Dissociation of mirroring and mentalising systems in autism.

The role of mirror neuron systems and mentalising systems in causing poor social and communication skills in individuals with autistic spectrum conditions is hotly debated. We studied 18 adults with autistic spectrum conditions in comparison to 19 age and IQ matched typical individuals. Behavioural assessments revealed difficulties in mental state attribution and action comprehension in the autism sample. We examined brain responses when observing rational and irrational hand actions, because these actions engage mirror and mentalising components of the social brain respectively. Both typical and autistic participants activated the left anterior intraparietal sulcus component of the mirror system when viewing hand actions compared to moving shapes. The typical but not autistic participants activated the posterior mid cingulate cortex/supplementary motor area and bilateral fusiform cortex when viewing hand actions. When viewing irrational hand actions, the medial prefrontal cortex of typical participants deactivated but this region did not distinguish the different stimuli in autistic participants. These results suggest that parietal mirror regions function normally in autism, while differences in action understanding could be due to abnormal function of cingulate, fusiform and medial prefrontal regions. Thus, brain regions associated with mirroring and mentalising functions are differentially affected in autistic spectrum conditions.