Although children with ASD show significant variation in language skills, research on what type(s) of language profiles they demonstrate has been limited. Using growth-curve analyses, we investigated how different groups of young children with ASD show increases in the size of their lexicon, morpho-syntactic production as measured by Brown’s 14 grammatical morphemes, and wh-question complexity, compared to TD children, across six time points. Children with ASD who had higher verbal skills were comparable to TD children on most language measures, whereas the children with ASD who had low verbal skills had flatter trajectories in most language measures. Thus, two distinct language profiles emerged for children with ASD.

No abstract

It has long been noted that listeners use top-down information from context to guide perception of speech sounds. A recent line of work employing a phenomenon termed ‘perceptual learning for speech’ shows that listeners use top-down information to not only resolve the identity of perceptually ambiguous speech sounds, but also to adjust perceptual boundaries in subsequent processing of speech from the same talker. Even so, the neural mechanisms that underlie this process are not well understood. Of particular interest is whether this type of adjustment comes about because of a retuning of sensitivities to phonetic category structure early in the neural processing stream or whether the boundary shift results from decision-related or attentional mechanisms further downstream. In the current study, neural activation was measured using fMRI as participants categorized speech sounds that were perceptually shifted as a result of exposure to these sounds in lexically-unambiguous contexts. Sensitivity to lexically-mediated shifts in phonetic categorization emerged in right hemisphere frontal and middle temporal regions, suggesting that the perceptual learning for speech phenomenon relies on the adjustment of perceptual criteria downstream from primary auditory cortex. By the end of the session, this same sensitivity was seen in left superior temporal areas, which suggests that a rapidly-adapting system may be accompanied by more slowly evolving shifts in regions of the brain related to phonetic processing.