The Ongoing Debate about Hippocampal Neurogenesis in Adult Humans is over.

modified from Franjic et al. (2022). Cross-species comparison shows transcriptomic signatures of neurogenesis in the hippocampus of adult mouse, pig, and monkey— but not human.Does the adult brain generate new neurons throughout the lifespan? The prevailing view in most of the 20th century was that no new neurons are born in the mammalian brain once development ceases. A series of studies inthe 1960s showed otherwise, but these were ignoreduntil the 1990s. A now-historical paper from 2000 recounted thedeath of a dogma: adult neurogenesis is here to stay,even in humans. Thousand of studies in animals (mostly rodents) demonstrated that new neurons are born in the dentate gyrus region of the adult hippocampus, and they can play an important role in learning and memory.More recently, several papers have questioned whether adult humans really do generate new neurons in the hippocampus (Sorrells et al, 2018,2021;Franjic et al., 2022). One such paper examined the morphology of dentate gyrus cells taken from post-mortem brains and from tissue surgically removed from epilepsy patients, with ages ranging from prenatal to elderly (Sorrells et al, 2018). The presence of progenitor cells and young neurons was determined usingimmunohistochemistry (selective staining methods, visible in green and yellow below).– click on images for larger view–modified from Fig 2a (Sorrells et al, 2018). Human dentate gyrus (DG) proliferation declines sharply during infancy.modified from Fig 3d (Sorre...

Source: The Neurocritic - February 28, 2022 Category: Neuroscience Authors: The Neurocritic Source Type: blogs