THE PHENOMENON OF BRAIN PLASTICITY 27fying neurobiological subjects and to debates over the relative influence
of nature and nurture. For example, the adolescent brain has come to be
defined in neuroscientific research as marked by “disparity in maturation
between the limbic and prefrontal regions of the brain” (259). The limbic
system, which includes the amygdala and is associated in the neuroscien-
tific literature with emotion, is understood to develop beginning at around
age 10, whereas the prefrontal region, associated with executive function,
such as self- control and planning, is purportedly in development until
the midtwenties. Some researchers (e.g., Casey et al. 2008; Giedd 2004;
Goddings et al. 2015; Johnson and Giedd 2014; Steinberg 2004, 2007, 2008)
have presented this cerebral configuration — a more active limbic system
combined with an immature prefrontal cortex — as the neurobiological
explanation for the purported risk- taking behavior of adolescents. Some
even describe it as the neurobiological substrate of social problems affect-
ing teenagers, such as “unintentional injuries, violence, substance abuse,
unintended pregnancy, and sexually transmitted diseases” (Casey et al.
2008, 111).
One serious critique of the adolescent brain research comes from so-
ciologist Michael Males (2009), who objects to the presumption that ado-
lescents are inherent risk- takers. While public health and criminal justice
discourses since the 1980s have identified youth with crime, dangerousness,
and unreliability, Males argues that adolescents actually show less, rather
than more, risky behavior on certain measures, with lower rates of suicide,
drug overdose, and overall accidents (except car accidents) than adults.
He also argues that socioeconomic status (ses), not age, is the dominant
factor influencing the higher rates of crime, traffic accidents, and “virtually
every behavior for which adolescents are accused of displaying excessive
risks” (15). When controlled for socioeconomic status, Males argues, the
age disparities disappear. He says that the real risk of adolescence is the
much higher rate of poverty than the population as a whole. The adolescent
brain, then, can easily be considered as a social construction: background
assumptions about the behavior of teenagers not only shape the interpreta-
tion of empirical data but also define the research question that the studies
seek to answer. But identifying the “origin of problematics” (Spanier 1995,
cited in Roy 2004, 265) in cultural assumptions does not invalidate that
there are distinguishable developmental phases of human brains, or that