Autism is a neurodevelopmental disorder that is characterized by deficits involving social interaction, communication, and perception. Although there is much research that has examined functional neural connectivity in individuals with autism, few have conducted these studies in very young children while awake across EEG power and coherence measures. Anomalies in EEG coherence and power have been associated with deficits in executive function and mental activity. The present study examined neural activation and functional connectivity with an EEG, in children ages 3 -5, during an eyesclosed baseline period. Discrete Fourier Transform was performed on artifact-free segments of EEG data to produce power density values. In addition, coherence measurements were examined to assess functional connectivity in the alpha bandwidth during the baseline recording. Children with autism spectrum disorder (ASD) demonstrated reduced alpha coherence in fronto-temporal regions and between right temporal sites when compared to typically developing (TD) children. In addition, the reduction in coherence was based on ASD severity, such that high-functioning children with ASD showed greater coherence than low-functioning children with ASD. Children with ASD also displayed reduced power in the alpha, beta, and theta frequency bandwidths in frontal, temporal, central, and occipital regions compared to TD children. Interestingly, delta power differentiated children based on developmental status such that high-functioning children with ASD demonstrated the greatest delta power, followed by TD children, and then low-functioning children with ASD. Finally, TD children demonstrated left anterior temporal EEG asymmetry in the alpha bandwidth, whereas children with high-functioning ASD exhibited left posterior temporal EEG asymmetry and right frontal EEG asymmetry. Thus, the results suggest that children with ASD exhibit atypical patterns of brain activity and functional connectivity compared to their typically developing counterparts. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2013.