Determined, page 10
“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?
And then on the right is the free will you supposedly exercise in choosing what you do with your biological attributes, the you who sits in a bunker in your brain but not of your brain. Your you-ness is made of nanochips, old vacuum tubes, ancient parchments with transcripts of Sunday-morning sermons, stalactites of your mother’s admonishing voice, streaks of brimstone, rivets made out of gumption. Whatever that real you is composed of, it sure ain’t squishy biological brain yuck.
When viewed as evidence of free will, the right side of the chart is a compatibilist playground of blame and praise. It seems so hard, so counterintuitive, to think that willpower is made of neurons, neurotransmitters, receptors, and so on. There seems a much easier answer—willpower is what happens when that nonbiological essence of you is bespangled with fairy dust.
And as one of the most important points of this book, we have as little control over the right side of the chart as over the left. Both sides are equally the outcome of uncontrollable biology interacting with uncontrollable environment.
To understand the biology of the right side of the chart, time to focus on the fanciest part of the brain, the frontal cortex, which was lightly touched on in the last two chapters.
Doing the Right Thing When It’s the Harder Thing to Do
Bragging for the frontal cortex, it’s the newest part of the brain; we primates have, proportionately, more of it than other mammals; when you examine gene variants that are unique to primates, a disproportionate percentage of them are expressed in the frontal cortex. Our human frontal cortex is proportionately bigger and/or more complexly wired than that of any other primate. As noted in the last chapter, it’s the last part of the brain to fully mature, not being fully constructed until your midtwenties; this is outrageously delayed, given that most of the brain is up and running within a few years of birth. And as a major implication of this delay, a quarter century of environmental influences shape how the frontal cortex is being put together. It’s one of the hardest-working parts of the brain, in terms of energy consumption. It has a type of neuron found nowhere else in the brain. And the most interesting part of the frontal cortex—the prefrontal cortex (PFC)—is proportionately even larger than the rest of the frontal cortex, and more recently evolved.[*],[10]
As a reminder, the PFC is central to executive function, decision-making. We saw this in chapter 2, where, way up in the chain of Libetian commands, there was the PFC making decisions up to ten seconds before subjects first became aware of that intent. What the PFC is most about is making tough decisions in the face of temptation—gratification postponement, long-term planning, impulse control, emotional regulation. The PFC is essential for getting you to do the right thing when it is the harder thing to do. Which is so pertinent to that false dichotomy between what attributes fate hands you and what you do with them.
The Cognitive PFC
As a warm-up, let’s examine “doing the right thing” in the cognitive realm. It’s the PFC that inhibits you from doing something the habitual way when you’re supposed to be doing it in a novel manner. Sit someone in front of a computer and say to them, “Here’s the rule—when a blue light flashes on the screen, hit the button on the left as fast as possible; red light, hit the button on the right.” Have them do that a bunch of times, get the hang of it. “Now reverse that—blue light, button on the right; red, left.” Have them do that awhile. “Now switch back again.” Each time the rule changes, the PFC is in charge of “Remember, blue now means . . .”
Now, quick, say the months of the year backward. The PFC activates, suppressing the overlearned response—“Remember, September-August this time, not September-October.” More frontal activation predicts a better performance here.
One of the best ways to appreciate these frontal functions is to examine people with a damaged PFC (as after certain types of strokes or dementias). There are huge problems with “reversal” tasks like these. It’s too hard to do that right thing when it is a change from the usual.
Thus, the PFC is for learning a new rule, or a new variant of a rule. Implied in that is that the functioning of the PFC can change. Once that novel rule persists and has stopped being novel, it becomes the task of other, more automatic brain circuitry. Few of us need to activate the PFC to pee nowhere but in the bathroom; but we sure did when we were three.
“Doing the right thing” requires two different skills from the PFC. There’s sending the decisive “do this” signal along the path from the PFC to the frontal cortex to the supplementary motor area (the SMA of chapter 2) to the motor cortex. But even more important, there is the “and don’t do that, even if that’s the usual” signal. Even more than sending excitatory signals to the motor cortex, the PFC is about inhibiting habitual brain circuits. To hark back again to chapter 2, the PFC is central to showing that we lack both free will and the conscious veto power of free won’t.[11]
The Social PFC
Obviously, the crowning achievement of millions of years of frontocortical evolution is not reciting months backward. It’s social—it’s suppressing the emotionally easier thing to do. The PFC is the center of our social brain. The bigger the average size of the social group in a primate species, the greater a percentage of the brain is devoted to the PFC; the bigger the size of some human’s texting network, the larger a particular subregion of the PFC and its connectivity with the limbic system. So does sociality enlarge the PFC, or does a large PFC drive sociality? At least partially the former—take individually housed monkeys and put them together in big, complex social groups, and a year later, everyone’s PFC will have enlarged; moreover, the individual who emerges at the top of the hierarchy shows the largest increase.[*],[12]
Neuroimaging studies show the PFC reining in more emotional brain regions in the name of doing (or thinking) the right thing. Stick a volunteer in a brain scanner and flash up pictures of faces. And in a depressing, well-replicated finding, flash up the face of someone of another race and in about 75 percent of subjects, there is activation of the amygdala, the brain region central to fear, anxiety, and aggression.[*] In under a tenth of a second.[*] And then the PFC does the harder thing. In most of those subjects, a few seconds after the amygdala activates, the PFC kicks in, turning off the amygdala. It’s a delayed frontocortical voice—“Don’t think that way. That’s not who I am.” And who are the folks in which the PFC doesn’t muzzle the amygdala? People whose racism is avowedly, unapologetically explicit—“That is who I am.”[13]
In another experimental paradigm, a subject in a brain scanner plays an online game with two other people—each is represented by a symbol on the screen, forming a triangle. They toss a virtual ball around—the subject presses one of two buttons, determining which of the two symbols the ball is tossed to; the other two toss it to each other, toss it back to the subject. This goes on for a while, everyone having a fine time, and then, oh no, the other two people stop tossing the ball to the subject. It’s the middle-school nightmare: “They know I’m a dork.” The amygdala rapidly activates, along with the insular cortex, a region associated with disgust and distress. And then, after a delay, the PFC inhibits these other regions—“Get this in perspective; this is just a stupid game.” In a subset of individuals, however, the PFC doesn’t activate as much, and the amygdala and insular cortex just keep going, as the subject feels more subjective distress. Who are these impaired individuals? Teenagers—the PFC isn’t up to the task yet of dismissing social ostracism as meaningless. There you have it.[*],[14]
More of the PFC reining in the amygdala. Give a volunteer a mild shock now and then; the amygdala majorly wakes up each time. Now condition the volunteer: just before each shock, show them a picture of some object with completely neutral associations—say, a pot, a pan, a broom, or a hat. Soon the mere sight of that previously innocuous object activates the amygdala.[*] The next day, show the subject a picture of that object that activates a conditioned fear response in them. Amygdala activation. Except today, there’s no shock. Do it again, and again. Each time, no shock. And slowly you “extinguish” the fear response; the amygdala stops reacting. Unless the PFC isn’t working. Yesterday it was the amygdala that learned “brooms are scary.” Today it is the PFC that learns, “but not today,” and calms down the amygdala.[*],[15]
More insight into the PFC comes from brilliant studies by neuroscientist Josh Greene of Harvard. Subjects in a brain scanner play repeated rounds of a chance guessing game with a 50 percent success rate. Then comes the fiendishly clever manipulation. Tell subjects there’s been a computer glitch so that they can’t enter their guess; that’s okay, they’re told, we’ll show you the answer and you can just tell us whether you were right. In other words, an opportunity to cheat. Throw in enough of those there-goes-that-computer-glitch-again opportunities, and you can tell if someone starts cheating—their success rate averages above 50 percent. What happens in the brains of cheaters when temptation arises? Massive activation of the PFC, the neural equivalent of the person wrestling with whether to cheat.[16]
And then for the profound additional finding. What about the people who never cheated—how do they do it? Maybe their astonishingly strong PFC pins Satan to the mat each time. Major willpower. But that’s not what happens. In those folks, the PFC doesn’t stir. At some point after “don’t pee in your pants” no longer required the PFC to flex its muscles, an equivalent happened in such individuals, generating an automatic “I don’t cheat.” As framed by Greene, rather than withstanding the siren call of sin thanks to “will,” this instead represents a state of “grace.” Doing the right thing isn’t the harder thing.
The frontal cortex reins in inappropriate behavior in additional ways. One example involves a brain region called the striatum that has to do with automatic, habitual behaviors, exactly the sort of things that the amygdala can take advantage of by activating. The PFC sends inhibitory projections to the striatum as a backup plan—“I warned the amygdala not to do it, but if that hothead does it anyway, don’t listen to it.”[17]
What happens to social behavior if the PFC is damaged? A syndrome of “frontal disinhibition.” We all have thoughts—hateful, lustful, boastful, petulant—we’d be mortified if anyone knew. Be frontally disinhibited and you say and do exactly those things. When one of those diseases[*] occurs in an eighty-year-old, it’s off to a neurologist. When it’s a fifty-year-old, it’s usually a psychiatrist. Or the police. As it turns out, a substantial percentage of people incarcerated for violent crime have a history of concussive head trauma to the PFC.[18]
Cognition versus Emotion, Cognition and Emotion, or Cognition via Emotion?
Thus, the frontal cortex isn’t just this cerebral, eggheady brain region weighing the pluses and minuses of each decision, sending nice rational Libetian commands to the motor cortex—i.e., an excitatory role. It’s also an inhibitory, rule-bound goody-goody telling more emotional parts of the brain not to do something because they’re going to regret it. And basically, those other brain regions think of the PFC as this moralizing pain with a stick up its butt, especially when it turns out to be right. This generates a dichotomy (spoiler alert: it’s false), that there is a major fault line between thought and emotion, between the cortex, captained by the PFC, and the part of the brain that processes emotions (broadly called the limbic system, containing the amygdala along with other structures[*] related to sexual arousal, maternal behavior, sadness, pleasure, aggression . . .).
A picture of a war of wills between the PFC and the limbic system certainly makes sense by now. After all, it’s the former telling the latter to stop those implicit racist thoughts, to put a stupid game in perspective, to resist cheating. And it’s the latter that runs wild with crazy stuff when the PFC is silent—e.g., during REM sleep, when you’re dreaming. But it’s not always the two regions wrestling.[*] Sometimes they simply have different purviews. The PFC handles April 15; the limbic system, February 14. The former makes you grudgingly respect Into the Woods; the latter makes you tearful during Les Mis, despite knowing that you’re being manipulated. The former is engaged when juries decide guilt or innocence; the latter, when they decide how much to punish the guilty.[19]
But—and this is a truly key point—rather than the PFC and limbic system either being in opposition or ignoring each other, they are usually intertwined. In order to do the correct, harder thing, the PFC requires a huge amount of limbic, emotional input.
To appreciate this, we must sink deeper into minutiae, considering two subregions of the PFC.
The first is the dorsolateral PFC (dlPFC), the definitive rational decider in the frontal cortex. Like a Russian nesting doll, the cortex is the newest part of the brain to evolve, the frontal cortex is the newest part of the cortex, the PFC is the newest part of the frontal cortex, and the dlPFC is the newest part of the PFC. The dlPFC is the last part of the PFC to fully mature.
The dlPFC is the essence of the PFC as tight-assed superego. It’s the most active part of the PFC during “count the months backward” tasks, or when considering temptation. It is fiercely utilitarian—more dlPFC activity during a moral-judgment task predicts that the subject chooses to kill an innocent person to save five.[20]
What happens when the dlPFC is silenced is really informative. This can be done experimentally with an immensely cool technique called transcranial magnetic stimulation (TMS—introduced on page 26 in the footnote), in which a strong magnetic pulse to the scalp can temporarily activate or inactivate the small patch of cortex just below. Activate the dlPFC this way, and subjects become more utilitarian in deciding to sacrifice one to save many. Inactivate the dlPFC, and subjects become more impulsive—they rate a lousy offer in an economic game as unfair but lack the self-control needed to hold out for a better reward. This is all about sociality—manipulating the dlPFC has no effect if subjects think their opponent is a computer.[*],[21]
Then there are people who have sustained selective damage to their dlPFC. The outcome is just what you’d expect—impaired planning or gratification postponement, perseveration on strategies that offer immediate reward, plus poor executive control over socially inappropriate behavior. A brain with no voice saying, “I wouldn’t do that if I were you.”
The other key subregion of the PFC is called the ventromedial PFC (vmPFC), and to savagely simplify, it’s the opposite of the dlPFC. That cerebral dlPFC is mostly getting inputs from other cortical regions, canvassing the outer districts to find out their well-considered thoughts. But the vmPFC carries in information from the limbic system, that brain region that’s swoony or overwrought with emotion—the vmPFC is how the PFC finds out what you’re feeling.[*]
What happens if the vmPFC is damaged? Great things, if you’re not big on emotion. For that crowd, we are at our best when we are rational, optimizing machines, thinking our way to our best moral decisions. In this view, the limbic system gums up decision-making by being all sentimental, sings too loud, dresses flamboyantly, has unsettling amounts of armpit hair. In this view, if we just could get rid of the vmPFC, we’d be calmer, more rational, and function better.
As a deeply significant finding, someone with vmPFC damage makes terrible decisions, but of a very different type from those with dlPFC damage. For starters, people with vmPFC damage have trouble making decisions, because they’re not getting gut feelings about how they should decide. When we are making a decision, the dlPFC is musing philosophically, running thought experiments about what decision to make. What the vmPFC is reporting to the dlPFC are the results of a feel experiment. “How will I feel if I do X and Z then happens?” And without that gut-feeling input, it’s immensely hard to make decisions.[22]
Moreover, the decisions made can be wrong by anyone’s standards. People with vmPFC damage don’t shift their behavior based on negative feedback. Suppose subjects are repeatedly choosing between two tasks, one of which is more rewarding. Switch which task is the more rewarding one, and people typically shift their strategy accordingly (even if they’re not consciously aware of the change in reward rates). But with vmPFC damage, the person can even say that it’s the other task that is now more rewarding . . . while sticking with the previous task. Without a vmPFC, you still know what negative feedback means, but not how it feels.[23]
