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Dernhelm23
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12 Jun 2010, 5:56 pm

I'm probably going to sound a little ignorant for asking this, but this whole AS thing is new to me and I have yet to find anything definitive on the internet, which contains a lot of misinformation anyway.

Where (if at all) in the body/brain/genetic makeup/etc. will visible (if only microscopic or chemical) differences between neurotypical and autistic people be located? I'm talking physical, measurable differences in the way something LOOKS. And I mean stuff that has been proven and found, not stuff that has been hypothesized about but not explored to an accurate extent.

(The reason I'm asking is because I have always been really wary of science vs. pseudo-science, and I've just really been wondering how much they actually KNOW. And who are "they," anyway? How widespread is this evidence/knowledge? Ugh I hate not having any resources. Hence the next topic I'm about to create in this forum.)



kia_williams
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12 Jun 2010, 6:01 pm

Im sorry to say so far the conclusive "pointers" have all been behavioural, there has been NO simple tests or telltales beyond the behaviours.

field of genetic exploration has been advancing in this area but yeah.. only the behavioural psychological stuff.


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happymusic
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12 Jun 2010, 6:42 pm

I think you can find brain scan images that show a difference between the autistic brain and the NT one. Temple Grandin had her brain scanned in one of those studies. I don't know where they are, though.

Here is a quote from an article she wrote:

Quote:
Scans of autistic brains have indicated that the white matter in the frontal cortex is overgrown and abnormal. Dr. Courchesne explains that white matter is the brain's "computer cables" connecting up different parts of the brain while the gray matter forms the information processing circuits. Instead of growing normally and connecting various parts of the brain together, the autistic frontal cortex has excessive overgrowth much like a thicket of tangled computer cables.


It's from here:
http://www.grandin.com/inc/visual.thinking.html



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12 Jun 2010, 7:38 pm

The stuff I read about that is from the book "Understanding the Nature of Autism and Asperger´s Disorder" by Edward R. Ritvo (MD). The book is interesting because the author was one of the first reserchers to study the biological base of autism and so doing displace the "refrigerator mother" theory. He tells in his book that in studying research materials of autopsy under the microscope it was found a significant decrease in the number of cells of cerebellum part of the brain in autistic patients. Also another finding by the author is the difference in the brain level of serotonin between autistic and non-autistic patients. In non-autistic patients the level of serotonin in the brain started high in the infancy and the levels gradually decreased until their teen years. On the other hand on most of his autistic patients the level of serotonin started high in infancy and stayed high as the patient grew older. That research was made using blood samples in which the number of platets a type of blood cell that carries serotonin was measured. A direct mesure of the level of serotonin in the brain was impossible for obvious reasons!

He also discovered that some but not all of his patients had measurable amounts of melatonin in their blood during the day. Melatonin is a hormone that is produced by a gland connected by special nerves to the eyes. When it gets dark at night it starts to make melatonin, which it pours into the bloodstream. The amount of melatonin in the blood reaches its peak about two in the morning, and then the gland shuts down, the melatonin level rapidly drops, and it should be all gone by sunrise but not in some autistic patients. The melatonin block the dopamine neurotransmitter and that was how the different levels of melatonin were discovered. Low levels of dopamine decreased the response of autistic patients in a test called ERG which measures the response of the eyes to a flashing light.

That research was made in the 60s and I don´t know if it stood the test of time but I think that it is interesting.



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12 Jun 2010, 9:17 pm

As stated above, and, significantly: lack of (or difference in expression of) Mirror Neurons (I'll leave looking up "mirror neurons" as an exercise to the reader, if one does now know). Mirror neurons imply Theory of Mind (ToM), or lack of, in our case.

When mirror neurons were "discovered" (Giacoma Rizzolatti (sp? apologies)) made great strides in research that linked lack of ToM to a neurophysiological difference associated with ASD.

Of course, most of our difference is due to rate of reaction (Kd) - neurochemical. ASD individuals have a skewed dopaminergic cycle too; a preponderance of homovanillic acid (aromatic metabolite) that is unexpected. One noted observation, from even many many decades ago (and before): In hospital wards that house just Autistics, there is a distinct (and pleasant) scent of vanilla. It's not just anecdotal - that's our homovanillic acid.

And, in some (not all) there *may* be a casual link (uncertain as to how/why): Lack of Sylvian Fissure (reader can look up Sylvian Fissure). For ex: I have no Sylvian Fissure. That's OK, one honestly doesn't need a Sylvian Fissure, but it's an anamoly.

Note: When Einstein's brain was autopsied (and yes, consensus of his Asperger's Syndrome) researchers initially found no difference in physiology. But, he had no Sylvian Fissure. As to why.....?

Also, increased neuroglial are often associated with HFA Autism/AS and a slightly larger head circumference. Some differences (variable) in brain wave function, but no "visible" under anatomical studies, obviously. Cerebellar dysfunction might be a factor - dopamine cycle related to balance/sleep.


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12 Jun 2010, 9:45 pm

A study at the University of Kentucky found that autistic people have thicker microcolumns in their brains. Also, another study (can't at the moment remember where) found a greater quantity of grey matter in autistic brains, but this second study was on average and in the aggregate, not on an individual basis like the microcolumns.


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13 Jun 2010, 12:20 am

There have actually been very few studies on AS, and traditionally a diagnosis of AS, autism, and other neurological/psychiatric disorders has been made based on behavioral observations, and the disorders have been categorized in much the same manner.

Some studies that have been done, however, suggest people with AS have abnormal sleep cycles, and tend to take longer to fall asleep that most.

A few studies have found that people with AS have right brain weakness. The right brain is responsible for pre-processing incoming sensory information before it is sent to the left brain for further clarification and analysis.