Messages between neurons pass through more than one billion synapses – tiny structures that are the tenth of the width of a single hair in size – in a very complicated process. Synaptic plasticity, which is the capability of synapses to get by in response to neuronal activity, was identified almost 50 years ago, giving the scientific community a clue to one of the vital functional components of learning and memorization.
A few years earlier, the said team of researchers in Bordeaux found that neurotransmitter receptors were not stationary as previously thought, but in a constant state of agitation. They surmised that controlling this agitation through neuronal activity could harness the effectiveness of synaptic transmission by regulating the number of receptors at a given time in a synapse.
The researchers also delved into the direct participation of synaptic plasticity in learning. By teaching mice to get used to a specific environment, they were able to illustrate that stopping receptor movement can be used to inhibit the acquisition of this type of memory, reiterating the role of synaptic plasticity in this process.
Why it is so hard to understand teenagers
It is said that children can be at their most difficult when they are in their teenage years. This is the time when they rebel, and do unreasonable things that would normally seem so out-of-touch from their once calm and predictable selves. Have you ever stopped to wonder why this was so?
Advanced brain imaging has recently shown that teenage brains have lots of plasticity, which means they are more prone to changing, adapting, and responding to their environment. A brain does not mature by growing larger during the teenage years but by having increased connectivity between brain regions.
This increase in connectivity is represented by white matter in the brain, which comes from a fatty substance called myelin, which envelops itself around nerve cells' axons – long, thin tendrils that extend from the cell and give off information – like insulation on an electrical wire as the brain further develops, thereby accelerating the communication between brain regions and influencing a person's basic learning abilities.
This process usually begins from the back of the brain and finishes to the front, where the prefontal cortex – or the area of the brain that is involved in planning, decision-making, and self-control – is located. Signals are not getting to teenagers' prefrontal cortex fast enough to regulate their emotions. This is why impulsive behavior and risk-taking are so prevalent among teenagers and young adults.
“This is why peer pressure rules at this time of life. It's why my teenage boys would come home without their textbook and realize at 8 p.m. that they have a test the next day. They don't have the fully developed capacity to think ahead at this time,” said Frances Jensen, chairperson of the neurology department at the Perelman School of Medicine at the University of Pennsylvania.
During the process of the prefrontal cortex's development, teenagers are subjected through many changes in their limbic system – the area of the brain that controls emotions – at the onset of puberty, which usually begins between the ages of 10 and 12.
Doctors said that this discrepancy between the development of the impulse-control part of the brain and the hormone-and-emotion-fueled part of the brain is what causes teenagers to become such risk-takers.
“The prefrontal cortex communicates with the brain's emotional centers through intricate connections. In adults, these connections have been strengthening with experience and maturation, but during adolescence, the connections are not fully developed, so it's more difficult for a teenager to shut off these emotional systems,” said B.J. Casey, director of the Fundamentals of the Adolescent Brain Lab at Yale University.
As such, health issues that stem from matters such as addiction are also more prevalent during these years. “Addiction is simply a form of learning. Addiction is repeated stimulation of the reward circuit in the brain, which is more mature than the frontal lobe at that point,” Jensen said.
“The biology of teens' brains [makes them] more susceptible to the effects of substances and stress,” she added.
Teenagers' I.Q.s not set in stone
A study that was published in 2011 in Nature was able to conclude that teenagers' intelligence quotients can change, leaving room for scientists to elucidate that a person has the capacity to become smarter as they grow into an adult.
The study tested 33 teenagers – 19 boys and 14 girls – in 2004 when they were 12 to 16 years old. The researchers had them retested in 2008 when they were 15 to 20 years old. The retests showed that some people got smarter, while other people exhibited less intellectual capability.
“These changes are real, and they are reflected in the brain. People's attitude is to decide early on that this is a clever kid and this is not a clever kid – but this suggests you can't make that assessment in the teenage years,” University College London neuroscientist Cathy Price said.
University of California, San Diego professor of psychiatry Jay Giedd said that the dramatic changes in teenagers' brain biology means that this period is the one most ripe for opportunity and vulnerability, noting, “It's a time of phenomenal leaps in our creativity and cognitive abilities. This seeming paradox of adolescence is not a coincidence.
Both the leaps in ability and the vulnerabilities to illness are related to the human adolescent brain's remarkable ability to change.” (Related: Brain Fitness should be Alongside All Fitness Protocols.)
For her part, Jensen added: “Teenagers are looking to understand themselves. It's great to have some explanations about why you did that stupid thing in front of your friends. I think talking about this gives them more insight.”
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