Some recent groundbreaking work @ Carnegie Mellon University (whose now dissolved Carnegie Mellon Research Institute BOD i chaired) indicates that a cause of autism may be the lack of adequate communication between different brain areas because the white matter, which is 45% of the brain, that is responsible for that communication is of lower quality or capability.
When we are doing almost anything, including thinking, ten to two dozen different brain areas are connected together in a synchronized fashion to accomplish different aspects of that function. If any of these centers are unable to communicate fully with the others, the function will suffer.
Psychology professor and director of CMU's Center for Cognitive Brain Imaging, Marcel Just and his collaborators, will have a paper published in Neuroscience and Behavioral Reviews "Autism As A Neural Systems Disorder: A Theory of Frontal-Posterior Underconnectivity", 36, 4, in April 2012, 1292 - 1313.
Their work, and that of other laboratories, discovered with diffusion tensor imaging that in autism the white matter which is responsible for this communication is of lower quality and capability than what is normal. This reduces the bandwidth and speed of communication along these pathways. This is particularly important in reducing the ability of the frontal and posterior regions of the brain to synchronize their functioning.
The red track in the diagram is the track which connects the front and posterior portions of the brain's languaging areas. If this white matter communication track is not adequately and properly formed during gestation, which is done by groups of axons which will be the white matter linking up the gray matter areas in an amazing feat of evolutionarily-developed "natural"wiring, the social challenges of autism occur. This model is not a diagram of the brain's wiring, it is the wiring.
Just, et. al, published in Brain, "Cortical Activation and Synchronization During Sentence Comprehension in High-Functioning Autism: Evidence of Underconnectivity", 127, 1811-1821, (2004) the first real analysis demonstrating that underconnectivity is a potential cause of autism.
In the figure at the left, from that 2004 paper, the Broca's and Wernicke's areas in autistism and in controls (shown below on right), are compared. Wernicke's area is associated with the understanding of written and spoken language. Broca's area is associated with speech production. As you can see in the circled areas, in austism Broca's area is less developed and Wernicke's is more developed. There are some excellent charts in the paper of these comparisons covering many different interacting regions.
The challenge with autism is trying to explain why otherwise high-functioning individuals have such great difficulty in making social interactions. As someone who has a "genius" relative with Asperger's syndrome, an autism spectrum disorder, this is something that i know well. As it turns out, what we view as a simple social interaction with others, requires massive complex computation and major communication and synchronization between the frontal and posterior parts of the brain.
Knowing what the issue is gives a focus for attempting to modify the white matter somehow. Amazingly, in work with 8 to 10 year old autistic children and their difficulty in reading, Keller and Just, in their 2009 paper "Altering Cortical Connectivity: Remediation-Induced Changes in the White Matter of Poor Readers" in Neuron looked at this possibility. They found that in as little as 100 hrs of intensive remedial instruction, the underfunctioning white matter associated with autism was found to be demonstrably improved; in some cases the deficit in their white matter was eliminated and reading improved. The big news is that white matter, which had been assumed to be unchangeable, is in fact changeable, and potentially fairly easily.
The four training protocols for the remedial instruction, which are described in the 2009 paper, were:
a) Corrective Reading
b) Failure Free Reading
c) Spell Read P.A.T.
d) Wilson Reading
A really important understanding from this work, in addition to the applicability to autism, is the realization that the white matter, the connective tissue highways, are critical to the successful functioning of the complex networks of active processing centers. The white matter is often overlooked as a causative factor in functioning as our traditional tools like the fMRI focus on the activity of specific centers.
As we develop better tools like the diffusion tensor imaging used in this work, we will be better able to differentiate the role of the connective networks. Because of the diagnostic tools we had, we treated white matter like copper wire, a given, and forgot about it. We need to remain cognizant that our connective white matter may be fiber optic or corroded, frayed copper, or anything in between.
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| Model of white matter connections that may be a/the cause of autism - Red track is connecting language areas Carnegie Mellon University |
When we are doing almost anything, including thinking, ten to two dozen different brain areas are connected together in a synchronized fashion to accomplish different aspects of that function. If any of these centers are unable to communicate fully with the others, the function will suffer.
Psychology professor and director of CMU's Center for Cognitive Brain Imaging, Marcel Just and his collaborators, will have a paper published in Neuroscience and Behavioral Reviews "Autism As A Neural Systems Disorder: A Theory of Frontal-Posterior Underconnectivity", 36, 4, in April 2012, 1292 - 1313.
 |
| Marcel Just |
The red track in the diagram is the track which connects the front and posterior portions of the brain's languaging areas. If this white matter communication track is not adequately and properly formed during gestation, which is done by groups of axons which will be the white matter linking up the gray matter areas in an amazing feat of evolutionarily-developed "natural"wiring, the social challenges of autism occur. This model is not a diagram of the brain's wiring, it is the wiring.
Just, et. al, published in Brain, "Cortical Activation and Synchronization During Sentence Comprehension in High-Functioning Autism: Evidence of Underconnectivity", 127, 1811-1821, (2004) the first real analysis demonstrating that underconnectivity is a potential cause of autism.
 |
| Brain activation in autistic (top) and controls (bottom) |
In the figure at the left, from that 2004 paper, the Broca's and Wernicke's areas in autistism and in controls (shown below on right), are compared. Wernicke's area is associated with the understanding of written and spoken language. Broca's area is associated with speech production. As you can see in the circled areas, in austism Broca's area is less developed and Wernicke's is more developed. There are some excellent charts in the paper of these comparisons covering many different interacting regions.
The challenge with autism is trying to explain why otherwise high-functioning individuals have such great difficulty in making social interactions. As someone who has a "genius" relative with Asperger's syndrome, an autism spectrum disorder, this is something that i know well. As it turns out, what we view as a simple social interaction with others, requires massive complex computation and major communication and synchronization between the frontal and posterior parts of the brain.
Knowing what the issue is gives a focus for attempting to modify the white matter somehow. Amazingly, in work with 8 to 10 year old autistic children and their difficulty in reading, Keller and Just, in their 2009 paper "Altering Cortical Connectivity: Remediation-Induced Changes in the White Matter of Poor Readers" in Neuron looked at this possibility. They found that in as little as 100 hrs of intensive remedial instruction, the underfunctioning white matter associated with autism was found to be demonstrably improved; in some cases the deficit in their white matter was eliminated and reading improved. The big news is that white matter, which had been assumed to be unchangeable, is in fact changeable, and potentially fairly easily.
The four training protocols for the remedial instruction, which are described in the 2009 paper, were:
a) Corrective Reading
b) Failure Free Reading
c) Spell Read P.A.T.
d) Wilson Reading
A really important understanding from this work, in addition to the applicability to autism, is the realization that the white matter, the connective tissue highways, are critical to the successful functioning of the complex networks of active processing centers. The white matter is often overlooked as a causative factor in functioning as our traditional tools like the fMRI focus on the activity of specific centers.
As we develop better tools like the diffusion tensor imaging used in this work, we will be better able to differentiate the role of the connective networks. Because of the diagnostic tools we had, we treated white matter like copper wire, a given, and forgot about it. We need to remain cognizant that our connective white matter may be fiber optic or corroded, frayed copper, or anything in between.
Hi Gary,
ReplyDeleteVery nice article. I translated it to Arabic with a few amendments in the following link.
http://blog.kau.edu.sa/neuroimaging/2012/04/07/التوحد-الأسباب-والعلاج-اعتماداً-على-ع/
Jamaan Alghamdi
http://www.easyneuroimaging.com/
Hi Jamaan,
ReplyDeleteTks for comments and your useful and insightful amendments.
For those folk who don't read Arabic and are reading this, remember that Google has a fantastic translator which will instantaneously translate the entire Arabic blog entry into English.
stillness
gary
Hi Gary,
ReplyDeleteThank you very much for mentioning my blog entry for English readers.
Please take in account that some sentences are translated wrongly.
For example, first sentence of the final paragraph was translated to "It is well known for a long time that the white matter in the human brain is subject to change or re-shape" while I meant "is not subject".
Best wishes,
Jamaan