March 21

Over the years, my romance with the brain has lost a bit of its spark. I majored in cognitive neuroscience (with the hope of understanding consciousness) and after college spent two years managing a neuroimaging lab. But in my career as a science writer, my interests have migrated toward the “softer” mind sciences, such as social psychology. I came to realize that exploring the fascinating computational power of neural networks would not shed much light on what it feels like to, well, feel. The gap betweenbrain and mind is too great.

Three new books by neuroscientists attempt to explain aspects of the mind in terms of the brain, with varying levels of optimism about neuroscience’s potential. In “Ha!,” Scott Weems shows where funniness lies in the head but remains agnostic about what deconstructing humor will tell us about experience. (Can a computer “appreciate” a joke? He calls this philosophical question “pointless.”) In “Joy, Guilt, Anger, Love,” Giovanni Frazzetto localizes emotion and explicitly addresses his field’s constraints in the subtitle: “What Neuroscience Can — and Can’t — Tell Us About How We Feel.” In “Consciousness and the Brain,” the most ambitious of these books, Stanislas Dehaene offers nothing less than a blueprint for brainsplaining one of the world’s deepest mysteries. He sees no limit to the horizons for neuroscience.

In trying to understand a joke, one can dissect it (and perhaps kill it) or, as Weems prefers, use scanners to dissect the brain that enjoys it. Weems notes, for instance, that traditional jokes activate the anterior cingulate cortex, an area engaged when the brain is conflicted, so they probably involve a clash of ideas. Comedy also activates the dopamine circuits that also respond to food, sex and cocaine. So there’s a hint of reward on the back end.

Is that all humor is? Conflict and resolution? That’s a big chunk of it. One study found that subjects laughed when they picked up a light object after lifting several heavier ones. It violated their expectations, but they quickly accommodated. (“Ha!” doesn’t explain why laughter then emanates. One evolutionary theory is that it’s a social signal that everything’s okay.)

(Jonathon Rosen for The Washington Post)

But the necessity of conflict and resolution is not the whole story. Weems’s book also discusses what counts as conflict. It often results from building and breaking social expectations, a task that’s hard to codify. One computer program failed at recognizing one-liners when given rules to follow but excelled when allowed to learn on its own. “Computers must be allowed to ‘think messy,’ just like people,” Weems writes. In the introduction he tells us, “Humor is idiosyncratic because it depends on the one thing that makes each of us unique — how we deal with disagreement in our complex brains.”

Will better neuroscience help us better understand humor? Here I must back up and ask how much it’s told us so far — didn’t we already know that humor was rewarding, without talk of dopamine? — and how much neuroscience can ever uniquely tell us about the conscious mind. What do you learn by localizing a mental process to a brain area? Staring at the piece of meat won’t tell you what it’s doing. You need to correlate that area with other mental functions. For instance, jokes activate the anterior cingulate cortex, which we know handles internal conflict because of other studies. Couldn’t we have skipped the neural middleman and tested whether behavioral measures of conflict predict funniness? If you’re trying to explain one psychological phenomenon (humor) in terms of another (competing ideas), why bring the brain into it?

In Frazzetto’s book, the Italian researcher and writer offers a fine primer on six emotions plus empathy. But before diving into the biology of each emotion (the role of the amygdala in fear and of serotonin reuptake in grief), he inspects his target through the lenses of psychology, philosophy, art and personal experience. What you see is that poetry offers more insight into our feelings than does neuroanatomy or biochemistry.

Compare: In discussing the idealization of romantic partners, he notes a study finding that “significant neural deactivations were observed in some parts of the brain involved in the processing of negative emotions [and] the formulation of judgments towards others.” On the next page, he writes, “The beloved becomes a ghost, a mere artifact of the imagination.” Which paints a better picture of love’s blindness: a brain with a splotch on it or the mental image of a haloed apparition?

Heidegger, Caravaggio and Proust were not neuroscientists, and we should be grateful; if they were, they might have had less to tell us about the life of the mind. Frazzetto acknowledges as much. “When I experience or examine an emotional incident along my trajectory as a man, a friend, a lover, a son or a colleague,” he writes, “the first reservoir of knowledge I consult for explanations and meaning is hardly ever neuroscience.”

This is not to say we shouldn’t study the brain — not by a long shot. Neuroscience is interesting in its own right, in the way it’s interesting to learn about how stars form or how computers work. And it’s immensely practical when something goes wrong with the brain and you need to poke around. But it lends little insight into the felt experience of emotion. We learn the triggers and salves of our feelings through daily experience and introspection, and through psychological experiment.

Dehaene shows how fascinating his field can be in his fantastic book on consciousness. It’s smart, thorough and lucid, though a terrible choice for beach reading. Dehaene outlines his “global neuronal workspace” theory of consciousness and tracks down four of its “signatures” in the brain. Some of the experiments in this hunt are ingenious, and we follow along as he and his colleagues circle their prey, eliminating neural correlates of complex but still unconscious behavior. Awareness results, he believes, when distant neurons become synchronized and distribute information widely, allowing a thought to be used in multiple ways by different brain modules — to be stored, reported, acted on or evaluated.

Dehaene’s neural signatures are tools that actually do offer unique insight into the conscious mind, at least when the mind is noncommunicative. He can test for consciousness in babies, animals and locked-in patients — people with awareness but full-body paralysis. Neurologist Allan Roper offers a note of caution, however. “Physicians and society are not ready for ‘I have brain activation, therefore I am,’ ” he said. “That would seriously put Descartes before the horse.” (Ha!)

Neuroscience has made great progress in locating the neural correlates of consciousness, but when we try to explain why consciousness exists at all, we hit a wall. Dehaene disagrees. He spends a paragraph or so on the central philosophical problem — why the functionality of the material brain should produce immaterial experience — and dismisses the issue, likening it to long-gone debates about vitalism. But the comparison is not sound. In principle, one can explain life in terms of objective physical processes because life’s defining behaviors are objectively observable. But you can’t bridge the gap between consciousness and biochemistry, because one’s conscious experience is inherently private, subjective. Among the body’s properties, it’s unique.

If neuroscientists decoding our thoughts ever reach a point where they can look into a comedian’s brain and burst out laughing, that will be a triumph of the field. But they still won’t know why we’re conscious. And they’ll still have something to learn from the comedian.

Matthew Hutson is a science writer and the author of “The 7 Laws of Magical Thinking: How Irrational Beliefs Keep Us Happy, Healthy, and Sane.”


The Science of When We Laugh and Why

By Scott Weems

Basic. 230 pp. $26.99


What Neuroscience Can — and Can’t — Tell Us About How We Feel

By Giovanni Frazzetto

Penguin. 312 pp. Paperback, $16


Deciphering How the Brain Codes Our Thoughts

By Stanislas Dehaene

Viking. 336 pp. $27.95