Electroencephalography correlates of transcranial direct-current stimulation enhanced surgical skill learning: A replication and extension study

Transcranial direct-current stimulation (tDCS), an increasingly applied form of non-invasive brain stimulation, can augment the acquisition of motor skills. Motor learning investigations of tDCS are limited to simple skills, where mechanisms are increasingly understood. Investigations of meaningful, complex motor skills possessed by humans, such as surgical skills, are limited. This replication and extension of our previous findings used elec-troencephalography (EEG) to determine how tDCS and complex surgical training alters electrical activity in the sensorimotor network to enhance complex surgical skill acquisition. In twenty-two participants, EEG was recorded during baseline performance of simulation-based laparoscopic surgical skills. Participants were randomized to receive 20 min of primary motor cortex targeting anodal tDCS or sham concurrent to 1 h of surgical skill training. EEG was reassessed following training, during a post-training repetition of the surgical tasks. Our results replicated our previous study suggesting that compared to sham, anodal tDCS enhanced the acquisition of unimanual surgical skill. Surgical training modulated delta frequency band activity in sensorimotor regions. Next, the performance of unimanual and bimanual skills evoked unique EEG profiles, primarily within the beta frequency-band in parietal regions. Finally, tDCS-paired surgical training independently modulated delta and alpha frequency-bands in sensorimotor regions. Application of tDCS during surgical skill training is feasible, safe and tolerable. In conclusion, we are the first to explore electrical brain activity during performance of surgical skills, how electrical activity may change during surgical training and how tDCS alters the brain to enhance skill acquisition. The results provide preliminary evidence of neural markers that can be targeted by neuromodulation to optimize complex surgical training.