Aging brain
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The human brain goes through several large-scale changes as the individual progresses from embryo through to old age.
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[edit] Pre-natal development
Developmental neurobiology concerns itself with the development of the brain. The process of neurogenesis populates the brain, then programmed cell death cuts the growing brain down to size.
[edit] Adolescence
During adolescence the brain goes through a process of synaptic pruning.
[edit] Aging
Over the years, the human brain shows a decline in function and a change in gene expression. This modulation in gene expression may be due to oxidative DNA damage at promoter regions in the genome. Genes that are down-regulated over the age of 40 include:
- GluR1 AMPA receptor subunit
- NMDA R2A receptor subunit (involved in learning)
- Subunits of the GABA-A receptor
- Genes involved in long-term potentiation e.g. calmodulin 1 and CAM kinase II alpha.
- Calcium signalling genes
- Synaptic plasticity genes
- Synaptic vesicle release & recycling genes
Genes that are upregulated include:
- Genes associated with stress response and DNA repair
- Antioxidant defence
Normal aging is distinct from Neurodegenerative disease. DNA damage due to oxidation increase as the brain ages, possibly due to impaired mitochondrial function.