Characterizing Dynamic Neural Indices of Sound Sensitivity in Autism - Project Summary/Abstract Up to seventy percent of autistic individuals report challenging auditory sensory experiences despite having normal hearing thresholds. These experiences include both increased and decreased sensitivities to sounds, as well as difficulties attending to and ignoring sounds. Furthermore, these experiences are exacerbated by stress and fatigue, indicating the role of arousal-related systems in mediating these sensitivities. Despite the prevalence of these experiences, prior research has failed to identify consistent differences in neural activity in brain regions responsible for auditory sensitivity, attention, and arousal, thus hindering the development of effective treatments and sensitive measures. Importantly, these brain regions compose a circuit that adjusts auditory sensitivity in response to the environment, but no research has investigated whether the dynamics of this circuit are different in autism. We will address this gap by measuring the integrity of the neural circuit through which arousal modulates auditory perception and vice versa. We hypothesize that auditory difficulties in autism emerge from different dynamics of the neural circuit that maintains auditory sensitivity, rather than unvarying increased or decreased activity in any of these regions in isolation. We test this hypothesis with a novel experimental approach. Participants will hear sounds of varying intensity as we co-register electroencephalography (EEG) and pupil diameter (PD). Simultaneous measurement of EEG and PD allows us to determine the extent to which individual brain responses reflect the influence of exogenous factors, such as sound intensity, relative to endogenous factors such as arousal. We quantify the strength of these associations using novel regression models developed for the analyses of time-varying relationships at the level of single trials. These neurophysiological measures will be integrated with clinical assessments of auditory sensitivity to understand relationships among circuit dynamics and auditory experience. This research will generate important knowledge elucidating the mechanisms of auditory sensitivity in autism. This knowledge will facilitate progress in the development of sensory-specific biomarkers and interventions, which the field currently lacks. Finally, unlike prior research that has focused on mean differences between groups, we aim to identify an explanatory mechanism for variability within individuals.
