Ripe for solution: Delayed development of multisensory processing in autism and its remediation

Abstract

Difficulty integrating inputs from different sensory sources is commonly reported in individuals with Autism Spectrum Disorder (ASD). Accumulating evidence consistently points to altered patterns of behavioral reactions and neural activity when individuals with ASD observe or act upon information arriving through multiple sensory systems. For example, impairments in the integration of seen and heard speech appear to be particularly acute, with obvious implications for interpersonal communication. Here, we explore the literature on multisensory processing in autism with a focus on developmental trajectories. While much remains to be understood, some consistent observations emerge. Broadly, sensory integration deficits are found in children with an ASD whereas these appear to be much ameliorated, or even fully recovered, in older teenagers and adults on the spectrum. This protracted delay in the development of multisensory processing raises the possibility of applying early intervention strategies focused on multisensory integration, to accelerate resolution of these functions. We also consider how dysfunctional cross-sensory oscillatory neural communication may be one key pathway to impaired multisensory processing in ASD.

Keywords: Amelioration; Autism spectrum disorder; Multisensory integration; Normalization; Oscillation; Phase alignment; Phase reset; Recovery; Sensory processing; Time window of integration; Typical development.

Figure 1:

Developmental delay in Multisensory Integration (MSI) tasks in Autism Spectrum Disorder (ASD). Psychometric developmental curve for MSI performance is altered for individuals with ASD (red curve), compared to individuals with Typical Development (TD; blue curve). While MSI in TD approaches mature levels around adolescence (Brandwein et al., 2011; Gori et al., 2012; Ross et al., 2011), MSI is delayed in individuals with ASD, who usually do not perform comparably to TD before adulthood (Foxe et al., 2015; Irwin et al., 2011; Foss-Feig et al., 2010; Taylor et al, 2010). Behavioral training starting at a young age can potentially shift the amelioration of MSI performance earlier (dashed green curve).

Figure 2:

Proposed model for MSI deficits in ASD. Typical reaction to multisensory stimuli, such as speech, is enhanced due to inter-regional phase alignment of neuro-oscillations (Mercier et al, 2015). Reduced MSI effects in children with ASD is possibly related to reduced interregional communication (Di Martino, 2014; Weng et al., 2010; Long et al., 2016) and, in turn, impaired phase alignment of neuro-oscillations.