Transcranial ultrasound stimulation of the medial frontal cortex transiently improves performance by modulating conflict monitoring dynamics

Conflict monitoring and error processing are fundamental mechanisms underlying cognitive control and adaptive behavior and have been consistently associated with increased activity in the anterior midcingulate cortex (aMCC). Here, we used transcranial ultrasound stimulation (TUS), an emerging technique that enables non-invasive, deep, and focal neuromodulation, and EEG to investigate the causal role of the aMCC in cognitive control. Our findings demonstrate that TUS of aMCC improved performance, modulated the relationship between conflict monitoring and the stimulus-locked N2, and strengthened the suppression of distracting flankers as revealed by drift-diffusion model analyses. This suggests that TUS of aMCC enhances proactive control. Interestingly, TUS did not affect the error-related negativity as a measure of error monitoring. Finally, the TUS effects were observed during early compared with later task blocks corroborating previous findings which suggested that TUS effects are temporally dynamic and characterized by a limited post-stimulation window.