The brain regions critical in allowing us to understand another person's thoughts and feelings have been revealed by a new imaging study.
People with autism lack this "Theory of Mind", and show abnormalities in these three key brain areas, says Francesca Happe of the Institute of Psychiatry in London.
Pinpointing brain dysfunctions involved in autism should lead to a better understanding of the causes of the disease. It should also help to develop accurate methods of evaluating autism treatments and to investigate whether animals have a Theory of Mind, she says.
Happe used fMRI (functional Magnetic Resonance Imaging) to study groups of adults with a mild form of autism called Asperger's Syndrome and healthy people while they completed a series of tests. "We gave them tasks where they have to work out what someone is thinking or feeling - such as a story about an incident involving a misunderstanding," she says.
Happe found that during these tasks, activity increased in three regions of the brains of healthy people: the paracingulate cortex towards the front of the brain, parts of the temporal poles, and a region called the tempoparietal junction. But the scans of patients with Asperger's revealed a very different picture.
"These individuals use different brain areas to solve the problems - it seems that they are using sheer intelligence rather than an innate social intelligence," Happe told New Scientist.
"For healthy people, mind reading is an innate and effortless ability, even though it's in fact very complicated. For people with autism, it's like doing mental arithmetic."
In the healthy patients, the increase in blood flow in the three key regions directly correlated with the time the patient talked about mental states, says Happe. Scans during similar tasks, such as talking about the thoughts and intentions of characters in newspaper cartoons, revealed similar results.
But activity in these three areas did not increase in the Asperger's patients while they completed the same tasks. "Instead they activate other areas of the frontal lobes. This fits in with the idea that they solve social problems through general intelligence," she says.
Other studies of Asperger's patients have found a lower density of grey matter in the region of the paracingulate cortex, says Happe. "It seems we're now closing in on the structural abnormalities involved in autism."
Significant differences between activity in the brains of healthy people mean that scans are unlikely to be useful for diagnosing autism, Happe says. But some researchers have attempted with limited success to teach children with autism a Theory of Mind, and scans could be used to evaluate whether there are any associated brain changes in the key areas, she says.
Some researchers have suggested that chimpanzees also possess a Theory of Mind. Brain scans could be used to probe these claims, Happe says.
This research was presented at the British Psychological Society's Centenary Conference in Glasgow, UK.
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