Over the past few years, a number of studies have been published linking differences in brain structure and function to autism spectrum disorders. For example… scientists have noted that:
At a certain point in post-natal development, autistic brains are larger.
Testosterone may be linked to autism.
Certain portions of the brain, such as the amygdala, may be enlarged in autistic brains.
Certain parts of the brain may function differently in autistic people.
"Minicolumns" in the brain may be formed differently and be more numerous in autistic brains.
The entire brain may function differently in autistic people.
The Autistic Brain is "Differently Wired"
What all of these brain findings have in common, Dr. Minshew explains, is that they point to autism as a disorder of the cortex. The cortex is the proverbial "gray matter": the part of the brain which is largely responsible for higher brain functions, including sensation, voluntary muscle movement, thought, reasoning, and memory.
In many autistic people, the brain develops too quickly beginning at about 12 months. By age ten, their brains are at a normal size, but "wired" atypically. "The brain is most complex thing on the planet," says Dr. Minshew. "So its wiring has to be very complex and intricate. With autism there's accelerated growth at the wrong time, and that creates havoc. The consequences, in terms of disturbing early development, include problems within the cortex and from the cortex to other regions of the cortex in ways that compromise language and reasoning abilities."
Minicolumns, which are small structures within the cortex, are also different among autistic people. Dr. Manuel Casanova, a researcher at the University of Kentucky, has found that autistic people have more minicolumns which include a greater number of smaller brain cells. In addition, the "insulation" between these minicolumns is not as effective as it is among typically developing people. The result may be that autistic people think and perceive differently and have less of an ability to block sensory input.
The Down Side of Unique Wiring
If autistic brains are wired differently across the board, is it a problem? Of course, for many people -- and in many ways -- the answer is "yes."
Says Dr. Minshew, "Autism really impacts behavioral function in the brain very broadly. It effects sensory, motor, memory, and postural control -- anything that requires a high degree of integration of information. The symptoms are most prominent in social interaction and problem solving because they require highest degree of interaction." In fact, she continues, "They're socially/emotionally far more delayed than anyone ever thought, even if they have a high IQ. Temple Grandin, a well-known speaker and writer with autism, says she's emotionally about 7 - 10 years old."
The Up Side of Unique Wiring
While social and communication skills may be compromised by unique wiring in the brain, other abilities are actually enhanced. For example, says Dr. Minshew, "Autistic people have a really stellar ability to use the visual parts of the right side of the brain to compensate for problems with language processing. This may be the basis for detail-oriented processing -- and may be a decided advantage!" In fact, as she describes it, "Control children can't find Waldo. Autistic children can."
What Brain Differences Mean to You
Autism may be described as a syndrome characterized by specific neurological differences. But what does that mean to the parent or teacher of a person with autism?
To start with, it provides an understanding of what's going on in an autistic person's mind. Says Minshew: "They think differently becaue their brain is wired differently. They think logically and predictably, but differently. It's as if they're colorblind. You wonder why someone doesn't stop at a red sign -- and it's because they can't see it. Teachers need to be taught this. When the teacher says "ok close your books and hop over to the door" and the child hops, the teacher feels mocked. She hasn't been mocked; she's been obeyed."
Understanding differences in the autistic brain may also provide hints for better communication.
For example, since it may be harder for a person with autism to process multiple ideas, or to multi-task, it makes sense to "say less; give the facts; don't give a lot of tone of voice and gestures and distractions. You'd be surprised how many behavior problems are related to that. Remember that the child is dealing with facts, not concepts."
How Understanding the Autistic Brain May Improve Outcomes
Will a better understanding of the autistic brain lead to better treatments? Minshew thinks the answer is "yes."
"I think treatments are coming. Functional underconnectivity studies show that there are increased neuronal fibers; these studies are consistent. Now we need to find out whether, if we do a certain cognitive paradigm, we increase connectivity. It probably can be done. But these will be very different cognitive therapies than ABA. There's a time for behavioral therapy, and a time for stopping that -- to shift from learning rules to being flexible and acquiring interactive circuity. In autistic brains, circuitry is developing into adulthood -- but it's not developing in the right way, and it stops developing too soon. With the right treatment, though, it can be pushed."
Minshew, Nancy. Telephone interview. September 14, 2006.
Minshew, Nancy, Antonio Y. Hardan, Ragy R. Girgis, Jason Adams, Andrew R. Gilbert, Matcheri S. Keshavan . "Abnormal brain size effect on the thalamus in autism ." Psychiatry Research: Neuroimaging 147(2006): 145-151 .
Ragy R. Girgis, Nancy J. Minshew, Nadine M. Melhem, Jeffrey J. Nutche, Matcheri S. Keshavan and Antonio Y. Hardan. "Volumetric alterations of the orbitofrontal cortex in autism." Progress in Neuro-Psychopharmacology and Biological Psychiatry, In Press, Corrected Proof, Available online 24 July 2006.
Hideya Koshino, Patricia A. Carpenter, Nancy J. Minshew, Vladimir L. Cherkassky, Timothy A. Keller and Marcel Adam Just. "Functional connectivity in an fMRI working memory task in high-functioning autism." NeuroImage, Volume 24, Issue 3, 1 February 2005, Pages 810-821
M.F. Casanova, I. van Kooten, A.E. Switala, H. van Engeland, H. Heinsen, H.W.M. Steinbusch, P.R. Hof and C. Schmitz. "Abnormalities of cortical minicolumnar organization in the prefrontal lobes of autistic patient." Clinical Neuroscience Research, In Press, Corrected Proof, Available online 1 September 2006
Isabel Dziobek, Stefan Fleck, Kimberley Rogers, Oliver T. Wolf and Antonio Convit. "The 'amygdala theory of autism' revisited: Linking structure to behavior." Neuropsychologia, Volume 44, Issue 10, 2006, Pages 1891-1899
David E. Welchew, Chris Ashwin, Karim Berkouk, Raymond Salvador, John Suckling, Simon Baron-Cohen and Ed Bullmore. "Functional disconnectivity of the medial temporal lobe in Asperger's syndrome." Brain Research, Volume 1043, Issues 1-2, 10 May 2005, Pages 12-2.
Rebecca Knickmeyer, Simon Baron-Cohen, Peter Raggatt, Kevin Taylor and Gerald Hackett. " Fetal testosterone and empathy." Hormones and Behavior, Volume 49, Issue 3, March 2006, Pages 282-292
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