Neurobiological Mechanisms of Sensory Hyper-sensitivity and Habituation in Autism Spectrum Disorders

Autism Spectrum Disorder (ASD) is one of the most common developmental disabilities, with an estimated 1 in 54 children receiving a diagnosis. The total economic burden of ASD in the United States is estimated to be $268 billion and will increase to $461 billion by 2025. People with ASD have deficiencies in social relationships and communications and an increased rate of anxiety disorders, with some estimates suggesting 84% of people with ASD have anxiety. This anxiety can lead to an individual with ASD to exhibit avoidant behavior, which can include exclusion from activities to escalated behaviors that could be self-injurious or harmful to others. These avoidant behaviors can make participation in activities of daily living challenging for people with ASD, as the avoidant behavior is often considered socially-unacceptable behavior. While there has been increasing interest in anxiety in ASD, there is still a major knowledge gap in understanding how sensory processing disorders play a role in anxiety and if this can be treated.

Sensory Processing in ASD: Sensory processing disorders were added to ASD diagnosis in The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition in 2013. Since then, there has been little research into the role that sensory processing disorders plays in the anxiety of people with ASD. Functional magnetic resonance imaging (fMRI) studies have demonstrated that people with ASD have greater brain activity in relevant sensory areas, the amygdala, and the orbital frontal cortex when exposed to combinations of unpleasant auditory, tactile, or visual stimuli. Further, people with ASD have a reduced ability to habituate to the same unpleasant stimuli in the relevant sensory cortices and amygdala, differences in the changes of brain activity in the orbital-frontal cortex, and differences in functional connectivity between the amygdala and orbital-frontal cortex. These brain responses have also been connected with physiological responses in children with ASD, as those with greater skin conductivity having reduced neural response in the orbital-frontal cortex and heart rate being positively correlated with activity in the inferior and medial frontal gyrus.

Even though the neurophysiological evidence supports sensory processing differences in ASD, current treatment strategies are sparse and the results are often inconsistent. The most successful paradigm is exposure therapy through systematic desensitization, which has been used in both ASD and people with anxiety. While multisensory integration skills may be malleable, it has been suggested that exposure therapy may not be an effective long-term strategy, as the clinical team cannot perform exposure to every stimulus in every environment. With this in mind, new therapeutic techniques need to be designed to enable personalization of exposure experiences.

Virtual Reality for ASD: One emerging technique that could enable quick personalization of unpleasant stimulus and environments is virtual reality (VR). Therapeutic VR software has shown to be an effective platform for skill training, mainly focusing on behavioral skills in social or educational environments. Two investigations demonstrated changes in neural activity after participating in VR social cognition training. However, the effects of using VR as a sensory exposure platform on the physiological response to unpleasant stimuli has not been explored.

Purpose The research objectives of this application are to quantify the neurophysiological changes that occur after participating in a virtual reality systematic desensitization protocol. The following aims will be achieved the top physiological recording devices for ASD to collect physiological responses, front-line virtual reality systems to provide automated desensitization exposure therapy, and University of Nebraska Medical Center's research MRI system. 30 people with ASD and 30 neurotypical peers will be recruited to utilize this software. This proposal will be the first step in developing evidence-based therapies aimed at addressing sensory processing differences in ASD.