Commentary: Cerebral Lateralization is Protective in the Very Prematurely Born

The cerebral hemispheres of the human brain have unique functional properties of information processing; an asymmetry that captures cerebral lateralization. Among cognitive functions, language is one of the most lateralized with left-sided dominance for the production and processing of language. Previous work has shown that the foundation of language circuitry emerges in the late second and third trimesters in developing fetuses, supported by a genetically driven phase of development (Pinel et al., 2012; Thomason et al., 2014). The significance of this developmental period in the neonate is underlined from research in individuals born preterm who show altered brain development, and who are at risk for developmental delays and impairments in neuropsychological performance such as deficits in language processing (Poggi Davis et al., 2011; Kwon et al., 2014). Due to advanced MRI techniques, new and detailed insights can be obtained from changes to the typical developmental pattern of cerebral lateralization. Scheinost et al. (2015) examined cerebral lateralization in adolescents who were born very preterm (VPT, with a mean gestational age of <30 weeks) in order to test the hypothesis that preterm birth remodels the intrinsic functional infrastructure of the brain. The authors made use of resting-state functional magnetic resonance imaging (rs-fMRI) alongside a novel voxel-based approach that estimates connectivity lateralization without the requirement to predefine regions of interest. Measuring brain connectivity at rest provides a powerful method for unraveling the neural correlates of the cognitive systems they support. A correlation analysis between the connectivity lateralization patterns and language performance—the Peabody Picture Vocabulary Test-Revised—was calculated for assessing an association between brain function and behavior. The data of the VPT group showed clusters of significant correlations between the language task and connectivity lateralization in left-sided frontal-temporal language regions and their right hemisphere homologs. In particular, a positive correlation was noted between the language task and connectivity lateralization in the left-sided areas whereas the correlation was negative between the language task and the right-sided regions. Most successful on the language task were the VPT individuals with the strongest lateralization in the left hemisphere and lowest lateralization in the right hemisphere, underlining the strength of the typical left-sided pattern alongside a rebalancing of activity within the existing neural circuitry. A further observation for the VPT individuals was that the right-sided language homolog regions highly correlated with one other, with the right angular gyrus operating as a functional integration hub that supported not only the intrahemispheric …