Duncan (top) looks at an MRI view of his brain as neuroscientist Adam Gazzaley interprets.
James Brewer takes a seat beside me in a café at the San Diego Convention Center, where we are both attending the largest neuroscience meeting in the world: thirty thousand brains researching brains. With his balding head, bright eyes, and baby cheeks, Brewer, a neurologist at the University of California at San Diego, looks like a large and curious toddler. An unlikely messenger, perhaps, in what for me is now a moment of truth. I had undergone a series of diagnostic procedures in his laboratory, and now, inside the laptop he has placed on the table, are the results of my brain tests.
“Your brain is shrinking,” he says.
This is the last thing I expected to hear. Not me, a man who considers himself healthy and ageless, at least in his own, er, mind.
“People’s brains begin to shrink when they are in their thirties,” Brewer explains with a smile, to suggest this isn’t really a big deal. “Yours is about average.”
I’m somewhat reassured but still concerned about what else I will soon learn. Brewer’s tests are just the first stage of a thorough investigation to see what state-of-the-art medical technology can tell me about the health of my noggin, part of a project I’m calling Experimental Man. I am exploring what diseases might be lurking in my head; what my memory is like at the age of 51; and how my brain responds to matters as diverse as fear, greed, the movies I like, and even the idea of God. It is a magical mystery tour of a single person’s brain. Mine.
Within the hundred billion neurons and trillion or so glial cells that hold neurons in place and feed and protect them (glia is Greek for “glue”) lie my hopes and fears, my feelings, my memories, even the words now recorded on this page. Without my specific blend of cells, tissues, genes, and experiences, there would be no individual person to take these tests, no personality to try to understand what the results mean.
Every brain contains secrets: memories we would rather dispose of, proclivities that we are not proud of or that we struggle to control. For instance, when I was younger I had an almost debilitating anxiety about certain social situations, a predilection I have now mostly learned to control. Yet the fear remains that I will say the wrong thing or do something embarrassing in public. I sometimes wonder if my anxieties are normal—something that through this investigation I would find out.
Before I launch this journey into my brain’s subtle workings, though, Brewer is taking a look at the overall structure of my thinking machine. I have already taken a “structural” MRI (magnetic resonance imaging) scan, which has evaluated the size and well-being of anatomical features in my brain, creating a map Brewer is about to show me on his laptop. Now I will see what these structures, such as the cerebellum and hippocampus, look like. He tells me that abnormalities in the brain can offer evidence of diseases that are present now or that may strike in the future. I already know, for instance, that patients with schizophrenia have distinctive aberrations in the right superior temporal gyrus and that those with attention- deficit/hyperactivity disorder have smaller brain volumes in all regions.
The brain images Brewer shows me —views from the side, back, and top—look like a cross between a nice, fat slice of sausage and a Rorschach inkblot test. A variety of computer-generated colors highlight my hippocampus, lateral ventricles, and other features that Brewer has measured to determine whether I have early signs of diseases such as Alzheimer’s.
Brewer calls up a picture of the brain of a person who actually has Alzheimer’s, and I see that various anatomical features look as if they are smushed or blurred. This distortion results from atrophy and an overaccumulation of proteins that cause the hippocampus to shrink and adjacent fluid-filled structures to expand into the space where the rest of the hippocampus used to be. Fortunately, my hippocampus seems fine. The only abnormality is a slightly larger left brain, the seat of most of what happens when we use language. “But as a writer, you didn’t need a scan to know that,” Brewer says. He adds, however, that he is mostly kidding. There is no hard evidence that the size of the left or right hemisphere affects one’s personality, despite pop neurology assertions (see The Brain, page 28).
Weeks later in another research lab, I will be scanned for brain function: what goes on in my brain when I experience fear or religious faith or when I make decisions. A functional MRI scan, known as an fMRI, will check for increases in blood flow in certain areas of the brain as I react to or record an experience, initiate an action, or ponder something. Blood is needed to fuel the neurons when they go to work, and the fMRI scan picks up signatures of iron in the blood. From this information a neural map can be created showing where brain activity occurs and how much blood is flowing there.
Since MRIs began to appear in the 1970s and ’80s in labs across the country, neuroscientists have been running virtually every fMRI scan imaginable, checking brain reactions to everything from pornography to pictures of sunsets. Nevertheless, applying MRI technology to healthy individuals to ascertain their proclivities toward certain diseases or behaviors is considered to be in its infancy. “These tests are so early, they are almost totally irrelevant to individuals,” warns Judy Illes, a neuroethicist at the University of British Columbia, “though I think there is so much that seems tantalizingly close to being understood.” At the National Institute of Neurological Disorders and Stroke (NINDS), neurologist Eric Wassermann agrees. “Data for brain scanning are noisy for an individual,” he says. “What we have is mostly group data relevant to an age group or people with or without a brain disorder.”
Yet Illes and Wassermann are enthusiastic about my investigation, seeing it as an opportunity for a nonscientist to describe what, if anything, MRIs and other emerging brain-reading technologies can tell us about the three pounds of mushy tissue between our ears, home organ to that mysterious realm called the “mind.”
MEMORY
On a perfect Bay Area day, with the temperature in the upper 60s and a hazy, warm sun shining, I’m in a brain lab at the University of California at San Francisco, attached to a machine that is going to test my ability to remember. Students of UCSF neuroscientist Adam Gazzaley have applied a gooey gel to my head and strapped on an electrode monitor, which looks like a cross between a bathing cap and a device a mad scientist might use to zap my brain. The tight plastic cap is covered with dozens of electrodes connected by wires to an electroencephalograph (EEG), which measures electrical activity in the brain.
Through his research, Gazzaley has set out to prove that the brain does not lose its ability to remember as it ages but rather loses its ability to filter out unwanted memories; in a sense it remembers too much. He is demonstrating that the frontal lobe—the rational and decision-making part of the brain—has a major influence on what is retained by the hippocampus and the brain’s other emotional centers. Neuroscientists call this function “top-down modulation,” a process by which the frontal lobe guides both what people recall and what they do not want or need to burn into their memory cells. The brain does the same thing with hearing. Young ears (and brains) can easily discern the voice of a friend sitting across a table in a noisy bar; as ears and brains age, they are less able to pick out the friend’s voice from the barrage of other sounds. “We think it’s a filtering problem,” Gazzaley says.
As the students strap the cap on me, Gazzaley explains that I’m an anomaly for this experiment. At age 51, I fall in between his two test groups: the young’uns, ages 19 to 30, and the seniors, ages 60 to 77. (I am actually much closer to the older group, but who’s counting?) This makes me wonder, as they ask me to fit my chin into a viselike contraption that will hold my head still: Will I test closer to the young subjects or the old?
The experiment has subjects watch numerous photographs of faces and landscapes shown for one second each on a monitor. The screen goes blank for eight seconds, and participants are then shown either a face or a landscape and asked, “Was this one of the images you just saw?” I’m told to click on a box I’m holding in my hands: yes with my left thumb, no with my right. To test the idea of filtering, Gazzaley asks subjects in some of the tests to ignore the faces; in others, to ignore the landscapes. He also runs series of photographs that are only passively viewed, to ascertain a baseline of what lights up in the brain when a person is not actively trying to suppress or enhance faces or landscapes.
I am feeling a touch of performance anxiety. James Brewer has already knocked down my sense of agelessness a notch or two with the news that my brain is shrinking. Now I am subjecting myself to a test that might reveal me to be prematurely transforming into mental codger-hood.
See David Ewing Duncan's previous article about subjecting himself to the latest in medical testing. Read about more of the author’s findings in his new book, Experimental Man: What One Man's Body Reveals about His Future, Your Health, and Our Toxic World, published by John Wiley and Sons.
