Individuals with autism find it difficult to regulate their emotions and interact with others. There is some evidence that the severity of these difficulties is influenced by higher serotonin levels in the brain. Kevin Pelphrey and his colleagues at Yale University plan to use a specialized brain imaging technique to examine the relationship between variants in the serotonin transporter gene and behavioral difficulties in individuals with autism.

The technique, called functional magnetic resonance imaging, detects neuronal activity and can home in on various regions of the brain. The researchers plan to record brain activity in a group of 5-year-old children — half with autism, and half typically developing controls — during laboratory tasks that test their ability to understand the intentions of others and cope with frustration. The development of these social functions will be tracked in the group over a two-year period.

The researchers also plan to sequence the serotonin transporter gene in each child to identify those who have the ‘short’ variant, which lowers the gene’s expression and has been linked to problems with social interaction in children with autism. The genotypes of the children will be related to information on the nature, severity and development of social difficulties gathered from the brain activity studies. For comparison with mature brains, the researchers also plan to repeat the brain activity and genetic studies in a group of 25- to 30-year-old adults with autism and healthy controls. The findings may explain how the neural circuitry involved in social and emotional behavior develops over time in normal children, how this process differs in children who have autism, and whether it is affected by genetic variation.