The social brain network is a complicated system of cortical & subcortical structures; integrated networks for stress, fear, social engagement and social motivation. The diagram on the left illustrates the major areas of the brain associated with face perception, the ability to reading expressions and understand the expressions of others, mirror neurons, unconsciously copying what is seen (such as looking up or yawning when someone else does) and mentalizing, thinking about what others may be feeling or thinking. 

Louis Cozolino (2013) refers to this as the "tribal brain" and suggests that the social brain network has evolved from a prehistoric need for survival in a time when being cast out of the tribe meant certain death. This could explain the adolescent need to impress, fit in, and conform to the pressure of the peer group.

This could be, in part, to the creation of personal identity. For it is our "looking glass self" that forms the beginning of how we create an image of ourselves. 

For a detailed explanation, read The Neuroscience of Human Relationships: Attachment and the Developing Social Brain (see below). 

There is scientific evidence explaining the risky behaviour evident in so many adolescents that points towards a developmental mismatch between the maturity and function of the limbic system (particularly the amygdala which processes emotions and the nucleus accumben which processes reward) and the prefrontal cortex (responsible for response inhibition and impulse control). 

The graphs on the left illustrate that the frontal lobes of the brain have an increase in maturation around the ages of 18- 20 (late adolescents) while the limbic system matures earlier, around the ages of 15-17 (early adolescence). Therefore, when we tell emotionally dysregulated junior high students to "act their age" we are really asking them to act older. 

The developing social brain of adolescents do not always perceive facial expressions in the same way as adult brains. Whereas most adults recognize the face on the left as have a fearful or shocked expression, many adolescents perceive it as angry.

This may be explained by the increases in stress hormones and increased sensitivity to social appraisal in the limbic area, in conjunction a not-yet fully mature prefrontal cortex (specifically the orbitofrontal cortex (OFC) as seen in the diagram above. 

As adolescents become more sensitive to their social environment, they also become more susceptible to peer evaluations and how these evaluations can affect their social and personal worth. Studies, such as the cyberball test, have shown that peer exclusion can result in lower overall mood and higher states of anxiety. "Stress exposure, including social stress, during adolescence may be longer lasting and qualitatively different from stress exposure at other periods of life" (Blakemore & Mills, 2013, p. 189-90). 

While today, the physical risk associated with being outcast from the tribe is minimal, the brain regions associated with survival respond to social or psychological threat in very much the same way. The adolescent brain is more sensitive to social stressors than at any other time of life. This may be one of the reasons for the onset for some common psychological disorders is in adolescence (see Figure 2). Click here for a more information.