance; however that in the random learning group was not significantly changed.
The results suggest that enhanced connectivity between the DLPFC and M1 may be an important explanation for the better performance in sequence learning. The results provide robust electrophysiological evidence for the role of DLPFC in motor learning.

Key words: dorsolateral prefrontal cortex, primary motor cortex, transcranial magnetic stimulation, procedural motor learning, sequence learning