Do patients with damage to the anterior cingulate and adjacent regions produce an error-related negativity (ERN)?

Abstract

Averaged EEG trials to erroneous responses consistently show a negative-going waveform which has been coined the error-related negativity (ERN) (for a summary see Falkenstein et al., 2000). Evidence points to the neural generator of the ERN to be distributed somewhere along the medial prefrontal cortex, most likely within the anterior cingulate. This suggests that patients with lesions in the anterior cingulate region should not produce an ERN. In order to test this hypothesis, we investigated five patients with a ruptured aneurysm of the anterior communicating artery (AACA) leading to damage of neural substrates in the anterior cingulate region. Four of the five patients did not produce an ERN in one paradigm, or they produced a highly deviant waveform. These results contrast with findings showing that patients with damage involving the lateral prefrontal cortex do produce an ERN (Gehring & Knight, 2000). This dissociation suggests that the anterior cingulate region is essential to initiate the ERN response. One patient showed an ERN in both paradigms possibly due to damage that differed from that of the other patients, or individual variation. It has further been suggested that elicitation of the ERN is dependent on overt error awareness. Two of our patients showed relatively good cognitive functioning compared to the other patients, and during EEG recording they noticed when they had made an error as indicated by swearing, comments or gestures. Nevertheless, one of the two patient clearly did not show an ERN in both paradigms, and the other patient did show an ERN in one but not in the other paradigm. It thus seems that awareness of errors as signaled by overt error detection may be mediated by circuits outside of those necessary for ERN production.