Just as preteens begin dealing with intensifying peer pressure, certain regions in the brain are actually developing in such a way as to increase the ability to stand firm against risky behavior, according to researchers at three West Coast institutions.
Functional magnetic resonance imaging (fMRI) scans were given twice to 24 girls and 14 boys from socioeconomically and ethnically diverse backgrounds, once at age 10 and again at age 13 (age 13 represented the transition from childhood into early adolescence). During each scan, the volunteers viewed photos of faces making neutral, angry, fearful, happy and sad expressions.
Researchers did a comparison between the fMRI results taken at age 10 and then at age 13. They discovered a significant increase in activity in the ventral striatum and the ventral medial portion of the prefrontal cortex during this three year time period. Investigators also considered the participants’ self-reports rating their own ability to withstand negative peer influences and avoid delinquent behavior.
The most obvious change took place in the ventral striatum, a region commonly associated with reward-related processing. Over time, this increase in activity correlated with increases in children’s resistance to peer pressure.
“This is a complex point, because people tend to think of adolescence as the time when teenagers are really susceptible to peer pressure,” said Jennifer H. Pfeifer, professor of psychology at the University of Oregon.
“That is the case, but in addition to that added susceptibility they are also improving their ability to resist it. It’s just that peer pressure is increasing because they spend a lot more time with peers during this time and less time with family. So it is a good thing that resistance to such influences is actually strengthening in their brains.”
Researchers believe this study to be the first to report longitudinal fMRI findings regarding changes in the way the brain processes emotion during this critical time of brain development. The results seem to confirm the growing evidence that ventral striatum development during early adolescence is vital to emotional regulation carried out by the brain’s prefrontal circuitry, the researchers concluded.
“This is basic research that hopefully is laying the foundation for future studies with even more clinical relevance,” said Pfeifer, director of the Developmental Social Neuroscience Lab. ”We really have a lot to learn about how the brain responds to really basic emotional stimuli across development.”
Pfeifer added that there was a surprise finding worthy of more study: the amygdala (a small almond-shaped structure in the midbrain) showed a significant response only to the sad faces. It’s possible, Pfeifer said, that this response to sad faces might somehow be tied to the emergence of depression, especially in girls.
“This response in the amygdala raises questions we hope to pursue,” she said. “The span from age 9 to 13 is critical in pubertal development. How do individual differences apply here? Identifying this response to ‘sadness’ in the amygdala opens the door to thinking about how changes in emotional reactivity might be related to the increase in depression that we see as kids enter puberty. Rates of depression are particularly enhanced for teen girls. Is this increased response to sad faces somehow part of that?”
“I think what we know about the ventral striatum may be poised to undergo a transformation over the next several years,” she added.
The study is published in the journal Neuron.
Source: University of Oregon