Effect of transcranial direct current stimulation on FRN and P2 during the performance of an auditory monetary incentive delay task

Abstract

Abstract Transcranial electrical stimulation (tES) is a powerful tool for elucidating the causal relationship between specific brain regions and behaviour. While tES generates consistent results in sensorimotor research, cognitive studies present a more diverse, often ambiguous response to stimulation. To further understand these complexities, our study employed cathodal transcranial direct current stimulation (tDCS) to modulate medial–frontal cortex activity during an auditory monetary incentive delay (MID) task. Participants responded to acoustic cues signaling expected monetary losses. We analysed feedback-related negativity (FRN), reflecting a reward prediction error processing when participants encountered losses and compared it to no-loss conditions across two subsequent MID task sessions. We also assessed the exogenous P2 response to stimulus onset, independent of monetary contingencies, anticipating an inhibitory effect of cathodal tDCS on both FRN and P2. Contrarily, we observed a facilitatory effect of stimulation on FRN and a suppressed learning effect of P2. The sham group demonstrated a difference in P2 amplitude between the first and second session, which was absent in the cathodal tDCS group. Our findings regarding the multidirectionality of tDCS effects on cognitive function challenge the utility of tES as a readily employable method for testing brain causality in highly complex neurocognitive events, such as decision-making.