Adult neurogenesis in the mammalian dentate gyrus

Abstract

Earlier observations in neuroscience suggested that no new neurons form in the mature central nervous system. Evidence now indicates that new neurons do form in the adult mammalian brain. Two regions of the mature mammalian brain generate new neurons: (a) the border of the lateral ventricles of the brain (subventricular zone) and (b) the subgranular zone (SGZ) of the dentate gyrus of the hippocampus. This review focuses only on new neuron formation in the dentate gyrus of the hippocampus. During normal prenatal and early postnatal development, neural stem cells (NSCs) give rise to differentiated neurons. NSCs persist in the dentate gyrus SGZ, undergoing cell division, with some daughter cells differentiating into functional neurons that participate in learning and memory and general cognition through integration into pre‐existing neural networks. Axons, which emanate from neurons in the entorhinal cortex, synapse with dendrites of the granule cells (small neurons) of the dentate gyrus. Axons from granule cells synapse with pyramidal cells in the hippocampal CA3 region, which send axons to synapse with CA1 hippocampal pyramidal cells that send their axons out of the hippocampus proper. Adult neurogenesis includes proliferation, differentiation, migration, the death of some newly formed cells and final integration of surviving cells into neural networks. We summarise these processes in adult mammalian hippocampal neurogenesis and discuss the roles of major signalling molecules that influence neurogenesis, including neurotransmitters and some hormones. The recent controversy raised concerning whether or not adult neurogenesis occurs in humans also is discussed.

Involvement of the hippocampus in chronic pain and depression

“…Hippocampal abnormalities, including impaired neuroplasticity and enriched-environment neurogenesis, have been associated with a different mechanism in chronic pain conditions [53]. At least two specific anatomical regions, the subventricular zone of the lateral ventricles and the subgranular zone of the dentate gyrus in the hippocampus, have been reported to be involved in the neurogenesis of the adult mammalian brain [54,55]. Adult hippocampal neurogenesis is associated with learning and memory [56], and findings suggest that reduced neurogenesis in the hippocampus region is involved in various neuropsychiatric disorders, including anxiety [57], depression [58], stress [59], and impaired contextual fear conditioning [60].…”

Investigation of alpl expression and Tnap-activity in zebrafish implies conserved functions during skeletal and neuronal development

“…Compared to zebrafish, the mammalian brain shows only limited capability of adult neurogenesis. Novel formation of neurons in adult brains is only possible in the subventricular zone (SVZ) of the lateral ventricles and the subgranular zone of the hippocampal dentate gyrus in humans 56 . Interestingly, Tnap-activity is indeed located in the ventricular and SVZ of mice including zones of adult neurogenesis 57 .…”

The Role of Alpha-Synuclein and Other Parkinson’s Genes in Neurodevelopmental and Neurodegenerative Disorders

“…Adult neurogenesis of the brain occurs in the subventricular zone (SVZ), also termed the subependymal zone (SEZ), and dentate gyrus of the hippocampus and contributes to neuronal plasticity [ 217 , 218 , 219 , 220 , 221 ], although there is some recent controversy around human adult hippocampal neurogenesis [ 222 , 223 , 224 ]. In addition, there is evidence that ischemic trauma can stimulate neurogenesis in human and rodent models [ 225 ], and a recent study described neurogenesis in the adult striatum using carbon-14 dating and IHC for neuronal progenitors [ 226 ].…”