Neurobiological correlates of violence perception in martial artists.

OBJECTIVES: The direct exertion as well as the visual perception of violence can have a hedonistic effect and elicit positive arousal in predisposed individuals. This appetitive aspect of aggression in healthy subjects has been neglected in psychiatric research so far. METHODS: Using functional magnetic resonance imaging, we tested whether subjects trained in sports with a violent component (martial arts) show altered brain responses in reward-associated brain areas when compared to controls. Sixteen martial artists (e.g., boxing, mixed martial arts) and 24 controls watched violent versus neutral pictures while performing a cognitive cover task. Subjects' aggressiveness was assessed by the aggressiveness factors questionnaire (FAF). RESULTS: While watching violent pictures, martial artists had a stronger activation in the left amygdala than controls. Within the martial artist group however, there was an inverse correlation between activation in the left amygdala and degree of aggressiveness. CONCLUSIONS: Higher amygdala activation while watching violent pictures might reflect that perception of violence conveys increased salience to martial artists as compared to controls. The inverse correlation between amygdala activation and aggressiveness within the martial artist group might be explained by the assumption that the more aggressive martial artists may be more accustomed to violent situations leading to a down-modulation of amygdala activation. Appetitive aggression should be taken into account as a factor contributing to violence.

Aggressiveness of martial artists correlates with reduced temporal pole grey matter concentration.

Perception and practice of violence have hedonistic aspects associated with positive arousal (appetitive aggression). Earlier studies have mainly investigated the aetiology of aggressive behaviour in forensic/psychiatric patients. The present study examined structural brain characteristics in healthy people practicing violent sports (martial artists) compared to controls not showing violent behaviour. Aggressiveness was assessed in 21 male healthy martial artists and 26 age-matched male healthy controls using the aggressivity factors questionnaire (FAF). Participants underwent structural T1-weighted MRI. Grey matter (GM) differences were analysed using voxel-based morphometry. Whole-brain analyses of the main effects of group and aggressiveness and their interaction were computed. An interaction effect between group and aggressiveness was evident in a brain cluster comprising the left temporal pole and left inferior temporal gyrus. In martial artists, aggressiveness was inversely related to mean GM concentration in this cluster while in controls the opposite pattern was evident. Since these temporal brain regions are relevant for emotion/aggression regulation and threat appraisal, the increased GM concentration in aggressive controls might reflect a stronger cognitive top-down inhibition of their aggressiveness. Lower GM concentration in more aggressive martial artists may indicate a reduced need of inhibitory cognitive control because of their improved self-regulation skills.