Because preterm newborns nowadays may show long-term brain microstructural alterations, including decreased white matter myelination [a clinical hallmark of preterm brain disorder (1)] and a reduced number of cortical interneurons (27), we investigated whether interfering with IGF-1 signaling early in development leads to similar alterations in JB1-treated mice when they are adolescents. This evidence concerns the gene IGF1 and brain disorder.