An extended multisensory temporal binding window in autism spectrum disorders

Autism spectrum disorders (ASD) form a continuum of neurodevelopmental disorders, characterized by deficits in communication and reciprocal social interaction, as well as by repetitive behaviors and restricted interests. Sensory disturbances are also frequently reported in clinical and autobiographical accounts. However, surprisingly few empirical studies have characterized the fundamental features of sensory and multisensory processing in ASD. The current study is structured to test for potential differences in multisensory temporal function in ASD by making use of a temporally dependent, low-level multisensory illusion. In this illusion, the presentation of a single flash of light accompanied by multiple sounds often results in the illusory perception of multiple flashes. By systematically varying the temporal structure of the audiovisual stimuli, a “temporal window” within which these stimuli are likely to be bound into a single perceptual entity can be defined. The results of this study revealed that children with ASD report the flash-beep illusion over an extended range of stimulus onset asynchronies relative to children with typical development, suggesting that children with ASD have altered multisensory temporal function. These findings provide valuable new insights into our understanding of sensory processing in ASD and may hold promise for the development of more sensitive diagnostic measures and improved remediation strategies

The rubber hand illusion in children with autism spectrum disorders: delayed influence of combined tactile and visual input on proprioception.

In the rubber hand illusion, perceived hand ownership can be transferred to a rubber hand after synchronous visual and tactile stimulation. Perceived body ownership and self-other relation are foundational for development of self-awareness, imitation, and empathy, which are all affected in autism spectrum disorders (ASD). We examined the rubber hand illusion in children with and without ASD. Children with ASD were initially less susceptible to the illusion than the comparison group, yet showed the effects of the illusion after 6 minutes. Delayed susceptibility to the illusion may result from atypical multisensory temporal integration and/or an unusually strong reliance on proprioception. Children with ASD who displayed less empathy were significantly less likely to experience the illusion than those with more intact ability to express empathy. A better understanding of body representation in ASD may elucidate neural underpinnings of social deficits, thus informing future intervention approaches

Anterior EEG asymmetry and the Modifier Model of Autism.

Individual differences in the expression of autism complicate research on the nature and treatment of this disorder. In the Modifier Model of Autism (Mundy et al. 2007), we proposed that individual differences in autism may result not only from syndrome specific causal processes, but also from variability in generic, non-syndrome specific modifier processes that affect the social and emotional development of all people. One study supporting this model found that measures of resting anterior EEG asymmetry, a measure reflecting complex brain processes associated with generic individual differences in approach and avoidance motivation, may help explain differences in the expression of autism in children without intellectual disabilities (Sutton et al. 2005). In the current study, we partially replicated the observation that children with autism who exhibited a pattern of left frontal EEG asymmetry tended to display milder levels of social symptoms, although in the current sample this pattern applied only to HFA children with relatively lower verbal IQs. New observations indicated that left frontal EEG asymmetry was also associated with retrospective parent reports of significantly later age of onset of symptoms, but also higher levels of self-reported outward expressions of anger as well as symptoms of obsessive compulsive disorder in school-age higher functioning children with ASD. Therefore, the results of this study provide a new and fully independent set of observations, which indicate that individual differences in anterior EEG asymmetry may significantly moderate the expression and developmental course of autism. This observation may have clinical implications for identifying meaningful diagnostic sub-groups among children with autism

Anterior EEG asymmetry and the Modifier Model of Autism.

Individual differences in the expression of autism complicate research on the nature and treatment of this disorder. In the Modifier Model of Autism (Mundy et al. 2007), we proposed that individual differences in autism may result not only from syndrome specific causal processes, but also from variability in generic, non-syndrome specific modifier processes that affect the social and emotional development of all people. One study supporting this model found that measures of resting anterior EEG asymmetry, a measure reflecting complex brain processes associated with generic individual differences in approach and avoidance motivation, may help explain differences in the expression of autism in children without intellectual disabilities (Sutton et al. 2005). In the current study, we partially replicated the observation that children with autism who exhibited a pattern of left frontal EEG asymmetry tended to display milder levels of social symptoms, although in the current sample this pattern applied only to HFA children with relatively lower verbal IQs. New observations indicated that left frontal EEG asymmetry was also associated with retrospective parent reports of significantly later age of onset of symptoms, but also higher levels of self-reported outward expressions of anger as well as symptoms of obsessive compulsive disorder in school-age higher functioning children with ASD. Therefore, the results of this study provide a new and fully independent set of observations, which indicate that individual differences in anterior EEG asymmetry may significantly moderate the expression and developmental course of autism. This observation may have clinical implications for identifying meaningful diagnostic sub-groups among children with autism