e all have our hobbies, our talents, our areas of professional expertise. For each of us, there are devices or images or stacks of figures that feel as familiar as the faces of our closest friends. And last month, neuroscientists at Vanderbilt University confirmed that this sense of familarity is all in our heads. Specifically, in our "fusiform face area."
Historically, anatomists have been able to draw vague inferences about the human brain by comparing it to the brains of animals. I.e., if mammalian brains have grown outward from a root structure--the brainstem--which resembles the complete brain of a reptile, it's a reasonable assumption that "reptilian" responses (e.g., breathing, heart rate, pleasure) might still reside there. Likewise, the more complex mammalian behaviors (e.g., pair bonding, social organization, nurturing of young) should logically be controlled from the newer regions such as the cerebellum, pons, midbrain and limbic system, which reptiles don't possess.
Complex mammals, including primates, also possess a "cerebral cortex," which is grossly enlarged in humans, and human brains have a large additional layer, the neocortex, which is much more developed than anything seen in even our closest cousins, the great apes. And since humans can perform supersimian feats like spoken and written language, logical abstraction and task planning, and real-time, high-resolution color image processing, it stands to reason that the neural wiring for these traits can be found somewhere in the distinctively wrinkled terrain of our cerebral cortex and neocortex.
Science's darker corners
But that's about as far as comparative anatomy will get you. To map the living brain in greater detail, researchers have traditionally resorted to waiting--some might say ghoulishly--for hapless humans to succumb to accident or disease or surgical mishap. When a hunk of brain is destroyed or disconnected, doctors can observe the (sometimes dramatic) changes in the victim's behavior, cognitive abilities, reported sensation, etc., and thereby deduce the function of the affected region. Since this kind of neurological damage can be devastating, bizarre and (so far) almost always incurable, it's hard not to see this as one of science's darker, less hospitable corners.
Still, over decades and centuries, the misfortunes of a few have provided crucial insights to the many, and a reasonably detailed map has emerged that can offer us helpful hints like "If you're an artist or a dancer, let the bus hit you on the left side. If you're an auctioneer or used car salesman, let it hit you on the right." In fact, this was exactly the technique by which the fusiform face area or FFA--the brain component responsible for identifying faces--was first discovered.
So far, so good. But what if your goal is more involved than that? What if your friend or loved one has a perfectly functioning brain but a body incapable of controlling even a simple speech synthesizer or an electric wheelchair? Or you're in the pilot's seat of a damaged airplane which no human reflex could land safely, or you're a hazardous materials worker in need of a telepathic robot assistant? Or, more simply, you're a doctor out to treat damaged brains, rather than simply studying and cataloging them. Wouldn't it be useful to measure brain activity directly and non-destructively, in high resolution, while it's happening?
Medical mindreading
Fortunately, beginning in the 1980s it became possible to do exactly that, using two exciting new technologies: Positron Emission Tomography and Magnetic Resonance Imaging. A PET scan relies on the detection of gamma rays that are emitted from radioactive fluorine, introduced through a glucose solution injected into the subject's bloodstream before the test. Since the gamma-ray "brightness" of any particular body or brain region is directly proportional to its intake of fluorine-enriched blood, and since blood carries oxygen, and oxygen consuption increases with metabolic activity, the PET scanner can take detailed neural "snapshots" or brightness maps which accurately reflect the levels of activity across the entire brain, all at once.
In an even cleverer trick, an image taken of a brain at rest can be "subtracted" from an image of a brain contemplating a specific task or sensory input, to yield a very exact picture whose bright spots highlight only the brain areas that are directly involved. These highlights are repeatable, too; the same areas will light up every time the subject performs that task. So while we can't yet tell what a person is thinking, we're rapidly developing the means to see where they're thinking, and thus, at least in rough terms, what they're thinking about.
The MRI scan operates on a different principle: sensing the
electromagnetic signature of oxygen
directly. It is less invasive than PET in the sense that it doesn't
require the subject to ingest a
radioactive liquid, but the sensors rely on powerful electromagnets
which can literally suck bits of
metal completely through a human body. So it's not always the first
choice of researchers, even
though it provides a more exact measure of activity in the brain.
Still, it's often useful, as in Nashville, Tenn. last month, where psychologist Isabel Gauthier used it to monitor the
brains of car and bird experts
answering questions about their specialties, and about each others'.
Rewiring ourselves for fun
Unexpectedly, the area stimulated by the familiar subject matter turns out to be the FFA. Does settling into your job or hobby feel like greeting a friend, or sometimes, perhaps, an enemy? There is anatomical basis for it! One imagines the FFA of Dr. Gauthier herself, twinkling away as it contemplates its own familiar image on the scanner. Hola, amigo!
As this kind of mapping continues and our brains' self-congratulatory self-understanding explodes, it isn't hard to imagine some sinister applications. What if enemy governments or criminal organizations had the ability literally to read our minds? We might not want even our friends and lovers to know us quite that well. Still, there are as many intriguing possibilities on the positive side. Knowing exactly how our brains function, we may find it possible--even trivial--to cure a host of neurological and psychological ailments, or even rewire ourselves for intellectual or social or recreational purposes, perhaps editing out a bit of that glitchy hunter-gatherer firmware that so plagues us in our cities and boardrooms today. To err is human, it's true, but why should forgiveness have to be divine?
Wil McCarthy is a rocket guidance engineer, robot designer, science fiction
author and occasional aquanaut. He has contributed to three interplanetary
spacecraft, five communication and weather satellites, a line of
landmine-clearing robots, and some other "really cool stuff" he can't tell
us about. His short fiction has graced the pages of Analog,
Asimov's, SF Age and other major publications, and his
novel-length works include Aggressor Six, the New York Times Notable
Bloom, and upcoming The Collapsium.
