brain plasticity: new neurons, more then pruned (Introduction)

by David Turell , Wednesday, May 04, 2016, 19:33 (2913 days ago) @ David Turell

As the brain develops new networks, more neurons are produced then needed, so some are pruned back. This makes sense to me as the brain is responsive to our needs, and must be prepared to go as far as the new use is expanded, but not overextending the network which will require more energy than is necessary.-http://www.salk.edu/news-release/adult-brain-prunes-branched-connections-of-new-neurons/-"New brain cells began with a period of overgrowth, sending out a plethora of neuronal branches, before the brain pruned back the connections. The observation, described May 2, 2016 in Nature Neuroscience, suggests that new cells in the adult brain have more in common with those in the embryonic brain than scientists previously thought.-***-"While most of the brain's billions of cells are formed before birth, Gage and others previously showed that in a few select areas of the mammalian brain, stem cells develop into new neurons during adulthood. In the new study, Gage's group focused on cells in the dentate gyrus, an area deep in the brain thought to be responsible for the formation of new memories. The scientists used a new microscopy technique to observe new cells being formed in the dentate gyrus of adult mice.-"What was really surprising was that the cells that initially grew faster and became bigger were pruned back so that, in the end, they resembled all the other cells,” says Gonçalves. He and his colleagues went on to show that changing signaling pathways could mimic some of the effects of the complex environment—cells grew more initially, but also pruned back earlier.-"Over a period of over a month, the Salk team kept track of each new neural branch, called a dendrite, on the growing neurons, as well as each dendrite that was pruned away. -"So why would the brain spend energy developing more dendrites than needed? The researchers suspect that the more dendrites a neuron starts with, the more flexibility it has to prune back exactly the right branches.-“'The results suggest that there is significant biological pressure to maintain or retain the dendrite tree of these neurons,” says Gage."-Comment: Note the last paragraph bold (mine). This will be managed by a molecular feedback loop for tight control. In this way as we try to learn new knowledge or physical maneuvers the brain carefully follows our needs.