Assessment of functional connectivity in autistic brain fMRI

Autism spectrum disorders (ASD) are associated with disturbances of neural connectivity. Functional connectivity is typically examined within the context of a cognitive task, but also exists in the absence of a task (i.e., “rest”). Connectivity during rest is particularly active in a set of structures called the default network, which includes the posterior cingulate cortex (PCC), lateral parietal cortex/angular gyrus, medical prefrontal cortex, superior frontal gyrus and temporal lobe. Literature suggests that adults with ASD relative to controls show weaker connectivity within the default mode network, indicating that poorer social skills and increases in restricted and repetitive behaviors and interests correlated with weaker connectivity whereas poorer verbal and non-verbal communication correlated with stronger connectivity in multiple areas of the default network. This work has been validated by computing the statistical measures, Granger Causality (GC) and Conditional Granger Causality (CGC) and performing T-tests. Results show that as connectivity decreases, correspondingly the GC and CGC values also get decreased. They are found to be proportional in their relationship. Finally, the results have found to be clinically relevant in the current trends of diagnosing autism in children.