Behavioral and electrocortical effects of transcranial alternating current stimulation during advice-guided decision-making.

In decision-making with uncertain outcomes people may rely on external cues, such as expert advice, even if this information has no predictive value. While the fronto-parietal event-related potential (ERP) components feedback-related negativity (FRN) and P3 are associated with both reward/punishment feedback processing, the relationship between ERP modulation and expert advice during decision making remains unclear. In this double-blind sham-controlled within-subject study transcranial alternating current stimulation (tACS) at an intensity of 1 mA was applied to the frontal cortex in twenty-four healthy volunteers. The aim was to decrease reliance on expert advice by targeting FRN, P3a and P3b components. Following administration of frontal delta (2.5 Hz), theta (5 Hz) and sham tACS, ERPs and advice-guided decision making were evaluated. Results showed a tentative behavioral effect of delta tACS in the response bias. In contrast, theta tACS significantly lowered P3b and P3a amplitudes, but no effects of tACS were observed for the FRN. Effects on electrophysiology and advice following behavior were uncorrelated. Our findings suggest that theta tACS may modulate electrocortical signals and delta tACS advice following, yet the relationship between both remains unresolved.