The Science of Adolescent Risk-Taking Workshop Report (2011) / Chapter Skim
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3 Biobehavioral Processes
3 Biobehavioral Processes
Pages 35-47
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From page 35... ...
THE DEVELOPING ADOLESCENT BRAIN One possible explanation for the risks adolescents take is that their brains work differently from those of younger children or adults. The availability of new technologies (structural and functional magnetic reso nance imaging and diffusion tensor imaging)
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From page 36... ...
They may foster acceptance among peers, and they may help the species avoid inbreeding by making males, females, or both more likely to leave their home territory by the time they are sexually mature, so they can seek mates elsewhere and avoid inbreeding. The biological changes that occur in mammals also include puberty, a period when a cascade of hormonal activity, beginning with the release of gonadotropin from the hypothalamus gland, culminates in the release of the gonadal hormones estrogen and testosterone.
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From page 37... ...
This aspect of brain function has been a focus for many researchers but by itself does not completely explain the behavior patterns adolescents exhibit. The relationship between the prefrontal cortex and 1 Spear explained that white matter in the brain is made up of collections of axons that are myelinated, that is, insulated by a fatty substance that appears white.
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From page 38... ...
Researchers have found a steady improvement in impulse control from childhood to adulthood, as shown in Figure 3-2, yet risk-taking still increases during adolescence (even though the definition of "risky" is dependent in part on Level of Functional Development Limbic regions prefrontal cortex Age Adolescence FIGURE 3-1 Different developmental trajectories. Fig 3-1.eps NOTE: Differential development of limbic subcortical relative to prefrontal control regions leads to imbalance in brain systems that may favor incentive/emotion driven over rational behaviors.
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From page 39... ...
is on a different trajectory from those that may override unwise choices.2 Spear noted that a range of studies of specific brain regions has shown the differences in the responses of adult brains and adolescent brains to stimuli, as well as perceptions of risk and reward. For example, adolescents seem more influenced by stressful, exciting, or emotionally charged situations when making decisions.
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From page 40... ...
The combination of exaggerated sensitivity to the rewards offered by many high-risk behaviors, a reduced sensitivity to adverse effects, and the insufficient power of immature frontal cognitive control all contribute to adolescent risk-taking. Since the neural underpinnings of adolescent behavior are likely to vary significantly in the course of adolescence, Spear suggested, it is important to recognize that approaches to managing or preventing
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From page 41... ...
Similarly, the insights about the changes in brain responses to rewards that occur during adolescence link well with findings from studies of the peripheral processes related to stress, Susman noted. Research on stress has identified regulation of the stress response -- a reduction in the normal physiological stress response -- in children who are displaying problem behavior.
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From page 42... ...
Emerging empirical evidence suggests specific neurobehavioral changes occurring in the systems of emotion and motivation that help account for these characteristics, Dahl suggested. Looking specifically at sensationseeking, he noted first that it is important to parse exactly what it means.
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From page 43... ...
With puberty happening earlier than ever before, sensation-seeking impulses are activated earlier relative to the slow and gradual development of cognitive control and the capacity for self-control. Dahl sees the balance between the affective load (the cluster of factors that increase stress on adolescents)
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From page 44... ...
The effects of being moderately sleepdeprived and imbibing moderate amounts of alcohol are about the same, Dahl explained, and together these two factors significantly increase the risk of impaired driving, for example. More broadly, however, the sleep issue demonstrates how a biologi cal change in adolescence can lead to a spiral of negative effects with potentially very significant consequences.
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From page 45... ...
In contemporary Western society, that frequently means experimentation with drugs and sex. Studies in animals have also supported a general association between elevated levels of the gonadal hormones and aggressive behavior (Sato et al., 2008)
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From page 46... ...
SUMMARY The physical and biochemical development taking place during ado lescence is complex, and the presenters highlighted not only ways that these processes affect behavior, but also ways they may interact with one another and with social influences on behavior. The imbalance between the gradual development of the prefrontal cortex, which, among other things, supports self-control, and the more rapidly developing limbic system, which, in turn, governs appetite and pleasure-seeking, helps to explain why adolescents are prone to seek novelty and take risks.
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From page 47... ...
BIOBEHAVIORAL PROCESSES average age for puberty has declined, and the gap between these developments and the development of the cognitive capacity for self-control is even greater than before. In modern Western cultures, many of the tempting risk behaviors are far less potentially beneficial than those for which humans may originally have adapted.
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