Autism and ASD undoubtedly have a multitude of risk factors, which lead to somewhat similar symptoms. What biological mechanisms do you think are converging from different risk factors to produce ASD symptoms?
I think all symptoms of ASD/autism arise in the first instance from auditory and/or vestibular hyperactivity in the inner ear, then secondarily from resultant brain miswiring, and finally from compensatory restructuring of intact brain functional systems.
I think research has shown that altered connectivity is the underlying mechanism with weak long distance connections and local over-connectivity.
I am coming from a sensory integration background, so it makes much sense to me that this neural basis causes hypo- and hypersensitivities, lack of perceptional coherence, a deficient or distorted body schema (action formation models) and consequently feedback and feedforward related praxis deficits which on a more cognitive level manifest as deficits in anticipation - lack of predictability is responsible for a lot of autistic "behaviors".
You may want to see "Alterations of neocortical development and maturation in autism: Insight from valproic acid exposure and animal models of autism" and "Neuronal connectivity as a convergent target of gene x environment interactions that confer risk for autism spectrum disorders" that both appeared last year in the Neurotoxicology & Teratology (vol 36, 2013) Autism special issue. Additionally, "Activity-dependent neuronal signalling and autism spectrum disorder" published in Nature last year as well.
For a discussion of etiology of autism spectrum disorders and how an intensive supportive network form of interpersonal psychotherapy can be harnessed. Intensive involvement of parents, teachers, peers and therapist on a daily basis for a school year can favorably alter the brain's limbic (emotional processing) system, can increase brain area connectivity, change some of the organic damages and prevent further expression of the genetic substrate, see Kliman, G. 2011 Reflective Network Therapy in the preschool classroom. University Press of America, Durham MD, available on amazon.com and Kindle.
" this neural basis causes hypo- and hypersensitivities, lack of perceptional coherence, a deficient or distorted body schema"
I know of no evidence to support the application of this adult neurological model to infants. It seems much more likely that the primary source of perceptual abnormalities are the organs of perception, and altered brain conectivity is secondary. Why should the environmental influences similar to those listed above and below not also be operative in infancy?
" Intensive involvement of parents, teachers, peers and therapist on a daily basis for a school year can favorably alter the brain's limbic (emotional processing) system, can increase brain area connectivity, change some of the organic damages"
"I think all symptoms of ASD/autism arise in the first instance from auditory and/or vestibular hyperactivity in the inner ear, then secondarily from resultant brain miswiring, and finally from compensatory restructuring of intact brain functional systems."
Really?
How does this explain the profound lack of social instinct that is the central feature of autism?
"How does this explain the profound lack of social instinct that is the central feature of autism?"
I don't think instinct is involved at all. Irrespective of my theory, there is much evidence to suggest that autism develops in the second half of the first year of life, and is not present at birth.
Audiosensitivity can induce fear of strangers, and lead to a conditioned aversion to the mother by virtue of the excessive loudness of her voice and/or heartbeat. Social bonding thus gets off to an irreversible start. Theory of Mind is abnormal in the congenitally deaf.
Theory of mind is affected in a range of conditions and I'm not sure that the fact that it is abnormal in people who are congenitally deaf really advances your argument. My experience of people with autism, and I've treated a lot of them, is that they are unusual in a broad variety of ways, many of which are hard to relate even indirectly to sensory pathology. Cognitive abnormalites such as weak central coherence are inexplicable in purely auditory-vestibular terms.
Autism research is littered with single aetiology theories, the most infamous of which was the now utterly discredited MMR theory. In the current state of knowledge we need to be circumspect in our evaluation of the aetiological evidence. My last word on the matter.
"Cognitive abnormalites such as weak central coherence are inexplicable in purely auditory-vestibular terms."
Yes, in an adult an acquired auditory-vestibular disorder would not explain weak central coherence. Such a disorder at a critical stage in very early development is a completely different matter, especially if the sensory disorders are fluctuant and unpredictable. My theory can be more easily discredited even than the MMR theory by finding a cause of autism that is not also a cause of deafness.
Hi
Please see the attached review dealing with what you asked. I think it will be of high relevancy to your question.
Boaz