Frontal evoked γ activity modulates behavioural performance in Autism Spectrum Disorders in a perceptual simultaneity task

Abstract

Autism spectrum disorders (ASDs) are associated with anomalies in time perception. In a perceptual simultaneity task, individuals with ASD demonstrate superior performance compared to typically developing (TD) controls. γ-activity, a robust marker of visual processing, is reportedly altered in ASD in response to a wide variety of tasks and these differences may be related to superior performance in perceptual simultaneity. Using time-frequency analysis, we assessed evoked γ-band phase-locking in magnetoencephalographic recordings of 16 ASD individuals and 17 age-matched TD controls. Individuals judged whether presented visual stimuli were simultaneous or asynchronous. We identified left frontal γ-activity in ASD, which was associated with a reduced perception of simultaneity. Where feature binding was observed at a neurophysiological level in parieto-occipital cortices in ASD in apparent simultaneity (asynchronous stimuli with short delay between them), this did not predict the correct behavioural outcome. These findings suggest distinct γ profiles in ASD associated with the perception of simultaneity.

Abbreviations

ADI-R, Autism Diagnostic Interview Revised;
ADOS-G, Autism Diagnostic Observation Schedule Generic;
ANOVA, analysis of variance;
ASD, Autism Spectrum Disorders;
DSM-V, diagnostic and statistical manual for mental disorders, fifth edition;
MEG, magnetoencephalography;
PCA, principal component analysis;
TD, typicallydeveloping;
WASI, Wechsler Abbreviated Scale of Intelligence

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