Brain imaging data from fetuses and infants show a sudden, dramatic surge in the level of functional connectivity across brain regions on a global scale between birth and the first few months of life, according to a study published on November 19 in the open-access journal PLOS Biology by Lanxin Ji and Moriah Thomason from New York University School of Medicine.
Understanding the development of brain functional networks in early human life is crucial. However, how human brain functional networks evolve and emerge during the birth transition remains largely unanswered. Thomason and colleagues bridge this knowledge gap by examining developmental trajectories of the brain’s functional networks spanning from 25 to 55 weeks of postconceptual gestational age, using a large functional magnetic resonance imaging dataset. 126 fetal scans and 58 infant scans from 140 subjects made up the final sample.
Distinct growth patterns arose in different regions among the researchers, revealing that neural changes during the birth transition are not universal across the brain. However, some brain areas showed barely any changes in resting-state functional connectivity (RSFC) — the degree of correlation between resting-state brain activity or BOLD signals in different parts of the brain. Other areas, however, had dramatic changes in RSFC at birth.
Regions in which reorganization is most rapid during this developmental stage include the subcortical network, sensorimotor network, and superior frontal network. Further analysis identified a significant increase in communication efficiency among neighboring nodes, but only in a subcortical network.
The subcortical network is a central hub of the network, relaying almost all the incoming and outgoing information to and from the cortex and engaging communication between cortical areas. Conversely, global efficiency steadily increased in sensorimotor and parietal-frontal regions from the fetal to neonatal state (T1–T2), potentially related to the development or strengthening of connections and the build-up and pruning of redundant ones.
The authors say that this work reveals fundamental aspects of early brain development and lays a foundation for future research on how environmental factors affect early brain development. More specifically, additional work could explore how sex, prematurity, and prenatal adversity impact children’s brain network development by the timing and growth pattern these develop over time.
The authors say, “This study, for the first time, documents the substantial change in brain functional networks across the birth transition. What we find is that growth patterns are specific to regions of the functional connectome, some areas changing little, others dramatically at birth”.
Reference: Ji L, Menu I, Majbri A, Bhatia T, Trentacosta CJ, Thomason ME. Trajectories of human brain functional connectome maturation across the birth transition. PLoS Biol. 2024;22(11):e3002909. Published 2024 Nov 19. doi:10.1371/journal.pbio.3002909
