字幕表 動画を再生する 英語字幕をプリント Imagine the brain could reboot, updating its withered and damaged cells with new, improved units. That may sound like science fiction, but it's a potential reality scientists are investigating right now. Will our brains one day be able to self-repair? It's well known that embryonic cells in our young developing brains produce new neurons, the microscopic units that make up the brain's tissue. Those newly generated neurons migrate to various parts of the developing brain, making it self-organize into different structures. But until recently, scientists thought cell production came to an abrupt halt soon after this initial growth, leading them to conclude that neurological diseases, like Alzheimer's and Parkinson's, and damaging events, like strokes, are irreversible. But a series of recent discoveries has revealed that adult brains actually do continue to produce new cells in at least three specialized locations. This process, known as neurogenesis, involves dedicated brain cells, called neural stem cells and progenitor cells, which manufacture new neurons or replace the old ones. The three regions where neurogenesis has been discovered are the dentate gyrus, associated with learning and memory, the subventricular zone, which may supply neurons to the olfactory bulb for communication between the nose and brain, and the striatum, which helps manage movement. Scientists don't yet have a good grasp on exactly what role neurogenesis plays in any of these regions, or why they have this ability that's absent from the rest of the brain, but the mere presence of a mechanism to grown new neurons in the adult brain opens up an amazing possibility. Could we harness that mechanism to get the brain to heal its scars similar to how new skin grows to patch up a wound, or a broken bone stitches itself back together? So here's where we stand. Certain proteins and other small molecules that mimick those proteins can be administered to the brain to make neural stem cells and progenitor cells produce more neurons in those three locations. This technique still needs improvement so that the cells reproduce more efficiently and more cells survive. But research shows that progenitor cells from these areas can actually migrate to places where injury has occurred and give rise to new neurons there. And another promising possible approach is to transplant healthy human neural stem cells, which are cultured in a laboratory, to injured tissue, like we can do with skin. Scientists are currently experimenting to determine whether transplanted donor cells can divide, differentiate and successfully give rise to new neurons in a damaged brain. They've also discovered that we might be able to teach other kinds of brain cells, such as astrocytes or oligodendrocytes to behave like neural stem cells and start generating neurons, too. So, a couple of decades from now will our brains be able to self-repair? We can't say for sure, but that has become one of the major goals of regenerative medicine. The human brain has 100 billion neurons and we're still figuring out the wiring behind this huge biological motherboard. But everyday, research on neurogenesis brings us closer to that reboot switch.