Is the search for the cause of autism a hall of mirrors?

The ‘broken mirror’ theory is a popular theory in autism research but it seems that all is not as it appears as  a high-profile paper in Neuron reports that people with autism do not have trouble understanding others’ actions or intentions or even imitating those actions1.

Monkey see, monkey do.

Mirror neurons were discovered by neuroscientists in the 90’s while recording the activity of nerve cells or neurons in the brains of monkeys where it was noticed that certain neurons remain silent when the monkeys observe other monkeys performing the same action2 – hence the name mirror neuron.

Scientists have extended this finding in the human brain to show that nerve activity in mirror neurons also remain silent when observing another person performing an action and/or expressing an emotion3 and this silence is not observed in people with autism – hence the ‘broken mirror’ theory of autism.

Getting it “write”

However in a 2007 study 25 children with autism were compared with non-autistic ‘controls’ on several goal-directed imitation (mirror) tasks shown to activate regions of the brain believed to contain mirror neurons4. In one experiment, the children sat at a table and were asked to copy an adult as she touched a pattern of dots on the tabletop. The study showed that normal healthy children make typical errors on this task – for instance copying the adult’s goal but using the wrong hand. The children with autism made exactly the same error, meaning that they selectively imitate the goal of the action and both groups show the same pattern of brain activity in brain regions believed to contain mirror neurons. These findings suggest that there is nothing wrong with basic mirror systems in people with autism.

Hall of mirrors

Part of the problem may be that the ‘broken mirror’ theory relies on several unsupported assumptions: that the mirror system is responsible for understanding goals and imitation, that goal understanding and imitation are abnormal in autism, and that these deficits cause the social difficulties seen in autism.

It’s all about connections

One possible explanation is that the mirror neuron system itself could be normal in autism, but its projections, or the brain regions it is projecting to, could be abnormal instead.  Also, the mixed findings could be due to the broad spread of the autism spectrum disorders.


  1. Dinstein, al. Neuron 13, 461-469 (2010) PubMed
  2. Rizolatti G. et al. Brain Res. Cogn. Brain Res. 3, 131-141 (1996) PubMed
  3. CochinS. et al. Electroencephalogr. Clin. Neurophysiol. 107, 287-295 (1998) PubMed
  4. HamiltonA. F. et al. Neuropsychologia 45, 1859-1868 (2007) PubMed