Mo over at Neurophilosophy:
MC: Autism is an umbrella term referring to numerous conditions. Can the broken mirror hypothesis account for all of them?
Ramachandran: Autism is characterized by a specific subset of symptoms. There may be three or four that are lumped together, but by and large it is one syndrome, as good a syndrome as any in neurology. It’s not like dyslexia, where there are half a dozen or a dozen types. With autism, people are debating whether high functioning and low functioning autistics should be lumped together or not. There’s a tendency to group them together rather than saying they’re distinct.
We have suggested that the mirror neuron system is deficient in autism, and there’s mixed evidence of that, but most groups support our view. [Marco] Iaconobi‘s group at UCLA did a brain imaging study showing that the mirror neuron system is deficient, but others claim that it’s normal. That may partly be based on the heterogeneity of autism. The mirror neuron system itself could be normal but its projections, or the regions it’s projecting to, could be abnormal. It’s still up in the air.
One of the things I say in my book [The Tell-Tale Brain] is that the mirror neuron system allows you to take an allocentric view of other peoples’ actions, to view the intentions to their actions. It may even be turning inwards and looking at one’s self from an allocentric perspective, so it may be partly contributing to self-awareness. In addition to an allocentric perceptual view, the same system then evolved into adopting an allocentric conceptual, or metaphorical, view – “I see your point of view”. This could have been an evolutionary step from perception to conception, but we don’t know exactly when than magic line was crossed.