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The Maps Our Brains Create

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The Warped, Wondrous Maps Written in Your Brain — and How They Guide You
By Rebecca Schwarzlose

On Saul Steinberg’s legendary 1976 New Yorker cover depicting a world map, Manhattan takes up the entire bottom half while the rest of the world is squished onto the top.

It’s a distortion of reality as are nearly all maps — including the ones inside of our heads, according to Rebecca Schwarzlose’s enlightening and ambitious new book, “Brainscapes.”

In an “exquisite choreography” orchestrated by genes and the environment, our billions of brain cells create all kinds of spatial representations. “What you ultimately see,” she writes, “is warped by your brain maps.” Same for hearing and touching and smelling and even remembering. The distortion inherent in these maps helps us work our way through the sensory overload that reality presents us with every day.

Schwarzlose, a neuroscientist at Washington University in St. Louis, writes with the zeal of an enthusiastic teacher yearning to share her passion with her students. For the most part she succeeds. Her prose is lively. She jettisons scientific jargon.

The attempt to understand brain mapping dates back nearly a hundred years, but 21st-century technology has allowed scientists to glean finer details and to realize the ever-shifting landscape — or “brainscape.” These advancements have taken us from brain maps that used to be like a Rand McNally Motor Carrier’s Road Atlas you might have brought on a road trip in the 1980s (which showed the roads but not the traffic) to the equivalent of Google Maps.

The first chapters lay out the premise of mapping and how it works, beginning with vision, followed by touch, sound, taste and smell. The basic idea of a map is easy enough to understand. But to grasp how and why our brains lay out information, and in what patterns, is challenging. Paul Kim’s illustrations, which ignited my visual center (my V1), helped tremendously.

By way of example, Schwarzlose explains how viewers “see” the “Mona Lisa” — that is, how we absorb what’s on the canvas. Our initial perception, unbeknown to us, exaggerates the nose and lips because these facial features contain crucial data about identity and emotions. Our brains then compensate for this enlargement, so that objects don’t appear to inflate and deflate every time we shift our gaze. And all this happens in a flash of a second.

When it comes to touch, the map created by our fingertips is the New York City of Steinberg’s cover, occupying much more brain-cell real estate than that delegated to, say, our backs.

The most engaging chapters are in the second half. The stories get quirkier. Also, Schwarzlose dives into the uses and potential abuses of technologies prompted by this mind-field of discoveries.

Drawing on the observations of patients with specific brain injuries, scientists have learned that there is a distinct brain map crucial for processing pictures. Schwarzlose recounts the story of one man who knew, for instance, what a carrot was when the word was spoken but couldn’t tell one from a picture. Noting the pointy bottom and feathery top, he guessed “some sort of a brush.”

We read about a device built using the insights of brain-mapping that helped a paralyzed man feed himself. Electrodes implanted in the right-hand region of his motor cortex allowed him to electrically stimulate his right-hand muscles. He could grasp mashed potatoes and lift them to his mouth.

With justified skepticism, Schwarzlose describes newfangled lie detector tests also inspired by brain-mapping findings. They work OK in a laboratory but warrant “careful scrutiny,” she writes. One false result would have dire consequences in a courtroom.

There are occasions when her conversational tone turns too goofy. She compares firing neurons to “a classroom of young children vying for the teacher’s attention: Me me me me, pick me! Ooh ooh ohh me!”

I was also irked that within this well-researched book, she added a few dubious claims gleaned from single studies. (Do people really have a tendency to subconsciously sniff their fingers after shaking hands with a stranger? I’m unconvinced.)

Still, these quibbles are trivial in a book that travels into rich terrain, charted by a smart and eager tour guide.


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