DYSFUNCTIONAL MIRROR-NEURON SYSTEM MIGHT UNDERLIE EMPATHY DEFICITS IN AUTISM

"In a small study of autistic children, severe mirror-neuron system dysfunction correlated with high impaired ability to imitate facial expressions or empathize with others".

The researchers, with lead author Stephany Cox, PhD, from the David Geffen School of Medicine, University of California, Los Angeles, determined this using functional magnetic resonance imaging (fMRI) to examine activity in the mirroring regions of the brain in 12 children with autism.

Their findings were presented at 6th International Meeting for Autism Research in Seattle, Washington.

This adds to a series of 8 papers published with convergent findings about mirror neurons, team member Mirella Dapretto, PhD, told Medscape. She added that researchers and clinicians should now focus on developing ways to boost the activities of mirror neurons in individuals with developmental problems. "Clearly, it's not like the neurons are dead and not firing at all," she said. "The system is there, it is just not functioning to the full extent that it should, to help out in social interactions."

She explained that mirror neurons were first discovered by scientists at the University of Parma in Italy who were studying single neurons in monkeys' brains. Mirror neurons that fired when a monkey was performing a certain action also fired when a monkey simply observed another monkey performing the same action. "Basically, what these mirror neurons can do for monkeys and humans is allow you to 'translate' others' actions . . . to get a good 'read' of what people are doing," Dr. Dapretto said, adding that when people watch other people talking and moving, neurons are firing in their brains that would be firing if they were doing these actions.

The team aimed to investigate the implications of an impaired mirror-neuron system on imitation and empathy in children with autism spectrum disorders.

They looked at the brain activity in a group of 12 high-functioning children with autism spectrum disorders (mean age, 12.3; mean IQ, 106) who underwent fMRI while they viewed and imitated faces depicting several emotions such as anger, fear, happiness, or sadness.

In the first part of the study, the children's ability to imitate facial expressions was measured using scores from the Autism Diagnostic Interview-Revised (ADI-R) communication subscale. Facial expressions that people make when they interact with other people are very meaningful in social interactions, noted Dr. Dapretto.

In the second part of the study, the children's empathetic behavior was assessed using a validated modified version of the Interpersonal Reactivity Index (IRI), which assesses 4 distinct facets of empathy.

Low Mirror-Neuron Activity, High Impairment

The researchers found that, after they controlled for IQ, poor ADI-R scores were linked with low activity in the right inferior frontal gyrus and to a lesser extent the insula and amygdala (2 brain regions previously associated with empathy). They also found that poor scores on the IRI correlated with low mirroring activity in these brain regions.

The correlations were "very strong," said Dr. Dapretto, adding that the more impaired the children were, the less activity they had in their mirror-neuron system, and, conversely, the less impaired they were, the more activity they had. "The fact that we found this relationship says that the system is there; it is just not functioning to the full extent that it should," she noted.

The group writes that their findings provide additional evidence that a dysfunctional mirror-neuron system might underlie impairments that are characteristic of autism. "Importantly, these results further indicate that mirror-neuron system abnormalities may also negatively affect imitative behavior, leading to a cascade of negative consequences for the development of key aspects of social cognition and behavior," they conclude.

6th International Meeting for Autism Research: Oral Session 07.2. May 3 '" 5, 2007.

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