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Do Bullies Enjoy Seeing Others In Pain?

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Unusually aggressive youth may actually enjoy inflicting pain on others, research using brain scans at the University of Chicago suggests.

When youth with aggressive conduct disorder watch an individual intentionally hurting another (like closing a piano lead), regions of the brain that process painful information are activated, as well as the amygdala and ventral striatum (part of the neural circuit involved in reward processing. These adolescents seem to enjoy seeing people in pain. (Credit: Photo by Jean Decety, University of Chicago)

Scans of the aggressive youth’s brains indicate that an area that is associated with rewards was highlighted when the youth watched a video clip of someone inflicting pain on another person. Youth without the unusually aggressive behavior did not have that response, the study showed.

“This is the first time that fMRI scans have been used to study situations that could otherwise provoke empathy,” said Jean Decety, Professor in Psychology and Psychiatry at the University of Chicago. “This work will help us better understand ways to work with juveniles inclined to aggression and violence.”

Decety is an internationally recognized expert on empathy and social neuroscience. The new research shows that some aggressive youths’ natural empathetic impulse may be disrupted in ways that increase aggression.

In the study, researchers compared eight 16- to 18-year-old boys with aggressive conduct disorder to a control group of adolescent boys with no unusual signs of aggression. The boys with the conduct disorder had exhibited disruptive behavior such as starting a fight, using a weapon and stealing after confronting a victim.

The youth were tested with fMRI while looking at video clips in which people endured pain accidentally, such as when a heavy bowl was dropped on their hands, and intentionally, such as when a person stepped on another’s foot.

“The aggressive youth activated the neural circuits underpinning pain processing to the same extent, and in some cases, even more so than the control participants without conduct disorder,” Decety said.

“Aggressive adolescents showed a specific and very strong activation of the amygdala and ventral striatum (an area that responds to feeling rewarded) when watching pain inflicted on others, which suggested that they enjoyed watching pain,” he said. Unlike the control group, the youth with conduct disorder did not activate the area of the brain involved in self-regulation (the medial prefrontal cortex and the temporoparietal junction).

The control group acted similarly to youth in a study released earlier this year, in which Decety and his colleagues used fMRI scans to show 7- to 12-year-olds are naturally empathetic toward people in pain.

The scans showed that when the children saw animations of someone hurt accidentally, the same portion of the brain that registered pain when they are hurt also was highlighted upon seeing someone else hurt. When they saw someone intentionally hurt, the portion of the brain associated with understanding social interaction and moral reasoning was highlighted.

What caution is needed to interpret such (f)MRI studies, is demonstrated by two other sets of research results, discussed earlier in this blog (see hate circuit and temporo-spatial sequences in neuronal activities). Not only do structures like the putamen and the insula seem to be involved in hatred and romantic love, the insula is part of the pain matrix as well. Given these complex spatial connectivity patterns and given too, the obviously coexisting temporal hierarchies of neuronal activation, any interpretation of the presented results seems rather bold, if one takes into account that these patterns have been studied at a mere overall number of 16 individuals.

Biol Psychol. 2008 Sep 30. [Epub ahead of print]
Atypical empathic responses in adolescents with aggressive conduct disorder: A functional MRI investigation.
Decety J, Michalska KJ, Akitsuki Y, Lahey BB.

Department of Psychology and Center for Cognitive and Social Neuroscience, The University of Chicago, United States; Department of Psychiatry, The University of Chicago, United States.

Because youth with aggressive conduct disorder (CD) often inflict pain on others, it is important to determine if they exhibit atypical empathic responses to viewing others in pain. In this initial functional magnetic resonance imaging (fMRI) study, eight adolescents with aggressive CD and eight matched controls with no CD symptoms were scanned while watching animated visual stimuli depicting other people experiencing pain or not experiencing pain. Furthermore, these situations involved either an individual whose pain was caused by accident or an individual whose pain was inflicted on purpose by another person. After scanning, participants rated how painful the situations were. In both groups the perception of others in pain was associated with activation of the pain matrix, including the ACC, insula, somatosensory cortex, supplementary motor area and periaqueductal gray. The pain matrix was activated to a specific extent in participants with CD, who also showed significantly greater amygdala, striatal, and temporal pole activation. When watching situations in which pain was intentionally inflicted, control youth exhibited signal increase in the medial prefrontal cortex, lateral orbitofrontal cortex, and right temporo-parietal junction, whereas youth with CD only exhibited activation in the insula and precentral gyrus. Furthermore, connectivity analyses demonstrated that youth with CD exhibited less amygdala/prefrontal coupling when watching pain inflicted by another than did control youth. These preliminary findings suggest that youth with aggressive CD exhibit an atypical pattern of neural response to viewing others in pain that should be explored in further studies.


Written by huehueteotl

November 8, 2008 at 2:52 pm

Posted in Neuroscience

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