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Mind over Matter: What’s Really Going on inside a Teenager’s Head
It is well known in our society that the behaviors we exhibit during our teenage years makes the adults question what they are thinking. For instance, driving at 100 miles per hour. Getting a tongue piercing on a whim. One moment they feel joy and crying their eyes out in the next.
In this month’s National Geographic article ‘Beautiful Brains,’ David Dobbs takes an evolutionary perspective on explaining the developmental changes that occur in the human brain during adolescence. Reading this article prompted me to go research for more information. As I went searching, I realized that there are many articles devoted to adolescent brain behavior. But before we begin talking about the main course, I would like to take a moment to explain some basic anatomy of the brain and nerve cell structure.
The Human Brain
A look at the brain if you cut it in half vertically...
The human brain is divided into four parts, the frontal lobe, parietal occipital, and temporal. We will focus on the frontal lobe of the brain, which serves as our emotional control, motor function, problem solving, memory, language, reasoning and planning skill center. Another area to be mentioned in the teenage brain is the area called the nucleus accumbens, which is an area sensitive to feelings such as rewards, motivation and addiction.
A nerve cell (neuron) consists of three to four major parts. The dendrites, the branch-like structures beginning at one end of the neuron, function to bring information into the cell body. The cell body itself does not participate in electrical impulse transmission. This structure is connected to the axon, the long fiberous structure which extends from the soma (cell body) down the length of the cell. Their task is to transmit information away from the cell the cell body. Covering the axons are a structure called myelin, a fatty substance that insulates the axon and increases the speed at which signals are passed down the cell. Myelin’s importance becomes evident when the loss of it triggers symptoms such as blurriness in vision and loss of coordination as well as diseases such as multiple sclerosis. Finally, the messages get sent down from one nerve cell to another cell via the synapse. This describes an area between neuron to neuron where electrochemical signals are sent from the axons of one nerve cell to the dendrite of the proceeding cell.
What is different about the teen brain?
Here comes the main course. What exactly is going on developmentally in the minds of these child-adults, who might look all grown up yet sometimes act in a way where we adults want to bang our heads against a wall. As children, we have an underdeveloped frontal lobe and during our teenage years, this area in the brain becomes more finely tuned. Between childhood to adolescence, grey matter count in the brain decreases in the prefrontal cortex (the very front of the frontal lobe) where the neurons in the cortex become more myelinated, thus increasing information processing speed. This area in the frontal lobe also undergoes synaptic pruning, which takes away unused synapses but reinforces and strengthens connections which are used heavily.
Normally, doctors would use an MRI to view images from the brain. Functional MRI is different from a regular MRI in that it allows us to look at the brain while in action by tracing the blood flow to certain regions of the brain. Looking at a fMRI studies, Kendall Powell writes in his article, How does the teenage brain work? researchers have found out that teenagers use the frontal lobe on overdrive compared to adults whose brains use frontal lobes coordinate with other parts of the brain, “a move from local-area networks to wide area networks,” making the mental process more efficient (867). Adolescents respond strongly to rewards as well. Powell mentions a study done by B.J. Casey from Cornell University where Casey did an experiment where teens would be either given a small, medium or large reward for a task performed correctly. For medium and large rewards, the teens exhibited large activity in the nucleus acumens, even more so than children and adults. However, when they were given a small reward, the ‘response decreased below that of children and adults—as if the small reward represented no reward at all in the teen’s view’ (867).
Now why do you behave so?
The last section covered some of the things that goes on biologically inside the adolescent’s mind. What we see in our everyday life translates into rebelliousness, peer interaction and thirst for risk-taking. One might guess that the teen has an affinity for risk-taking perhaps because of the underdeveloped prefrontal cortex (the reasoning and planning center) and therefore they cannot think ahead to the severity of the consequences of their actions. That seems not to be the case. Laurence Steinberg writes in his article, Cognitive and affective development in adolescence that adults and teens have the same cognitive capacity, but in teens, their emotions and social relationships influences them to take more risks. Dobbs remarks about an experiment done by Steinberg to prove this point. Steinberg uses a video game where the adolescents have to drive across town in the shortest time possible. Along the way, they encounter traffic lights where the more green lights they drive through, the more points they could score. However, if they were to encounter a yellow light, and don’t cross in time before it turns red, they lose more points than if they were to not have crossed. When the teens were playing by themselves, they exhibited safe driving behavior. But when the teens were playing with their friends watching, they speeded through the traffic lights twice as often as before. Steinberg explains this as not because the teens feel careless but because of a ‘higher regard for reward’ where the reward would be peer acceptance (5).
The evolutionary advantage
But Dobbs believes this necessity for thrill and attraction to peers their own age, combined with an immature prefrontal cortex has an evolutionary advantage. Looking at animal studies, Dobbs remarks that the most successful individuals are the ones who get the best mates and have a stable source of food and shelter(6). Powell, also observes an idea that these two behaviors stems from our biological need to continue the next generation. These behaviors require people to ‘engage in high-risk behaviour to leave
your village and find a mate’ (867). Furthermore, Dobbs writes that social rejection has been attributed to having the same effect as if one did not have adequate food or be physically healthy (6).
I hope that demystifies some of the strange behaviors that we see (or maybe you went through) during that time period. What do you think?
Mind over Matter: What’s Really Going on inside a Teenager’s Head by StellaSee is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License