Background Transcranial direct current stimulation (tDCS) has been used to alter the excitability of neurons within the cerebral cortex. Improvements in motor learning have been found in multiple studies when tDCS was applied to the motor cortex before or during task learning. The motor cortex is also active during the performance of motor imagination, a cognitive task during which a person imagines, but does not execute, a movement. Motor imagery can be used with noninvasive brain computer interfaces (BCIs) to control virtual objects in up to three dimensions, but to master control of such devices requires long training times. Objective To evaluate the effect of high-definition tDCS on the performance and underlying electrophysiology of motor imagery based BCI. Methods We utilize high-definition tDCS to investigate the effect of stimulation on motor imagery-based BCI performance across and within sessions over multiple training days. Results We report a decreased time-to-hit with anodal stimulation both within and across sessions. We also found differing electrophysiological changes of the stimulated sensorimotor cortex during online BCI task performance for left vs. right trials. Cathodal stimulation led to a decrease in alpha and beta band power during task performance compared to sham stimulation for right hand imagination trials. Conclusion These results suggest that unilateral tDCS over the sensorimotor motor cortex differentially affects cortical areas based on task specific neural activation.
Bibliographical noteFunding Information:
The authors would like to thank Abhrajeet Roy, Albert You, and Angeliki Beyko for technical assistance. This work was supported in part by NSF CBET-1264782 , CBET-1450956 , DGE-1069104 , and NIH EY023101 , EB021027 and NS096761 . BSB was supported in part by a MnDRIVE Neuromodulation Fellowship from the University of Minnesota.
© 2016 Elsevier Inc.
- Brain-computer interface
- Motor imagery
- Sensorimotor rhythm
- Transcranial direct current stimulation