Abstract
Failure to appropriately develop multisensory integration (MSI) of audiovisual speech may affect a child's ability to attain optimal communication. Studies have shown protracted development of MSI into late-childhood and identified deficits in MSI in children with an autism spectrum disorder (ASD). Currently, the neural basis of acquisition of this ability is not well understood. Here, we developed a computational model informed by neurophysiology to analyze possible mechanisms underlying MSI maturation, and its delayed development in ASD. The model posits that strengthening of feedforward and cross-sensory connections, responsible for the alignment of auditory and visual speech sound representations in posterior superior temporal gyrus/sulcus, can explain behavioral data on the acquisition of MSI. This was simulated by a training phase during which the network was exposed to unisensory and multisensory stimuli, and projections were crafted by Hebbian rules of potentiation and depression. In its mature architecture, the network also reproduced the well-known multisensory McGurk speech effect. Deficits in audiovisual speech perception in ASD were well accounted for by fewer multisensory exposures, compatible with a lack of attention, but not by reduced synaptic connectivity or synaptic plasticity.
Highlights
As an organism interacts with its environment, objects and events stimulate its sundry sensory epithelia, providing oftentimes redundant and/or complementary cues to an object’s presence, location, and identity
The effects of different “perturbations” to the network on the developmental trajectories of unisensory and audiovisual speech perception are considered in order to test possible explanations of the delayed development of speech Multisensory integration (MSI) that is seen in autism spectrum disorder (ASD) (Foxe et al, 2015)
Results are not displayed for briefness, but they support the previous finding: unisensory and multisensory abilities are impacted by this modification. This does not provide a good account of the pattern of deficits seen in ASD, which are considerably greater for MSI
Summary
As an organism interacts with its environment, objects and events stimulate its sundry sensory epithelia, providing oftentimes redundant and/or complementary cues to an object’s presence, location, and identity. Neurocomputational-Model of MSI in Autism impacts the development of human communication. Great strides have been made in understanding the neural circuits necessary for the emergence of MSI and how this is impacted by environment (Wallace and Stein, 1997; Wallace et al, 2004, 2006; Cuppini et al, 2011b, 2012; Xu et al, 2012; Yu et al, 2013; Stein et al, 2014), the neural basis of the development of MSI for complex multisensory signals such as speech is not yet well understood. To make headway on this front, here we used a set of previously collected behavioral data (Foxe et al, 2015; Ross et al, 2015) to test a neurocomputational model of the development of multisensory speech perception
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