MRI's: The new phrenology?
What can brain scans really tell us about ourselves?
Posted Feb 01, 2011
Austrian physician Franz Joseph Gall sought to understand the mind of murderers and other criminals by feeling the outside of their skulls. This practice, which he first used in 1796, later came to be called phrenology. Now largely discredited, it turned out that neither Gall nor anyone could systematically link the bumps and lumps on the head to any regular patterns of behavior, criminal or otherwise.
Psychologists no longer need to use scalp massages as diagnostic tools. They can now look at what's happening inside the skull using one of several types of brain scans. The most successful of these methods is the magnetic resonance imaging (MRI) brain scan, particularly the functional MRI (or fMRI). Patients are placed within a scanning device that causes nuclei within the cells to produce a rotating magnetic field detected by the scanner. The fMRI provides a picture almost in real time of how a person's brain is reacting to particular stimuli. For example, a participant may be shown several photographs depicting emotional stimuli. If certain parts of the brain become more active when the person is viewing these stimuli, the researchers conclude that it's in those brain regions that emotional stimuli are registered. The brain's "reward center," for example, becomes active while participants view and react to attractive sex objects, food, or money.
Brain scans are clearly an advance over phrenology, but they also have their limitations. The biggest problem is that we can't precisely localize specific brain functions. Though it's possible to speak in general terms of a "reward center," it's not possible to pin down the exact nature of which reward goes with which set of neurons. Neurosurgeons discovered many decades ago that there is redundancy in the brain and that there are substantial variations from person to person. In fact, during brain surgery, it is common for physicians to keep the patient conscious so that they can avoid destroying particular language, memory, or visual processing centers. We're not like auto engines or computers, all put together in exactly the same way. Genetics, experiences, and the combination of the two alter the development of the brain over our lifetimes.
You'd never know about these limitations by reading the headlines in many popular science websites. Researchers boast that they've localized brain structures responsible for everything from anger, love, rage, jealousy, and criminality (Gall would be pleased). In fact, there are brain centers responsible for chess expertise, shogi prowess, and the joy of seeing a baby's smile, according to these sources.
Time for a reality check. fMRI's can tell us that clumps of certain neurons (nerve cells) become active when certain other things happen. This activity is represented the dark red patches shown in this figure. Blue patches illustrate low levels of activity. You'd swear that your brain becomes an amazing technicolor dream coat in response to the activity of your neurons. It might surprise you to learn, then, that the brain is not in fact "lighting up" (as researchers claim). The colors are artificially and arbitrarily added using computer technology. It's like colorizing a 1930s movie originally recorded in black and white, Red is used to show more activity because it stands out; the blue seems a lot cooler. Don't be seduced by these pyrotechnics. What you should look for instead is statistical evidence. Unfortunately, this evidence isn't provided in a very user-friendly form, if it is provided at all.
The "wow" factor is only part of the story. According to brain researcher Nelson Cowan, "the ability to do brain imaging makes grant proposals stronger." My question is this-- shouldn't it be the science that makes a grant proposal stronger? Whatever happened to a good hypothesis? Furthermore, exactly what is explained by showing what the brain does under certain conditions? We need to know why the brain is reacting as it does. A brain region becomes more active due to something we do that triggers its reactions. It's our thoughts that control our brain's most interesting reactions, not the other way around.
By now you're thinking that I must be a troglodyte thoroughly opposed to advances in science, technology, and diagnosis. I can assure you that I love technology as much as the next person, and when it comes to science, I am uncompromising in making sure that my own writing uses only the latest findings. If I could, I would cite an article written in 2013 right now, in early 2011. However, I've gotten increasingly concerned about the weirdness of some of this wired science. As a consumer of brain research, I just want the truth. I don't want sound bites intended to bring the researcher more federal or (even worse) private funding intended to serve the researcher's, the institution's, or the company's self-interests. Science needs to be responsibly reported.
Now that brain scan reporting has become part of the steady newsfeed in everything from your local news sources to popular science websites, you might consider asking yourself these questions the next time you read about yet another apparent brain-behavior connection:
1. Was the article actually published? Although publication in a scientific journal doesn't guarantee that you can trust the results, a published article still has a greater likelihood of being reviewed and hence subjected to scrutiny through the so-called (and unfortunately termed) "peer review" process.
2. Are there unaccounted for factors that weren't tested? That old "correlation does not equal to causation" mantra comes in handy here. Look for other possible causes than the ones cited by the authors. High-tech methods don't guarantee high-quality findings.
3. Did the researchers over-reach? Researchers often base their studies on one type of participant and then try to claim that their findings apply to another type of participant. We may feel like we're all "rats in a cage," but studies based only on lab animals that attempt to explain human behavior may be making one too many logical leaps.
4. Were statistical analyses actually conducted? You may have a hard time getting the answer to this question without reading the article, but you can find clues in the wording that science writers use, such as when they use terms such as "trend," or "tend to," or "seem to," and so on.
5. Would you give Aunt Polly the advice from this study? This question is particularly important for studies that claim to have quick and easy solutions to thorny diagnostic problems. Look carefully and thoroughly at the scientific evidence and particularly try to get information from reputable scientific sources. Even university websites may not have the best answers because they may be exaggerating the conclusions to to promote their own research funding agendas.
Research on the human brain is proceeding at a phenomenal pace, and it's bound to produce important findings about ourselves and the organ inside our skulls. Before you find your brain turning red after reading the newest study's results add in a healthy dose of skepticism.
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Copyright Susan Krauss Whitbourne, Ph.D. 2010