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Spectrum: Autism Research News

Unconscious awareness of others’ thoughts shows in the brain

by  /  11 November 2013
THIS ARTICLE IS MORE THAN FIVE YEARS OLD

This article is more than five years old. Autism research — and science in general — is constantly evolving, so older articles may contain information or theories that have been reevaluated since their original publication date.

Keeping tabs: People track the beliefs of others even when their conscious attention is focused on something else.

People are unconsciously alert to what’s going on in the minds of others, and this activity can be traced to two specific regions of the brain, according to unpublished results presented Sunday at the 2013 Society for Neuroscience annual meeting in San Diego.

The ability to understand what others are thinking and feeling is known as theory of mind. Individuals with autism are thought to have trouble with this ability, particularly with unconsciously keeping tabs on others’ mental states, dubbed ‘implict theory of mind.’

In contrast, ‘explicit theory of mind’ involves consciously working out what others are thinking.

“The idea that these are separate networks is still very new,” says Paul Dux, professor of psychology at the University of Queensland in Australia, who led the new study.

Dux and his colleagues found that implicit and explicit theory of mind have different neural signatures.

They used magnetic resonance imaging (MRI) and tracked the eye movements of 18 healthy adults while they watched a movie featuring a classic theory of mind task. In the movie, an actor watches a ball being put into one of two boxes. After the actor leaves the room, a puppet either moves the ball to the other box or leaves the ball alone. Finally, the actor comes back into the room.

Eye-tracking during this test measures implicit theory of mind, a previous study by Dux’s group has shown: Toward the end of the movie, viewers look more at the box the actor believes the ball is in, even though when asked about the experience later they are not aware of having done so.

Conscious attention:

Dux and his colleagues also distracted study participants by asking them to focus on discriminating between high and low sounds that they heard while the movie played on a screen in front of them. Even when focusing their conscious attention elsewhere, the researchers found, people still look at the box where the actor will expect the ball to be.

“They’re moving their eyes to where the beliefs are,” Dux says.

The researchers analyzed regions of the brain activated when the movie shows the ball being moved to the second box, and those when the ball is not moved.

This separates brain activity in response to watching the movie from activity specifically involved in implicitly tracking others’ beliefs.

Two regions of the cerebral cortex, the precuneus and the left superior temporal sulcus, show greater activation when the ball is moved, suggesting that they are involved in implicit theory of mind. These areas also play a role in explicit theory of mind, but the latter involves a wider network in the frontal, temporal and parietal lobes of the brain.

“The right temporoparietal junction doesn’t seem to be involved” in implicit theory of mind, Dux adds. That’s surprising because this is the brain region most strongly implicated in theory of mind in general.

Dux says he would like to test brain activity during the implicit theory of mind task in individuals with autism.

In work published earlier this year, he showed that individuals with high-functioning autism do not show typical patterns of eye movement during this task.

“People with high-functioning autism have a real impairment in implicit theory of mind, but not explicit,” he says.

This jibes with a paradox that has emerged in past studies: Some people with high-functioning autism can pass theory of mind tests in the lab, even though they struggle with it in everyday life.

Eventually, Dux says, better understanding the subtleties of theory of mind deficits in autism could lead to ways to overcome them.

For more reports from the 2013 Society for Neuroscience annual meeting, please click here.