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How making friends builds your brain | NeuroConnections

Katie Brohawn

Katie Brohawn directs research for ExpandED Schools. This blog is part of our NeuroConnections blog series, where we explore the bridge between neuroscience and education.


Students at PS 89/Cypress Hills Community School play an ice breaker game during an expanded day activity that teaches leadership and peer connection skills. PS 89 partners with Cypress Hills Local Development Corp. to enrich and expand the school day.


As we likely all can remember (some of us more fondly than others), adolescence marks a critical period in the development of self-concept (who we are). How we define who we are is shaped by many different factors, including the people with whom we surround ourselves. And while most adolescents in the throws of this period would like to think they are solely in charge of determining their own self-concept, research suggests that, due to brain development during this time, how they define themselves is heavily influenced by their relationships with their peers.

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From a neuroscientific perspective, the interconnected brain regions involved in the development of self-concept are referred to as the ‘self-network.’ While much research has been conducted in adults, the study of this network in adolescents is relatively new. Two keys structures identified to date as being important in self-relevant processing, in both adults and adolescents, are the ventromedial prefrontal cortex (vMPFC) and the medial posterior parietal cortex (mPPC). Research by Schenider and colleagues in 2012 was the first to document similar neural activation when adolescents compared trait words referring to themselves to those referring to close friends. However, left unknown was whether that effect was due to the relationship between the adolescent and friend or simply due to a familiarity with that other person.  

Recently, Romund and colleagues assessed the hypothesis that it is actually the specific peer relationship, as opposed to familiarity, driving this neural activation by adding in additional reference groups for comparison. As reported in their 2017 study in Human Brain Mapping entitled Neural Correlates of the Self-Concept in Adolescence—A Focus on the Significance of Friends, adolescents were scanned via fMRI while being asked to judge personality traits of themselves, their friends, their (familiar) teachers and (unfamiliar) politicians.

From a behavioral perspective, students were faster to judge traits about themselves and their friends than to judge their teachers or politicians. Paralleling this finding, from a neural perspective, the vMPFC and mPPC activation seen when students judged traits about themselves was more similar to the activation when students judged traits about their friends than when they judged traits about their teachers or politicians. Thus the areas of the brain traditionally involved in self-concept were activated more in response to friends than either familiar or unfamiliar adults, supporting the hypothesis that friends are more relevant to the development of self-concept during the adolescent period than others, regardless of an adolescent’s familiarity with that person. (Sorry to break this news to all of our parent readers out there, but don’t worry. Plenty of research exists to show that your influence matters greatly!)

Expanded learning programs provide more time for students to be exposed to a variety of new experiences alongside their peers. Numerous formal observation tools of out-of-school time (OST) include measures of peer relationships as a marker of strong program quality. These findings support, from a neuroscientific perspective, the importance of fostering friendships, especially during the critical adolescent period, as youth work to develop a strong sense of self.




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