番茄社区

SAN DIEGO -- Teens were more likely to actively respond to aggressive cues than were children or adults, researchers reported here.

In a go/no-go task, where aggressive faces were a target for "no go," teens showed a higher propensity than adults or children to react (pressing a button) when presented with an aggressive face, according to Kristina Caudle, PhD, of the Weill Cornell Medical College in New York City, and colleagues.

Additionally, teens who successfully avoided pressing the button during the no-go cue showed greater activation of the ventromedial prefrontal cortex -- the part of the brain that monitors personality and impulse control -- when showing restraint against reacting to the aggressive stimulus, Caudle reported during an oral presentation at the Society for Neuroscience meeting.

"Adolescents may be at greater risk for impulsive and even criminal behavior, especially in the face of potential threat," her group wrote.

There has not been much research looking into the biological mechanisms that underlie teens' aggressive behaviors. Soda consumption has been associated with aggressive behavior in teens, and parental yelling at adolescents doesn't curb their bad behavior.

Caudle's group noted that "there is an inflection in criminal behavior during adolescence," particularly in young males, so she and her co-authors conducted a study to measure impulsivity "in combination with cues that signal threat or safety to assess changes in emotional response to threat cues across development."

For this research, 57 people participated in a go/no-go task in which they were asked to not press a button when exposed to a fearful face, but to press the button when exposed to a happy or neutral face. During this task, participants had brain region activation measured through functional MRI (fMRI).

The study population included 18 children (ages 6 to 12), 19 teens (ages 13 to 17), and 20 adults (ages 18 to 27). In each age group, 10 participants were male. All participants were psychologically and neurologically healthy, she noted in an interview with 番茄社区.

Teens had the greatest mean number of false alarms versus children and adults. They also showed "adolescent-specific" activation in the limbic regions and "increases in prefrontal control regions when correctly suppressing responses to threat non-targets" on fMRI scans.

Compared with females, males were also more likely to make a greater number of false alarm cues and showed greater activation of the orbitofrontal cortex, a region associated with confrontational behavior. Females showed greater activation in the medial prefrontal cortex, which is tied to avoidant behavior.

The findings "suggest that nonlinear changes in limbic prefrontal circuitry during adolescence coincide with the likelihood of approaching, rather than retreating, from danger in emotionally charged contexts," Caudle said during her presentation.

She added that a likely explanation for this difference in impulsivity by age is that teen brains are undergoing change during puberty, and that brain chemistry is in a state of flux. These findings may also help explain why adolescents engage in criminal activity more than adults or children, Caudle said.

Her group pointed out that the propensity to act on impulse is a transient developmental stage in teens.

She noted that follow-up research should be conducted in participants who have a clinically confirmed pathology.

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