Neural correlates of childhood language disorder: a systematic review

Abstract

ABBREVIATIONS ASDAutism understood. Yet there is increasing evidence that language disorder is associated with differences in brain structure and/or function in core language regions. A key hypothesis has been that children with language disorder do not show the same degree of leftward asymmetry of these regions as observed in typically developing children. We aimed to systematically review structural and functional magnetic resonance imaging (fMRI) studies to examine brain commonalities and differences between children with language disorder and typically developing controls; and differences in leftward asymmetry between these groups.METHOD A systematic review was conducted using MeSH terms synonymous with childhood language disorder and brain MRI methods. The search identified 1443 papers, and 18 articles met the criteria and were appraised for level and quality of evidence.RESULTS Atypical brain structure and function was reported within traditionally recognized language regions across studies, including the inferior frontal gyrus, posterior superior temporal gyrus, and caudate nucleus. The direction of difference (e.g. increased/decreased) was variable, however, likely because of differences in language disorder groups examined and magnetic resonance data acquisition and analysis approaches. As regards asymmetry, there was some evidence of reduction of the anticipated structural and functional leftward asymmetry in frontal language regions in language disorder groups.INTERPRETATION Mounting evidence suggests that children with language disorder have atypical brain structure and function within neural regions integral to language. There is limited support for the hypothesis that children with language disorder show a reduction of leftward structural and/or functional asymmetry in frontal language regions. Interpretation is limited, however, by a high degree of variability in language disorder assessment and phenotype, and in magnetic resonance methodologies. A large-scale magnetic resonance study of brain structure and function is required in a well-defined language disorder population cohort, with replication, to provide confirmatory data on the neural correlates of childhood language disorder.

What can autism teach us about the role of sensorimotor systems in higher cognition? New clues from studies on language, action semantics, and abstract emotional concept processing

“…It is highly likely that the motor deficits seen in the different developmental conditions, which may not always be distinguishable behaviourally, have differing neural origins, hence the different symptom complexes in these conditions. The neural substrates of motor dysfunction in DCD, ADHD and SLI have not received quite as much attention: there are many hypotheses regarding DCD but few with neurobiological support from brain imaging (see reviews by Brown-Lum &Zwicker, 2015, andGomez &Sirigu, 2015: of these, the corpus callosum, cerebellum, parietal lobe and basal ganglia are highlighted, but studies contain extremely small samples); studies of SLI have mainly focused on perisylvian language cortices (see Mayes, Reilly, & Morgan, 2015 for review, but note that these authors admit the confusion regarding classification of this condition across studies). ADHD and autism are commonly comorbid, both more commonly diagnosed in males 10 and seem to both be characterized by abnormal connectivity (Kern et al, 2015;Konrad & Eickhoff, 2010); they may be set apart by the concentration of dysconnectivity in particular regions.…”

ASD Validity

“…Both ASD and ID have been found with gene variants that cause impairment in many aspects of brain development and function, including neurogenesis, neuronal migration, synaptic function, and regulation of transcription and translation (Vissers et al 2016). Mayes et al (2015) found that language impairment in children without ASD was associated with atypical structure and function in traditional language regions including the inferior frontal gyrus, posterior superior temporal gyrus, and caudate nucleus. As noted earlier, Venkataraman et al (2015) reported that ASD included impaired brain connectivity in language regions including right temporal pole, left posterior cingulate cortex, left supramarginal gyrus, and left middle temporal gyrus.…”

Subcortical Brain and Behavior Phenotypes Differentiate Infants With Autism Versus Language Delay

“…Likewise, determining familial or disorder-specific risk factors in subgroups of infants at high-risk for ASD may improve the specificity of early identification efforts and investigations of causal pathways (42). For a review of neurobiological language disorder studies see (43, 44). …”