The dogma that the adult mammalian brain is incapable of generating new neurons has been finally overcome, since neurogenesis in the adult brain was described in the subventricular zone (SVZ) adjacent to the lateral ventricles and in the subgranular zone (SGZ) in the dentate gyrus of the hippocampus (see figure).
In contrast to these two so-called neurogenic areas, the remainder of the brain is considered to be non-neurogenic, implying that no new neurons are produced there under normal conditions. This distinction seems critical, since various groups have shown that, at least under pathological conditions, neurogenesis can occur in brain areas other than SVZ and SGZ.
Neurogenic areas are defined by the presence of neurogenic cells and their neurogenesis-permissive microenvironment, which is likely to include both histological peculiarities and specific local soluble signals. The neurogenic behavior of the progenitor cells throughout adult life appears determined by environmental signals in their niche. Still, populations of neural stem cells (NSCs) with neurogenic potential have been reported to exist in the normal adult cortex, amygdala, dorsal vagal complex of the adult brainstem, area CA1 of the hippocampus, substantia nigra, spinal cord, hypothalamus, striatum and white matter tracts (see figure). Even though the generation of neurons from NSCs in vivo in these regions remains controversial, the majority of the available data support the view that the potential of the NSCs is restricted by inhibitory cues, thus defining these brain areas as being primarily non-neurogenic in nature.
Arias-Carrión O, Yamada E, Freundlieb N, Djufri M, Maurer L, Hermanns G, Ipach B, Chiu WH, Steiner C, Oertel WH, Höglinger GU. Neurogenesis in substantia nigra of Parkinsonian brains? J Neural Transm Suppl 73:279-85 (2009)
Depboylu C, Schäfer MKH, Arias-Carrión O, Oertel WH, Weihe E, Höglinger GU. Possible Involvement of complement factor C1q in the clearance of extracellular neuromelanin from the substantia nigra in Parkinson’s disease. J Neuropathol Exp Neurol 70 (2) 125-132 (2011)
Arias-Carrión O, Freundlieb N, Oertel WH, Höglinger GU. Adult Neurogenesis and Parkinson’s disease. CNS Neurol Disord Drug Targets 6:326-35 (2007)
References
Arias-Carrión O, Yamada E, Freundlieb N, Djufri M, Maurer L, Hermanns G, Ipach B, Chiu WH, Steiner C, Oertel WH, Höglinger GU. Neurogenesis in substantia nigra of Parkinsonian brains? J Neural Transm Suppl 73:279-85 (2009)
Depboylu C, Schäfer MKH, Arias-Carrión O, Oertel WH, Weihe E, Höglinger GU. Possible Involvement of complement factor C1q in the clearance of extracellular neuromelanin from the substantia nigra in Parkinson’s disease. J Neuropathol Exp Neurol 70 (2) 125-132 (2011)
Arias-Carrión O, Freundlieb N, Oertel WH, Höglinger GU. Adult Neurogenesis and Parkinson’s disease. CNS Neurol Disord Drug Targets 6:326-35 (2007)
Arias-Carrión O, Drucker-Colín R. Neurogenesis as a therapeutic strategy to regenerate central nervous system. Rev Neurol 45: 739-745 (2007)
Arias-Carrión O. Basic mechanisms of rTMS: Implications in Parkinson's disease. Int Arch Med 1(1):2 (2008)
Yuan TF, Arias-Carrión O. Adult neurogenesis in the hypothalamus: Evidences, functions and implications. CNS Neurol Disord Drug Targets 10(4):433-439 (2011)
