In search of my own brain

A few days pass, and Joy sends an e-mail to let me know that the results are in. "You're going to like this," she writes temptingly. The next afternoon I take the A train up to 168th Street, and Joy and I sit down at a conference table to spend some quality time with my brain.

Joy has assembled a collection of about forty color printouts, each displaying four images of my brain at work. The images are overhead views, and each one is a "slice" of my brain, starting with the brain stem, at the very bottom, and ending with the tip of the cortex. For each stage of the experiment -- there are four in total -- the fMRI has captured twenty-five slices of my brain going about its business. That business takes the form of changes in blood flow to different regions; the scanner first looks at my brain during the "rest" periods, then during the "activity" period, and it records any salient differences between the two. These images let you see the areas that are relevant to a particular task, and shut out the background processing that the brain is always doing. My brain stem, for instance, was steadily plugging away maintaining my breathing pattern -- along with many other mission-critical operations -- but that area doesn't light up on the scan images because those patterns didn't change during the experiment.

Areas that do show noticeable changes appear on the images as a cluster of bright yellow pixels, fading out to orange and red at their peripheries. The images look strikingly like the Doppler radar images you see on the Weather Channel. (If you blur your eyes a little, you might think that yellow patch on the image was a thunderhead, not a brainstorm.) The image is projected over a grid with numbers running along each axis. The numbered grid and the slices create a three-dimensional system of coordinates, the latitude and longitude of neuromapping. The grid is made up of small cubes called "voxels," and each voxel has a specific address.

Joy begins by laying down the twenty-five slices for stage one of our experiment, the dreaded checkerboard. The pattern of activity is immediately visible, even to my untutored eyes, mostly because there's literally nothing going on in 95 percent of my brain. Only a thin band wrapping around the back of my head, roughly at ear level, glows yellow.

"We know that the flashing checkerboard is a very salient stimulus for just the visual processing areas of the brain," she says. "And that's exactly what's happening here."

She points to the yellow band: "This part of the brain is all primary visual cortex. What's unique about this is that this activity doesn't get out of the occipital lobe -- and nothing goes on in the frontal lobes. Nothing. This is just as exclusively visual as you can get." We both start to laugh. "Your brain is doing the minimal amount it has to do to sit there and look at that stupid checkerboard!"

Looking at those blank areas on my mental map reminds me of all the times that someone had gravely explained to me that we only use 10 percent of our brains, and then waxed rhapsodic about how smart we'd be if we could tap 100 percent. Of course we only use a small percentage of our brain at any given time -- and it's a good thing, too! Your brain has dozens of dedicated tools, most of which aren't relevant to whatever it is you're focusing on right now. If your visual cortex keeps kicking into overdrive as you're trying to memorize a speech, the words won't stay in your head as readily. Only using 10 percent of your brain is a sign of efficiency, not underachievement. Arguing that we'd be better off with 100 percent is like raving about how great Shakespeare would have been if he'd managed to use all twenty-six letters in each of his words, instead of a small fraction of the alphabet.

There's something in Joy Hirsch spreading out the images on the table that brings to mind a tarot card reader, but there's nothing mystical in her analysis. I find myself thinking, This person I barely know has ventured inside my head in a way that no one has ever ventured before. That's why the hall-of-mirrors interpretation feels wrong to me. It's not an endless simulation I've entered into here, but rather something that feels authentic, even intimate.

Thus far all the images we've examined have been composite sketches: each stage included two runs, and so the images are a combined look at activity over the two of them. But with the rumination round, I had asked Joy to look at the two runs separately, because I had fared so poorly the first time around and because in the final run of the day, I had managed to get my brain exactly where I'd wanted it to be for my forty seconds in the spotlight.

The images from those two sessions do not disappoint. In the first run, small spots of activity are scattered across my brain, mostly in red voxels (suggesting less activity than the yellow). There's little shape or symmetry to the map; my brain looks cluttered. But in the second run, what jumps out at me immediately is how silent most of my brain appears. Only the language centers light up with any intensity, along with a sharp yellow rod at the center of my brain, extending up to the very top of my cranium. There's very little visual activity, and almost nothing from the eye-movement regions.

"There's a concept of efficiency that has emerged in the neuroimaging community in the last few years," Joy says. "It's basically that when there's a task that the brain is having difficulty doing, the pattern looks very distributed, like this here." She points to the cluttered image of run number 1. "This was not an efficient action -- as opposed to here, where the specific tools of the brain are contributing in an efficient way to the task at hand."

"You really look like you got your act together here." She's pointing to that bright yellow dot on the upper images of run number 2. "Here's more evidence of that -- look at this very focused medial frontal gyrus. This is one of the most distinguishing characteristics of this scan -- this is a very high-level executive function of the brain, and you can see it running like a pole all the way down to the cingulate. I think that the medial frontal gyrus is important in coordinating different activities in the brain, reaching for the right tool at the right time. In this last scan, the entire structure -- not just a part of it -- is active." In Joy's phrasing, my language areas were perfectly "robust" during these inspired forty seconds, but they didn't turn out to be the most interesting element of the image. It was the overall orchestration, the clarity of the pattern, that stood out, the lack of mental clutter.

What had I been hoping to find? I thought about this on the subway ride home. In the crudest sense, I suppose I thought that my skill at stitching words together in my head might turn out to have its own modulelike presence in the scan: a distinct patch of neurons devoted to imagining sentences. If the brain is filled with all these modular tools, then somehow it seems logical that tasks you're good at should have some visible presence on the brain map. Sometimes this is the case: Einstein's brain had unusually large inferior parietal lobes, which we think gave him his extraordinary spatio-logical skills. (He famously solved problems as images in his head weeks before he could turn them into working equations.) Such a skill most likely would have shown up directly on an fMRI: a person gifted in spatial intelligence shows more activity in regions of the brain dedicated to spatial processing.

But in my case, the scan revealed something quite different. (I'm no Einstein, as it turns out.) There was no special module. What caught Joy's eye in the final rumination scan was not a specific region, but the overall pattern of brain activity. The tools in the toolbox weren't particularly impressive, but the toolbox itself was well organized. In fact, the only specific region that seemed to be at all above average was the one responsible for coordinating activity in other regions. Perhaps the most telling thing about my brain map was what didn't show up on the images: when I was focused, there was almost no activity in areas that weren't related directly to the task at hand. Compare that to my episode of cognitive flailing in the first run of the rumination stage: on that scan, there's hardly a discernible pattern. It's mostly noise, and little signal.

I have no idea how replicable my fMRI results would be if I tried the exact experiment again, and it's unclear whether that pattern of organization -- with its strong medial frontal gyrus and its many silent regions -- holds true for my brain generally, or just for this little snapshot. But I suspect there is a larger truth nestled in that last fMRI image, one that has begun to change the way I think about people I know. I suspect that the world of talent is made up of two kinds of brains: some that have specific modules that are unusually good at their job, and some that are unusually good at keeping all the different modules organized. Both types of brains come across to us as talented, as intelligent, but I think the types are different enough that you can learn to recognize them if you know what to look for. We all know people who have dazzling skills: they can sit down at a piano and pick out a tune they heard last week; they can calculate interest rate payments in their head; they can actually understand quantum mechanics. But we also know people whose brains seem gifted in a different way: no stunning, off-the-chart skills, but a general competence and efficiency, with very little noise complicating their signal.

My dad used to say to me during my high school years: "You're not a rocket scientist, but you're smart and you've got a lot of talent." I used to bristle at the remark. (If I wanted to, maybe I could be a rocket scientist!) But now I think he was onto something. I've met rocket scientists -- and astrophysicists, and programming wizards, and architectural geniuses -- and I don't possess anything like what they've got mentally. I don't have their special gifts. But those fMRI images made me think that perhaps I have something else, a little less dazzling, but nothing to be ashamed of either. Maybe I have a well-orchestrated brain -- with no world-famous soloists but a nice sound nonetheless. In a sense, this is what my dad had been trying to say, in slightly different language: I was talented in an orderly brain kind of way, not a supermodule kind of way.

It was only one experiment, but the machine had given me something that machines don't normally deal out: a hunch about myself, and maybe a larger hunch about people in general. I'd been dreaming for more than a year of capturing my brain as it came up with an idea, and thanks to Joy and her uncanny device, I'd managed to catch precisely that glimpse. The results were mesmerizing and remarkably legible, even to my untrained eyes. But they didn't provide unequivocal answers or magic bullets. They were more like clues. Seeing my brain come up with an idea had given me another, more interesting idea, one that still reverberates in my head as I write. Wouldn't it be nice to have a scan of that?

- - - - - - - - - - - -

Copyright © 2004 Steven Johnson, reprinted with permission of Simon & Schuster.

• View blog reactions