Adolescence is a time of dramatic changes in brain organization as well. Early in adolescence there is marked growth in brain gray matter, particularly in the frontal lobe. This is caused by a burst of synaptogenesis, the creation of synaptic connections between neurons. Following this growth spurt, however, there is increased pruning, which refers to the dying off of unused synapses and dendrites. This enhances efficiency in the brain by ridding the brain of unused circuitry, like throwing out clothes that are never worn.

Myelination also continues, which enhances the speed and efficiency of electrical impulses traveling through the brain. This increase in brain connectivity and efficiency results in profound changes in cognitive abilities, bringing about a seismic shift in the adolescent’s understanding of the world.

Additionally, there are changes in the density of neurotransmitters, the chemical messengers that help neurons communicate with each other. Changes in the level of excitatory neurotransmitters (such as glutamate and dopamine) relative to the level of inhibitory neurotransmitters (such as GABA) may make adolescents more reactive to emotional stimuli, possibly contributing both to the emotional turbulence and thrill-seeking tendencies commonly found in adolescents.