Functional neurogenesis in the adult hippocampus Icq interracial chat
While the precise functional implications of the continuous production of new neurons with hyperexcitability and enhanced synaptic plasticity are still under intense investigation, it has become increasingly apparent that neurogenesis in the adult DG contributes to various types of hippocampus-dependent learning and memory.The first definitive evidence was provided by the demonstration that a substantial reduction in the number of newly generated DGCs by an antimitotic agent MAM disrupted trace eye-blink conditioning and trace fear conditioning, both of which are regarded to be hippocampus-dependent .Neuroblasts migrate into the granule cell layer (GCL) and differentiate into dentate granule cells (DGCs).Newborn DGCs gradually develop elaborate dendritic trees in the molecular layer (Mol) to receive inputs from the EC and project to CA3 pyramidal neurons (red) as well as hilar interneurons (blue).The gradual intraneuronal accumulation of neurofibrillary tangles formed as a result of abnormal hyperphosphorylation of cytoskeletal tau protein, extracellular deposition of amyloid-β (Aβ) protein as senile plaques, and massive neuronal death represent important neuropathological hallmarks of AD .The hippocampus is a mammalian brain structure that lies under the medial temporal lobe, with one on each side of the brain.Although there is a lack of consensus relating to terms describing the hippocampus and its adjacent cortex, the term hippocampus or hippocampal formation generally applies to the dentate gyrus (DG), the hippocampus proper - composed of CA1, CA2 and CA3 fields - and the subiculum.
They coexist with actively proliferating nonradial NSCs (type 2 cells) that generate both astrocytes and neuroblasts.
These cells have been hypothesized to be the quiescent stem cells that generate the second type of NSC, the actively self-amplifying, nonradial type 2 cells.
These intermediate cells, expressing Sox2, Nestin but not GFAP, subsequently give rise to DCX neuroblasts that differentiate into glutamatergic dentate granule cells (DGCs) populating the inner third of the granule cell layer.
Additionally, intrinsic factors such as mi RNAs, transcription factors, cell-cycle regulators, and epigenetic factors exhibit cell-autonomous characteristics that provide adult NSCs with the potential to proliferate, differentiate, and survive as newborn neurons.
Comprehensive reviews on this subject can be found elsewhere [ Neurogenesis in the adult hippocampus.