Brain Influences Teenagers’ Reactions to Peer Pressure

Summary
The critical transition phase from childhood to adolescence involves a range of developmental and psychological changes. There is a heightened sensitivity to sensation-seeking and risky behavior without concurrent control over emotions. Most of these are attributed solely to hormonal fluctuations. However, the integral part played by neurological changes during this phase has not yet been studied in detail until now. This study attempted to examine social and emotional reactions of an individual by quantifying the changes occurring in certain areas of the brain, such as the ventral striatum (VS) and amygdale, which contribute to these behavioral transformations.

Introduction
A most susceptible age bracket of 10 to 13 years was considered for this study because this is the time when children are exposed to peer impact, risk/sensation-seeking situations and yearn for rewards. Participants were shown different facial expressions of emotions to study the response in the participants while measuring the changes at the neural level in regions of the brain (amygdala, ventromedial prefrontal cortex (VMPFC) and ventral striatum (VS).) The VMPFC functions simultaneously with the amygdala in familiarizing a person with emotional stimuli. However, the development of the prefrontal cortex or the PFC is spread out over adolescence and the effect might be experienced later in early adulthood. Hence, the VS assumes a critical role in regulating emotion perception. This results in a moderation of decreased susceptibility to peer influence and risk-taking tendency.

Methodology
* The study enrolled 38 participants who underwent fMRI scans at two time points — at the ages of 10 and 13 years.
* Their response to two-second long facial displays of such emotions as anger, fear, happiness, sadness and neutrality were measured.
* They also gave information on self-reported peer influence measures and the tendency to take risks or behave wrongly.
* Their physical development was scaled on a standard Pubertal Development Scale.

Results/Key findings
* The brain recorded vigorous activity in response to emotions displayed facially in the transformation period from childhood to adolescence.
* Neutral expressions also elicited a response that served as a control for the study.
* The increase in certain brain activity was significant for all emotions, especially sadness and happiness, with a slight increase in the case of neutral expressions.
* The right amygdala’s response was significantly higher to sad expressions than to neutral ones.
* Correlating these scores showed that a rise in VS activity matched well with self-reported high scores of resistance to peer influence and risky behavior with time. This indicates that the VS activity could be critical in preventing vulnerability in early adolescence.
* The activity of amygdala and VS were more inversely related to each other at 13 years for processing both sad and happy expressions. The same was not true for anger or fear.

Next Steps/Shortcomings
Interactions between amygdala and VS deserve exploration. The regulatory function of the VS needs further probing, with respect to brain function patterns with deliberate or incidental emotional stimuli. The implication of emotions such as happiness and sadness versus other emotions at the neural level needs further research. Late adolescence should also be included for analysis as this also signifies intense peer effects.

Conclusion
The current study establishes the role of neurological developments and maps pertinent areas of the brain to behavioral changes occurring during adolescence, such as peer pressure, inclination to take risks and steering to antagonistic attitudes. It is indeed a major find that increase in VS activity corresponds to avoidance of succumbing to peer pressure. This suggests that the VS could be critically involved in regulating emotional responses at this age and has the potential to balance out the tendency to misbehave. Changes corresponding to happy/sad expressions are most pronounced. Other regions of interest in the brain are the temporal pole, dorsal striatum and hippocampus. These, could collectively aid in methods of controlling peer pressure. An important observation is that changes in the brain during adolescence are not always associated with a disorder but instead could be a pivotal clue in moderating the behavioral outcomes in this important developmental phase.

For More Information:
Entering Adolescence: Resistance to Peer Influence, Risky Behavior, and Neural Changes in Emotion Reactivity
Publication Journal: Neuron, March 2011
By Jennifer H. Pfeifer; Carrie L. Masten; University of Oregon, Eugene, Oregon, and, University of California, Davis, California

*FYI Living Lab Reports Are Summaries of the Original Research.

 


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