Brain Scans "Read Minds" With Surprising Accuracy

Brian Handwerk
for National Geographic News
February 18, 2009

Could MRI someday stand for Mind Reading Imagery?

Functional magnetic resonance imaging (fMRI) technology can tell what people are thinking with startling accuracy, a new study found.

Volunteers were shown two different patterns, then asked to picture one or the other.

Using fMRI brain scans, the researchers predicted—at better than 80 percent—which of the two patterns each person was actively holding in memory 11 seconds later.

By measuring blood flow, fMRI images reveal which groups of neurons are active.

Some of the visual cortex's neurons are associated more with vertical visual patterns, and others with horizontal or angled patterns, explained neuroscientist Frank Tong of Vanderbilt University, who led the study.

That distinction allowed the team to predict which pattern volunteers had in mind, even well after the images were removed from the screen.

(Related: "'Brain Reading' Device Can Predict What People See.")

"Here we find that the visual parts of the brain, those involved in seeing, are also involved in actively remembering something," Tong said.

"That's not been shown before. What might be happening is that you're maintaining a representation of what you just saw by very faint levels of activity in the visual cortex."

Tong's research was published online today in the journal Nature.

"Pretty Convincing Evidence"

Research on an area of the primary visual cortex called V1 suggests the region performs complex functions, like focusing one's attention, independently of other brain regions, according to Henry Rusinek, a radiologist at New York University School of Medicine.

The primary visual cortex receives the visual signal from the eyes and then sends these signals to a host of higher visual areas.

Rusinek called the study "pretty convincing evidence that [the] V1 network—only a couple of neurons distant from the eye—has a short-term memory."




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