EBD Blog

By studying differences in how their brains function during efforts to imitate emotions, Mirella Dapretto and colleagues have discovered that adolescents with high functioning autism (HFA) have no activity in the part of the brain that is employed in many important activities including imitation and language production. The HFA participants can mimic others’ facial expressions, but when they do so, the inferior frontal gyrus (IFG) pars opercularis is not activated, although it is activated in non-disabled peers.

Notably, activity in this area was inversely related to symptom severity in the social domain, suggesting that a dysfunctional ‘mirror neuron system’ may underlie the social deficits observed in autism.

The findings of the study by Ms. Depretto and colleagues align with other findings and theories about autism. The theory about dysfunction in the mirror neuron system in autism is gaining momentum. For example, another group (first author: Lindsay Oberman) has shown that brain waves (mu) that are usually muted when people see, do, or think about performing actions were not muted in individuals with HFA.

As expected, mu wave suppression was recorded in the control subjects both when they moved and when they watched another human move. In other words, their mirror neuron systems acted normally. The mirror neurons of the subjects with autism spectrum disorders, however, responded anomalously – only to their own movement.

The brain region called the inferior frontal gyrus (IFG) pars opercularis has been the focus of studies recently. Scientists have been able to localize functions with increasing precision. Istvan Molnar-Szakacs and colleagues (including Marco Iacoboni, an author on the fMRI autism study, too) aggregated fMRI studies of the IFG and were able to segregate functions in the pars opercularis:

For imitation we found two peaks of activation in the pars opercularis, one in its dorsal sector and the other in its ventral sector. The dorsal sector of the pars opercularis was also activated during action observation, whereas the ventral sector was not. In addition, the pars triangularis was activated during action observation but not during imitation.

I think imitation is terribly critical in learning, making these findings really noteworthy. That the behavioral neurologists are coming up with these sorts of findings is very exciting. I wonder if we will soon see studies parallel to those in reading showing that promoting higher levels of imitation changes the fMRI results. Meanwhile, note that most of these studies are with HFA individuals.

Links to

• The abstract for the study of autism andunderstanding emotions in others
• The abstract for the study of functional segregation
• The news release about the study of EEG activity during imitation and observation.
• Coverage of the Dapretto et al. study by John Bohanon in Science.