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mirror neuron minutae revisited

Posted May 15 2010 12:00am
Regular readers of autism's gadfly will remember last year I wrote a piece about mirror neurons . I discussed the work of one of my idols, Marco Iacoboni and his wife Mirella Dapretto who have done work showing that certain areas of the brain that have been shown not only to be involved in motor responses but in the learning of motor responses and the firing when other people are doing them might be involved in the etiology of autism

Recently, a researcher named Ilan Dinstein along with several coauthors has published work refuting the mirror neuron hypothesis in autism . Though this is just one study, out of many replicated studies showing dysfunction in the mirror neuron systems. The media has picked this up and in some instances implied that it refutes the mirror neuron hypothesis of autism. It is Dinstein's contention that the previous mirror neuron studies in autism have not assessed for selectivity of cortical activity in mirror system areas for particular movements. For example a different set of mirror neurons may respond differently to a thumbs down movement seen and/or executed than a thumbs up movement. Their results showed that the autistic subjects had the same cortical responses during observation and execution of the movements. They observed repeated versus nonrepeated movements, showing that the autistics had the same responses as the controls on motor fatigue, i.e., the mirror neurons programmed for a certain type of movement getting used to the image of thumbs up, thumbs down or a hawaian hang loose hand sign. Dr. Dapretto's work, however, was a little different in that she observed reactions to various facial expressions. It is possible that hand movements are mediated differently than facial responses. In other studies Dinstein and colleagues assert that movement selectivity was not controlled for and this confounded the results.

Again, Dinstein's work has one of the same problems so rampant in autism research in that the current research techniques are not suitable for lower functioning autistics with IQ's of less than 100 due to movement in an MRI scanner and lack of compliance. The subjects were also older than those in Dapretto's work, average age of 27, whereas Dapretto used all children, so this might limit comparison. One possibility is that even if autism's etiology in higher functioning persons is due to mirror neuron dysfunction that they might develop compensatory functions in adulthood. Apparently the autistics and the controls were not matched on IQ. Also they were not matched on gender. All of the autistic subjects were male, half the controls female, and men and women certainly have different brain physiologies and possibly responses.

To summarize Dinstein and his coauthors argue that the entire mirror neuron areas in the frontal and parietal lobes were measured in other studies (If I am not misunderstanding this, anyone can correct me in comments if i am wrong and I will edit the post) They measured specific brain areas as well as the habituation of repeated exposure to these specific which they claim is necessary to show whether or not mirror neurons are an issue in autism. The results, they claim suggest that there is no mirror neuron impairment in autism. It seemed to me that Dinstein was implying that artifacts could have contributed to some of the positive findings of mirror neurons in autism, such as autistics imitating the movement more slowly than healthy controls. Also, the fact that they did not select for areas of particular movements in the prior studies suggest that other areas than mirror neurons could have been recruited such as visual areas and working memory. But Iacoboni is apparently standing by his work and stating that the results don’t prove what the researchers say they do, because their trick of focusing on fatigued neurons will miss some mirror neurons. Furthermore, he says, simply testing brain activity involved in identifying and mimicking movements does not accurately model the brain activity underlying complex social tasks.

On a more personal note, when I read Dinstein's study, it elicited an emotional response for me. I don't know whether to believe Iacaboni/Dapretto or Dinstein. Of course, if I am not mistaken there is a lot of evidence in the literature that suggests that mirror neurons may play an etiologic role in autism and Dr. Dinstein's study has not yet been replicated by an independent investigator. For almost all of my life I have wanted to know what caused my problems. Of course there were the various theories I have heard throughout my life. I first heard in the 1960s it was in part because I saw my sister naked when she was born nearly 3 years after I was and I noticed she did not have something I had and I was worried mine would be cut off. This was one of the standard beliefs during the Bettelheim era of the 1950s and 1960s, which, as I have written before, I am an actual veteran of, unlike most persons in the autism blogosphere. I then heard about the cerebellar things that Courchesne wrote about, but that did not seem to tell me a whole lot. Then there was the mirror neuron stuff which was very intriguing. But my pipe dream of knowing exactly what has caused this horrible disability in myself will most likely not be fulfilled. I was even more frustrated to read the stuff that Michelle Dawson and Morton Gernsbacher write about how autistics brains are not damaged variations of neurotypical brains.

In a fit of frustration, I did sort of a silly thing ( I do and say silly things because of my disability sometimes) and I wrote Dr. Iacaboni an email asking him if he would make a statement on his twitter and facebook pages (which I read from time to time) about Dinstein's study and what the implications were for the result of his own work. I wrote to him about my frustration and anger and how I wish I could find out exactly what was wrong with me and how frustrated I was with Gernsbacher and some others. I told him that I would understand if he did not wish to answer me.

He wrote me a very nice reply back stating that there were numerous methodological problems in Dinstein's work but that given that it was nearing the end of the academic year he was busier than he usually was assisting students in graduating from graduate school and other things, but that he was revamping the website of their lab and was going to add a blog where he would go by a blow by blow of the problems with the current study and that he would tweet about it soon. He also gave me some advice on how I could work on my attitude.

I enjoyed very much receiving a reply from this well known and eminent neuroscientist and stellar individual whose book "mirroring people" I read last year.

Of course I am too low functioning and my knowledge of science and research methodology is probably too limited to determine which of the two are correct. Of course there is the old saying about killing the messenger. I guess I can't be angry at either Iacoboni or Dinstein for disagreeing and not being able to give me some real answers as to what the etiology of my handicaps are.

I guess I will have to live and make do without some real answers.
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