Objectives: To examine whether HRA infants show atypical electrophysiological response to words, and if so whether this is more closely linked to language delay, autism symptoms, or both.
Methods: As part of a larger longitudinal study, we recorded ERPs to words in HRA infants and low-risk control (LRC) infants at 18 (HRA n=26; LRC n=25) and 24 months (HRA n=28; LRC n=18). Participants listened to a stream of words, half of which were known to the infant (confirmed with parent report) and half of which were unknown. The Mullen Scales of Early Learning (MSEL) and Autism Diagnostic Observation Schedule (ADOS) were administered at both ages in order to obtain indices of language ability and autism symptoms.
Results: Grand averaged waveforms revealed a negative inflection maximal over posterior electrodes (N200). A preliminary analysis from a subset of 17 HRA and 10 LRC infants at 18 months indicated that this N200 was larger to known than unknown words in LRC infants over the left parietal region (p=.002). In contrast, this difference was not significant in HRA infants, although they did show a trend in the same direction (p=.095). Planned analyses will examine this component in infants at 24 months and will explore the relationship between N200, language ability, and autism symptoms at both ages.
Conclusions: We have preliminary evidence that HRA infants do not show the same pattern of response to words as LRC at 18 months. This suggests that atypical processing of lexical stimuli may be a trait of the ASD endophenotype. Our work will investigate the nature of this atypical processing with the hope of identifying whether this is driven by infants with delayed language or by infants who are displaying symptoms of ASD.
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See more of: Brain Structure & Function