Researchers at the Vanderbilt Kennedy Center, University of Washington, and Duke University have found correlations between brain waves and sensory under-reaction in toddlers at high risk for ASD, suggesting that distinct features of neural activity could help with earlier identification and targeted intervention.
Atypical responses to sensory stimuli are regarded as a core feature of autism spectrum disorder (ASD). Although sensory responses in ASD range widely, hyporesponsiveness is of special interest.
“When a child doesn’t turn in the direction of a novel sound, or respond to his or her name, or respond to something negative or even painful, as one expects in typically developing children, that is hyporesponsiveness,” said Carissa Cascio, principal investigator on the study, a VKC investigator, and assistant professor of Psychiatry and Behavioral Sciences. “It is highly prevalent in ASD, emerges early in development, and differentiates ASD from other types of developmental disabilities.”
This lack of or delayed responsiveness results in children with ASD missing critical learning opportunities. Research is needed to uncover the early neurophysiological substrates underlying hyporesponsiveness, but ASD cannot be diagnosed reliably in early development, before age 2.
In this neuroimaging study, the research team used electrophysiology (EEG) to investigate differences in neural activity in 22 young siblings (18 months) of children diagnosed with ASD, since younger siblings are at high risk for a future diagnosis of ASD and are predisposed to being hyporesponsive.
The research procedure was that the toddler, wearing a light sensory net on the head to measure brain activity, sat in the parent’s lap while they together watched a child-appealing movie. In addition, parents completed the Sensory Experiences Questionnaire.
“EEG allows us to track rhythmic neural oscillations, or brain waves, in areas of the brain,” Cascio said. “In our study, we were especially interested in neural activity in the frontal cortex, the area of the brain important for regulating and mediating intellectual functioning and behavior. EEG allows us to track brain activity without a child needing to respond behaviorally in any specific way.”
The research team found correlations between hyporesponsiveness and patterns of oscillatory power, particularly with respect to the right frontal cortex. They also saw correlations with functional connectivity, and signal complexity in a more distributed pattern across the brain as a whole.
The research team found evidence that a hyproresponsive profile involves an array of network changes, contrasted to dysfunction in the frontal cortex alone.
“Our results indicate that a disrupted trajectory maps onto the severity of altered sensory responsiveness that emerges during this developmental period,” said Cascio. “Next, we need studies involving larger numbers of children followed over an extended period of time in order to figure out whether deficits in frontal neural activity precede and predict the appearance of sensory hyporesponsiveness.”
“Because we can link neural signals to a particular behavioral feature of ASD, we hope that eventually these kinds of neural markers will help us to identify children early who would benefit from an intervention approach targeted to sensory hyporesponsiveness and hopefully to improve the developmental trajectory.”
The study was funded by NIH U54 HD083211, R01 MH 102272, R01 HD057284, the Marino Autism Research Institute, the Wallace Foundation, the Simons Foundation Autism Research Initiative, and by CTSA award No. KL2TR000446 from the National Center for Advancing Translational Sciences.
Simon, D. M., Damiano, C. R., Woynaroski, T. G., Ibanez, L. V., Murias, M., Stone, W. L., Wallace, M. T., & Cascio, C. J. (2017). Neural correlates of sensory hyporesponsiveness in toddlers at high risk for autism spectrum disorder. Journal of Autism and Developmental Disorders, 2017 June 8 [Epub ahead of print]
Jan Rosemergy is VKC deputy director and director of Communications and Dissemination.
Pictured top of page: A soft sensory head net allows researchers to observe brain activation in infant siblings of children with ASD as they watch a child-appealing movie.