Project Summary Sensory symptoms are a core diagnostic feature of autism and cause substantial functional impairment. Auditory processing is one of the most affected domains and is hypothesized to play a role in the socio- communicative and restricted/repetitive behavior symptoms in autism. Measurement of real-time auditory processing using electroencephalography (EEG) has shown that latency delays and reduced gamma synchrony are potential powerful biomarkers in autism. Using EEG, we have shown that auditory processing is dependent on attention abilities among autistic adults. Compared to neurotypical peers, autistic adults showed delayed auditory latencies and reduced gamma synchrony during a passive listening task. However, autistic adults showed more efficient neural processing (typical latencies and gamma synchrony) when they were actively engaged with the auditory stimuli. Additionally, we showed a strong association between longer latencies and greater sensory and social symptoms on behavioral self-report measures. Using innovative structural equation modeling, we validated a model of brain-behavior relationships, wherein attention mediated the relationship between delayed latencies (EEG) and behavioral sensory symptoms, that together predicted social behaviors in autistic adults. Given these compelling findings in autistic adults, it is crucial that we validate these findings in children on the autism spectrum. In aim 1, we will determine the role of attention (top-down) on neural auditory processing in autistic children. We hypothesize that compared to age-matched typically developing peers, autistic children will show delayed latencies and reduced gamma synchrony during a passive auditory paired-click paradigm and show more typical latencies and gamma synchrony during an active paired-click paradigm involving a motor response. In aim 2, we will validate a novel brain-behavior model of attention, sensory processing, and social behaviors. We hypothesize that attention will mediate the relationship between auditory EEG measures and behavioral parent-report measures of sensory symptoms and social responsiveness in children on the autism spectrum. We will use structural equation modeling to assess this model. In aim 3, we will determine the reliability of brain-behavior relationships of auditory EEG measures. We hypothesize that auditory latencies and gamma synchrony will show strong test-retest reliability when tested one-week and 6-months apart with maintained brain-behavior relationships to clinical correlates of autism. Results generated here will systematically validate a novel model that determines the role of top-down attention on sensory symptoms in autism using a multi-model approach. These results will provide a framework to measure pharmacological and behavioral therapies for attention in autism. Validation of auditory EEG biomarkers of latency and gamma synchrony will provide an innovative, objective, and reliable method of measur...