Some scientists turning away from brain scans
NEWYORK >> Brain scans offer a tantalizing glimpse into the mind’s mysteries, promising an almost Xray-like vision into how we feel pain, interpret faces and wiggle fingers.
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.
With so many questions being raised, some researchers are acknowledging the scans’ limitations and working to overcome them or simply turning to other tests.
Earlier this year, Duke Universit y resea rcher Annchen Knodt’s lab published the latest paper challenging the reliability of common brain scan projects, based on about 60 studies of the past decade including her own.
Watching brains
The research being reexamined relies on a technique called functional magnetic resonance imaging, or fMRI.
Using large magnets, the scans detect where oxygenated blood rushes to when someone does an activity — such as memorizing a list of words or touching fingertips together — allowing scientists to indirectly measure brain activity.
When the technology debuted in the early 1990s, it opened a seemingly revolutionary window into the human brain.
Other previous imaging techniques tracked brain activity through electrodes placed on the skull or radioactive tracers injected into the bloodstream. In comparison, fMRI seemed like a fast, high-resolution and non-invasive alternative.
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.
Questions emerge
In 2009, a group of scientists investigated papers that had linked individual differences in brain activity to various personality types. They found many used a type of analysis that reported only the strongest correlations, leading to potentially coincidental conclusions. A “disturbingly large” amount of fMRI research on emotion and persona lit y relied on these “seriously defective research methods,” the group wrote.
Later that year, another pair of researchers demonstrated that the raw results of imaging scans — without the proper statistical corrections — could detect brain activity in a dead Atlantic salmon. Four years ago, another group of scientists claimed a different common statistical error had led thousands of fMRI projects astray.