Dr Martha Herbert MD PhD, a pediatric neurologist at the
"The positions in the parallel sets of debates tend to cluster into two provisional models, each of which links clinical and research data into a different gestalt. One model sees autism as a strongly genetic brain-based disorder, with a constant prevalence but a recent increase in awareness that has led to the appearance—but not the reality—of an epidemic. The other model sees autism as a genetically influenced but environmentally modulated condition involving multiple systems of the body, with increased numbers being real and related to changes in environmental factors."
Basically, the disagreement is whether autism is the RESULT of abnormalities in the brain, or whether abnormalities found in the brain are CLUES to a deeper underlying cause that was probably triggered by environmental factors. If you believe that abnormalities in the brain cause autism, then it makes sense to fish around until you find the abnormalities and then simply identify the genes responsible. As Dr Herbert so eloquently points out in the above article, this approach has not really lead anywhere. If you view abnormalities in the brain as the result of deeper, underlying causes- if you view autism as a disorder that affects the brain, as Dr Herbert says, rather than one that is of the brain, finding abnormalities in the brain leads to the conclusion that autism is a whole-body, multi-system disorder. While there is a component of genetic involvement, it is not in a deterministic way- a saying that you hear over and over in the biomedical world is that "genes load the gun, the environment pulls the trigger". The above article by Dr Herbert is a good introduction to the basics of the biology of autism, including increased oxidative stress, widespread inflammation (including neuroinflammation), impaired mitochondrial function, impaired detoxification ability, and impaired cellular metabolism.
Autism: a Brain Disorder, or a Disorder that Affects the Brain? by Martha Herbert
Clinical Neuropsychiatry (2005) 2, 6, 354-379
In this paper, Dr Herbert discusses the ideas presented in the article
linked to above in much greater detail. Additionally, she discusses
some of the brain research more specifically and flushes out the
implications of the different models in regards to interpretation of the
results.
So, keeping in mind that brain research in autism is most useful as one piece of a much larger puzzle, here are some studies that provide some insight. Studies that find involvement of one or more particular brain region:
Stanford Scientists Successfully Reverse Autism Symptoms in Mice
"Overactivity
in the reticular thalamic nucleus was shown to cause autism-like
behaviors in mice. Drugs that reduce this activity reversed the
symptoms."
Left-hemispheric atypicalities in the primary auditory cortex are associated with language comprehension and social skills in children with Autism Spectrum Disorder
"First, the results revealed a reduction of M200 and altered M200 sensory gating effect in the left auditory cortex in children with ASD. Second, these alterations were related to lower language comprehension skills and higher autistic symptom severity. Finally, altered MEG responses were associated with gray matter thickness reduction as well as abnormal gyrification in the primary auditory cortex in ASD. The study revealed low-level functional and structural atypicalities in children with ASD and their relation to clinical phenotype."
Studies suggesting abnormalities in cortical development:
