Alterations in Functional Connectivity of Neural Networks in Adolescents with Autism Spectrum Disorders.

The present set of studies sought to examine functional connectivity in adolescents with autism spectrum disorders (ASD) using functional magnetic resonance imaging (fMRI). In Chapter II, functional connectivity was examined in the context of a social task with emotional faces. The task was designed to control for attention differences between groups as well as to elicit robust amygdala activation in both groups. Using a psychophysiological interaction (PPI) analytic technique, we examined relationships between the amygdala and various cortical structures involved in face processing. The results showed that although behavioral performance did not differ between groups, adolescents with ASD relative to controls, showed weaker positive amygdala-cortical connectivity within the temporal and frontal regions when viewing emotional faces relative to baseline. In addition, weaker positive connectivity was associated with the degree of social impairment in the ASD group. The findings suggest that adolescents with ASD show a disruption in functional connectivity in the neural networks involved in face processing and that these disruptions relate to social impairment, and are not driven by behavioral differences in emotion recognition. In Chapter III, functional connectivity within the default network was examined using a seed in the posterior cingulate cortex (PCC) in the absence of a cognitive task (subjects lay in the MRI and viewed a cross on a screen). The default network is of interest as others have identified it as the brain’s intrinsic activation, important in maintaining the equilibrium between excitatory and inhibitory neuronal inputs and low-level monitoring of the external surroundings. The results of the resting connectivity study revealed that relative to controls, adolescents with ASD showed weaker connectivity between the PCC and a majority of areas within the default network, with the exception of tighter connectivity between the PCC and the right superior temporal gyrus. Moreover, poorer adaptive behavior was related to weaker connectivity between the PCC and left angular gyrus in adolescents with ASD. To summarize, the present set of studies show evidence for widespread reduced connectivity and isolated areas of increased connectivity in adolescents with ASD relative to controls.PhDPsychologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/62259/1/sweng_1.pd