Altered lateralization of dorsal language tracts in 6‐week‐old infants at risk for autism

Abstract

Altered structural connectivity has been identified as a possible biomarker of autism spectrum disorder (ASD) risk in the developing brain. Core features of ASD include impaired social communication and early language delay. Thus, examining white matter tracts associated with language may lend further insight into early signs of ASD risk and the mechanisms that underlie language impairments associated with the disorder. Evidence of altered structural connectivity has previously been detected in 6-month-old infants at high familial risk for developing ASD. However, as language processing begins in utero, differences in structural connectivity between language regions may be present in the early infant brain shortly after birth. Here we investigated key white matter pathways of the dorsal language network in 6-week-old infants at high (HR) and low (LR) risk for ASD to identify atypicalities in structural connectivity that may predict altered developmental trajectories prior to overt language delays and the onset of ASD symptomatology. Compared to HR infants, LR infants showed higher fractional anisotropy (FA) in the left superior longitudinal fasciculus (SLF); in contrast, in the right SLF, HR infants showed higher FA than LR infants. Additionally, HR infants showed more rightward lateralization of the SLF.Across both groups, measures of FA and lateralization of these pathways at 6 weeks of age were related to later language development at 18 months of age as well as ASD symptomatology at 36 months of age. These findings indicate that early differences in the structure of language pathways may provide an early predictor of future language development and ASD risk. K E Y W O R D Sautism, development, DTI, infant, language, structural connectivity

Functional connectivity during language processing in 3‐month‐old infants at familial risk for autism spectrum disorder

“…As language function is dependent on the structural integrity of language networks, it is expected that infants who later develop ASD and language delay should exhibit aberrant trajectories in both structural and functional connectivity of language networks during the first year of life. A recent neuroimaging study of a subset of infants from our cohort has documented altered structural lateralization of language networks in FR infants at 6‐weeks of age (Liu et al., 2019).…”

Emerging atypicalities in functional connectivity of language-related networks in young infants at high familial risk for ASD

“…In addition, anatomical connections between frontal and temporal language regions subserve language production and syntactic processing ( Friederici, 2009 , 2011 ). These white matter tracts, which are critical for language development, are present in early infancy ( Liu et al, 2018 ; Perani et al, 2011 ) and are altered in HR infants as early as 1.5 months of age ( Liu et al, 2018 ). Our findings highlight that functional connectivity of these regions is also disrupted in HR infants.…”

“…In the present study, we focused on examining connectivity between regions canonically associated with language processing and sensorimotor integration. Structural factors such as cortical surface area ( Hazlett et al, 2017 ), subcortical volume ( Swanson et al, 2017 ), and white matter development ( Liu et al, 2018 ; Wolff et al, 2012 , 2017a , 2017b ) are also altered in HR infants and may influence functional connectivity of these networks. Future research should thus aim to integrate structural metrics with measures of functional connectivity in the developing brain in at-risk populations.…”

The neural basis for mental state attribution: A voxel‐based lesion mapping study

“…Several studies also found alterations in the SLF among individuals with ASD (Fitzgerald et al, 2018; Poustka et al, 2012; Weinstein et al, 2011). Moreover, a recent study showed that 6‐week‐old infants at risk for autism showed higher fractional anisotropy in the right SLF compared to low risk infants (Liu et al, 2019).…”