As we know that the neurons can make new connections (synaptogenesis) and it also undergoes synaptic plasticity mechanisms(strengthen/weak) the connections between neurons over time. Very recently, I read that Hippocampal region retains its ability to build new neurons throughout life even in adult mammalian brains. I am very curious to know why Neurogenesis happens (Does it mean, the brain doesn't have enough resource to process information) and at what rate it occurs? If new cells born, then what happen to the old cells (Then how does brain maintain balance between Excitatory and inhibitory neuron population?).
Please, read the following paper:
Guo-li Ming and Hongjun Song. Adult Neurogenesis in the Mammalian Brain: Significant Answers and Significant Questions. Neuron. 2011 May 26; 70(4): 687–702.
I am happy to contact you, neuron cells weren't can replicate or division to form new neural cells because it specialized cells, but may be created by the stem cell therapy to forms new neural cells.
Thank you @Ahmed R. G. for the reference and though the article is lengthy, but is quite worth reading, Thanks again.
Thank you Ahmed Al-Mukhtar, Neural cells are amitotic but restricted regions of the brain (Olfactory bulb and Hippocampus) consistently (symmetrically) develop new cells. Reference here for you, https://www.ncbi.nlm.nih.gov/books/NBK10920/
Thanks again
It is very unlikely that the neurons that we had at birth remain after many years in the nervous system; as all other cells in the organism, neurons progressively die during our lives; so neurogenesis should occur to compensate the progressive loss of neurons. Stem cells appear to cover this requirement; unfortunately stem cells in mammals don´t work as fast as needed during neurodegenerative diseases, like Parkinson; Alzheimer ; or Retinitis Pigmentosa. By knowing more precisely how to control stem cells we hope these diseases may be controlled or , eventually, cured in a future.
Follow the link for a 2016 review of the literature:
Adult Mammalian Neural Stem Cells and Neurogenesis: Five Decades Later
Bond et al
https://dx.doi.org/10.1016%2Fj.stem.2015.09.003
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4683085/
1) Why neurogenesis occurs?: Considering a condition such as major depressive disorder and demonstrating that the hippocampus in depressed individuals is smaller and contains fewer cells than in healthy individuals, and seeing expansion of the cell population in that region w the administration of antidepressants we have a real-word scenario to base an answer for that question. It would seem that neurogenesis is required in this case to regain function. Also it is not just cell proliferation, but also an increase in the branching and lengthening of dendritic terminals - a process known as arborization. The hippocampus can be divided into 2 functional regions. One for cognitive and memory process, and the other for endocrine, emotion regulation. With depression, both regions of the hippocampus tend to atrophy, which correlates with the difficulty with managing mood, impaired memory and ability to focus. With successful treatment using antidepressants for instance these abilities improve which correlates w an increased ability to process information. In psychiatry, patients usually require taking their medication for 4-6 weeks before effects will take place. If they do not, an insufficient dosage is assumed and so the dosage is increased and you wait again. If the drug fails at the highest dose, then you try a different class of antidepressant. While new cells are being born, it is most likely the old ones are dying and their cell bodies recycled. There are cells in the brain whose responsibility is the function as the "care-taker" and clean up old cells destined for death. Recently it has been shown in the gut of mice whereby the entirety of nervous system innervating the small intestine turns over every few weeks.
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