Vilayanur S. Ramachandran and Lindsay M. Oberman recently published an article in Scientific American ("Broken Mirrors: A Theory of Autism") in which they discuss the possibility that mirror neuron dysfunction and a distorted salience landscape may be implicated is autism disorders. They conclude:

Our two candidate theories for explaining the symptoms of autism--mirror neuron dysfunction and distorted salience landscape--are not necessarily contradictory. It is possible that the same event that distorts a child's salience landscape--the scrambled connections between the limbic system and the rest of the brain--also damages the mirror neurons. Alternatively, the altered limbic connections could be a side effect of the same genes that trigger the dysfunctions in the mirror neuron system. Further experiments are needed to rigorously test these conjectures. The ultimate cause of autism remains to be discovered. In the meantime, our speculations may provide a useful framework for future research.

Both hypotheses are interesting. I particularly like the suggestion that genes malfunctioning early in the developmental schedule might trigger a cascade of neural dysfunctions that lead to the symptoms of autism. Identifying the array of dysfunctioning neural mechanisms is an essential steps in tracing back the root causes of autism and related disorders.

Mixing Memory posts a discussion of an unpublished paper on autism and television ("Does Televsion Cause Autism?"). I've heard of a proposed link between increased television viewing and increased incidence of autism, but I haven't pursued it. But someone is looking into it, apparently. Here's the MM overview:

One of the explanations for the increase in the incidence of autism spectrum disorders over the last few decades is that the genetic predisposition requires some sort of environmental trigger, and that the prevalence of this trigger has increased during the period that has seen an increased incidence of autism. Waldeman et al. hypothesize that television is that trigger.

Why do they pick television? They list four reasons, which, when taken together, suggest television as a candidate for the environmental trigger. The reasons include the fact that television viewing has increased among children over the last few decades (due largely to increased access to cable television), the connection between television watching and ADHD, and behaviors consistent with television watching among "at risk" infants. That's only three, right? I saved the last for a sentence of its own, because once again, it's just odd: autism rates are extremely low among the Amish, who don't watch any TV at all (you have to have electricity to watch TV).

But, of course, lot's of things are correlated with the increased incidence of autism. We really need some story about how TV viewing would be or could be a trigger for the disorder. Increased TV viewing is also part of the contemporary onslaught of a more complex and highly stimulated lifestyle that developing children experience. I've seen nothing that isolates TV from all the other sources of overstimulation we might consider. (And even my suggestion the overstimulation mght be involved is only a hunch!)

UPDATE 10/21/06: The TV/Autism article ("A Bizarre Study") was discussed in Time this week with the appropriate skepticism.

Could there be something to this strange piece of statistical derring-do? It's not impossible, but it would take a lot more research to tease out its true significance. Meanwhile, it's hard to say just what these correlations measure. "You have to be very definitive about what you are looking at," says Vanderbilt University geneticist Pat Levitt. "How do you know, for instance, that it's not mold or mildew in the counties that have a lot of rain?" How do you know, for that matter, that as counties get more cable access, they don't also get more pediatricians scanning for autism? Easterbrook, though intrigued by the study, concedes that it could be indoor air quality rather than television that has a bearing on the development of autism. On a more biological level there's this problem, says Drexel Univeristy epidemiologist Craig Newschaffer: "They ignore the reasonable body of evidence that suggest that the pathologic process behind autism probably starts in utero" ? i.e., long before a baby is born.

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