Intervention Principles and Practice Guidelines for - Underage ...

The progression of development of the various lobes of the brain advances from back to front.
Thus, the frontal lobe containing the prefrontal cortex, which controls reasoning, advanced thought,
and impulses, is the last area of the brain to mature (Coalition for Juvenile Justice, 2006; Ruder, 2008).
Various changes that occur in the brain during adolescence include (ACT for Youth, 2002; Coalition
for Juvenile Justice, 2006; Spinks, 2002):
• Significant restructuring of the frontal lobe.
• The corpus callosum, the seat of intelligence, consciousness, and self-awareness doesn’t reach
full maturity until after age 20.
• The parietal lobes that integrate auditory, visual, and tactile signals remain immature until
about age 16.
• The temporal lobes, where emotional maturity develops, are still evolving after age 16.
• Changes in the brain’s neurotransmitters occur during adolescence. For example, dopamine,
which influences memory, concentration, problem-solving, and other mental functions, is not
yet at its most effective level in adolescence.
The restructuring of the frontal lobe that occurs during adolescence and affects the cognitive
abilities of youth includes:
• Death of a series of cells.
• Breaking of synaptic connections.
• Creation of new synaptic connections.
• Completion of myelination in the prefrontal lobe.
Typically, some brain cells die during childhood and adolescence. When this occurs, it changes the
pattern of brain circuitry. In other cases, brain cells do not die, but they become disconnected from
adjacent cells by the pruning of connections between cells (synapses). Thus, some messages can no
longer travel the same paths they did previously, and functions may change. As the adolescent brain
matures, new synaptic connections are forged and old ones are eliminated. The formation of these
new connections and reduction of old ones may be influenced by genetic factors, experiences and
behavior, or chemicals. Connections among brain neurons that are not used may wither away, while
those that are used remain. That makes adolescent activities especially important, as this is the period
when new connections are being formed. It also makes the brain especially vulnerable to the effects of
alcohol and other substances during adolescence that may interfere with the formation of these new
connections.
The dendrites at the end of neurons also may increase their number of branches, which increases
the potential for greater numbers of connections and increasingly complex brain networks. Several
105