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

Abstract

<p>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 to 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 ms. 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.</p>

Behavioural and neural indices of perceptual decision-making in autistic children during visual motion tasks

“…There seem to be some similarities in how autistic children and children with dyslexia process motion information. For example, both autistic and dyslexic children differ from typically developing children at ~430 ms following stimulus onset in an occipital component specifically in the motion coherence task, but not the direction integration task 35 , and both groups of children appear to show slightly reduced amplitudes in the response-locked centroparietal component, as shown in the current study and that of Manning et al 34 . Yet, the pattern of behavioural performance, diffusion model parameters and relationship between model parameters and EEG differs in the two developmental conditions.…”

“…If this is the case, the EEG component we identified might reflect more than just evidence accumulation, so that any differences in early sensory encoding and / or motor planning in autistic participants might affect the EEG component while the drift-rate is similar to non-autistic participants: a speculation requiring further investigation. While not the focus of the current investigation, we also note that the early stimulus-locked waveforms (up to ~400 ms following stimulus onset) for autistic and typically developing children look very similar (see also [35]), suggesting that early encoding of evidence (i.e., the input to the decision-making stage) is also not disrupted in autistic children, so future studies could focus on motor planning as an alternative / additional reason why the typical relationship between EEG and drift rate in autistic children might not hold.…”

“…The response-locked waveforms are presented in Figure 3 and stimulus-locked waveforms are presented in Supplementary Figure S1. Additionally, as a complement to previous analyses 35 , Supplementary Figure S2 shows stimulus-locked waveforms relating to the second-most reliable component, previously linked to motion-specific processing 35 . While not the focus of the current investigation, this figure suggests that the groups were similar in their early encoding of motion evidence (up to ~400 ms following stimulus onset, see also [35]).…”

“…For example, a response-locked neural marker of the decision-making process that correlates with drift rate has been identified in both typically developing children 33 and children with dyslexia 34 , with children with dyslexia showing a reduced drift-rate compared to typically developing children, and corresponding reductions in the neural marker. An analysis of evoked potentials locked to the global motion onset in a subset of autistic participants revealed no differences in early neural responses to motion onset, but suggested that later processing stages may be affected 35 . We therefore focus on response-locked markers of the decision-making process in this study.…”

“…EEG data were collected during task performance in a subset of these children: in the motion coherence task we had EEG data for 46 typically developing and 43 autistic children and in the direction integration task we had EEG data for 45 typically developing and 45 autistic children. The EEG data from some of these participants has been included in a paper investigating responses locked to the onset of global motion in autistic and dyslexic children 35 . Datasets from an additional 2 typically developing children were excluded due to poor visual acuity (n = 1) or not meeting the criterion of correct responses in the practice phase (n = 1), and datasets from an additional 7 autistic children were excluded due to poor visual acuity (n = 1), having an IQ below 70 (n = 2) or not meeting the autism cut-offs in either the SCQ or ADOS (n = 4).…”