Abstract
This article considers potential roles of orbital frontal cortex in the modulation of antisocial behavior. Two forms of aggression are distinguished: reactive aggression elicited in response to frustration/threat and goal directed, instrumental aggression. It is suggested that orbital frontal cortex is directly involved in the modulation of reactive aggression. It is argued that orbital frontal cortex does not “inhibit” reactive aggression but rather may both increase or decrease its probability as a function of social cues present in the environment. Early dysfunction in this function of orbital frontal cortex may be linked to the development of Borderline Personality Disorder. Instrumental aggression is linked to a fundamental failure in moral socialization. However, the available data suggest that the amygdala, but not orbital frontal cortex, is required for functions such as aversive conditioning and passive avoidance learning that are necessary for moral socialization. Psychopathic individuals who present with significant instrumental aggression, are impaired in aversive conditioning and passive avoidance learning and show evidence of amygdala dysfunction. Orbital frontal cortex and the amygdala are involved in response reversal where instrumental responses must be reversed following contingency change. Impairments in response reversal are also seen in psychopathic individuals. However, it remains unclear whether impairment in response reversal per se is associated with antisocial behavior
Introduction
The level of antisocial behavior in society is a continual source of concern. More than 3 million violent crimes are committed in the US annually (Reiss, Miczek, & Roth, 1994). Twenty thousand of these involve the murder of Americans by gunfire (Sourcebook of Criminal Justice Statistics Online, 1998). There is a growing body of data indicating that there are neuro-biological risk factors for antisocial behavior. In this article the role of orbital frontal cortex in the modulation of antisocial behavior will be considered.
It is necessary to first draw a distinction will be drawn between reactive and instrumental aggression (cf. Barratt, Stanford, Dowdy, Liebman, & Kent, 1999; Barratt, Stanford, Kent, & Felthous, 1997; Berkowitz, 1993; Linnoila et al., 1983). In reactive aggression (also referred to as affective aggression), a frustrating or threatening event triggers the aggressive act and frequently also induces anger. Importantly, the aggression is initiated without regard for any potential goal (for example, gaining the victim’s possessions or increasing status within the hierarchy). In contrast, instrumental aggression (also referred to as proactive aggression) is purposeful and goal directed. The aggression is used instrumentally to achieve a specific desired goal (Berkowitz, 1993). This is not usually the pain of the victim but rather the victim’s possessions or to increase status within a group hierarchy. Bullying is an example of instrumental aggression and, unsurprisingly, individuals who engage in bullying behaviors, frequently engage in other forms of instrumental antisocial behavior in other contexts (Roland & Idsoe, 2001).
The distinction between reactive and instrumental aggression has been criticized because of some difficulty in characterizing the nature of specific human aggressive episodes (Bushman & Anderson, 2001). However, there is considerable data that there are two relatively separable populations of aggressive individuals; individuals who present with solely reactive aggression and individuals who present with very high levels of instrumental aggression and also reactive aggression (Barratt et al., 1999; Crick & Dodge, 1996; Linnoila et al., 1983). The potential role of orbital frontal cortex in the modulation of both these forms of aggression will be discussed in turn.
General conclusion
In conclusion, it is important to distinguish between reactive and instrumental aggression. These forms of aggression are associated with different developmental disorders. Patients with Borderline Personality Disorder present with reactive aggression. Psychopathic individuals present with marked levels of instrumental aggression as well as reactive aggression.
Orbital frontal cortex is involved in the modulation of reactive aggression. It does not “inhibit” reactive aggression but rather may both increase or decrease its probability as a function of social cues present in the environment. Orbital frontal cortex is less obviously involved in the modulation of instrumental aggression. Orbital frontal cortex is not necessary for those functions such as aversive conditioning and passive avoidance learning that are necessary for moral socialization. However, orbital frontal cortex is involved in response reversal. Impairments in response reversal are seen in psychopathic individuals. However, it remains unclear whether impairment in response reversal is associated with antisocial behavior.
