Adolescence is a developmental period between childhood and adulthood. It is often associated with suboptimal decision making, leading to risky actions such as increased incidence of unintentional injuries, violence, substance abuse, unintended pregnancy, and sexually transmitted diseases (STDs) . Teenagers are sometimes considered to be bad decision makers. But these sentiments doesn’t come out of nowhere. The rational part of the brain isn’t fully developed until the age of 25.
Basics of Decision Making
Researchers have found that adult and teen brains operate differently. While adults primarily use the prefrontal cortex, the brain’s rational part, teen decision making is based mainly around the amygdala: the emotional part. Lacking full development in the prefrontal cortex, teenage brain are missing an essential part of the brain present in adult ones. It’s the prefrontal cortex that is responsible for awareness of future consequences. The connections between the emotional part of the brain and the decision making center are not fully developed in adolescent brains.
Several parts of the human brain’s frontal lobe are critical in the process of decision making. Research in the past has shown that there are distinctive patterns of neural activation in the frontal lobe depending on whether decisions were made on the basis of perceived personal volition or followed directions .
The Prefrontal Cortex in the Teen Brain
Many hypotheses regarding neurobiological developments have been postulated to explain why teenagers are vulnerable to suboptimal behaviors. In a recent publication, it is briefly explained that cognitive developments during adolescence are associated with greater efficiency of cognition in the future. An increase in development and activity in the prefrontal sections of the brain as an indication of maturation is described as the neurobiological explanation for the behavioral changes associated with adolescence. This general pattern of improved cognitive and emotion regulation in regards to maturation of the prefrontal cortex suggests a rapid increase in development from childhood to adulthood.
The traditional explanation of adolescent behavior has been that it is due to the protracted development of the prefrontal cortex. This model takes into consideration the development of the prefrontal cortex together with subcortical limbic regions (e.g., nucleus accumbens and amygdala) that have been implicated in risky choices and emotional reactivity.
Historically, studies have used structural MRI to track the developmental process of the brain. Although about 90% of the brain reaches its mature state by age six, white and gray matter components of the brain experience frequent changes throughout teen age. This suggests that regions associated with primary cognitive functions mature earlier than higher order association regions which are responsible for coordination of primary cognitive functions .
The studies also show loss of cortical gray matter first in primary sensory motor areas and then in the dorsolateral prefrontal and lateral temporal cortices. This change indicates that the prefrontal cortex is one of the last brain regions to mature. But unlike gray matter, white volume increases at a constant pattern. These changes most likely reflect ongoing myelination of axons by oligodendrocytes enhancing neuronal conduction and communication .
Some researchers disagree that prefrontal cortex development contributes to risky behavior trends seen during adolescence. They argue that if immaturity of the frontal lobe was the root cause of such behavior, then children, who have even less developed prefrontal cortexes, should be more behaviorally and socially volatile. Thus, immature prefrontal lobe function alone cannot be held accountable for adolescent behavior .
These scientists conclude that traditional neurobiological and cognitive explanations for teenage behavior have failed to consider for the nonlinear changes in behavior observed during adolescence, relative to both childhood and adulthood .
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