The findings, published in the April issue of the Journal of Cognitive Neuroscience, are expected to have implications for the treatment of developmental disorders such as autism.
Led by Mark Sabbagh, the study is supported by a grant from the Natural Sciences and Engineering Research Council (NSERC). Also on the team, from the Queen's Psychology Department, are Margaret Moulson and Kate Harkness.
The study helps us understand the neural bases of everyday "theory of mind": our ability to explain behaviour in terms of mental states like intentions and desires. "What we're showing is that an important first step [in theory of mind] is being able to decode other people's mental states, and that this skill is carried out within a very specific neural pathway,"says Dr. Sabbagh.
The researchers used a technique called event-related potential.This involves fitting people with what looks like a hairnet containing 128 sponge electrodes that attach to their scalps and record electroencephalogram (EEG) signals. Images of eyes conveying different emotions (e.g. anger, sadness, embarrassment) are shown to the subjects, who are then asked to identify both the mental state and gender of the person in each picture, based solely on seeing that person's eyes.
By comparing the EEG signals associated with each response, the researchers identified two precise areas in the brain that were specifically activated when the participants made judgments about mental states: the medial temporal region and the orbital frontal cortex.
These "neural correlates" are already known to be associated with viewing emotional stimuli, such as a frightened face. Until now, however, there has been no evidence that their activation can be intentionally controlled.
"Our study shows that, not only will this brain activity happen when people passively react to an emotional stimulus, it also occurs when they actively search for mental state information," says Dr. Sabbagh.
Problems in "mental state decoding" are associated with developmental disorders such as autism. As a next step, the researchers plan to investigate whether autistic individuals have difficulty activating these two areas of the brain when making mental state judgments, Dr. Sabbagh explains.
"If problems in social interaction are related to brain circuitry, having a better understanding of that relationship will help us design both behavioural and other types of interventions to improve these individuals' social skills."
Nancy Dorrance, Queen's News & Media Services, 613.533.2869
Lorinda Peterson, Queen's News & Media Services, 613.533.3234
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Journal of Cognitive Neuroscience