A bully's brain: new research on the maladaptive reward system

Once thought to be a rite of passage when coming-of-age, bullying has come under the scrutiny of researchers, policy makers, educators, and parents as concerns rise over the long-term effects of a bullied brain.

While the neurological effects of the bullied brain have been studied extensively, less is known about the neurological cohorts of a bully's brain. New research published by Mount Sinai's Icahn School of Medicine in New York is attempting to find the neural correlates of bullying behavior.

Aggressive and violent behaviors are thought to be linked to inappropriate activation of the brain's reward systems when exposed to aggressive stimuli. The ventromedial hypothalamus, amygdala, and limbic system are involved in initiating aggressive behaviors, but little is known about the mechanisms behind the motivation to perform aggressive or violent acts, such as bullying.



The study tracked the bullying behavior of a dominant mouse toward a subordinate intruder mouse and found an increase in activity of GABA (inhibitory) neuron projections in the basal forebrain of the dominant mouse. These inhibitory projections reduce the activity of the lateral habenula, which is normally in charge of reducing action to aggressive stimuli. Thus, the bully's brain actually potentiates a reward mechanism in response to the act of bullying, making it potentially enjoyable.

With knowledge of this reward mechanism, approaches toward treating aggressive forms of behavior manifested in bullying can be tailored to increase the effectiveness of therapeutic programs.

Research has identified different pathways that lead to problematic behaviors such as bullying in children. One pathway is characterized by genetics, a lack of empathy, and an abnormal, maladapted reaction to punishment. These children are considered to exhibit "callous-unemotional traits." The other is characterized as a reactive pathway, and these children exhibit the ability to empathize. Studies using fMRI scans of children with callous-unemotional traits show abnormal response and function in the amygdala and pre-frontal ventromedial cortex. The different pathways suggest different approaches should be taken in treating different kinds of brains. As the research suggests, perhaps an intervention focused on the interest of the aggressor would be more effective than trying to train and provoke empathy or punish traditionally.

With knowledge about the reward circuits involved in bullying behavior, strides can be taken to not only improve treatment programs, but potentially prevent aggressive behavior by targeting more specific receptors identified by this new research. Bullying may soon be a folk tale rather than a detrimental school yard reality.

Research originally published in Nature. 

Mount Sinai School of Medicine. (2016, June 29). Basal forebrain projections to the paternal habenula modulate aggression reward. Nature, 2016; 534 (7609): 688 DOI: 10.1038/nature18601

References

Viding, E. et al. (2011). Behavioral problems and bullying at school: an cognitive neuroscience shed new light on an old problem? Trends in Cognitive Science, 15(7).