“The Split Brain: A Tale of Two Halves”
by David Wolman
Nature, March 14, 2012
The Last of Their Kind
Most anyone who has taken an introductory psychology class (or skimmed an Oliver Sachs book) has probably heard of the split-brain patients. But few people are aware that there are only a few of them still alive and fit for research. Let’s do a retrospective on this area of brain science, and ask the scientists who’re working with these last patients what kind of questions they’re still trying to answer before this patient population is gone for good.
In the ’60s and ’70s, as a last-resort treatment of their patients’ intractable epilepsy, doctors severed the corpus callosum, the primary bundle of fibers connecting the left and right hemispheres of the brain. The extreme surgery worked relatively well to mitigate intense seizures. Unexpectedly, it also created a population of experimental subjects whose experience revealed major new insights about duality of all brains. Because of these patients, we know that the mind can sometimes look like two markedly different brains, cabled together and exchanging a torrent of information. The left side leading the way for speech and language computation, for instance, and the right hemisphere superior in visual-spatial processing. The research later earned Caltech’s Roger Sperry a Nobel Prize. (Only a small number of patients had super-clean cuts and were otherwise neurologically healthy enough to be useful to researchers. Nowadays, doctors have better drugs for treating epilepsy, or they will disconnect only part of the tissue.)
Our lead character on the science side is Michael Miller of UC Santa Barbara. As a PhD (and protégé of one of the field’s pioneers, Michael Gazzaniga), Miller worried that his interest in split-brain science was something of a dead end. A few years ago, though, he learned of three split-brain patients in Italy. Miller has just started a sabbatical year at a neuro-imaging facility in Trento, to conduct both behavioral and imaging studies on the men who could be the very last of their kind. Some of his recent results suggest that the brain’s right hemisphere has important capabilities and responsibilities previously undetected, and we’ll wrap this and other current science into the story.
Another compelling character could be one of the patients themselves. Her name in the literature is V.P. She lives inOhio, and Miller or Gazzaniga sometimes fly her out to California for
studies. Another is J.W, a salty old New Englander who was the pivotal subject in countless major papers over the decades, but who now, because of age and other health problems, isn’t useful for research. Finally, there’s the small cohort that has turned Italy into something of
a Mecca for this niche area of neuropsychology. Who are these people? How does their condition and relative star status impact their everyday lives? And what additional secrets about the mind might they reveal?
Although there are some concerns about patient privacy to be ironed out, Miller says I’m welcome as an observer in his lab, and the other researchers and doctors who work closest with these patients have expressed support for this project. I also have the background to do this story well: My autism piece for Wired was selected for the 2009 Best American Science Writing, and for my 2005 book about left-handedness, I did substantial research and layperson-friendly writing about the dual nature of the brain.