TY - JOUR TI - Phylogenetic variation in cortical layer II immature neuron reservoir of mammals AU - La Rosa, Chiara AU - Cavallo, Francesca AU - Pecora, Alessandra AU - Chincarini, Matteo AU - Ala, Ugo AU - Faulkes, Chris G AU - Nacher, Juan AU - Cozzi, Bruno AU - Sherwood, Chet C AU - Amrein, Irmgard AU - Bonfanti, Luca A2 - Dulac, Catherine A2 - Lucassen, Paul A2 - Lucassen, Paul A2 - Kempermann, Gerd VL - 9 PY - 2020 DA - 2020/07/21 SP - e55456 C1 - eLife 2020;9:e55456 DO - 10.7554/eLife.55456 UR - https://doi.org/10.7554/eLife.55456 AB - The adult mammalian brain is mainly composed of mature neurons. A limited amount of stem cell-driven neurogenesis persists in postnatal life and is reduced in large-brained species. Another source of immature neurons in adult brains is cortical layer II. These cortical immature neurons (cINs) retain developmentally undifferentiated states in adulthood, though they are generated before birth. Here, the occurrence, distribution and cellular features of cINs were systematically studied in 12 diverse mammalian species spanning from small-lissencephalic to large-gyrencephalic brains. In spite of well-preserved morphological and molecular features, the distribution of cINs was highly heterogeneous, particularly in neocortex. While virtually absent in rodents, they are present in the entire neocortex of many other species and their linear density in cortical layer II generally increased with brain size. These findings suggest an evolutionary developmental mechanism for plasticity that varies among mammalian species, granting a reservoir of young cells for the cerebral cortex. KW - immature neurons KW - neocortex KW - doublecortin KW - brain size KW - mammals JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -