Scientists Find New Evidence To Support Plasticity In Aging Brain
Researchers have looked at various influences on brain structure through fMRI (functional magnetic resonance imaging) and have witnessed the change in size and shape in various parts of the brain influenced by certain emotions. In a new study from Columbia University Medical Center, brain plasticity is demonstrated by the production of neurons and neural stem cells produced in the hippocampus.
The hippocampus, which is involved in memory, learning, and emotion, produces stem cells. Through lineage studies in two groups of mice, the scientists followed lines of stem cells to their eventual differentiation into cell types, specifically tracking those stem cells that produced neurons. The two groups were 1) mice that lived in physically and socially isolated housing ('deprived'), and 2) mice that live in 'enriched' housing.
Both groups of mice created neuronal stem cells, the enriched mice, about 14 percent more than the deprived. But in the enriched group, the hippocampi also produced neurons, something that had not been reported before now.
The study leader, Alex Dranovsky, MD PhD, neuroscientist and clinical psychiatrist, that the ability of the enriched mice hippocampi to create neurons is "an adaptation to stressful environments" ("stressful" being a good thing, generally, in this situation, as an enriched environment involves change and challenge).
The mice who had been in the deprived group did not lose their stem cells after three months, when they were switched to an enriched environment. In that environment, their hippocampi also began to produce neurons. "When conditions turn more favorable, the stockpiled stem cells have the opportunity to produce more neurons—a form of 'neurons on demand,'" Dranovsky said.
Future studies will look into whether the production of neurons is a generalized response to stress or a response to socialization, and whether all neuronal stem cells have the same capacity to produce neurons.
Ultimately, the Columbia team wants to figure out how to stimulate stem cells to produce neurons. "This could lead to the eventual use of stem cells in neuronal replacement therapy for neurodegenerative diseases and other central nervous system conditions," said Dranovsky.
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