The correct development of the brain cortex is an essential process for the acquisition of correct cognitive skills. Reelin (image), a key extracellular protein in neuronal migration and synaptic plasticity, is determinant in this process. For this reason, the dysfunction--genetic or at an expression level--of this protein is involved in neurodevelopmental pathologies —such as lissencephalies, epilepsy, or some psychiatric disorders, particularly autism, schizophrenia and bipolar disorder--or neurodegenerative diseases. Now, an article published on September 6, 2022 in PNAS reveals the decisive role of reelin expressed by the Cajal-Retzius pioneer neurons (CR) or cortical GABAergic neurons in the process of corticogenesis and neuronal migration. The study was led by Professor Eduardo Soriano, from the Department of Cell Biology, Physiology and Immunology of the Faculty of Biology and the Institute of Neurosciences (UBNeuro) of the University of Barcelona, and the Biomedical Research Networking Center on Neurodegenerative Diseases (CIBERNED), and its first authors are the researchers Alba Vílchez and Yasmina Manso (UB-UBNeuro-CIBERNED). The PNAS article is titled “Specific Contribution of Reelin Expressed by Cajal–Retzius Cells or GABAergic Interneurons to Cortical Lamination.”