Atypicalities in sleep and semantic consolidation in autism

Abstract

Sleep is known to support the neocortical consolidation of declarative memory, including the acquisition of new language. Autism spectrum disorder (ASD) is often characterized by both sleep and language learning difficulties, but few studies have explored a potential connection between the two. Here, 54 children with and without ASD (matched on age, nonverbal ability and vocabulary) were taught nine rare animal names (e.g., pipa). Memory was assessed via definitions, naming and speeded semantic decision tasks immediately after learning (pre‐sleep), the next day (post‐sleep, with a night of polysomnography between pre‐ and post‐sleep tests) and roughly 1 month later (follow‐up). Both groups showed comparable performance at pre‐test and similar levels of overnight change on all tasks; but at follow‐up children with ASD showed significantly greater forgetting of the unique features of the new animals (e.g., pipa is a flat frog). Children with ASD had significantly lower central non‐rapid eye movement (NREM) sigma power. Associations between spindle properties and overnight changes in speeded semantic decisions differed by group. For the TD group, spindle duration predicted overnight changes in responses to novel animals but not familiar animals, reinforcing a role for sleep in the stabilization of new semantic knowledge. For the ASD group, sigma power and spindle duration were associated with improvements in responses to novel and particularly familiar animals, perhaps reflecting more general sleep‐associated improvements in task performance. Plausibly, microstructural sleep atypicalities in children with ASD and differences in how information is prioritized for consolidation may lead to cumulative consolidation difficulties, compromising the quality of newly formed semantic representations in long‐term memory.

Sleep Promotes Phonological Learning in Children Across Language and Autism Spectra

“…None of the log-transformed sleep variables considered here differed between AI groups (see Table 7). That being said, in a partially overlapping sample of 17 children with typical language ability and a diagnosis or pending diagnosis of ASD from the same cohort, presented in a separate article (Fletcher et al, 2019), it did show significantly reduced overall spindle power across Stages 2 and 3 when compared to 28 typically developing controls. We present sleep data from all the children who contributed data to the SleepSmart sample and provide group differences for all sleep parameters considered across each paper via the Open Science Framework at https://osf.io/82eqm/files/.…”

“…Testing was completed in a one-to-one setting with one of a small team of researchers and was conducted either at the child's home, at school, or in the Department of Psychology at the University of York. All children who completed behavioral testing for this study were also participants in a study of semantic learning, training and testing for which were completed during the Day1:PM and Day2:AM sessions (see Fletcher et al, 2019).…”

How do children with autism spectrum disorder form gist memory during sleep? A study of slow oscillation–spindle coupling

“…Due to the heterogeneity of the disorder itself and methodological differences among studies, no consistent pattern regarding microstructural sleep alterations in ASD has been identified so far [ 23 ]. Findings range from reduced spindle power [ 24 , 25 ] or spindle density [ 26 , 27 ] to increased delta [ 25 ] and theta power [ 28 ] in ASD children. Some studies did not find any remarkable differences for the spindle and SO characteristics and power between children with ASD and typically developing (TD) children [ 29 , 30 ].…”

Neural Responses to Novel and Existing Words in Children with Autism Spectrum and Developmental Language Disorders

“…Electrophysiological responses to highly familiar lexicalsemantic mismatch (e.g., a picture of a FROG paired with the word BRUSH) are weak in verbally-able children with ASD (McCleery et al, 2010). This attenuated neural response may result from a loss of lexical (Henderson et al, 2014) and semantic (Fletcher et al, 2019;Norbury et al, 2010) knowledge about new words over time, compared to TD children. Such semantic memory consolidation di culties in autism have been linked to atypicalities in sleep parameters (Fletcher et al, 2019).…”

“…This attenuated neural response may result from a loss of lexical (Henderson et al, 2014) and semantic (Fletcher et al, 2019;Norbury et al, 2010) knowledge about new words over time, compared to TD children. Such semantic memory consolidation di culties in autism have been linked to atypicalities in sleep parameters (Fletcher et al, 2019). Therefore, while DLD represents a case where early encoding is an issue, but longer-term maintenance may not be, ASD could represent the reverse.…”