Many cells in the human body can divide and reproduce, making healing possible. Neurons, however, cannot reproduce, which makes diseases affecting the brain particularly crippling. Why can't neurons divide - that is, what makes them different from "normal" cells? Are there any ways to artificially stimulate neuron cell division?
Answer
Neurons do not divide due to the reasons mentioned in Cornelius's answer. However, some new neurons can be generated in adults (Ref: Neuroscience, 2nd edition).
Generation of new neurons in adults was first demonstrated in birds, where labeled DNA precursors could be found in differentiated neurons. Experiments in mammals and humans demonstrated later that new neurons are created in the central nervous system (CNS) in adults, although it seems to be restricted to some particular regions: granule cell layer of the olfactory bulb and dentate gyrus of the hippocampus. These new neurons seem to be local circuit neurons and interneurons (i.e. no long distance neurons).
How are the new neurons produced if neurons cannot divide? They come from neural stem cells (NSCs) that were preserved in the sub-ventricular zone during development. NSCs are presumed to play a part in brain plasticity in the adult brain. However, they have therapeutic potential. Check the brief information in wikipedia), or this perspective in Nature neuroscience that may contain further details.
References:
- Neuroscience, 2nd edition. Purves D, Augustine GJ, Fitzpatrick D, et al., editors. Sunderland (MA): Sinauer Associates; 2001.
- Gene therapy: can neural stem cells deliver? Müller FJ, Snyder EY, Loring JF. Nat Rev Neurosci. 2006 Jan;7(1):75-84. Review. Erratum in: Nat Rev Neurosci. 2006 Feb;7(2):167. PMID: 16371952 [PubMed - indexed for MEDLINE]
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