Teens and Impulsivity: Blame it on the Brain

February 24, 2014

Wake Forest Baptist Study Looks at Cognitive Development 


For children dealing with attention deficit hyperactivity disorder (ADHD) or autism, the ability to control their actions and resist distraction is difficult.

Neuroscience research from Wake Forest Baptist Medical Center conducted in an animal model might be able to shed some light as to what's going on in the brains of these children. Christos Constantinidis, Ph.D, associate professor of neurobiology and anatomy, at Wake Forest Baptist, and colleagues looked at whether the strength of connections between neurons of the prefrontal cortex may be a marker of cognitive development.

The way in which prefrontal cortex activity changes during adolescence is largely unknown, he said. "Maturation of cognitive abilities in humans, particularly control of inhibition and resistance to distraction, lags in conditions such as ADHD and autism. Whereas most areas of the cerebral cortex mature by childhood, prefrontal cortex maturation continues through adolescence and into early adulthood."

Cognitive abilities, such as visual-spatial working memory, impulse control, and retention of information in the face of distraction, also mature late. Impulsivity, for example, peaks during adolescence, Constantinidis said.

Training that helps strengthen working memory, typically in the form of computerized games, has shown promise for children with ADHD, Constantinidis said. The research suggests that this type of training may affect the strength of connections between prefrontal neurons.

To better understand this cognitive development, Constantinidis and his team trained adolescent and adult monkeys to perform working memory tasks, conducted behavioral and neurophysiological tests as the monkeys performed them, and evaluated the strength of functional connectivity between neurons, based on the patterns of activity of single neurons.

"The study reports differences in functional connectivity between neurons in the prefrontal cortex (intrinsic connectivity) in adolescent versus adult monkeys," Constantinidis said. "The results also point to the role of inhibitory neurons and connections in functions such as impulse control, working memory, resistance to distraction, and in conditions where these are impacted, such as autism, ADHD and schizophrenia."

Lead author of the study is Xin Zhou, a former doctoral student who worked in Constantinidis' lab. The research was supported in part by the National Institutes of Mental Health through award MH86946 and by the Tab Williams Family Endowment Fund; the National Institutes of Health Awards R33MH86946, R01EY016773, R01EY017077, and T32NS073553; and in part by National Center for Research Resources/National Institutes of Health Grant P51 RR000167 to the Wisconsin National Primate Research Center (University of Wisconsin- Madison). This research was conducted in part at a facility constructed with support from Research Facilities Improvement Program Grants RR15459-01 and RR020141-01.

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Bonnie Davis: bdavis@wakehealth.edu, 336-713-1597