How the brain suppresses the act of revenge?

A UNIGE team has discovered which brain zones are activated in anger, and how the brain suppresses the resulting act of revenge.

revenge act
Image: University of Geneva

Revenge is a form of establishing justice and that the threat of revenge may serve as a form of protection, a kind of enforcement of social cooperation. The desire for revenge can be the result of a feeling of outrage. Be that as it may, is this the case at the cerebral level? What occurs in the human brain when injustice is felt?

To answer these questions, scientists from the University of Geneva (UNIGE), Switzerland, have built up an economic game in which a member need to is confronted with the fair behavior of one player and the unfair provocations of another player.

They wanted to know to locate live which areas of the brain reacted when the person became angry and how this feeling materialized into vengeful behavior.

Olga Klimecki-Lenz, game developer said, “Almost 25 people participated in the study. The participant has economic interactions with two players, whose behavior is actually pre-programmed – which he doesn’t know about. One is friendly, offers the participant only mutually beneficial financial interactions and sends nice messages, while the other player makes sure to multiply only his own profits, going against the participant’s interest and sending annoying messages.”

Olga Klimecki-LenzaThe game takes place in three stages, amid which the member is installed in a magnetic resonance imaging (MRI) scanner enabling researchers to quantify his brain activity. The member is then gone confronted with the photos of the other two players and the messages and money related exchanges that he gets and issues. In the primary stage, the member is in charge and picks which benefits he appropriates to whom.

Olga Klimecki-Lenz said, “We noticed that on average, participants here are fair towards both other players. The second phase is that of provocation: the participant passively receives the decisions of the other two players, and especially the provocations and injustice of the unfair player, which induce a feeling of anger rated on a scale from 0 to 10 by the participant himself.”

“In the last phase, the participant is again the master of the game and can choose to take revenge or not by penalizing the other two players. Overall, participants remained nice to the fair play, but took revenge for the injustices committed by the unfair player.”

“The provocation phase played a crucial role in localizing the feeling of anger in the brain. It was during this phase that we were able to identify which areas were related to feelings of anger. Thanks to MRI, researchers observed the activity of the superior temporal lobe, but also of the amygdala, known mainly for its role in the feeling of fear and in processing the relevance of emotions, when participants looked at the photograph of the unfair player.”

“These two areas correlated with feelings of anger: the higher the level of anger reported by the participant, the stronger their activity.”

Olga Klimecki-Lenz explained, “But the Inequality game allowed us above all to identify the crucial role of the prefrontal dorsolateral cortex (DLPFC), a zone which is key for the regulation of emotions and which is located at the front of the brain!”

“On average, participants took revenge on the unfair player. However, the researchers observed a variability in behavior that shows that 11 participants nevertheless remained fair to the unfair player. But why so? The CISA team observed that the greater the DLPFC activity during the provocation phase, the fewer participants punished the unfair player. On the contrary, low DLPFC activity was associated with a more pronounced revenge on the participant following provocation by the unfair player.”

CISA said, “We observed that DLPFC is coordinated with the motor cortex that directs the hand that makes the choice of vengeful behavior or not. There is therefore a direct correlation between brain activity in DLPFC, known for emotional regulation, and behavioural choices.”

Olga Klimecki-Lenz said, “One can then wonder if an increase in the activity of DLPFC obtained through transmagnetic stimulation, would allow to decrease the acts of vengeance or even to suppress them.”

These results can be read in Scientific Reports.