Summary: Researchers identified widespread left-right differences in brain structure and function in regions tied to language and visual tasks such as face recognition in newborn infants. These asymmetries were present in both full-term and preterm babies scanned at the same postmenstrual age, suggesting that certain brain asymmetries are present at birth and may be intrinsic to early development.
Source: King’s College London
Researchers publishing in Nature Human Behaviour examined how asymmetric the left and right sides of newborns’ brains are—looking at both cortical shape and spontaneous activity patterns—to establish a reference for future studies that will explore links between brain asymmetry and neurodevelopmental or psychiatric conditions.
Previous work in older children and adults has shown links between altered brain asymmetry and a variety of cognitive and mental health conditions. However, there has been limited knowledge about how asymmetric the human brain is at birth. Because newborns cannot perform tasks in the scanner and their behaviour differs from that of older children and adults, it has been unclear whether the asymmetries seen later in life are already present at birth or emerge with development. This study directly addresses that gap.
The investigators analysed structural and functional MRI data from 442 healthy, term-born neonates (infants within the first month after birth) drawn from the Developing Human Connectome Project. To contextualize these findings, they compared asymmetry patterns in this term cohort with MRI data from 103 preterm neonates scanned at term-equivalent age, and with cortical structural asymmetries observed in 1,110 healthy young adults from the Human Connectome Project.
Across multiple cortical regions, the neonatal brain showed clear structural and functional asymmetries. Notably, asymmetries were present in areas typically associated with language processing and visual recognition in later life. When the researchers compared term-born infants with babies born prematurely but scanned at the same age, they found the same pattern of asymmetries. In other words, being born preterm did not appear to alter the presence of these early left-right differences.
Logan Williams, a Ph.D. student in the School of Biomedical Engineering & Imaging Sciences, commented that this result is striking given that preterm birth is known to impact many aspects of brain growth and organization. The persistence of typical asymmetry patterns despite prematurity suggests that some aspects of cortical lateralization are innate and may be established before or around the time of birth.
The similarity between neonatal and adult asymmetry patterns was not complete—there are developmental changes between birth and adulthood—but many foundational asymmetric features are already present in the newborn cortex. Establishing this neonatal baseline matters for future research: scientists can now compare individual infant data or patient groups against a detailed reference to better interpret when and how deviations in brain asymmetry may relate to later cognitive outcomes or disorders.
About this neurodevelopment research news
Author: Emma Robinson
Source: King’s College London
Contact: Emma Robinson – King’s College London
Image: The image is in the public domain
Original Research: Open access.
“Structural and functional asymmetry of the neonatal cerebral cortex” by Logan Z. J. Williams et al., Nature Human Behaviour
Abstract
Structural and functional asymmetry of the neonatal cerebral cortex
Features of brain asymmetry have been implicated in a broad range of cognitive processes, yet the developmental origins of these lateralized cortical features are not well understood.
In this study, cortical asymmetries were examined in 442 healthy term-born neonates using structural and functional magnetic resonance imaging from the Developing Human Connectome Project. The results show that the neonatal cortex already exhibits marked structural and functional left-right differences.
To better understand these findings, the term-born cohort was compared with 103 preterm neonates scanned at term-equivalent age and with structural asymmetries observed in 1,110 healthy young adults from the Human Connectome Project. Associations between asymmetry and factors such as preterm birth or biological sex were generally small, while measurable differences between neonatal and adult asymmetry patterns highlight ongoing developmental changes after birth.