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Auditory Event-Related Potentials As a Function of Clinical Sensory Subtype in Autism Spectrum Disorder
Clinical sensory features are reported in many children with Autism Spectrum Disorder (ASD) and present as sensory hyper-reactivity (e.g. covering ears to loud or unexpected sounds), sensory hypo-reactivity (e.g. failure to orient to name or react to painful stimuli), and/or unusual sensory interests or behaviors (e.g. rocking, compulsive touching and noise-making). Distinct clinical sensory subtypes have been identified in ASD resulting in a two-factor behavioral theory positing that sensory features are characterized by impairment in sensory reactivity and/or multisensory integration (Lane et al 2014). Research in this area, however, is hindered by a lack of rigorously developed clinical protocols to accurately identify and characterize sensory features. Clinical practice relies on parent or proxy-report measures and clinician impression to identify sensory features. While more precise electrophysiological and imaging measures have been used to quantify neural sensory impairment in ASD (Marco, Hinkley, Hill & Nagarajan, 2011), there are limited reports of the correspondence between clinically observed sensory features and neural deviations.
Objectives:
The broad aim of this study was to gather preliminary neural evidence to support a two-factor behavioural theory of sensory features in ASD. We used measures derived from auditory event-related potentials (ERP) to examine variations in neural profiles in children with ASD as a function of clinical sensory subtype.
Methods:
Participants for the study were children aged 6-10 years with a diagnosis of ASD (n=19) and typically developing same-aged peers (TYP; n=30). Participants in the study completed a clinical protocol that assessed sensory features (via administration of the Short Sensory Profile (SSP)), autism symptoms and hearing function, and an ERP protocol assessing auditory (phoneme) novelty detection in an oddball paradigm. Classification of participants’ clinical sensory differences into sensory subtypes was made using scores from the SSP using an algorithm derived by Lane et al, (2014). ERP data was collected on an EGI GES 300 system utilizing a HydroCel 128 channel sensor net. A number of procedures were implemented to improve children’s compliance with the ERP experiment and to retain maximum data for analysis. Subsequently, our findings include data from individuals with a variety of functional abilities. We analysed data across all channels and by distinct regions of interest.
Results:
Participants exhibiting sensory subtypes associated with sensory reactivity displayed heightened responses to the onset of novel auditory stimuli (p=0.009) and a sustained, elevated response during later auditory processing (p=0.05). Further, our findings suggest that classification of children with ASD using clinical sensory subtype reveals auditory response differences that are not apparent when grouping children by diagnostic classification alone.
Conclusions:
The results of our study suggest that auditory event-related potentials in an oddball paradigm discriminate between individuals with clinically significant sensory reactivity, multisensory integration impairments and those who are sensory adaptive. Our study provides preliminary neural evidence validating a two-factor behavioral theory of sensory features in ASD.