Reply to Tassy et al.: Increased DLPFC activity during moral decision-making in psychopathy
Andrea L. Glenn, Adrian Raine, Robert A. Schug, Liane Young, & Marc Hauser
The DLPFC region of interest was defined as in previous studiesS1 using the software WFU_PickAtlas (www.ansir.wfumc.edu) and intersecting the following parts: the middle frontal gyrus in the TD AAL (Automated anatomical labeling) atlas and the gray matter in the TD Type atlas. The insula region of interest for this area was defined by intersecting the insula in the TD AAL atlas, and the gray matter in the TD Type atlas.
Analyses of the DLPFC and insula regions of interest were performed using the same statistical analyses as previously reportedS2, using psychopathy scores as a covariate of interest in the second-level multiple regression model. Both positive and negative relationships were examined for all regions of interest.
The four factors of psychopathyS3 are as follows: Factor 1 (Interpersonal) involves manipulation, conning, superficial charm, and egocentricity. Factor 2 (Affective) involves lack of guilt, remorse, and empathy. Factor 3 (Lifestyle) involves impulsivity and stimulation-seeking. Factor 4 (Antisocial) involves criminal versatility and antisocial behavior at an early age.
Tassy et al. are correct that in the study by Rilling et al.S4, subjects scoring higher in psychopathy had reduced DLPFC activation when deciding to defect during a socially interactive game. In that study, subjects scoring higher in psychopathy appeared to have a prepotent response to defect, whereas lower-scoring subjects were found to have a prepotent response to cooperate. Thus, when deciding to defect, higher-scoring subjects did not have a prepotent response to override, and therefore demonstrated reduced DLPFC activity. However, when deciding to cooperate, Rilling et al.S4 found increased activity in the DLPFC in higher-scoring participants. Two possible explanations were offered—subjects scoring higher in psychopathy may be exerting effortful cognitive control to opt for the morally appropriate action (cooperating), or they may be using abstract reasoning processes to determine the response that would result in the greatest long-term benefit. Thus, it may be that psychopathic individuals require greater DLPFC involvement to choose a morally appropriate option; this finding could lend support for the hypotheses regarding cognitive control or abstract reasoning processes.
Although we raise the possibility that our findings of increased DLPFC may be indicative of increased reliance on abstract reasoning about the moral dilemmas, alternative explanations are certainly possible. Furthermore, our data do not contradict the role of the DLPFC in cognitive control during moral decision-making, a process which appears to be gaining evidence in recent literature.S5, S6
Finally, our lack of significant findings in the behavioral responses to the moral dilemmas is in contrast to findings of increased utilitarian moral judgment in patients with lesions to the ventromedial prefrontal cortex or with frontotemporal dementia. Two important differences between psychopathic individuals and these patients should be noted. First, although there may be some overlap between brain regions that are disrupted in lesion patients and regions that have been implicated in psychopathy, there are many differences that exist in the regions involved in these two conditions and the corresponding emotional deficits likely differ. Second, the brain differences observed in psychopathy are much less pronounced than in patients who have brain lesions, so it is likely that the emotional deficits are less severe, and may impact moral judgment to a lesser degree.
S1 Zhou, Y et al. Neuroscience Letters 2007; 417: 297-302.
S2 Glenn AL, Raine A, Schug RA. Molecular Psychiatry 2009; 14: 5-9.
S3 Hare RD. Psychopathy Checklist—Revised (PCL-R), 2nd edn. Multi-Health Systems Inc.:
S4 Rilling JK, Glenn AL, Jairam MR, Pagnoni G, Goldsmith DR, Elfenbein HA, Lilienfeld SO. Biol Psychiatry 2007; 61: 1260-1271.
S5 Moore AB, Clark BA, Kane MJ. Psychol Sci 2008; 19: 549-557.
S6 Greene JD, Morelli SA, Lowenberg K, Nystrom LE, Cohen JD. Cognition 2008; 107: 1144-1154.