Multisensory Contributions to Autism: Behavioral and Neural Evidence

Background:  

In addition to deficits in social communication and the presence of restricted interests and repetitive behaviors, autism spectrum disorder (ASD) is characterized by changes in sensory function. These changes have been observed in a number of different sensory modalities, suggesting that it may be useful to think of these changes in a more multisensory framework. Indeed, the integration of information across the different sensory systems is essential for the construction of healthy perceptual and cognitive representations. Consequently, it is vitally important to understand the nature of the sensory and multisensory changes in ASD and their contributions to higher-order function. 

Objectives: To characterize the nature of sensory and multisensory changes, and to examine associations with higher-order function, in children with ASD.

Methods:  

A cohort of children with ASD ages 10-14 and a matched cohort of children who were typically developing (TD) were examined on a battery of tasks assessing various aspects of auditory, visual and audiovisual (i.e., multisensory) performance. The battery included tasks that are focused on general aspects of sensory and multisensory performance (i.e., speeded reaction times, sound-induced flash illusion, McGurk effect) as well as tasks that focus on temporal acuity within and across the sensory systems (i.e., temporal order judgments, simultaneity judgments).  These measures of (multi)sensory function were compared with a battery of neuropsychological measures. In addition, neuroimaging (EEG and fMRI) was carried out on a subset of children in an effort to examine for differences in networks subserving sensory and multisensory function.

Results:  

Children with ASD were found to differ from their TD peers on a number of measures within the sensory battery. The two most salient of these differences were in heightened trial-by-trial variability in their reaction times to sensory stimuli in children with ASD, as well as poorer audiovisual temporal acuity compared to children with TD.  Measures of audiovisual temporal acuity were found to correlate with the magnitude of multisensory integration or “binding,” most notably for speech stimuli. Ongoing correlational analyses are focused on exploring the links between these changes in sensory function and changes on the neuropsychological tasks, and on differences in sensory networks and their relationship to networks supporting social communication.

Conclusions:

These results provide one of the first empirical characterizations of both sensory and multisensory function in a cohort of children with ASD, and demonstrate a pattern of sensory changes characterized by greater variability and poorer multisensory temporal function.  Perhaps more important than the changes in sensory function is the putative formative role that these processing alterations are playing in the more established deficits seen in ASD (i.e., in the domain of social communication). Indeed, sensory and multisensory function forms the “building blocks” for perceptual and cognitive representations, and changes in (multi)sensory function appear to scaffold changes in these higher-order domains.