Electrophysiological indices of aberrant error-processing in adults with ADHD: a new region of interest.

Deficits in error-processing are postulated in core symptoms of ADHD. Our goal was to investigate the neurophysiological basis of abnormal error-processing and adaptive adjustments in ADHD, and examine whether error-related alterations extend beyond traditional Regions of Interest (ROIs), particularly to those involved in adaptive adjustments, such as the Salience Network system. We obtained event-related potentials (ERPs) during a Go/NoGo task from 22 adult-ADHD patients and 29 matched healthy controls using a high-density 256-electrode array. Error-related ERPs with error-negativity (ERN) and error-positivity (Pe) served as probes of error-processing. In ADHD patients both ERN and Pe were significantly reduced, and the reduction was associated with core psychopathological symptoms. The ERP-attenuation was prominent not only at traditional ROI-electrodes but across many other brain areas, with a distinctive subset of group-differences and symptom-correlations manifested at temporo-parietal sites, with right-lateralization. Source-localization uncovered two neural-sources for the error-related ERPs: one in the cingulate cortex near midline, which was present in both groups; and one in the right insular cortex, which was present only in the control group. The neural patterns of impairments may be the result of coexisting deficits in the dorsal midline error-processing brain network involved in "error-processing proper" and the right-lateralized temporo-parietal salience network involved in the evaluation of significance of the error-signals. Our source-localization findings potentially identify a missing link between the previously reported structural change, i.e., reduced insular volume, and the well-established behavioral deficits in ADHD.