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Medical tablet displaying cerebral activity
Medical tablet displaying cerebral activity

Why Are Some Scientists Turning Away From Brain Scans?

Sometimes, brain scans just sound like popular opinion. What's wrong?

Brain scans have brought us many benefits, including the discovery that people (or rats for that matter) can function normally without most of their brain. Without such scans, there was no way to be sure.

But, as with any technology, there are problems:

Studies of brain images have suggested that Republicans and Democrats have visibly different thinking, that overweight adults have stronger responses to pictures of food and that it’s possible to predict a sober person’s likelihood of relapse.

But such buzzy findings are coming under growing scrutiny as scientists grapple with the fact that some brain scan research doesn’t seem to hold up.

Such studies have been criticized for relying on too few subjects and for incorrectly analyzing or interpreting data. Researchers have also realized a person’s brain scan results can differ from day to day — even under identical conditions — casting a doubt on how to document consistent patterns.

Marion Renault, “Why are some scientists turning away from brain scans?” at AP

Reality check: Truly significant findings from neuroscience have come, not from the pursuit of questions such as whether Republicans “think” differently from Democrats, but from situations where there was no reason to suspect anything unusual about a person—until a brain scan of some type was ordered. Here’s one story from 2006:

More than 20 years ago the campus doctor at Sheffield University was treating a student of mathematics for a minor ailment. The student was bright, having an IQ of 126. The doctor noticed that the student’s head seemed a little larger than normal and he referred him to Dr Lorber for further examination.

Dr Lorber examined the boy’s head by Cat-scan to discover that the student had virtually no brain. The normal brain consists of two hemispheres that fill the cranial cavity, some 4.5cm deep. This student had a layer of cerebral tissue less than 1mm deep covering the top of his spinal column. The student had a condition called hydrocephalus in which the cerebrospinal fluid (clear colourless fluid in the spaces in and around the spinal cord and the brain) becomes dammed up in the brain instead of circulating around the brain and spinal cord.

William Reville, “Remarkable story of maths genius who had almost no brain” at Irish Times

The research that is coming under question involves fMRI (detecting the changes in blood oxygenation and flow that occur in response to neural activity), not CATscans (a combination of X-rays and a computer) as in the story from Ireland above. fMRI may be more subject to misinterpretation or misuse simply because it is measuring a more fluid situation.

One Duke University lab ended up discrediting much of its own fMRI research in an open access paper: “The ability to identify meaningful biomarkers is limited by measurement reliability; unreliable measures are unsuitable for predicting clinical outcomes.”

As AP tells us,

A flurry of papers and press coverage followed the technique’s invention, pointing to parts of the brain that “light up” when we fall in love, feel pain, gamble or make difficult decisions. But as years passed, troubling evidence began to surface that challenged some of those findings.

“It’s a very powerful thing to show a picture of the brain. It lends itself to abuse, in some ways,” said Damian Stanley, a brain scientist at Adelphi University. “People eat them up, things get overblown. Somewhere in there, we lost the nuance.”

Marion Renault, “Why are some scientists turning away from brain scans?” at AP

So yes, fMRI is still useful for neurologists mapping brain disorders like Alzheimer syndrome. But a disease like Alzheimer syndrome, when it sets in seriously, is not a matter of preference or opinion. The other stuff should be treated as popular entertainment.

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Why Are Some Scientists Turning Away From Brain Scans?