Know Your Brain: The Frontal Lobe — The Brain’s Powerhouse

On Valentine’s Day, 2018, tragedy struck. A lone assailant, carrying a backpack and a duffel bag entered the hallways of his former high school and opened fire — killing 17 people at Marjory Stoneman Douglas High School. While not the worst, the horrific episode ranks as one of the world’s deadliest school shootings. What comes in the aftermath has seemed almost too commonplace — politicians of both sides argue about possible gun control laws and Second Amendment rights until the news cycle changes. Things didn’t quite go back to normal — as a wave of protesters took to social media and to the streets — many of them students who demanded stricter gun control laws and saw activism as the only way things could be changed.


“High school kids are able to do more abstract thinking than ever before in their lives,” says Dr. Gene Beresin, a professor of psychiatry at Harvard University. “They can think about justice and altruism and fairness and rights and duties and responsibilities. They are really grappling with these things, and in past years they couldn’t do that. They can look at complexities and nuances they never could before.” Their frontal lobe is just coming into focus — it develops later than nearly the rest of our brain and yet its properties will likely diminish the earliest, but perhaps tackling complex social issues is a good way to help it reach its full potential.

PUT IN PERSPECTIVE

It’s the largest, and perhaps best-known, lobe of the brain — one of four regions making up the cerebrum. Altogether, it makes up one-third of the entire organ. You might even say it’s the part with the most personality. We use it when we recall episodic memories — events that stand out from childhood, as well as the proud and/or embarrassing ones that have come to define us. The dorsolateral prefrontal cortex portion of the frontal lobe is responsible for executive decision-making: making plans, solving problems, giving you the capacity for abstract thought, and allowing an individual to think about multiple subjects simultaneously. This cortex also unlocks your working memory — it’s the reason you never forget how to drive or ride a bike.

The frontal lobe’s anterior cingulate cortex (ACC) is also involved in weighing routine decisions — it’s the part of the brain that anticipates reward, and is connected with the frontal eye fields and motor system. This is also the part involved in regulating emotions — both our own and recognizing the emotions in others. Functional MRI studies have shown that the ACC became more active when patients were shown video clips of people grieving. The ACC is also what helps us determine the appropriate response based on the information our brain processes — think of it as an abbreviation for the so-called common-sense filter.

The orbitofrontal cortex (OFC) portion of the frontal lobe evaluates the significance of potential rewards — acting as a second opinion for whether or not you should eat that slice of cake. It also monitors ongoing behavior it’s why you second guess how you’re doing at any given moment at a party, or can never be too sure how your yearly performance review will go. The OFC also allows you to revisit emotional experiences in the past — allowing you to relate when your friend loses a grandparent or has a terminally ill parent.

The frontal lobe actually contains the most dopamine-sensitive receptors of any part of the brain — so behaviors can be learned and rewarded quickly. These cortices all work together to form what we like to refer to as the conscience — we filter out socially unacceptable behaviors and weigh out the potential rewards of our actions. In each situation, the brain gives us sensory information that we process — the frontal lobe enables us to take the information and envision ourselves taking a course of action before we act — imagining the possible consequences depending on which path we take. Even spontaneity is a function of the frontal lobe, allowing us to think on our feet.

A MARK ON TOMORROW

While the frontal lobe seems to be a powerhouse to so much of our mental faculties, it is also vulnerable to a number of disorders — a whole host of symptoms not fully understood occur here due to lesions — more often than in any other part of the brain. Difficulty in information feedback has been observed, which has been attributed to greater risk-taking than normal. Left frontal lesions have been known to impair the ability to recognize and use fewer spoken words as well as fewer facial gestures. Those with lesions on the right frontal lobe tended to use both verbal language and facial movements to excess. Even when patients make a successful recovery from traumatic brain injury, it’s not uncommon to have difficulty concentrating or remembering things as well as they once did.

In the wake of tragedies such as Stoneman Douglas, the shooter’s mental health often comes up in debate, though little is changed to make psychological help more readily available to people who might commit violent crimes. While legislation may have a ways to go, modern medicine may be on the verge of breakthroughs that could help to relieve some of the stigma of mental illness and also make it easier to explore options for treatment.

Matthew Scult and fellow researchers at Duke University are working on one such breakthrough. They are currently in the early stages of creating a noninvasive physical test to diagnose known mental disorders, one that you could get as routinely as you have your blood pressure checked. To know what sort of “biomarkers” to look for, Scult’s team looked at brain-activity patterns related to depression and post-traumatic stress disorder. They performed a series of fMRI scans that looked at the prefrontal cortex of the frontal lobe, the connected ventral striatum, which responds to positive stimuli like pleasant scenes or faces, and the amygdala, an almond-shaped portion of the brain in the temporal lobe that recognizes sensory input and assigns emotions to it. While most of these regions are consistently similar in ordinary people, activity in each one is not always consistent — particularly in people suffering with anxiety or depression.

In their first task, the test subjects played a guessing game — they were presented with a playing card and asked if the card would be higher or lower than five. If they guessed correctly, the researchers told them they would win $10 at the end of the game. The ventral striatum became active when the participants were informed that they had guessed correctly. The second task activated the amygdala — subjects had to look at pictures of faces expressing fear and anger. Lastly, participants were given two sets of mathematical problems — solving simple calculations on a computer screen and another set from memory, activating the prefrontal cortex.


Scult initially hoped to use all three patterns put together as a biomarker that would predict depression and anxiety in his patients, but after gathering a large enough sample size, realized that they might be able to predict one or the other. This is a significant find as the symptoms of both tend to overlap. High prefrontal cortex activity suggested that people were less likely to suffer from anxiety, while high activity in the amygdala, and low reward-related activity in the ventral striatum were both markers that the patient would suffer from worsening anxiety over the next six months. As the participants, all college students, were not asked to regulate their emotions during any of the assessments, the activity could potentially gauge how the brain functions on a number of tasks.

There are still a number of unanswered questions — and Scult is currently performing follow-up studies with people in different age groups to get a larger sample. At present, psychotherapy as well as magnets directly stimulating brain waves are being looked at as two options. (Using electromagnetic waves to stimulate nerve cells in the brain is already being used to treat cases of severe depression.) A question to further explore is how to increase prefrontal cortex activity in people at risk of developing anxiety. Mindful meditation — bringing the mind to reflect on the present moment — may be effective in activating the prefrontal cortex and relieving more mild symptoms of anxiety.

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