Adolescence and emerging adulthood: A cultural approach by Jeffrey Arnett and Malcolm Hughes (sixth edition) – Chapter 3 summary

PET (positron emission tomography) scans and fMRI (functional magnetic resonance imaging) are useful for studying the brain.

A lot of the thickening of synaptic connections occurs around the time puberty begins. Overproduction (i.e. exuberance) refers to the thickening of synaptic connection and this mainly occurs around the time puberty begins. It peaks around the age of 11 or 12. It also occurs during prenatal development. Exuberance during puberty is focused in the frontal lobes. The frontal lobes are associated with the higher functions of the brain (e.g. planning; problem solving; moral judgement).

Synaptic pruning refers to the selective ‘death’ of synapses. This occurs after exuberance and occurs between the ages of 12 and 20. The synapses that are used remain while the ones that are not used disappear (i.e. “use it or lose it”). Synaptic pruning is especially rapid among adolescents with high intelligence. It allows the brain to work more efficiently as brain pathways become more specialized. The brain becomes less plastic due to synaptic pruning.

Myelination refers to the production of a myelin layer around axons. This increases the speed of electrical signals between neurons. This process continues throughout the teenage years. The brain thus becomes faster and more efficient during adolescence although it becomes less plastic.

The cerebellum also grows during adolescence and into emerging adulthood.  It is important for basic functions such as movement but also for higher functions (e.g. mathematics; music; decision making; social skills). It is the last brain area that stops growing.

Adolescents are cognitively more advanced than children but are not yet mature. Decision making (1), anticipation of consequences (2) and problem solving (3) has not fully matured yet.