+ fMRI Scans: How Much Do They Really Tell Us?

other topics: click a “category” or use search box

An article by Jonah Lehrer in the Boston Globe suggests that we’re looking for too much from fMRI brain scans.  The brain scan image has become a staple of popular culture.  We’ve allowed ourselves to believe that the black box of the mind has been flung wide open.

According to Kelly Joyce, a sociologist at the College of William and Mary, “These images get people excited in a way that other research just doesn’t.  The pictures have tremendous authority, not only among scientists but among people who might just glance at a brain scan picture in a newspaper.”

In recent weeks several high-profile papers have opened a fierce debate over whether these images are being widely misused.  Eminent researchers in the field have taken issue with the metaphors typically used to describe the images, such as “transparent brain.”

What the fMRI scans excel at is measuring certain types of brain activity.  But they are effectively blind when it comes to the detection of more subtle aspects of cognition, and these pictures that seem so precise are often “deeply skewed snapshots” of mental activity.

One of the most common uses of brain scanning devices is to take a complex psychological phenomenon and pin it to a particular bit of cortex.   These interpretations are being criticized as a potentially serious oversimplifications of how the brain works.

The critics stress the interconnectivity of the brain: virtually every thought and feeling emerges from the crosstalk of different areas spread across the cortex.  “If fMRI is a window into the soul, the glass is very, very dirty,” according to Lehrer.

Nikos Logothetis, director of the Max Planck Institute for Biological Cybernetics in Germany, says “Too many of these experiments are being done by people who unfortunately don’t really understand what the technology can and cannot do.  You can’t just put people in a scanner and ask them whatever question you want.  Many of these papers are such oversimplifications of what’s happening in the brain as to be worthless.”

He points out that the critical flaw of such studies is that they neglect the vast interconnectivity of the brain.  How a voter feels about a politician is almost certainly the result of numerous interacting brain regions, and can’t easily be reduced to the activity of a single area.

Large swaths of the cortex are involved in almost every aspect of cognition.  Even a mind at rest exhibits widespread neural activity.  So the typical fMRI image, with its bright spots of localized color, can be deceptive.

“Unfortunately, these pretty pictures hide the susage factory,” says Geoffrey K Aguirre, professor of neurology at the University of Pennsylvania.

Logothetis and other scientists believe that brain scanners are best used in conjunction with other experimental tools, such as those that measure brain waves or the electrical activity of individual neurons.  “The only way to really know what the brain is doing is to look at the brain in a variety of different ways,” he says.

sole source: Jonah Lehrer’s article in the Boston Globe on 8/17/08.  www.boston.com Lehrer is an editor at large for ‘Seed’ magazine, writes a blog called “The Frontal Cortex,” and his book “Proust Was a Neuroscientist,”  (Mariner Books) is now available in paper [ISBN 978-0-547-08590-6].

tutoring in Columbus OH:   Adrienne Edwards   614-579-6021   or email  aedwardstutor@columbus.rr.com


Comments are closed.