The effect of anodal transcranial direct current stimulation on motor sequence learning in healthy individuals: A systematic review and meta-analysis

•This manuscript is the first meta-analysis shedding light on the effects of single and multiple session anodal transcranial direct current stimulation (a-tDCS) during different stages of motor sequence learning.•Given the increasing interest in the potential clinical utility of a-tDCS for improving motor skills, systematic and meta-analysis studies are needed to provide information for future studies.•The results of this meta-analysis determine that application of a-tDCS over primary motor cortex across the three or five days induces significant improvement in performance of motor sequence learning. A large number of studies have indicated the effect of anodal transcranial direct current stimulation (a-tDCS) on the primary motor cortex (M1) during motor skill training. The effects of a-tDCS on different stages of motor sequence learning are not yet completely understood. The purpose of this meta-analysis was to determine the effects of single and multiple sessions of a-tDCS on two different tasks: the sequential finger tapping task/serial reaction time task (SEQTAP/SRTT) and the sequential visual isometric pinch task (SVIPT). We searched electronic databases for M1 a-tDCS studies. Thirteen studies met the inclusion criteria. The results indicate that application of multiple sessions of a-tDCS, compared to single session a-tDCS induced a significant improvement in skill in both SEQTAP/SRTT and SVIPT. Retention after a single day and multiple days of a-tDCS was statistically significant for the SEQTAP/SRTT task but not for SVIPT. Therefore, our findings suggest that application of M1 a-tDCS across the three or five consecutive days can be helpful to improve motor sequence learning