Reviewed by Wray Herbert
Sunday, October 28, 2007
THE BODY HAS A MIND OF ITS OWN
How Body Maps in Your Brain Help You Do (Almost) Everything Better
By Sandra Blakeslee and Matthew Blakeslee
Random House. 228 pp. $24.95
Sometimes, science advances on luck, and so it was with the monkey and the ice cream cone. On a summer day in 1991, neuroscientists in a laboratory at Parma University had wired up a monkey's brain for a simple experiment. They wanted to see which neurons fired during the series of movements involved in the everyday act of drinking from a cup: the reaching, the finger curling, the grasping and so forth. But on that day the monkey was more interested in a student eating an ice cream cone. The monkey watched intently as the student moved the cone to his mouth and, as it watched, the motor neurons in its brain began to fire. The firing was a classic neurological signature. It indicated that the animal was moving its arms and hands -- but in fact the monkey was quite still.
What the Italian scientists were witnessing was the first evidence for what are now known as "mirror neurons": specialized cells in the brain that inextricably link intention with movement and perception. They explain why yawns are contagious, why sports fans contort their bodies in unison, and -- on a more profound level -- why one human being can empathically "feel" the distress or joy of another. They are nothing less than the neurological foundation for all human connection.
Science writers Sandra Blakeslee and Matthew Blakeslee (mother and son) tell the monkey story in a late chapter of The Body Has a Mind of Its Own, their captivating exploration of the brain's uncanny ability to map the world. The discovery of mirror neurons, while fortuitous, was actually the culmination of decades of painstaking scientific inquiry in dozens of brain laboratories around the world, and the authors take us into those labs to watch this important scientific tale unfold. They also take us on a tour through the squishy gray matter that embodies our sense of self and otherness.
The narrative begins in the laboratory of Wilder Penfield, a Montreal neurosurgeon who in the 1930s began poking around in the brains of his patients. Literally. He would saw open their skulls and zap various clusters of neurons while interviewing the patients: What do you feel now? How about now? Over 20 years, he gathered data on which neurons corresponded to which body parts, ultimately compiling the data into his now-famous homunculus: the first map of where the various body parts reside in the tissue of the brain -- the knee, the tongue, right down to the ring finger.
And the ring itself, as it turns out, because, get this: The brain has lots of built-in maps, and they don't stop at our toes and fingertips. Indeed, every time we put on a piece of jewelry or pick up a hoe or scribble with a fountain pen, the brain incorporates those objects -- and the space they occupy -- into our personal maps. That's why you can actually perceive the texture of a steak through a knife and fork, and never mistake it for Jello. From the brain's perspective, those tools are simply extensions of you.
Such complex neuronal interplay is bound to get mixed up sometimes; indeed, the breakdowns provide some of the most valuable -- and bizarre -- insights into the brain's cartography. Consider the unfortunate woman who, following a stroke, came to believe that her left hand actually belonged to her niece. Or "amputee wannabes," people who feel deeply that one of their limbs is not really part of them and that only amputation will make them "whole." Or the woman who, following surgery for a brain tumor, looked down and "saw" two left legs and two right legs. These neurological freaks would once have been labeled psychotic. Today, we know they suffer from severely disordered body maps.
These psychological aberrations will remind some readers of Oliver Sacks's wonderfully insightful The Man Who Mistook His Wife for a Hat. But don't be misled. The Blakeslees' brief clinical descriptions lack both the richness and the eloquence of Sacks's macabre and compelling case studies.
But that's a quibble. The authors have essayed some difficult terrain here and, for the most part, with clarity. They know the inner workings of both the scientific laboratory and the brain and wisely keep their heady subject matter anchored in those worlds. Readers will emerge with a far keener sense of where they are. *
Wray Herbert writes the "Mind Matters" column for Newsweek.com.