Where Two Roads [Seem] to Diverge: Executive Functions and the Adolescent Brain
By: Mirela C. C. Ramacciotti
My task in this article is one: to explain why executive functions and adolescent behavior seem to be out of sync. To that end, I decided to pick a line from one of Frost’s most pervasive poems, “The Road Not Taken,” as a hook for my title. The poem follows below and I intend to make my reasons clear. But first, I need to make a disclaimer. It has to do with time, memory and the scientific method.
Let me start with the last, the scientific method. Whenever we breach a topic that seeks to access reality in a reproducible and representative way, we need structure. In the case of science, that structuring takes the form of competences. Thus, we structure and assess competences, like the competence to store and manipulate internal information, or the competence to shift your thoughts to achieve the intended result or even the competence of inhibiting desires and responses to manifest what is most adequate and safe. In short, when studying executive functions[1], we break them down into competencies, devise tasks to measure them in order to assess behaviors that are displayed (or not) in the world. Using the scientific method is more effective for treating information and data. The reason is that such treatment does not lie with one individual or one situation–or memories that may be skewed by biases–it is about an average of people who display similar behavior.
The second disclaimer deals with memories and time. Here I invoke Kahneman (TED TALK, 2010) and the riddle of experience versus memory. Whenever we discuss the self (as we will do in this article because all of us have been—some may still be—adolescents at some point in our lives), we need to bear in mind that there are two kinds of self: the experiencing self, the one that knows and lives the present moment; and the remembering self, the one that keeps score and tells us stories about our lives. Distinguishing them may give us some headway to avoid cognitive traps. Examples of these traps are: reluctance to admit complexity; confusion between experience and memory; and a focus on illusions.
Now, science has been telling us that our memories are not set in stone. In fact, memories tell us stories that are subject to change, biased in relation to significant moments and emotions and subjected to distortions (Miron-Shatz et al., 2009; Schacter et al., 2011). Time here is of the essence. Not only does it preside over destinies but, in this particular instance involving the two kinds of self, time is the critical variable that allows us to distinguish one from the other. That has to do with a track record of our past and decisions made in our present. In other words, while the experiencing self keeps score of things lived, the remembering self is the one that presides over decisions.
Disclaimers made, let us go back to the title and its relation to my objective for this article. In tandem with the poem, many of us–once adolescents–as well as many of today’s teenagers seem to forsake their own well-traveled road of executive functioning, a road which we believe to have been heavily trodden since toddlerhood. This road seems forsaken for “the better claim” of some ‘unwonted’ behavior. The funny thing is, when confronted with the unsuitability of such behavior–either by force of circumstances or by the unforgiving pull of time–our once adolescent self usually thinks along the line of Frost’s poem that says “Oh, I kept the first [road] for another day.” Why? What sort of puzzle are we dealing with here?
The Road Not Taken (1916) By Robert Frost Two roads diverged in a yellow wood, And sorry I could not travel both And be one traveler, long I stood And looked down one as far as I could To where it bent in the undergrowth; Then took the other, as just as fair, And having perhaps the better claim, Because it was grassy and wanted wear; Though as for that the passing there Had worn them really about the same, And both that morning equally lay In leaves no step had trodden black. Oh, I kept the first for another day! Yet knowing how way leads on to way, I doubted if I should ever come back. I shall be telling this with a sigh Somewhere ages and ages hence: Two roads diverged in a wood, and I— I took the one less traveled by, And that has made all the difference. Source: Poetry Foundation |
To unpack reasons that are of different orders, I will first lay out a road map of typical adolescent behaviors. Then I will add to that map reasons for such behaviors that hinge upon different levels of analysis that neuroscience research has unfolded, that is, the behavior, system, cellular, and molecular levels. It is not my intention here to examine each in depth. That would demand a lot of space–of both a physical and cognitive nature. Here I’ll call upon findings that have been consolidated over decades of research into how brain mechanisms underlie certain unseemly adolescent moves. And they all bear consequences for executive functioning.
Let’s start with a challenge: I’ll lay out six baffling characteristics of adolescent behavior, but you have to make a [little] effort to get them. The effort relates to filling in the missing letters (one dot per letter) for each of the characteristics below. The reduced amount of cognitive effort you’ll need to exert relates to matching your predictions with the definitions and/or explanations that come after each of them. Here they are:
- s..f – ab…pt..n: means that teens are self-engrossed.
- ap..o..l se….g: means that they crave acknowledgement and validation.
- r..k t.k..g: equivalent to reckless behavior.
- n..d of i.cl….n: seeking to be among others (that they consider their peers).
- s.ci.l pr..s..e: happens when they feel pushed to behave in a certain way.
- hy…s..s.tiv..y: makes them feel like they are wearing their skins out.
If you are unsure about getting the characteristics correct before moving on, please check the footnote[2].
Now that we have established the roadmap of typical adolescent behavior (if you want to see more, visit Royal Albert Hall, 2014), I’ll move on to how each can be understood in relation to our neurobiological drivers. These are reasons that spring from how our bodies, which are controlled and supervised by the brain, and push us towards behaviors that are widespread among people–in our case, teens—irrespective of time, space, and culture. This is important to notice as many behaviors seem to follow the latest trend, seem justified by the way that certain societies operate, or even by a blanket statement that vaguely relates them to the brain.
By getting acquainted with the neurobiology of our species, we may advance understandings that remind us of a very humbling truth—we are bound to behave in a certain way given the circumstances of our organisms in time-bound cycles.
The first drive that I’ll explore is that of puberty onset. Around the age of 8 years old, the five stages of Tanner, better known as Tanner Staging[3], evidence the beginning of developmental changes that will lead children to become adults. But everything starts in the brain.
There is a subcortical structure, sitting at the base of our skull called the hypothalamus. It answers for most of the functions that keep us up and running, like body temperature, hunger, thirst, sleep cycles, emotional responses, and reproduction. This last function is relevant because puberty is the life-cycle stage that sets our bodies into motion to enable the continuity of our species. The process starts when the hypothalamus produces a hormone called gonadotropin-releasing hormone (GnRH). The path of that hormone goes through the pituitary gland which releases two more hormones that end up in our sex organs.
If this has rung bells for you stemming from biology classes or visits to your doctor, then you will already know that we are talking about the hormones that are monitored throughout life, that is, estrogen and testosterone. The important thing here is to make clear that when these hormones spring from that cascade, puberty begins. This is why puberty is a biological term closely related to sexual maturity. This relation reflects hormonal changes that will have an effect on mental and emotional development. In short, teens’ bodies go through a stress period. Puberty also detonates morphological modifications affecting physical appearance. These can span over more than a decade (from pre-teen until adulthood) and involve breast/genital growth and pubic hair (see details here). Besides glands and hair, height is another noticeable characteristic that changes. Girls tend to display these characteristics earlier, although boys show spurts of greater size. This obeys the evolutionary push that relies on female bodies to safeguard the reproduction of our species. This push related to pubertal changes brings about a cascade of gender differences (in mind and body). Such a state of things absorbs and sequesters adolescents’ attention, making them more self-absorbed and hypersensitive at this life stage. When push comes to shove, where do you think teens’ attention will be?
To finish up our discussion on this neurobiological driver, here is one last piece of information. Sex differences (girls with female gonads and boys with male gonads) mean differences in stages of pubertal development. Girls start to mature earlier than boys. Racial and ethnic differences also apply (Black and Hispanic populations mature earlier).
Closely linked to puberty onset is the next neurobiological driver to enter our examination: that of a chemical upheaval. Ponder the circumstances; teens’ sexual life is taking shape–regardless of their will–but they, nonetheless, suffer consequences from it in the form of attention that is driven inwards. Outwardly comes the need to be included and approved by their peers. Because of the surge in sex hormones and emotional instability, together with characteristic number 5 above (social pressure), adolescents may display moody behavior and emotional outbursts. This may drive them towards taking risks that they should avoid. The problem is that most of the neurochemicals that should be part of the mediating process in decisions–gauging pros and cons–are in rollercoaster mode (Blakemore, 2018).
Before we move further, it’s time we shifted our terminology. I hope I have made it clear that puberty is a neurobiological term for the developmental period encompassing mainly the second decade of human development. When we consider interpersonal relationships in social strata (peers, community groups, school, etc.), we need to use another term: adolescence. That is because biology happens in ecologies and these are situated. When time and space dimensions interweave, terminology has to enlarge its reach. From now on, I’ll be referring to the changes promoted by neurobiological drivers in relation to adolescence.
If you have heard of neurochemicals, those signaling messengers that mediate synaptic transmission, you might have heard of dopamine. It is not only a neurotransmitter, but a whole system (it is a mediator and a modulator) that acts on behavioral control. The relevant role of dopamine that we examine here is related to prediction error, motivation, and event salience (Peters & Naneix, 2022).
For good or bad, dopamine has a reputation. This means that much of the information we have easily available in media outlets is not actually in tandem with what dopamine really does. The first mistake: dopamine is not simply about pleasure; the second, it is not about reward either. The case is more complex. Dopamine signals salience for reward (Schultz, 2010) and modulates expectancy of pleasure (Sharot et al., 2009). It becomes a totally different story when we look at behavior–especially adolescent behavior. Dopamine is also deeply involved in motor commands, which is why it is highly related to Parkinson’s, for instance.
The dopamine system takes time to mature. And that happens throughout adolescence. This means that there is much vigor in dopamine-related synapses, that is, everything that is perceived as a reward becomes very salient in adolescents’ brains. Such vigor needs to be counterbalanced when the teen reaches early adulthood. Pruning is necessary if efficiency is to be reached. Such a need is deeply felt in relation to action control for working memory processes, goal-directed behaviors, response inhibition, and behavioral flexibility (Peters & Naneix, 2022). In short, executive functions are subjected to fluctuations in this period as teens are operating them in a dopaminergic spurt mode. And this is just as it should be because the dopamine system is getting adjusted for better neurophysiological performance throughout life. The problem is that–at the behavioral level–things may get complicated.
Think about the combination of increased sensitivity to salience involving rewards, as in the case of teens needing social approval, coupled with increased attention to contextual stimuli that might give them pleasure, as in belonging to a certain clique or getting their peers’ attention. On top of that, teens also deal with impulsivity, derived from difficulty in controlling motor responses. To sum up, behaviors that seem unfathomable do not come out of the blue. I think you might get the picture here: wearing the adolescent’s skin is not an easy task!
Although it seems plausible that, from a biological standpoint, adolescence is an essential developmental stage as it promotes exploration and novelty seeking, what we find is the other side of that coin, i.e., risk-taking behaviors, also seem very plausible. That is where problems may abound, as every teacher and parent of adolescents knows.
Up to this point I hope that it has become clear that attentional and correction mechanisms, mediated by neurochemicals, are maturing. The fear conditioning system is also immature while the emotional control system leans toward hypoactivation (Zimmermann et al., 2019). Notice how the ground is fertile for mood and anxiety disorders. On the other hand, as we have seen before, there is an amplification of the reward and stress response systems. This means that their bodies are undergoing a period of hypersensitivity due to the imbalance of neurochemistry in their development (Xie et al., 2021). Let’s see how this unfolds at the behavioral level.
As their goals have shifted towards social inclusion, adolescents seek peer approval. This may translate into questioning authority and rebellious attitudes. Sometimes, fear of social exclusion is so highly felt that they take unimaginable risks just to be accepted by their peers (read Curtis Kelly’s article in this issue for many examples of this). To illustrate such needs, teens who seek approval by peers that do not pay much heed to school grades might let their grades fall or might even drop out of courses.
Yet, there is good news about the wobbly executive functioning during adolescence. Although emotions may unbalance what seemed to be developing well–like their goal maintenance abilities–teens do seem to get more engrossed when they really dedicate attention to certain tasks or subjects. And this has to do with the second greatest period of pruning in the brain (the first being around age 2).
Around age 11, there is a growth spurt in the brain’s gray matter (the cell bodies) involved in all the basic processes. After getting thicker and denser, synapses peak but then decline by pruning. As we know, this is a process that safeguards efficiency by eliminating excess and stabilizing density (Goldfus & Karny-Tagger, 2017). Again, this signals a process of maturation, i.e, it is a neurobiological driver. If the brain were the alphabet, we would not have a new set of letters, but rather a process of “combining earlier formed letters into words, and then words into sentences, and then sentences into paragraphs” (Giedd, 2008, p. 340). This means that the adolescent brain gets better at associative cognitive capacity. Their brains can do more!
And the good news does not stop there. As gray matter gets pruned towards efficiency, white matter, which speeds communication between cells, follows. What this means is that connecting fibers get faster at delivering the important messaging between nerve cells. At a systems level, what can be noticed are cognitive improvements in the language and memory domains (Goldfus & Karny-Tagger, 2017). At the behavioral level, we have a window of opportunity. As connections are myelinating, those that are reinforced tend to get more stable. Teachers and schools are great actors in this process. By offering and sustaining activities that foster healthy interactions and activities, they give adolescents a better chance of stabilizing neural processes that favor those activities throughout life.
And how does that relate to executive functions? Pruning in the brain is orderly. It happens from back to front, from bottom to top. As the executive functions are mainly dependent upon the prefrontal cortex (the top-most part of the brain) you can guess what that means. Processes relying on the frontal lobe network, including focused attention and logical reasoning, will take time to mature. But they mature before other abilities like balancing risks and rewards. In short, the process takes time.
Another important piece of the puzzle concerning reward: there is a region that gets more active in adolescence. It is the ventral striatum. This subcortical structure operates like a translator; it encodes emotional and motivational signals, like the expected value of outcomes, into action. Closely related to dopaminergic pathways, this region may get hyperactivated during adolescence (Schreuders et al., 2018). When it happens, what we see is a tendency to repeat behaviors that offer a reward, like smoking when it is taken to be an entry ticket for peer approval. The thing is, this region at this time in our life course, is more active than the prefrontal cortex. This means that risk-taking behaviors override logical reasoning (Mascarelli, 2012).
So that which may seem paradoxical concerning risks, can be better understood. For instance, at school, the same risk-taking adolescents that crave social acceptance may also display a risk-avoidance behavior, i.e., they become extremely shy and avoid participating in class activities. Whenever this happens–either to your teen or in your classroom, remember that adolescence is about maturation. The same thing, risk in this case, gets processed in very different ways due to the balancing acts involved.
You may be wondering if some of the bad decisions and faulty executive functioning that adults display may be related to all that is happening in adolescence. In fact, you are not alone. A very recent study (Mousley et al., 2025) looked at changes in the brain’s efficiency by examining white matter across different life cycles (childhood, adolescence, early adulthood, middle adulthood and old age). What they found may surprise you. First, it seems that implications relative to adolescent changes extend until the early 30s. Second, those changes happen in leaps and bounds and vary from individual to individual. Third, we may have trouble marking the end of adolescence. Fourth, do not think that everything is stabilized by adulthood. It seems that our neural efficiency keeps changing as we age.
To cap, as teens usually get a bad rap (Aitkenhead, 2018) we focus way too much on what may seem divergent from the standpoints or values we uphold in our present (or mature) life stage. Perhaps we should pay heed to the evidence of adolescent change that life is constantly inviting us to look at things in novel ways.
Endnotes
[1] In this article I will not delve into what Executive Functions are as I have done that already in the March and April issues this year. Feel free to refer to those articles for a deep dive.
[2] Self-absorption; 2. Approval seeking; 3. Risk taking; 4. Need of inclusion; 5. Social pressure; 6. Hypersensitivity
[3] “Tanner Staging, also known as Sexual Maturity Rating (SMR), is an objective classification system that providers use to document and track the development and sequence of secondary sex characteristics of children during puberty. It was developed by Marshall and Tanner while conducting a longitudinal study from the 1940s to the 1960s in England. Based on observational data, they developed separate scales for the development of external genitalia: phallus, scrotum, and testes volume in males, breasts in females, and pubic hair in both males and females.” from Emmanuel & Bokor (2022)
References
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Mirela C. C. Ramacciotti is presently engaged as an external lecturer on the topics of Mind, Brain, and Education and the Bayesian Brain at the Graduate Level Course with the Psychology Department at the University of São Paulo. She holds a PhD in Neuroscience and Behavior and another in Human Communication Disorders.