Neuroscience Letters 418 (2007) 149–153 Response inhibition in psychopathy: The frontal N2 and P3 Gillian E.S. Munro a , Jane Dywan b,∗ , Grant T. Harris c , Shari McKee c , Ayse Unsal c,d , Sidney J. Segalowitz b a Psychology Department, University of Waterloo, Waterloo, Ontario, Canada b Psychology Department, Brock University, St. Catharines, Ontario L2S 3A1, Canada c Oak Ridge Division, Mental Health Centre, Penetanguishene, Ontario, Canada d McMaster Health Science Centre, Hamilton, Ontario, Canada Received 16 October 2006; received in revised form 28 February 2007; accepted 6 March 2007 Abstract Psychopathy has been associated with atypical function of the anterior cingulate cortex (ACC) and adjacent brain regions and with abnormalities in performance monitoring, which is thought to rely on these structures. The ACC and adjacent regions are also involved in the generation of two characteristic components of the event-related potential: the frontal N2 and P3. Both components are enhanced when a response is withheld (NoGo trial) within a series of positive-responses (Go trials) and are considered an index of response inhibition. We recorded event-related potentials while violent offenders who varied on the dimension of psychopathy and non-offender controls performed a Go/NoGo task. The offenders made more errors of commission on NoGo trials but this effect was unrelated to level of psychopathy within the group and, inconsistent with a previous report, they produced the enhanced frontal N2 and P3 effect in response to NoGo relative to Go conditions. We conclude that the neural processes involved in response inhibition are not abnormal in psychopaths when both stimuli and context are affectively neutral and suggest that a more nuanced perspective regarding impulsivity in this population be considered. © 2007 Elsevier Ireland Ltd. All rights reserved. Keywords: Inhibitory control; Violent offenders; Antisocial behavior; Impulsivity; EEG; ERPs ACC function has been associated with a number of conditions for which issues of strategic control are of concern. Psychopa- thy is such a condition. Features of psychopathy include a lack of empathy and remorse, impulsivity, callousness, and grandiosity [17]. Besides these clinical manifestations, psy- chopathy has been associated with deficits in fear conditioning [4], impairment in passive avoidance learning [31], failure to exhibit post-error slowing after negative feedback [30], and difficulty inhibiting a prepotent response [26]. These types of performance-monitoring deficits would be consistent with abnormal ACC function. Moreover, recent data from imaging studies [24,29] suggest some degree of atypical function in the ACC and adjacent brain regions in this population. ACC is implicated in response-withholding paradigms. The stimuli in Go/NoGo tasks elicit two characteristic components of the event-related potential (ERP), the N2 and P3. These com- ∗ Corresponding author. Tel.: +1 905 688 5550x3119/3543; fax: +1 905 688 6922. E-mail address: jdywan@brocku.ca (J. Dywan). ponents are typically larger on NoGo compared to Go trials and are thought to reflect response inhibition [6,11,13,25]. Data from ERP and imaging studies [2,5,35] indicate that the NoGo N2 is particularly associated with ACC activation, a region heavily implicated in response monitoring and attentional control [32]. The P3 on NoGo trials is shifted anteriorly compared to Go trials and has also been associated with increased ACC activa- tion [14,15] and with a generator in the left lateral orbitofrontal cortex [5], a region with reciprocal projections to ACC. Besides reports of reduced inhibitory control among psy- chopaths [22,26], Kiehl et al. have reported that psychopaths failed to demonstrate a NoGo N2 effect during a visual Go/NoGo task [23]. It was our goal, therefore, to replicate these results in a group of violent offenders who represented a full range on psychopathy so as to examine within-group correlations. Find- ing a diminished NoGo N2 effect and a reduced, less anterior inhibitory P3 in the offender group that also correlated with degree of psychopathy within the group would be consistent with the hypothesized ACC involvement in psychopathy and would confirm the sensitivity of the inhibitory N2 and P3 as indices of ACC function. 0304-3940/$ – see front matter © 2007 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.neulet.2007.03.017