Using high-definition transcranial direct current stimulation to investigate the role of the dorsolateral prefrontal cortex in explicit sequence learning

Abstract

Though we have a general understanding of the brain areas involved in motor sequence learning, there is more to discover about the neural mechanisms underlying skill acquisition. Skill acquisition may be subserved, in part, by interactions between the cerebellum and prefrontal cortex through a cerebello-thalamo-prefrontal network. In prior work, we investigated this network by targeting the cerebellum; here, we explored the consequence of stimulating the dorsolateral prefrontal cortex using high-definition transcranial direct current stimulation (HD-tDCS) before administering an explicit motor sequence learning paradigm. Using a mixed within- and between- subjects design, we employed anodal (n = 24) and cathodal (n = 25) HD-tDCS (relative to sham) to temporarily alter brain function and examine effects on skill acquisition. The results indicate that both anodal and cathodal prefrontal stimulation impedes motor sequence learning, relative to sham. These findings suggest an overall negative influence of active prefrontal stimulation on the acquisition of a sequential pattern of finger movements. Collectively, this provides novel insight on the role of the dorsolateral prefrontal cortex in initial skill acquisition, when cognitive processes such as working memory are used. Exploring methods that may improve motor learning is important in developing therapeutic strategies for motor-related diseases and rehabilitation.

Fig 1. Modeled current flow for prefrontal stimulation (BA 46) using HD-Targets software.

Color bar indicates field intensity (V/m) on a scale of 0–0.35 (bottom to top). L: Left; R: Right; F: Front; B: Back.

Fig 2. Overview of experimental procedure.

HD-tDCS image source: Soterix Medical.

Fig 3

A: Accuracy across sequence learning phases by prefrontal stimulation group (Cathodal vs. Anodal) and session (Active vs. Sham). B: Accuracy by stimulation session, groups combined. Error bars indicate standard error (SE).

Fig 4

A: Reaction time across all blocks by prefrontal stimulation group (Cathodal vs. Anodal) and session (Active vs. Sham). B: Reaction time by stimulation session, groups combined. Error bars indicate SE.