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Brain Development

The Brain Continues to Grow Throughout Adolescence

Until recently, increased hormone activity during puberty has always been the blame for the characteristic behaviours expressed by teenagers at home and at school. Although different types of hormones are responsible for the many changes that occur during adolescents, including sexual maturation and acne, it has now know that increased myelination of the frontal lobe also plays a major role in teenage behaviour. The frontal lobe, as the name suggests, is an area of the human brain located anterior to the parietal lobe (Figure 1). This area of the brain is involved in: judgment, impulse control, behavioural spontaneity, reasoning, planning, sexual behaviour, long-term memory, and language, and is often referred to as the seat of 'executive functions' (Teenage Brain, 2008). Furthermore, myelin is a soft, white, fatty material that insults a neuron by forming a sheath around the axon, thus, serving as a protective barrier. As the brain processes information, the development of myelination within the nervous system adds to the speed and efficiency of messages as they are transmitted (Auger & Rich, 2007).

Figure 1. The human cerebral cortex. Each side of the cerebral cortex is divided into four lobes, and each lobe has specialized functions. Some of the association areas on the left side (shown here) have different functions than those on the right side. For further information on the four lobes displayed, click on the lobe of interest.

Prior to recent studies, research had shown that the brain would overproduce gray matter during prenatal development to the first 18 months of life, and then would undergo pruning. These discoveries were heavily challenged in 1999 when a group of scientists discovered that a second wave of gray matter is produced just prior to puberty in the frontal lobe (Castellanos et al., 1999). This suggests that the frontal lobe is not fully matured during a person's adolescent years. To confirm this discovery, researchers compared MRI scans of young adults, 23 to 30, with results obtained from teenagers aged 12 to 16 (Holmes et al., 1999). They looked for signs of myelin, because more myelin would imply greater development within the gray matter. As expected, areas of the frontal lobe showed the largest differences between young adults and teens. This increased myelination in the adult frontal cortex likely relates to the maturation of cognitive processing and other "executive" functions (Teenage Brain, 2008). In other words, prior to becoming an adult, sense of reason and the control of impulses have yet to ripen.

Figure 2. Structure of a neuron.

The knowledge of this information will highly benefit all secondary school teachers and intermediate-level elementary school teachers as they try to piece together their students' complicated and diverse ways of thinking. Educators who are aware of the physiological aspects of the brain will know better than to criticize a student for not thinking ahead before making an unwise remark in class. Adolescence have a difficult time trying to reason about a more sensible way to do things, partly because their frontal lobe has yet to develop. Therefore, it is easier for an educator to understand these circumstances and accept that most students do have a hard time foreseeing the future consequences for their faulty actions (Pertler, 2007). On the contrary, lack of this knowledge may prevent an educator from handling this situation more professionally; that is, they may become short-tempered and unmotivated when confronted with intolerance in the classroom. The frontal lobe also plays an important role in retaining long-term memory. That said, a teacher should regularly update the homework board and remind students of any assignment due dates. Finally, since emotional responses are processed in the frontal lobe, attitudes towards learning can be seriously influenced or seriously comprised by negative emotional states during this myelination period (Auger & Rich, 2007). Therefore, educators must be mindful of the importance of promoting a positive emotional learning environment for students of all ages through motivation and encouragement. This will keep their learning experiences positive and improve their emotional status, stimulating them to want to learn.