Assessment of the Autonomic Response to Sensory Stimulation in Autism Spectrum Disorder

Defined as the ability of the nervous systems to reduce their response over repeated stimulation, habituation inflects its parameters in terms of frequency, intensity, recovery and anticipation of responses. Although its concepts have developed from the study of the Central Nervous System (CNS) in processing stimuli at the cortical level, we aim at defining habituation from an autonomic point of view, via heart rate and heart rate variability assessments. To this extent, by using a point-process approach, we devise a novel Autonomic Reactivity Function (ARF) describing the time-varying Autonomic Nervous System (ANS) response in terms of intensity and anticipation, whose reduction (or increment) over repeated stimuli can be ascribed to habituating (or sensitizating) patterns. We tested the mathematical formalization of such metrics in both neurotypical subjects and children with autism spectrum disorder. By eliciting autonomic responses via multisensory stimulation, we collected electrocardiography (ECG) signals, pulled ARFs out from them and performed the Persons coefficient between autonomic habituation metrics and participants sensory profiles and disorder severeness. Results show a relevant positive correlation with Short Sensory Profile (SSP-2) questionnaire (60%) and with Autism Diagnostic Observation Schedule (ADOS-2) questionnaire (76%).