A Review of Altered Neurophysiology and Connectivity of the Brain in Autism Spectrum Disorder and its Impact on Common Symptoms

Abstract

Autism Spectrum Disorder (ASD) is a developmental condition which refers to a broad range of abnormalities and challenges with social skills, cognitive abilities, and behaviour. The prevalence of ASD is increasing, yet we currently do not have a clear pathophysiological understanding of this complex disorder. A general review is done on the topic of abnormal functional connectivity in ASD and its relation to some of the symptoms and consequences which have been observed in the literature. No formal process was used to carry out this review and no attempt was made to conduct a statistical analysis of the data. Rather, the purpose of this review is to integrate the findings related to the topic in a meaningful and logical manner. The review will also discuss related topics such as white matter connectivity, anatomical and pathological findings, in addition to chemical changes observed in the ASD brain. As such, different brain imaging modalities and basic science techniques are brought to attention. A review of the literature guides us to the conclusion that there is no single causal gene or exclusive physiological factor for ASD. Furthermore, we find that there is also no universal case of hypo- or hyperconnectivity in autistic brains. Instead, we observe variation in abnormal connectivity between different brain areas, which are suspected to be associated with some of the commonly reported symptoms in ASD.