Determined, page 11
As we saw, dlPFC damage produces inappropriate, emotionally disinhibited behaviors. But without a vmPFC, you desiccate into heartless detachment. This is the person who, meeting someone, says, “Hello, good to meet you. I see that you’re quite overweight.” And when castigated later by their mortified partner will ask with calm puzzlement, “What’s wrong? It’s true.” Unlike most people, those with vmPFC damage don’t advocate harsher punishment for violent versus nonviolent crimes, don’t alter game play if they think they’re playing against a computer rather than a human, and don’t distinguish between a loved one and a stranger when deciding whether to sacrifice them in order to save five people. The vmPFC is not the vestigial appendix of the PFC, where emotion is like appendicitis, inflaming a sensible brain. Instead, it’s essential.
So the PFC does the harder thing when it’s the right thing to do. But as a crucial point, right is used in a neurobiological and instrumental sense rather than a moral one.
Consider lying, and the obvious role the PFC plays in resisting the temptation to lie. But you also use the PFC to lie competently; pathological liars, for example, have atypically complex wiring in the PFC. Moreover, lying competently is value-free, amoral. A child schooled in situational ethics lies about how she loves the dinner that Grandma made. A Buddhist monk plays liar’s dice superbly. A dictator fabricates the occurrence of a massacre as an excuse to invade a country. A spawn of Ponzi defrauds investors. As with much about the frontal cortex, it’s context, context, context.
With this tour of the PFC complete, we return to the hideously destructive false dichotomy between your attributes, those natural gifts and weaknesses that you just happen to have, and your supposedly freely chosen choices as to what you do with those attributes.
“Biological stuff”
Do you have grit?
Having destructive sexual urges
Do you resist acting upon them?
Being a natural marathoner
Do you fight through the pain?
Not being all that bright
Do you triumph by studying extra hard?
Having a proclivity toward alcoholism
Do you order ginger ale instead?
Having a beautiful face
Do you resist concluding that you’re entitled to people being nice to you because of it?
The Same Exact Stuff
Look once again at the actions in the right column, those crossroads that test our mettle. Do you resist acting on your destructive sexual urges? Do you fight through the pain, work extra hard to overcome your weaknesses? You can see where this is heading. If you want to finish this paragraph and then skip the rest of the chapter, here are the three punch lines: (a) grit, character, backbone, tenacity, strong moral compass, willing spirit winning out over weak flesh, are all produced by the PFC; (b) the PFC is made of biological stuff identical to the rest of your brain; (c) your current PFC is the outcome of all that uncontrollable biology interacting with all that uncontrollable environment.
Chapter 3 explored the biological answer to the question, Why did that behavior just occur?, the answer being, because of what came a second before, and a minute before, and . . . Now we ask the more focused question of why that PFC functioned the way it did just now. And it’s the same answer.
The Legacy of the Preceding Seconds to an Hour
You sit there, alert, on task. Each time the blue light comes on, you rapidly hit the button on the left; red light, button on the right. Then, the rule reverses—blue right, red left. Then it reverses again, and then again . . .
What’s going on in your brain during this task? Each time a light flashes, your visual cortex briefly activates. An instant later, there’s brief activation of the pathway carrying that information from the visual cortex to the PFC. An instant later, the pathways from there to your motor cortex and then from your motor cortex to your muscles activate your motor cortex to your muscles. What’s happening IN the PFC? It’s sitting there having to focus, repeating, “Blue left, red right” or “Blue right, red left.” It’s working hard the entire time, chanting which rule is in effect. When you’re trying to do the right, harder thing, the PFC becomes the most expensive part of the brain.
Expensive. Nice metaphor. But it’s not a metaphor. Any given neuron in the PFC is firing nonstop, each action potential triggering waves of ions flowing across membranes and then having to be corralled and pumped back to where they started. And those action potentials can occur a hundred times a second while you’re concentrating on the rule that is now in place. Those PFC neurons consume mammoth amounts of energy.
You can demonstrate this with brain-imaging techniques, showing how a working PFC consumes tons of glucose and oxygen from the bloodstream, or by measuring how much biochemical cash is available in each neuron at any given time.[*] Which leads to the main point of this section—when the PFC doesn’t have enough energy on board, it doesn’t work well.
This is the cellular underpinning of concepts like “cognitive load” or “cognitive reserve,” alluded to in chapter 3.[*] As your PFC works hard on a task, those reserves are depleted.[24]
For example, place a bowl of M&M’s in front of someone dieting. “Here, have all you want.” They’re trying to resist. And if the person has just done something frontally demanding, even some idiotically irrelevant red light / blue light task, the person snacks on more candy than usual. In the words of part of the charming title of a paper on the subject, “Deplete us not into temptation.” Same thing in reverse—deplete frontal reserve by sitting for fifteen minutes resisting those M&M’s, and afterward you’ll be lousy at red light / blue light.[25]
PFC function and self-regulation go down the tubes if you’re terrified or in pain—the PFC is using up energy dealing with the stress. Recall the Macbeth effect, where reflecting on something unethical you once did impairs frontal cognition (unless you’ve relieved yourself of that burdensome soiling by washing your hands). Frontal competence even declines if it’s keeping you from being distracted by something positive—patients are more likely to die as a result of surgery if it is the surgeon’s birthday.[26]
Fatigue also depletes frontal resources. As the workday progresses, doctors take the easier way out, ordering up fewer tests, being more likely to prescribe opiates (but not a nonproblematic drug like an anti-inflammatory, or physical therapy). Subjects are more likely to behave unethically and become less morally reflective as the day progresses, or after they’ve struggled with a cognitively challenging task. In an immensely unsettling study of emergency room doctors, the more cognitively demanding the workday (as measured by patient load), the higher the levels of implicit racial bias by the end of the day.[27]
It’s the same with hunger. Here’s one study that should stop you in your tracks (and was first referred to in the last chapter). The researchers studied a group of judges overseeing more than a thousand parole board decisions. What best predicted whether a judge granted someone parole versus more jail time? How long it had been since they had eaten a meal. Appear before the judge soon after she’s had a meal, and there was a roughly 65 percent chance of parole; appear a few hours after a meal, and there was close to a 0 percent chance.[*],[28]
What’s that about? It’s not like judges would get light-headed by late afternoon, slurring their words, getting all confused, and jailing the court stenographer. Nobel laureate psychologist Daniel Kahneman, in discussing this study, suggests that as the hours since a meal creep by, and the PFC becomes less adept at focusing on the details of each case, the judge becomes more likely to default into the easiest, most reflexive thing, which is sending the person back to jail. Important support for this idea comes from a study in which subjects had to make judgments of increasing complexity; as this progressed, the more sluggish the dlPFC became during deliberating, the more likely subjects were to fall back on a habitual decision.[29]
Why is denying parole the easy, habitual response to fall back on? Because it’s less demanding of the PFC. Someone is facing you who has done bad things but has been behaving himself in jail. It takes a mighty energetic PFC to try to understand, to feel, what the prisoner’s life—filled with horrible luck—has been like, to view the world from his perspective, to search his face and see those hints of change and potential beneath the toughness. It takes a lot of frontal effort for a judge to walk in a prisoner’s shoes before deciding on his parole. And reflecting that, across all those judicial decisions, judges averaged a longer length of time before deciding to parole the person rather than before sending them back to jail.[*],[*],[30]
Thus, events in the world around you will be modulating the ability of your PFC to resist those M&M’s, or a quick, easy judicial decision. Another relevant factor is the brain chemistry of just how tempting the temptation is. This has a lot to do with the neurotransmitter dopamine being released into the PFC from neurons originating back in the nucleus accumbens in the limbic system. What is the dopamine doing in the PFC? Signaling the salience of a temptation, how much your neurons are imagining how great M&M’s taste. The more of a dopamine dump in the PFC, the stronger the salience signal of the temptation, the more of a challenge it is for the PFC to resist. Boost dopamine levels in your PFC, and you’ll suddenly have trouble keeping a lid on your impulses.[*] And exactly as you’d expect, there’s a whole world of factors out of your control influencing the amount of dopamine that is going to be soaking your PFC (i.e., understanding the dopamine system also requires a one-second-before, one-century-before . . . analysis).[31]
In those seconds to hours before, sensory information modulates PFC function without your awareness. Have a subject smell a vial of sweat from someone frightened, and her amygdala activates, making it harder for the PFC to rein it in.[*] How’s this for rapidly altering frontal function—take an average heterosexual male and expose him to a particular stimulus, and his PFC becomes more likely to decide that jaywalking is a good idea. What’s the stimulus? The proximity of an attractive woman. I know, pathetic.[*],[32]
Thus, all sorts of things often out of your control—stress, pain, hunger, fatigue, whose sweat you’re smelling, who’s in your peripheral vision—can modulate how effectively your PFC does its job. Usually without your knowing it’s happening. No judge, if asked why she just made her judicial decision, cites her blood glucose levels. Instead, we’re going to hear a philosophical discourse about some bearded dead guy in a toga.
To ask a question derived from the last chapter, do findings like these prove that there’s no such thing as freely chosen grit? Even if the sizes of these effects were enormous (which they rarely are, although 65 percent versus nearly 0 percent parole rates in the judge/hunger study sure isn’t minor), not on their own. We now zoom out more.
The Legacy of the Preceding Hours to Days
This lands us in the realm of what hormones have been doing to the PFC when you need to show what would be interpreted as some agentic grit.
As a reminder from the last chapters, elevations of testosterone during this time frame make people more impulsive, more self-confident and risk-taking, more self-centered, less generous or empathic, and more likely to react aggressively to a provocation. Glucocorticoids and stress make people poorer at executive function and impulse control and more likely to perseverate on a habitual response to a challenge that isn’t working, instead of changing strategies. Then there’s oxytocin, which enhances trust, sociality, and social recognition. Estrogen enhances executive function, working memory, and impulse control and makes people better at rapidly switching tasks when needed.[33]
Lots of these hormonal effects play out in the PFC. Have a horribly stressed morning, and by noon, glucocorticoids will have changed gene expression in the dlPFC, making it less excitable and less able to couple to the amygdala and calm it down. Meanwhile, stress and glucocorticoids make that emotional vmPFC more excitable and more impervious to negative feedback about social behavior. Stress also causes release in the PFC of a neurotransmitter called norepinephrine (sort of the brain’s equivalent of adrenaline), which also disrupts the dlPFC.[34]
In that time span, testosterone will have changed the expression of genes in neurons in another part of the PFC (called the orbitofrontal cortex), making them more sensitive to an inhibitory neurotransmitter, quieting the neurons, and decreasing their ability to talk sense to the limbic system. Testosterone also reduces the coupling between one part of the PFC and a region implicated in empathy; this helps explain why the hormone makes people less accurate at assessing someone’s emotions by looking at their eyes. Meanwhile, oxytocin has its prosocial effects by strengthening the orbitofrontal cortex and by changing the rates at which the vmPFC utilizes the neurotransmitters serotonin and dopamine. Then there’s estrogen, which not only increases the number of receptors for the neurotransmitter acetylcholine but even changes the structure of neurons in the vmPFC.[*],[35]
Please tell me that you haven’t been writing down and starting to memorize these factoids. The point is the mechanistic nature of all this. Depending on where you are in your ovulatory cycle, if it’s the middle of the night or day, if someone gave you a wonderful hug that’s left you still tingling, or someone gave you a threatening ultimatum that’s left you still trembling—gears and widgets in your PFC will be working differently. And, as before, rarely with large enough effects to spell doom for the myth of grit all on their own. Just another piece.
The Legacy of the Preceding Days to Years
Chapter 3 covered how over this time span, the structure and function of the brain can change dramatically. Recall how years of depression can cause the hippocampus to atrophy, how the sort of trauma that produces PTSD can enlarge the amygdala. Naturally, neuroplasticity in response to experience occurs in the PFC as well. Suffer from major depression or, to a lesser extent, a major anxiety disorder for years, and the PFC atrophies; the longer the mood disorder persists, the greater the atrophy. Prolonged stress or exposure to stress levels of glucocorticoids accomplishes the same; the hormone suppresses the level or efficacy of a key neuronal growth factor called BDNF[*] in the PFC, causing dendritic spines and dendritic branches to retract so much that the layers of the PFC thin out. This impairs PFC function, including a really unhelpful twist: As noted, when activated, the amygdala helps initiate the body’s stress response (including the secretion of glucocorticoids). The PFC works to end this stress response by calming down the amygdala. Elevated glucocorticoid levels impair PFC function; the PFC isn’t as good at calming the amygdala, resulting in the person secreting ever higher levels of glucocorticoids, which then impair . . . A vicious cycle.[36]
The list of other regulators stretches out. Estrogen causes PFC neurons to form thicker, more complex branches connecting to other neurons; remove estrogen entirely and some PFC neurons die. Alcohol abuse destroys neurons in that orbitofrontal cortex, causing it to shrink; the more shrinkage, the more likely an abstinent alcoholic is to relapse. Chronic cannabis use decreases blood flow and activity in both the dlPFC and the vmPFC. Exercise aerobically on a regular basis, and genes related to neurotransmitter signaling are turned on in the PFC, more BDNF growth factor is made, and coupling of activity among various PFC subregions becomes tighter and more efficient; roughly the opposite happens with eating disorders. The list goes on and on.[37]
Some of these effects are subtle. If you want to see something unsubtle, watch what happens days to years after the PFC is damaged by a traumatic brain injury (TBI—à la Phineas Gage), or frontotemporal dementia redux. Extensive damage to the PFC increases the likelihood long after of disinhibited behavior, antisocial tendencies, and violence, a phenomenon that has been called “acquired sociopathy”[*]—remarkably, such individuals can tell you that, say, murder is wrong; they know, but they just can’t regulate their impulses. Roughly half the people incarcerated for violent antisocial criminality have a history of TBI, versus about 8 percent of the general population; having had a TBI increases the likelihood of recidivism in prison populations. Moreover, neuroimaging studies reveal elevated rates of structural and functional abnormalities in the PFC among prisoners with a history of violent, antisocial criminality.[*],[38]
Then there’s the effect of decades of experiencing racial discrimination, which is a predictor of poor health in every corner of the body. African Americans with more severe histories of suffering discrimination (based on the score from a questionnaire, after controlling for PTSD and trauma history) have greater resting levels of activity in the amygdala and greater coupling between the amygdala and the downstream brain regions that it activates. If the subjects in that miserable social-exclusion paradigm (where the other two players stop throwing the virtual ball to you) are African American, the more the ostracizing is attributed to racism, the more vmPFC activation there is. In another neuroimaging study, performance on a frontal task declined in subjects primed with pictures of spiders (versus birds); among African American subjects, the more of a history of discrimination, the more spiders activated the vmPFC and the more performance declined. What are the effects of a history of prolonged discrimination? A brain that is in a resting state of don’t-let-your-guard-down vigilance, that is more reactive to perceived threat, and a PFC burdened by a torrent of reporting from the vmPFC about this constant state of dis-ease.[39]
To summarize this section, when you try to do the harder thing that’s better, the PFC you’re working with is going to be displaying the consequences of whatever the previous years have handed you.
