Search results for "ADULT NEUROGENESIS"
showing 10 items of 30 documents
PSA-NCAM is expressed in immature, but not recently generated, neurons in the adult cat cerebral cortex layer II
2011
Neuronal production persists during adulthood in the dentate gyrus and the olfactory bulb, where substantial numbers of immature neurons can be found. These cells can also be found in the paleocortex layer II of adult rodents, but in this case most of them have been generated during embryogenesis. Recent reports have described the presence of similar cells, with a wider distribution, in the cerebral cortex of adult cats and primates and have suggested that they may develop into interneurons. The objective of this study is to verify this hypothesis and to explore the origin of these immature neurons in adult cats. We have analyzed their distribution using immunohistochemical analysis of the …
Neural Stem Cell Regulation by Adhesion Molecules Within the Subependymal Niche
2019
In the mammalian adult brain, neural stem cells persist in neurogenic niches. The subependymal zone is the most prolific neurogenic niche in adult rodents, where residing stem cells generate large numbers of immature neurons that migrate into the olfactory bulb, where they differentiate into different types of interneurons. Subependymal neural stem cells derive from embryonic radial glia and retain some of their features like apico-basal polarity, with apical processes piercing the ependymal layer, and a basal process contacting blood vessels, constituting an epithelial niche. Conservation of the cytoarchitecture of the niche is of crucial importance for the maintenance of stem cells and fo…
Neural stem cells in the adult olfactory bulb core generate mature neurons in vivo.
2021
17 páginas, 7 figuras.
Cocaine and MDMA Induce Cellular and Molecular Changes in Adult Neurogenic Systems: Functional Implications
2011
The capacity of the brain to generate new adult neurons is a recent discovery that challenges the old theory of an immutable adult brain. A new and fascinating field of research now focuses on this regenerative process. The two brain systems that constantly produce new adult neurons, known as the adult neurogenic systems, are the dentate gyrus (DG) of the hippocampus and the lateral ventricules/olfactory bulb system. Both systems are involved in memory and learning processes. Different drugs of abuse, such as cocaine and MDMA, have been shown to produce cellular and molecular changes that affect adult neurogenesis. This review summarizes the effects that these drugs have on the adult neurog…
Olfactory and cortical projections to bulbar and hippocampal adult-born neurons
2015
New neurons are continually generated in the subependymal layer of the lateral ventricles and the subgranular zone of dentate gyrus during adulthood. In the subventricular zone, neuroblasts migrate a long distance to the olfactory bulb where they differentiate into granule or periglomerular interneurons. In the hippocampus, neuroblasts migrate a short distance from the subgranular zone to the granule cell layer of the dentate gyrus to become granule neurons. In addition to the short-distance inputs, bulbar interneurons receive long-distance centrifugal afferents from olfactory-recipient structures. Similarly, dentate granule cells receive differential inputs from the medial and lateral ento…
Occurrence of new neurons in the piriform cortex
2015
In a recent mini-review (Yuan et al., 2015), support is given to the idea that neurons are generated during adulthood in the mammalian piriform cortex (PC), their periventricular origin being also discussed. It is known since long time that a subpopulation of cortical layer II cells in the adult PC of rodents express immature neuronal markers such as polysialylated NCAM (PSA-NCAM; Seki and Arai, 1991; Bonfanti et al., 1992) and doublecortin (DCX; Nacher et al., 2002). These immature neurons have been found in most mammals studied so far, their occurrence being restricted to the paleocortex in rodents (Seki and Arai, 1991; Bonfanti et al., 1992; Nacher et al., 2002), and extended to neocorti…
Axons take a dive
2014
In the walls of the lateral ventricles of the adult mammalian brain, neural stem cells (NSCs) and ependymal (E1) cells share the apical surface of the ventricular-subventricular zone (V-SVZ). In a recent article, we show that supraependymal serotonergic (5HT) axons originating from the raphe nuclei in mice form an extensive plexus on the walls of the lateral ventricles where they contact E1 cells and NSCs. Here we further characterize the contacts between 5HT supraependymal axons and E1 cells in mice, and show that suprependymal axons tightly associated to E1 cells are also present in the walls of the human lateral ventricles. These observations raise interesting questions about the functio…
Functional hypoxia drives neuroplasticity and neurogenesis via brain erythropoietin.
2020
Erythropoietin (EPO), named after its role in hematopoiesis, is also expressed in mammalian brain. In clinical settings, recombinant EPO treatment has revealed a remarkable improvement of cognition, but underlying mechanisms have remained obscure. Here, we show with a novel line of reporter mice that cognitive challenge induces local/endogenous hypoxia in hippocampal pyramidal neurons, hence enhancing expression of EPO and EPO receptor (EPOR). High-dose EPO administration, amplifying auto/paracrine EPO/EPOR signaling, prompts the emergence of new CA1 neurons and enhanced dendritic spine densities. Single-cell sequencing reveals rapid increase in newly differentiating neurons. Importantly, i…
New scenarios for neuronal structural plasticity in non-neurogenic brain parenchyma: the case of cortical layer II immature neurons
2011
The mammalian central nervous system, due to its interaction with the environment, must be endowed with plasticity. Conversely, the nervous tissue must be substantially static to ensure connectional invariability. Structural plasticity can be viewed as a compromise between these requirements. In adult mammals, brain structural plasticity is strongly reduced with respect to other animal groups in the phylogenetic tree. It persists under different forms, which mainly consist of remodeling of neuronal shape and connectivity, and, to a lesser extent, the production of new neurons. Adult neurogenesis is mainly restricted within two neurogenic niches, yet some gliogenic and neurogenic processes a…
Increasing Neural Stem Cell Division Asymmetry and Quiescence Are Predicted to Contribute to the Age-Related Decline in Neurogenesis.
2018
Summary: Adult murine neural stem cells (NSCs) generate neurons in drastically declining numbers with age. How cellular dynamics sustain neurogenesis and how alterations with age may result in this decline are unresolved issues. We therefore clonally traced NSC lineages using confetti reporters in young and middle-aged adult mice. To understand the underlying mechanisms, we derived mathematical models that explain observed clonal cell type abundances. The best models consistently show self-renewal of transit-amplifying progenitors and rapid neuroblast cell cycle exit. In middle-aged mice, we identified an increased probability of asymmetric stem cell divisions at the expense of symmetric di…