The heterogeneity of autism spectrum disorders (ASD) can be summarized by the following maxim: "If you've seen one person with autism, then you've seen ONE person with autism." Ironically, much of the research into the neurobiology of ASD has made the opposite assumption, searching for a unifying anomaly to explain what is currently accepted as a broad spectrum of disorders. Despite decades of research, the underlying neurobiology of ASD remains unclear, suggesting the timely need for a paradigm shift. Given that there is tremendous heterogeneity in the behavioral phenotype strongly suggests a heterogeneous neural phenotype within the limits of a "social brain" model where widely dispersed cortical nodes and their long-range connectivity must be intact. According to this model, the core symptoms of ASD can arise from a variety of structural defects including abnormalities of gray matter (processing nodes), white matter (neural connectivity), or any combination of these. This dissertation contains a series of studies using structural magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI), demonstrating that a maxim similar to the aforementioned also applies for the neurobiology of ASD. Using structural MRI, volumetric studies point to abnormal processing nodes and cortical folding studies suggest aberrant neural circuitry. DTI studies point to widespread impairments in long-range cortico-cortical connectivity and expression of illness may depend on pattern of impairment. In summary, the neural phenotype of ASD mirrors the behavioral phenotype, consisting of heterogeneous and distributed abnormalities in social brain modules and its long-range connectivity.
|Advisor:||Duncan, James S., Volkmar, Fred R.|
|School Location:||United States -- Connecticut|
|Source:||DAI-B 73/12(E), Dissertation Abstracts International|
|Subjects:||Neurosciences, Mental health, Behavioral psychology|
|Keywords:||Abnormalities, Autism spectrum disorder, Fiber tracts, Long-range connectivity, Neuroimaging, Social brain|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be