Fifteen-year-old Randall was a participant in a research study on risk taking. According to his answers on the survey, Randall understands the dangers of drinking and driving, having unprotected sex, and using marijuana. However, at a party last week, Randall was seen smoking marijuana and getting into a car with an intoxicated driver. How would you explain this inconsistency in Randall's behavior in terms of the physical aspects of brain development? Obviously, he knows the right answers, yet he engages in risky behavior.

Question

What will be an ideal response?

Answer 1

1. Synaptic pruning-unused connections between neurons are eliminated, but different regions of the brain are pruned at different points in development. During adolescence the prefrontal cortex (PFC) is pruned, making more efficient pathways for information processing. Because Randall is 15, he is not likely to have completely finished undergoing PFC synapse pruning.

2. Myelination-Related to the idea of synaptic pruning is the myelination of the preserved neurons. This process, which involves covering parts of neurons in myelin (fat) sheaths, makes information transfer quicker and more efficient. At age 15, Randall is not fully myelinated, so he processes information less efficiently than an adult would.

3. Changes in neurotransmitters in the limbic system-Notably, changes in how the brain is affected by dopamine and serotonin, two neurotransmitters, can make adolescents like Randall more emotional and responsive to stress or rewards. This too contributes to Randall's risk-taking behavior-he is highly concerned with what his peers think of him, and his limbic system is motivating him to take greater risks in order to relieve boredom.

4. Frontal lobe maturation-the prefrontal cortex (PFC) is also maturing at this point in Randall's life. Although the limbic system changes at puberty, the PFC, the part of the brain that is responsible for decision making, planning ahead, and controlling impulses, is not finished maturing until the mid-20s. Therefore, 15-year-old Randall may have some advanced cognitive skills relative to his preadolescent self, but he is not yet fully mature. This, too, explains the discrepancy in his understanding of right and wrong and his choices to make risky decisions.

Key Points:

a) Synaptic pruning (name and define)

b) Myelination (name and define)

c) PFC maturation (name and define)

d) Changes in neurotransmitters (name and define)

e) Relate changes to Randall's current risk-taking behavior

f) Gap in timing between limbic system and prefrontal cortex