Mirror neurons in autistic children abnormal

Dec 5 2005

Researchers have found, through the use of functional MRI scans that looked at the brain, that there is an abnormal activity in the some of the neurons in the brains of autistic children.

These neurons help individuals imitate others and this deficit may underlie some of the social shortcomings found in autism.

The U.S. researchers say their study found autistic children had less brain activation in an area involved in understanding others' state of mind.

Apparently the degree of activation of the 'mirror neurons' housed in this area correlated with measures of social impairment, and it appears the lower the activation, the stronger the impairment the children had.

Autism can profoundly affect a person's ability to communicate with others and to respond appropriately to environmental cues.

It has been seen in animals, that similar neurons fire both when the animal observes another performing an act, and when they perform the same act themselves.

Dr Mirella Dapretto and colleagues from the University of California, Los Angeles, studied the brain activity patterns of 10 children with autism as the children either imitated facial gestures or passively watched facial gestures; the facial gestures reflected emotions including fear, anger, sadness and happiness.

It seems the idea of linking mirror neurons with the social deficit in autism is quite reasonable.

In their study the researchers compared these outcomes with those of 10 children of the same age and IQ but who did not have autism.

It appeared that although the autistic children were able to perform the task, they had lower activation in a brain area containing mirror neurons, both when watching and imitating facial gestures, compared to the other children.

The children with autism also had reduced activity in emotional centres of the brain.

Researcher Dr Dapretto says their findings suggest that a dysfunctional mirror neuron system may underlie the social deficits observed in autism, and support recent data for a mirror neuron theory of autism.

Dapretto says the results are exciting because they may finally explain all core symptoms of the disorder.

The researchers believe that children with autism must use other parts of the brain in order to be able to perform the task that they tested.

For example, the autistic children might pay more attention to visual and motor clues without experiencing the internally felt emotional significance of the imitated facial expression.

Professor Michael Rutter from the Institute of Psychiatry, London, says that the mirror neurons are interesting and there is already good research in animals in looking at how they function, which makes linking mirror neurons with the social deficit in autism quite reasonable.

But he does also say that more research into the brain systems that might be involved is needed.

The National Autistic Society says they welcome research into all areas which may throw light on the causes behind autism, and agree that there is strong evidence to suggest that autism may be caused by a variety of physical factors, all of which affect brain development and is not attributable to emotional deprivation or the way a person has been brought up.

The study is published in the journal Nature Neuroscience.