Contrary to popular belief, our neurons are able to regenerate, even in adults. This process is called neurogenesis. Years ago, popular wisdom said that we had a finite number of neurons. In other words, any accident or problem such as drinking alcohol or brain trauma could eliminate these essential populations of specialised cells that are vital to the proper functioning of our bodies.
However, this legend has been tied to a long list of science myths that still persist, in combination with others, such as the effects of the light from displays on our vision or certain health-related beliefs. Some time ago, researchers were surprised to discover the process of neurogenesis , through which our nervous system is able to generate new neurons, even in adults.
Earlier this year, QBI researchers made the world-first discovery that new adult brain cells are also produced in the amygdala , a region of the brain important for processing fear and emotional memories. The amygdala, an ancient part of the brain, is important for attaching emotional significance to memories, and also plays a key role in fear learning, which causes us to learn that an experience or an object is frightening. Disrupted connections in the amygdala are linked to depression, and anxiety disorders such as post-traumatic stress disorder PTSD , and the hope is that the discovery could lead to new treatments for these conditions.
The discovery shed further light on the brain's ability to change and adapt, and further research will look at understanding the function of new cells in the the amygdala.
As the brain ages, our ability to learn and remember gradually declines. It's thought that these changes in memory occur as a result of decreased neurogenesis — that stem cells in regions such as the dentate gyrus, in the hippocampus, lose their ability to produce new neurons.
The hippocampus is known to shrink with age. But it's not all bad news — these changes aren't necessarily permanent. He and Dr Daniel Blackmore have found in mice that exercise is able to increase production of new brain cells and improve learning and memory in the ageing brain.
They are now heading up a clinical trial monitoring people aged 65 and older to identify the right amount, intensity and type of exercise that leads to cognitive improvement.
Subscribe to A Grey Matter. In recent years, researchers have significantly advanced the possibility of using grafted neural stem cells to spur spinal cord injury repairs and restore lost function, essentially by inducing neurons to extend axons through and across an injury site, reconnecting severed nerves.
Last year, for example, a multi-disciplinary team led by Kobi Koffler, PhD, assistant professor of neuroscience, Tuszynski, and Shaochen Chen, PhD, professor of nanoengineering and a faculty member in the Institute of Engineering in Medicine at UC San Diego, described using 3D printed implants to promote nerve cell growth in spinal cord injuries in rats, restoring connections and lost functions. The latest study produced a second surprise: In promoting neuronal growth and repair, one of the essential genetic pathways involves the gene Huntingtin HTT , which, when mutated, causes Huntington's disease, a devastating disorder characterized by the progressive breakdown of nerve cells in the brain.
Tuszynski's team found that the "regenerative transcriptome" -- the collection of messenger RNA molecules used by corticospinal neurons -- is sustained by the HTT gene. In mice genetically engineered to lack the HTT gene, spinal cord injuries showed significantly less neuronal sprouting and regeneration. Thus, mutations in this gene would be predicted to result in a loss of the adult neuron to repair itself.
This, in turn, might result in the slow neuronal degeneration that results in Huntington's disease. Materials provided by University of California - San Diego. Original written by Scott LaFee. Note: Content may be edited for style and length. Science News. Journal Reference : Gunnar H. Injured adult neurons regress to an embryonic transcriptional growth state.
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