Brain Imaging: What Good Is It?

You’ve no doubt seen those colorful pictures of the brain, with different sections of the brain colored yellow, red, green, and blue–a rainbow pattern of colors spread out across the brain. These images are generated by a brain imaging technology called “functional magnetic resonance imaging” or fMRI for short. fMRI can detect the relative degree of brain activity in a very small region of the brain, approximately 3 millimeters cubed. These little imaginary cubes are called “voxels”; and then, using some expensive and fancy technology, researchers can measure the brain activity in each voxel while you’re engaged in a specific mental task. To communicate the results, each of the voxels is assigned a color based on how much the neurons inside it are firing. Scientists, journalists, and trade book authors are really excited about this technology, because it seems to give us a window into what is really going on when we’re thinking. National funding agencies have been granting lots of money to this sort of research (and it’s not cheap, because it requires expensive machines that are often located inside the medical school, because they’re also used for clinical diagnoses).

So what good is it? More and more scholars are asking this question, and we’re seeing a growing backlash. Knowledgeable scholars have been arguing that we haven’t learned much from this expensive brain imaging. Adam Gopnik, writing in The New Yorker magazine, recently reviewed three new books that all argue “that brain science promises much and delivers little.” The books are A Skeptic’s Guide to the Mind, by Robert A. Burton; Brainwashed: The Seductive Appeal of Mindless Neuro-Science, by Sally Satel and Scott O. Lilienfeld; and Neuro: The New Brain Sciences and the Management of the Mind, by a pair of cognitive scientists, Nikolas Rose and Joelle M. Abi-Rached. (Not included in this review is the 2011 book Neuromania: On the Limits of Brain Science, by Paolo Legrenzi, Carlo Umilta, and Frances Anderson.) As Professor Roger Carpenter writes, in a letter supporting Gopnik’s review, this “is indeed neo-phrenology, and, intellectually, represents a regression to the nineteenth century.” (Sep. 23, 2013, pp. 12-14)

In 2011, I published a scientific article titled “The cognitive neuroscience of creativity,”* and I came to the same conclusion about the limits of brain imaging. The first challenge is that you have to learn a lot of technical detail to really understand how little information the technology provides. For example, in my article I reported that fMRI, which indirectly measures neuronal activity by measuring blood flow to each voxel, is in fact only measuring changes in blood flow above a baseline state of 1 percent to 3 percent. That means that even when your neurons are firing like crazy, you won’t see more than a 3 percent increase above a baseline state (i.e., sleeping or daydreaming). Second, when neurons start firing, the blood flow doesn’t increase until 4 to 6 seconds later. Third, when neurons become more active, they draw in more blood, but blood flow also increases over a larger area that extends to a few millimeters distant, where there may not be any increase in neuronal activity.

Fourth, different people’s brains operate in different ways–not everyone’s brain responds to a given task in exactly the same way. Even for a single person, their brain responds differently to the same task on each occurrence of the task. So researchers have everyone do the task tens or hundreds of times, and then they take a statistical average across all of the tasks. And after that, they average across everyone’s brain. So those colorful pictures you are seeing represent an average–and it doesn’t mean that every person, every time, displays exactly that activation pattern.

And finally, the colorful pictures hide a very important fact: The entire brain is active pretty much all of the time. Neurons are always firing, at least a few times every second. The brain is a complex system, and every cognitive activity is widely distributed across the neocortex. If you showed those pictures in a magazine, it would look like a jumbled mess. So researchers do what’s called paired image subtraction–they get the average brain activity in one task, and then they get another average, of brain activity in some comparison baseline task, and they subtract out the activity of the baseline task.

Are you confused yet? I said there were a lot of technical details. (And the above is a highly simplified version.) But all this led me to draw the following conclusions in my 2011 article:

1. For the most part, brain imaging has discovered facts that were already known from classic experimental cognitive psychology. We have no breakthrough surprises; no 1970s experimental findings have been overturned.

2. All thought involves many regions of the brain. There is no such thing as “the brain location for creativity” or anything else.

3. You can’t use brain imaging to make claims about causation, such as “activation in this part of the brain caused you to have a creative insight,” because the activated areas might not play a critical role in performing the task; they might be “listening” or monitoring some other brain area that is actually responsible.

4. Because the brain imaging results are always averaged over many trials and many subjects, it is incorrect to interpret the studies as showing that “creativity is located in the anterior cingulate cortex” (or wherever).

5. Higher cognitive functions, like creativity, are complex and involve many parts of the brain simultaneously. They can’t be reduced to one small location in the brain. And when you think about it, that’s just common sense.

Perhaps new technologies will emerge in the future that can address some of these issues. But whatever new brain imaging technology emerges, these five points will still apply. I’ll certainly keep following this research, and if I see some exciting new finding about creativity and the brain, you’ll read it here!

*Sawyer, Keith. 2011. The cognitive neuroscience of creativity: A critical review. Creativity Research Journal, 23(2), 137-154.

Your Brain on Jazz

Two researchers at the National Institutes of Health, Charles Limb and Allen Braun, asked six jazz pianists to improvise at the keyboard, while their heads were inside a brain scanner known as a functional magnetic resonance imaging (fMRI) machine.  The brain scanner is immense–it fills up an entire room–and to get your brain scanned, you have to be lying down so that the immense donut shaped scanning ring can be moved into place around your head.  So the researchers designed a special keyboard that could be propped up in the pianist’s lap.

Then they had each of the six pianists play four different exercises, two that were not improvised and two that were.  The first exercise was a simple C major scale (not improvised); in the second exercise, they were asked to improvise on the C major scale (using only quarter notes and in time with a metronome); in the third exercise, they played a blues melody that they had all memorized in advance (not improvised); and for the fourth, they were asked to improvise their own tune.

To figure out which areas of the brain are unique to improvisation, you’d want to see which brain areas were active only for the second and fourth exercises.  So the researchers “subtracted” the images while the brain was not improvising, from the brain images during improvisation–leaving only the areas that were different during improvisation.  In both of the improvised activities, there was a particular region that slowed down during improvisation: the dorsolateral prefrontal cortex.  This area is associated with planned actions and self-censoring.  The researchers hypothesized that lower activity in this area should be associated with lower inhibitions.

And, there was another brain region that showed increased activity: the medial prefrontal cortex, an area associated with self-expression.

What’s perhaps most important about this research is that these findings aren’t unique to jazz pianists.  The researchers point out that the same brain patterns should be found in any improvised behavior, including everyday activities like telling a story for the first time, or improvising your way through the neighborhoods to get around a traffic jam.  The key is a combination of reduced inhibition and heightened self-expression.

Feb. 27 issue of the Public Library of Science (PLoS) One.

The Neuroscience of Creativity

I just returned from speaking at a workshop hosted by the National Science Foundation headquarters in Arlington, Virginia. I know everyone loves to bash government bureaucracy, but the NSF is a quality organization and I’m always impressed with everything they do. This workshop was no different, with the title “Art, Creativity, and Learning”. The mission our group of experts faced: to prepare a list of important research questions for the future, and to advise the NSF on what types of research should be funded in the next few years.

The event was organized by Christopher Tyler of the Smith-Kettlewell Institute in San Francisco, and neuroscience research was a constant theme–what does the brain look like when it’s being creative?  Or when it’s listening to music?  Or looking at a painting?  The other constant theme was, when we participate in the arts or in creative pursuits, do we learn things that can make us smarter in general?  For example, everyone seems to believe that playing music makes you better at math.  But, surprisingly, there’s no solid evidence that’s true.  We proposed several research projects that could help us to understand what’s uniquely valuable about the arts.

For me, the high points of the conference were presentations by Ellen WInner of Boston College, perhaps the leading scholar asking questions about the arts, development, and learning; and Dan Levitin, a neuroscientist and author of the best seller This is Your Brain on Music.

I wish I could report some surprising new answers, but our goal was to ask the big unanswered questions, and we did a good job of that: Does participating in the arts give you any increase in general mental ability that transfers to others domains?  If you use dance, music, or painting in math or science class, does it help people learn math or science better?  (This is a common belief that has no solid research support.)  I personally love the arts and I want them to remain in the curriculum.  But, as a scientist, I want to be able to argue for the arts using solid data and research findings, not just wishful thinking.