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.