Course: Lifespan Development (PSYC 290) Required Resources Read/review the following resources for this activity: See Attached Documents from LessonMinimum of 2 scholarly sources Instructions Your te
THE BRAIN
Along with the rest of the body, the brain changes during adolescence, but the study of adolescent brain development is still in its infancy. As advances in technology take place, significant strides are also likely to be made in charting developmental changes in the adolescent brain (Cohen & Casey, 2017; Crone, Peters, & Steinbeis, 2018; Sherman, Steinberg, & Chein, 2018; Steinberg & others, 2018; Vijayakumar & others, 2018). What do we know now?
The dogma of the unchanging brain has been discarded, and researchers are mainly focused on context-induced plasticity of the brain over time (Romeo, 2017; Steinberg, 2017; Zelazo, 2013). The development of the brain mainly changes in a bottom-up, top-down sequence with sensory, appetitive (eating, drinking), sexual, sensation-seeking, and risk-taking brain linkages maturing first and higher-level brain linkages such as self-control, planning, and reasoning maturing later (Zelazo, 2013).
Using fMRI brain scans, scientists have recently discovered that adolescents’ brains undergo significant structural changes (Aoki, Romeo, & Smith, 2017; Crone, Peters, & Steinbeis, 2018; Goddings & Mills, 2017; Rudolph & others, 2017). The corpus callosum, where fibers connect the brain’s left and right hemispheres, thickens in adolescence, and this improves adolescents’ ability to process information (Chavarria & others, 2014). We have described advances in the development of the prefrontal cortex—the highest level of the frontal lobes involved in reasoning, decision making, and self-control. However, the prefrontal cortex doesn’t finish maturing until the emerging adult years, approximately 18 to 25 years of age, or later (Cohen & Casey, 2017; Juraska & Willing, 2017; Sousa & others, 2018).
developmental connection
Brain Development
Although the prefrontal cortex shows considerable development in childhood, it is still not fully mature even in adolescence. Connect to “Physical and Cognitive Development in Middle and Late Childhood.”
At a lower, subcortical level, the limbic system, which is the seat of emotions and where rewards are experienced, matures much earlier than the prefrontal cortex and is almost completely developed in early adolescence (Mueller & others, 2017). The limbic system structure that is especially involved in emotion is the amygdala. Figure 4 shows the locations of the corpus callosum, prefrontal cortex, and the limbic system.
FIGURE 4 THE CHANGING ADOLESCENT BRAIN: PREFRONTAL CORTEX, LIMBIC SYSTEM, AND CORPUS CALLOSUM
With the onset of puberty, the levels of neurotransmitters change (Cohen & Casey, 2017). For example, an increase in the neurotransmitter dopamine occurs in both the prefrontal cortex and the limbic system during adolescence (Cohen & Casey, 2017). Increases in dopamine have been linked to increased risk taking and the use of addictive drugs (Webber & others, 2017). Researchers also have found that dopamine plays an important role in reward seeking during adolescence (Dubol & others, 2018).
Earlier we described the increased focal activation that is linked to synaptic pruning in a specific region, such as the prefrontal cortex. In middle and late childhood, while there is increased focal activation within a specific brain region such as the prefrontal cortex, there are limited connections across distant brain regions. As adolescents develop, they have more connections across brain areas (Lebel & Deoni, 2018; Quinlin & others, 2017; Sousa & others, 2018; Tashjian, Goldenberg, & Galvan, 2017). The increased connectedness (referred to as brain networks) is especially prevalent across more distant brain regions. Thus, as children develop, greater efficiency and focal activation occurs in close Page 345 -by areas of the brain, and simultaneously there is an increase in brain networks connecting more distant brain regions. In a recent study, reduced connectivity between the brain’s frontal lobes and amygdala during adolescence was linked to increased depression (Scheuer & others, 2017).
Many of the changes in the adolescent brain that have been described here involve the rapidly emerging fields of developmental cognitive neuroscience and developmental social neuroscience, in which connections between development, the brain, and cognitive or socioemotional processes are studied (Lauharatanahirun & others, 2018; Mueller & others, 2017; Romer, Reyna, & Sattherthwaite, 2017; Sherman, Steinberg, & Chein, 2018; Steinberg & others, 2018). For example, consider leading researcher Charles Nelson’s (2003) view that, although adolescents are capable of very strong emotions, their prefrontal cortex hasn’t adequately developed to the point at which they can control these passions. It is as if their brain doesn’t have the brakes to slow down their emotions. Or consider this interpretation of the development of emotion and cognition in adolescents: “early activation of strong ‘turbo-charged’ feelings with a relatively unskilled set of ‘driving skills’ or cognitive abilities to modulate strong emotions and motivations” (Dahl, 2004, p. 18).
Of course, a major question is which comes first, biological changes in the brain or experiences that stimulate these changes (Lerner, Boyd, & Du, 2008; Steinberg, 2017). In a longitudinal study, 11- to 18-year-olds who lived in poverty conditions had diminished brain functioning at 25 years of age (Brody & others, 2017). However, the adolescents from poverty backgrounds whose families participated in a supportive parenting intervention did not show this diminished brain functioning in adulthood. Another study found that the prefrontal cortex thickened and more brain connections formed when adolescents resisted peer pressure (Paus & others, 2007). Scientists have yet to determine whether the brain changes come first or whether they result from experiences with peers, parents, and others (Lauharatanahirun & others, 2018; Webber & others, 2017). Once again, we encounter the nature-nurture issue that is so prominent in an examination of development through the life span. Nonetheless, there is adequate evidence that environmental experiences make important contributions to the brain’s development (Cohen & Casey, 2017; Crone, 2017; Sherman, Steinberg, & Chein, 2018).
In closing this section on the development of the brain in adolescence, a further caution is in order. Much of the research on neuroscience and the development of the brain in adolescence is correlational in nature, and thus causal statements need to be scrutinized (Steinberg & others, 2018). This caution, of course, applies to any period in the human life span.
