eLife assessment
This important study details the development of brain functional connectivity in a longitudinal cohort of Gambian children assessed outside a lab setup with functional near-infrared spectroscopy (fNIRS) from age 5 to 24 months, in relation to early physical growth and cognitive flexibility capacities at 4-5 years of age. Although the evidence supporting some conclusions is solid, the relevance of the results would be improved by defining clearer hypotheses regarding the developmental changes expected for the different connections, and by discussing the unexpected findings on early negative connectivity and connectivity decreases. Considering more advanced analytical approaches would allow the authors to deal with longitudinal data and integrate mediation links, even if the study might be underpowered to link adverse conditions such as undernutrition and later cognitive development. This study will be of interest to neuroscientists, psychologists, and neuroimaging researchers working on infant development in relation to environmental factors.