Dysregulated Oscillatory Connectivity in the Visual System in Autism Spectrum Disorder

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Abstract

Autism Spectrum Disorder (ASD) is increasingly associated with atypical perceptual and sensory symptoms. Here we explore the hypothesis that aberrant sensory processing in ASD could be linked to atypical intra- (local) and inter-regional (global) brain connectivity. To elucidate oscillatory dynamics and connectivity in the visual domain we used magnetoencephalography (MEG) and a simple visual grating paradigm with a group of 18 adolescent autistic participants and 18 typically developing controls. Both groups showed similar increases in gamma (40-80Hz) and decreases in alpha (8-13Hz) frequency power in occipital cortex. However, systematic group differences emerged when analysing local and global connectivity in detail. Firstly, directed connectivity was estimated using non-parametric Granger causality between visual areas V1 and V4. Feedforward V1-to-V4 connectivity, mediated by gamma oscillations, was equivalent between ASD and control groups, but importantly, feedback V4-to-V1 connectivity, mediated by alpha (8-14Hz) oscillations, was significantly reduced in the ASD group. This reduction was correlated with autistic traits, indicating an atypical visual hierarchy in autism, with reduced top-down modulation of visual input via alpha-band oscillations. Secondly, at the local level in V1, coupling of alpha-phase to gamma amplitude (alpha-gamma PAC) was reduced in the ASD group. This implies dysregulated local visual processing, with gamma oscillations decoupled from patterns of wider alpha-band phase synchrony, possibly due to an excitation-inhibition imbalance. More generally, these results are in agreement with predictive coding accounts of neurotypical perception and indicate that visual processes in autism are less modulated by contextual feedback information.

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  • Dysregulated Oscillatory Connectivity in the Visual System in Autism Spectrum Disorder

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Original languageEnglish
JournalBrain
Publication statusAccepted/In press - 20 May 2019

Bibliographic note

Funding: Wellcome Trust, Dr Hadwen Trust and Tommy’s Fund, The Netherlands Organisation for Scientific Research (NWO Vidi: 864.14.011), PhD studentship from Aston University and Macquarie University.

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