Scientific American MIND Reviews "The Superhuman Mind"

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Remarkable Brains: Hudson Street Press, 2015 ($25.95)

Ask about the color of a painful toothache or the sound of a delicious lamb shank, and most people will respond with confusion. But artist Carol Steen would say that pain is orange, and researcher Lidell Simpson might tell you that all the noise in the restaurant makes it difficult to hear the flavor of the food. Such seemingly illogical pairings are the hallmark of synesthesia, a neurological phenomenon that causes some people to form strong connections between otherwise unrelated sensations.

So-called synesthetes such as Steen and Simpson experience these sensory links automatically. In , neuroscience and philosophy researchers Brogaard—a synesthete herself—and Marlow contend that anyone can acquire a form of synesthesia and open “a gateway into inaccessible neural regions of our brains.”

Central to their case is the idea that even “normal” brains unconsciously perform incredibly complicated feats all the time. Coordinating the many muscles in our hand and arm to pick up a mug, for example, requires scores of intricate calculations to which our conscious mind is not privy. The mental algorithms that allow us to carry out such mundane actions are in a sense preprogrammed, but the authors surmise that via targeted brain training, we can fashion new algorithms to tap into existing neural networks.

Brogaard and Marlow highlight this vast potential of the human brain using extreme real-life examples. They explore a study in which sighted people, after being blindfolded for a week, began to spontaneously echolocate, a technique more commonly used by bats for sensing their surroundings. Brain scans showed that these people's brains apparently began to recruit their visual cortices to echolocate.

Brain trauma may similarly prompt a rewiring of our neural connections. For instance, soon after jumping headfirst into the shallow end of a pool, one man discovered an all-new talent—the ability to play the piano proficiently. A brain scan revealed that he had a lesion on his parietal cortex, the region responsible for producing language and music. Researchers investigating his condition thought that some form of compensation for the lesion could explain his new prowess at the keyboard.

Of course, Brogaard and Marlow do not advocate that anyone live in darkness or seek brain injuries to achieve new cognitive skills. Rather they relay such stories to highlight the intriguing possibilities that can emerge when we form new neural connections. And they describe related tricks people can use to build mental shortcuts for memory, math and even carrying out savantlike calendar calculations. (Which day of the week was April 23, 1987? Anyone?) Participants in memory competitions generally have neurologically ordinary brains but take advantage of our innate affinity for remembering emotions and stories to achieve remarkable feats of memory. To recall the irrational number pi to more than 20,000 decimal points, memory champ Mark Aarøe Nissen crafted a narrative to connect each digit to some element of the story.

For a book about the power of leveraging connections—between brain circuits and pieces of information— is rather disjointed. Even the main theme of synesthesia puzzlingly fades in and out. The brain-training strategies are fascinating but do not always feel realistic to apply. Still, as an exploration of the extraordinary reach of the human brain, the book delivers.

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