Global motion evoked potentials in autistic and dyslexic children: A cross-syndrome approach

Abstract

Atypicalities in psychophysical thresholds for global motion processing have been reported in many neurodevelopmental conditions, including autism and dyslexia. Cross-syndrome comparisons of neural dynamics may help determine whether altered motion processing is a general marker of atypical development or condition-specific. Here, we assessed group differences in N2 peak amplitude (previously proposed as a marker of motion-specific processing) in typically developing (n = 57), autistic (n = 29) and dyslexic children (n = 44) aged 6–14 years, in two global motion tasks. High-density EEG data were collected while children judged the direction of global motion stimuli as quickly and accurately as possible, following a period of random motion. Using a data-driven component decomposition technique, we identified a reliable component that was maximal over occipital electrodes and had an N2-like peak at ~160 msec. We found no group differences in N2 peak amplitude, in either task. However, for both autistic and dyslexic children, there was evidence of atypicalities in later stages of processing that require follow up in future research. Our results suggest that early sensory encoding of motion information is unimpaired in dyslexic and autistic children. Group differences in later processing stages could reflect sustained global motion responses, decision-making, metacognitive processes and/or response generation, which may also distinguish between autistic and dyslexic individuals.

Visual Motion and Decision-Making in Dyslexia: Reduced Accumulation of Sensory Evidence and Related Neural Dynamics

“…Together with the results from stimulus-locked analyses using a similar dataset ( Toffoli et al, 2021 ), our results suggest that early sensory encoding of motion information is not altered in children with dyslexia. While differences in drift-rate cannot completely tease apart sensory and decision-making processes, in the current study we found no evidence of group differences in non-decision time – a measure which includes the time taken for sensory encoding.…”

“…These general difficulties could reflect reduced temporal and/or spatial integration of motion signals ( Benassi et al, 2010 ; Hill & Raymond, 2002 ; Raymond & Sorensen, 1998 ). This conclusion does not negate the possibility that dyslexic individuals face additional difficulties when segregating signal from noise, as we suggested based on stimulus-locked analyses using a similar dataset ( Toffoli et al, 2021 ).…”

“…EEG data were collected during task performance in 47 typically developing and 44 children with dyslexia (although EEG data were available only in the motion coherence task for one child with dyslexia and one typically developing child). The EEG data from these participants were included in a paper investigating responses locked to the onset of coherent motion in typically developing children and children with autism or dyslexia ( Toffoli et al, 2021 ), and the larger group of 60 typically developing children were used to form the comparison group in an autism study ( Manning et al, 2021b ).…”

The reverse motion illusion in random dot motion displays and implications for understanding development

“…One child said that they were pressing the 'up' key if the stimulus dots were 'jumping down'. Alongside other task differences, the study by Toffoli et al (2021) lengthened the limited lifetime duration compared to Manning et al (2019Manning et al ( , 2021, which could have contributed to a smaller proportion of participants experiencing the reverse motion illusion in this later study. Notwithstanding the need for more systematic evidence, one child participant who experienced the reverse motion illusion with limited lifetime stimuli in Manning et al's (2019Manning et al's ( , 2021 study did not show this illusory percept when the lifetime was extended.…”

“…A modified version of Manning et al's (2019 , 2021 ) task was presented to typically developing children and children with an autism or dyslexia diagnosis aged between 6 and 14 years by Toffoli and colleagues ( Toffoli, Scerif, Snowling, Norcia & Manning, 2021 ). In this study, some changes were made to the task with the aim of minimizing the reverse motion illusion in children.…”