Neural Basis Underlying The Effect Of Intentionality On Reactive Aggression

Reactive aggression, human’s common behaviors during socialization, is usually defined as an aggressive response to provocation. When facing with provocation, individuals might tend to care about the intentionality of the instigator. Our study explored the neural basis underlying the effect of other’s intentionality on reactive aggression from the similarity and individual difference, using a variant of Taylor Aggression Paradigm (TAP), with task-functional Magnetic Resonance Imaging (task-fMRI) and Resting-State functional Magnetic Resonance Imaging (RS-fMRI) technology. During the TAP, participants were asked to play successive competitive reaction-time tasks with four opponents in turn and the loser who responded slowly would be punished by the winner. The participants’aggressive behaviors were elicited by provocation (i.e. aggressive degree) of opponents in the task. The four opponents were intentional provocative, non-provocative opponent (i.e. intentional situation), unintentional provocative and non-provocative opponents (i.e. unintentional situation) respectively.Behavioral results showed that participants gave higher punishment to high-aggressive opponents than that to low-aggressive opponents, especially in the intentional situation. Moreover, there were individual differences in the effect of intentionality on reactive aggression which referred to the aggressive intensity of individuals giving to the different opponents (i.e. the effect of intentionality of provocation). At the neural level, we found the activations of striatum and temporo-parietal junction were modulated by intentionality. Additionally, within participants and across trials, we found that the activities of anterior insula and bilateral striatum were positively correlated with intentional, but not unintentional aggressive behaviors. On the other hand, we found that there were significant relationships between regional homogeneity (ReHo) in the striatum as well as temporo-parietal junction and value of the effect of intentionality. Significant positive correlations between the effect of intentionality and ReHo values were observed in the temporo-parietal junction. Significant negative correlations between the effect of intentionality and ReHo values were observed in the striatum.In conclusion, we found that individuals cared about the intentionality from others and tended to exhibit stronger aggressive behavior to intentional provocation. Temporo-parietal junction and striatum were involved in the process. On the other hand, the individual differences that subjects responded to different intentionality existed. The ReHo values of temporo-parietal junction and striatum were closely associated with this individual differences.