Abstract
Despite much current research into the visual processing style of individuals with Autism Spectrum Disorder (ASD), understanding of the neural mechanisms is lagging, especially with respect to the contributions of the overlapping dichotomies of magnocellular/parvocellular (afferent neural pathways), global/local (perception) and dorsal/ventral (cortical streams). Here, we addressed this deficiency by measuring inspection times (ITs) for novel global/local stimuli as well as recording nonlinear visually evoked potentials (VEPs), in particular, magnocellular and parvocellular temporal efficiencies. The study was conducted on a group of male ASD children and a typically developing (TD) group matched for mean age and mean non-verbal intelligence, as measured by the Raven’s Progressive Matrices. The IT results did not differ between groups, however a negative correlation between global IT and Raven’s score was found in the ASD group, that was not evident in the TD group. Nonlinear VEP showed the ASD group had smaller amplitude parvocellular-generated second order responses compared to the TD group. This is a sign of improved temporal responsiveness in ASD vs. TD groups. Principal Component Analysis linked global IT, non-verbal intelligence scores and VEP parvocellular efficiency in a single factor for the ASD but not the TD group. The results are suggestive of a constraint on pathways available for cognitive response in the ASD group, with temporal processing for those with ASD becoming more reliant on the parvocellular pathway.
Highlights
Autism Spectrum Disorder (ASD) encompasses the previously discrete diagnoses of autism, Asperger’s disorder and pervasive developmental disorder (PDD) not otherwise specified (NOS; American Psychiatric Association, 2013)
When familiarizing the children with the stimuli, 3 out of the 11 ASD children identified the local shapes in the stimuli before the global image; there were no instances of this occurring in the typically developing (TD) group
Despite claims of diversity in the genetics of ASD (Happé et al, 2006), the results presented here show a singular relationship linking non-verbal intelligence, global perception and the neural efficiency of the parvocellular pathway, present in the ASD group, but not shown in the TD group
Summary
Autism Spectrum Disorder (ASD) encompasses the previously discrete diagnoses of autism, Asperger’s disorder and pervasive developmental disorder (PDD) not otherwise specified (NOS; American Psychiatric Association, 2013). The Weak Central Coherence (WCC) theory proposed that individuals with ASD have a local processing style bias as they use gestalt principles less (Happé, 1999; Happé and Frith, 2006). Both of these theories allude to there being less processing in the later stages of visual processing. A meta-analysis of global/local perception in ASD by Van der Hallen et al (2015) combining data from several different tasks, found no evidence of enhanced local processing, and found that global processing was slowed. The idea of altered neural noise has been used to explain aspects of autism (Simmons et al, 2009; Pellicano and Burr, 2012; Greenaway et al, 2013), work is still required to make a strongly predictive theory
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