Language lateralization in very preterm children: associating dichotic listening to interhemispheric connectivity and language performance

Abstract

BACKGROUND: Language difficulties of very preterm (VPT) children might be related to weaker cerebral hemispheric lateralization of language. Language lateralization refers to the development of an expert region for language processing in the left hemisphere during the first years of life. Children born VPT might not develop such a dominant left hemisphere for language processing. A dichotic listening task may be a functional task to show the dominance of the left hemisphere during language processing. During this task, different acoustic events are simultaneously presented to both ears. Due to crossing fibers in the brain, right ear stimuli are transferred directly to the left hemisphere, and left ear stimuli are transferred first to the right hemisphere and then, through the corpus callosum (CC), to the left hemisphere. Dichotic listening typically shows a right ear advantage, assuming to reflect left hemispherical language dominance. The CC, in particular the splenium, is associated with auditory processing and is considered important for language lateralization. The objective of this work was to explore whether dichotic listening performance in schoolaged VPT children are associated with language performance and interhemispheric connectivity. METHODS: This is a cross-sectional study of 58 VPT children and 30 full term controls at age 10 years. Language performance and dichotic digit test (DDT) were assessed. In 44 VPT children, additionally diffusion weighted imaging (DWI) was performed using a 3 T MRI scanner. Fractional anisotropy (FA) and mean diffusivity (MD) values of the splenium of the CC were extracted. RESULTS: Poorer right ear DDT scores were associated with poorer language performance in VPT children only (p = 0.015). Association between right ear DDT scores and MD of the splenium approached the level of significance (p = 0.051). CONCLUSIONS: These results support the hypothesis that poor language performance in VPT children may be a consequence of weaker lateralized language organization, due to a poorly developed splenium of the CC. Dichotic listening may reflect the level of language lateralization in VPT children.

Occupation-modulated language networks and its lateralization: A resting-state fMRI study of seafarers

“…Based on seed regions in Broca and Wernicke, seed-based RSFC were applied to the characterization and reproducibility of functional connectivity of language networks ( Tomasi and Volkow, 2012 ; Zhu et al, 2014 ; Wang et al, 2019 ). Meanwhile, language lateralization has been widely approached to detect different patterns in children ( Phillips et al, 2021 ; Stipdonk et al, 2021 ), tumors ( Połczyńska et al, 2021 ), psychiatric disorders ( Jouravlev et al, 2020 ), and neurological disorders ( Rolinski et al, 2020 ).…”

Analysis of distributions reveals real differences on dichotic listening scores between left- and right-handers

“…Another reason that the focus on hemispheric specialization has faded from the dichotic listening literature to some extent is the emergence of newer technologies such as fMRI. However, dichotic listening only requires headphones and a digital device, is quick to administer, and is well suited for large sample efforts with university undergraduates, younger people, and individuals for whom scanning is unpleasant or impossible ( Stipdonk et al. 2022 ).…”