Determined: A Science of Life without Free Will

by Robert M. Sapolsky

Throw down the gauntlet from chapter 3—present me with the neuron, right here, right now, that caused that behavior, independent of any other current or historical biological influence.

we are moths pulled to the flame of the most entrenched free-will myth. We’ve already examined versions of partial free will—not now but in the past; not here but where you’re not looking. This is another version of partial free will—yes, there are our attributes, gifts, shortcomings, and deficiencies over which we had no control, but it is us, we agentic, free, captain-of-our-own-fate selves who choose what we do with those attributes.

Psychologist James Cantor of the University of Toronto reviewed the neurobiology of pedophilia. The wrong mix of genes, endocrine abnormalities in fetal life, and childhood head injury all increase the likelihood.

Cantor concludes correctly, “One cannot choose to not be a pedophile.”

We’re usually pretty good at remembering that the biological stuff on the left is out of our control.[9] “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?

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.

It seems so hard, so counterintuitive, to think that willpower is made of neurons, neurotransmitters, receptors, and so on.

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.

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.

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.

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.

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 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 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.”

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.”

As it turns out, a substantial percentage of people incarcerated for violent crime have a history of concussive head trauma to the PFC.[18]

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.

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.

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 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 this page in the footnote), in which a strong magnetic pulse to the scalp can temporarily activate or inactivate the small patch of cortex just below.

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.

The other key subregion of the PFC is called the ventromedial PFC (vmPFC), and to savagely simplify, it’s the opposite of the dlPFC.

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.[*15] What happens if the vmPFC is damaged? Great things, if you’re not big on emotion.

In this view, if we just could get rid of the vmPFC, we’d be calmer, more rational, and function better.

people with vmPFC damage have trouble making decisions, because they’re not getting gut feelings about how they should decide.

And without that gut-feeling input, it’s immensely hard to make decisions.[22]

dlPFC damage produces inappropriate, emotionally disinhibited behaviors. But without a vmPFC, you desiccate into heartless detachment.

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.

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.

(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.

When you’re trying to do the right, harder thing, the PFC becomes the most expensive part of the brain.

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,

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.[*17] As your PFC works hard on a task, those reserves are depleted.[24]

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.

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

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.

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.[*21] 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

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.

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

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]

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]

Testosterone also reduces the coupling between one part of the PFC and a region implicated in empathy;

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.

Recall how years of depression can cause the hippocampus to atrophy, how the sort of trauma that produces PTSD can enlarge the amygdala.

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.

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]

Estrogen causes PFC neurons to form thicker, more complex branches connecting to other neurons; remove estrogen entirely and some PFC neurons die.

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,

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”[*26]