One of the most widely cited features of the neural phenotype of autism is reduced "integrity" of long-range white matter tracts, a claim based primarily on diffusion imaging studies. However, many prior studies have small sample sizes and/or fail to address differences in data quality between those with autism spectrum disorder (ASD) and typical participants, and there is little consensus on which tracts are affected. To overcome these problems, we scanned a large sample of children with autism (n = 52) and typically developing children (n = 73). Data quality was variable, and worse in the ASD group, with some scans unusable because of head motion artifacts. When we follow standard data analysis practices (i.e., without matching head motion between groups), we replicate the finding of lower fractional anisotropy (FA) in multiple white matter tracts. However, when we carefully match data quality between groups, all these effects disappear except in one tract, the right inferior longitudinal fasciculus (ILF). Additional analyses showed the expected developmental increases in the FA of fiber tracts within ASD and typical groups individually, demonstrating that we had sufficient statistical power to detect known group differences. Our data challenge the widely claimed general disruption of white matter tracts in autism, instead implicating only one tract, the right ILF, in the ASD phenotype.diffusion-weighted imaging | connectivity W hat is the key difference in the brains of individuals with autism that accounts for the distinctive cognitive profile of this disorder? One of the most widely claimed brain signatures of autism spectrum disorder (ASD), reported in dozens of papers that used diffusion-weighted imaging (DWI), is reduced integrity of long-range fiber tracts (1). This finding has been taken as evidence that autism is fundamentally a "disconnection" syndrome, in which the core cognitive deficits result from reduced integration of information at the neural and cognitive levels (2-5). For example, it has been argued that the characteristic deficits in social cognition and language arise because these functions require rapid integration of information across spatially distant brain areas (3, 6, 7), which would likely be affected if major white matter tracts are compromised.Evidence for a general reduction in the "integrity"* of white matter in autism has come primarily from diffusion imaging studies that report reduced directionality of the diffusion of water molecules, or fractional anisotropy (FA), and increased speed of diffusion, or mean diffusivity (MD) of many major fiber bundles. However, the literature reveals little actual agreement on the existence and direction of group differences in diffusion parameters (reviewed in ref. 1). White-matter differences have been reported in various brain regions in positive and negative directions. Possible reasons for these inconsistent findings include small sample sizes [mean of ∼20 in each group, with 40% of studies scanning 15 or fewer participants with ASD (1)...

This study examined sequential associations between child play and caregiver talk in 98 caregiver-child dyads (M = 14 months). Fifty dyads included a child with autism spectrum disorder (ASD). Analyses revealed sequential associations between child play and caregiver follow-in (FI) utterances (utterances related to the child's attentional focus) were stronger in the ASD as compared to the typically developing (TD) group. FI utterances were more likely to elicit functional play than caregiver-focused utterances, and more so in the ASD group. Across groups, FI directives were more likely to elicit functional play than FI comments. These findings have important implications for research involving caregiver-child play as an early intervention context for children with ASD.

Adults and children recruit a specific network of brain regions when engaged in "Theory of Mind" (ToM) reasoning. Recently, fMRI studies of adults have used multivariate analyses to provide a deeper characterization of responses in these regions. These analyses characterize representational distinctions within the social domain, rather than comparing responses across preferred (social) and non-preferred stimuli. Here, we conducted opportunistic multivariate analyses in two previously collected datasets (Experiment 1: n=20 5-11 year old children and n=37 adults; Experiment 2: n=76 neurotypical and n=29 5-12 year old children diagnosed with Autism Spectrum Disorder (ASD)) in order to characterize the structure of representations in the developing social brain, and in order to discover if this structure is disrupted in ASD. Children listened to stories that described characters' mental states (Mental), non-mentalistic social information (Social), and causal events in the environment (Physical), while undergoing fMRI. We measured the extent to which neural responses in ToM brain regions were organized according to two ToM-relevant models: 1) a condition model, which reflected the experimentergenerated condition labels, and 2) a data-driven emotion model, which organized stimuli according to their emotion content. We additionally constructed two control models based on linguistic and narrative features of the stories. In both experiments, the two ToM-relevant models outperformed the control models. The fit of the condition model increased with age in neurotypical children. Moreover, the fit of the condition model to neural response patterns was reduced in the RTPJ in children diagnosed with ASD. These results provide a first glimpse into the conceptual structure of information in ToM brain regions in childhood, and suggest that there are real, stable features that predict responses in these regions in children. Multivariate analyses are a promising approach for sensitively measuring conceptual and neural developmental change and individual differences in ToM.

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