Saccade dysmetria indicates attenuated visual exploration in autism spectrum disorder. (25th May 2020)

• Record Type: Journal Article
• Authors: Bast, Nico; Mason, Luke; Freitag, Christine M.; Smith, Tim; Portugal, Ana Maria; Poustka, Luise; Banaschewski, Tobias; Johnson, Mark
• Is Part Of: Journal of child psychology and psychiatry and allied disciplines. Volume 62:Number 2(2021)
• Page Start: 149
• Page End: 159
• Publication Date: 2020-05-25
• Subjects: Eye tracking -- pupillometry -- visual attention -- biomarker -- brainstem -- cerebellum -- locus coeruleus; Child psychology -- Periodicals; Child psychiatry -- Periodicals; 155.4
• DOI: 10.1111/jcpp.13267
• Languages: English
• ISSNs: 0021-9630

Abstract

Abstract : Background: Visual exploration in autism spectrum disorder (ASD) is characterized by attenuated social attention. The underlying oculomotor function during visual exploration is understudied, whereas oculomotor function during restricted viewing suggested saccade dysmetria in ASD by altered pontocerebellar motor modulation. Methods: Oculomotor function was recorded using remote eye tracking in 142 ASD participants and 142 matched neurotypical controls during free viewing of naturalistic videos with and without human content. The sample was heterogenous concerning age (6–30 years), cognitive ability (60–140 IQ), and male/female ratio (3:1). Oculomotor function was defined as saccade, fixation, and pupil‐dilation features that were compared between groups in linear mixed models. Oculomotor function was investigated as ASD classifier and features were correlated with clinical measures. Results: We observed decreased saccade duration (∆ M = −0.50, CI [−0.21, −0.78]) and amplitude (∆ M = −0.42, CI [−0.12, −0.72]), which was independent of human video content. We observed null findings concerning fixation and pupil‐dilation features (POWER = .81). Oculomotor function is a valid ASD classifier comparable to social attention concerning discriminative power. Within ASD, saccade features correlated with measures of restricted and repetitive behavior. Conclusions: We conclude saccade dysmetria as ASD oculomotor phenotype relevant to visual exploration. Decreased saccade amplitude and duration indicate spatially clustered fixations that attenuate visual exploration and emphasize endogenous over exogenous attention. We propose altered pontocerebellar motor modulation as underlying mechanism that contributes to atypical (oculo‐)motor coordination and attention function in ASD.