Anodal transcranial direct current stimulation enhances the effects of motor imagery training in a finger tapping task

Abstract

Motor imagery (MI) training and anodal transcranial direct current stimulation (tDCS) applied over the primary motor cortex can independently improve hand motor function. The main objective of this double-blind, sham-controlled study was to examine whether anodal tDCS over the primary motor cortex could enhance the effects of MI training on the learning of a finger tapping sequence. Thirty-six right-handed young human adults were assigned to one of three groups: (i) who performed MI training combined with anodal tDCS applied over the primary motor cortex; (ii) who performed MI training combined with sham tDCS; and (iii) who received tDCS while reading a book. The MI training consisted of mentally rehearsing an eight-item complex finger sequence for 13 min. Before (Pre-test), immediately after (Post-test 1), and at 90 min after (Post-test 2) MI training, the participants physically repeated the sequence as fast and as accurately as possible. An anova showed that the number of sequences correctly performed significantly increased between Pre-test and Post-test 1 and remained stable at Post-test 2 in the three groups (P < 0.001). Furthermore, the percentage increase in performance between Pre-test and Post-test 1 and Post-test 2 was significantly greater in the group that performed MI training combined with anodal tDCS compared with the other two groups (P < 0.05). As a potential physiological explanation, the synaptic strength within the primary motor cortex could have been reinforced by the association of MI training and tDCS compared with MI training alone and tDCS alone.

Anodal tDCS over the primary motor cortex improves motor imagery benefits on postural control: A pilot study

“…Based on recent findings by Saimpont et al . 30 , however, coupling MIP with tDCS applied over M 1 resulted in significant greater performance compared to tDCS alone. Finally, other experimental conditions should ideally be included in future experimental designs to adequately frame and conclude about the relevance of combining MIP and tDCS.…”

“…Using a finger sequential task, Saimpont et al . 30 further showed that MIP contributed to improve performance, however with results when tDCS was simultaneously applied over M 1 . Yet, only these two experimental studies focusing on upper-limb motor performance investigated the combined effect of both tDCS and MIP.…”

“…29 and Saimpont et al . 30 , tDCS may therefore appear a promising stimulation method to potentiate the effects of MIP.…”

“…Saimpont et al . 30 finally reported greater performance increase after MIP combined with anodal tDCS compared to both MIP and tDCS alone in a sequential task.…”

Modulating Motor Learning through Transcranial Direct-Current Stimulation: An Integrative View

“…Additional studies have revealed significant benefits of tDCS on SFTT learning. Interestingly, the number of correctly executed sequences increased both when M1-tDCS was applied concurrently with performance (Saucedo Marquez et al, 2013), and when tDCS was applied during motor imagery of sequences (Saimpont et al, 2016). When individuals received M1-atDCS during performance, RTs decreased during training (Stagg et al, 2011), whereas when M1-atDCS was applied between two training sessions, reduced execution time of correct sequences was found during early consolidation (Tecchio et al, 2010), i.e., stabilization of the motor memory rapidly after its initial acquisition (Brashers-Krug et al, 1996).…”