The review outlined above concludes that the brain regions most implicated to date in antisocial, aggressive and psychopathic behavior are the prefrontal (dorsolateral and ventral) and temporal cortices. Some evidence also exists implicating the amygdala, hippocampus, angular gyrus and anterior cingulate. It has also been argued that the best-replicated neural correlates of morality are the polar/medial PFC, ventral PFC and angular gyrus, with significant support also for the posterior cingulate and amygdala. We also argue that a critical driving force of antisocial and psychopathic behavior is a disruption to the neural circuitry underlying moral thinking and feeling. juxtaposes these two sets of empirical data to create an initial neural model of morality and antisociality, highlighting those regions impaired only in antisocial populations (red), areas activated only by moral judgment tasks (green) and areas common to both antisociality and morality (yellow).
A schematic diagram of brain regions impaired only in antisocial groups (red), activated only in moral decision-making (green) and regions common to both antisocial behavior and moral decision-making (yellow).
It can be seen both that there are substantial areas of overlap between antisocial/psychopathic behavior and moral judgment-emotion, and also significant differences. Brain regions common to both include ventral and polar/medial PFC sectors, the amygdala and angular gyrus/posterior superior temporal gyrus. A key difference is that while there is increasing evidence for hippocampal and anterior cingulate impairment in antisocial/psychopathic individuals, moral studies consistently fail to observe selective activation in these structures. Similarly, there is some replicable evidence implicating the posterior cingulate in moral judgment tasks, but evidence implicating this region in antisocial behavior is to date sparse. A further qualification is that only two studies have documented reduced functioning in the angular gyrus in antisocial populations, although few studies have explored this parietal structure which should be a target region-of-interest in future imaging studies.
The partial overlap of structures implicated in antisocial populations and moral judgment tasks gives rise to the hypothesis that some of the brain impairments found in antisocial individuals disrupt moral emotion/decision-making, which in turn predisposes the individual to rule-breaking, antisocial behavior. A critical question raised by this theoretical perspective of antisocial behavior concerns which component of ‘morality’ is impaired—cognition (i.e. moral ‘reasoning’), emotion (i.e. moral ‘feelings’) or both?
A tentative answer would be that the emotional component is most impaired in antisocial, psychopathic populations. Regarding basic cognitive processes involved in moral decision-making, at a fundamental level there is little question that almost all criminal and psychopathic individuals know right from wrong. While some evidence exists for a difference in level of moral reasoning in delinquent, criminal and psychopathic groups (Raine, 1993
; Blair, 1995
), antisocial behavior could cause differences in moral thinking, rather than vice versa. That is, living an antisocial way of life may change moral thinking to justify the individual's repeated antisocial actions and reduce cognitive dissonance. Furthermore, it has also been argued that psychopaths show excellent (not poor) moral reasoning ability when discussing hypothetical situations—their real failure comes in applying their excellent moral conceptual formulations to guiding their own behavior (Cleckley, 1976
The feeling of what's right and wrong
Given the above, it is suggested that it is predominantly the feeling of what is moral that is deficient in antisocial groups, rather than the knowing of what is moral. This moral feeling, centered on the PFC and amygdala, is the engine that translates the cognitive recognition that an act is immoral into behavioral inhibition—and it is this engine that functions less well in antisocial, violent and psychopathic individuals.
We also hypothesize that while deficits in the affective component of morality is the primary impairment in antisocial individuals, cognitive components of morality could also be compromised for three reasons. First, both the polar/medial PFC and posterior cingulate have been shown to play an important role in self-appraisal and self-reflection (Ochsner et al
; Johnson et al
), while the OFC is also involved in the process of self-perception and insight (Beer et al
). If an individual is unable to relate back onto themselves the negative emotion associated with the thought of perpetrating an immoral act due to impairments to either the medial PFC or posterior cingulate, they may become predisposed to rule-breaking behavior, despite intact emotional processing. Second, cognition and emotion in moral decision-making cannot be easily dissociated. The medial PFC is activated during the suppression of moral emotions (Harenski and Hamann 2006
). If an individual lacks this regulatory control, there may be an inability to down-regulate moral outrage triggered by a third party's negative acts, resulting in impulsive, reactive aggression by that individual, and/or more planned, controlled retaliatory actions. Third, and relatedly, the angular gyrus has been speculated to be associated with a sense of responsibility for one's actions (Borg et al
); while intact moral emotions may normally place a brake on rule-breaking behavior, the lack of a sense of responsibility may move the individual more in an immoral direction if the rewards are sufficient. Consequently, both emotional and cognitive components of the morality circuit may be implicated in antisocial, psychopathic behavior.