a piece in Nature today
, a major line of research about autism might be seriously flawed:
One of the most popular and widely accepted theories on the cause of autism spectrum disorders attributes the condition to disrupted connectivity between different regions of the brain.
This 'connectivity hypothesis' claims that the social and cognitive abnormalities in people with autism can be explained by a dearth of connections between distant regions of the brain. Some flavours of this theory also predict more connections between nearby brain regions.
Recent studies, however, have found that when a person moves their head while undergoing functional magnetic resonance imaging (fMRI) - a method that maps how different neuroanatomical structures of the brain interact in real time, its functional connectivity - it looks like the neural activity observed in autism. That's a sobering discovery...
So the characteristic pattern of "abnormal connectivity" in autism might not be real: it might just reflect the fact that people with autism move around more during the scan.
A sobering idea, indeed... but not an entirely new one. I suggested it over a year ago:
Head motion affects estimates of functional connectivity. The more motion, the weaker the measured connectivity in long-range networks, while shorter range connections were stronger... Disconcertingly, this is exactly what's been
to happen in autism (although in fairness,
not allthe evidence for this comes from fMRI). This clearly doesn't prove that the autism studies are all dodgy, but it's an issue. People with autism, and people with almost any mental or physical disorder, on average tend to move more than healthy controls.
Ben Deen, and Kevin Pelphrey (2012). Perspective: Brain scans need a rethink Nature
