Effects of theta transcranial alternating current stimulation over the frontal cortex on reversal learning

Background: Theta oscillations in the electroencephalogram (EEG) are associated with learning and behavioral adaptation. Objective: To investigate the effects of theta transcranial alternating current stimulation (tACS) applied to the frontal cortex on reversal learning. Methods: Healthy volunteers participated in a sham-controlled between subjects design. TACS at 1 mA peak-to-peak was administered during a reward-punishment reversal learning task. Resting state EEG was measured before and after tACS and the task. Results: Active tACS improved learning ability, but at the same time interfered with applying the rule to optimize behavior. Furthermore, a significant decrease in frontal theta-beta EEG ratios was observed following active tACS. Conclusions: Results provide behavioral and electrophysiological evidence for influencing reversal learning with exogenous oscillatory electric field potentials applied to the frontal cortex