Chemicals That Fix the Brain :: Biology Essays Research Papers

Chemicals That Fix the Brain The discovery of how the brain heals itself began, as discoveries often do, with a question: Why do children who suffer brain damage often recover fully, while adults with the same kind of damage are permanently incapacitated? University of Wisconsin neurobiologist Ronald Kalil was among those who pursued the question (15). His studies in young cats showed that entire networks of brain cells could be routed around damaged areas. Young animals whose primary vision centers were destroyed could still learn to see normally, he found, because cells in another part of their brains took up the job of processing vision. Yet, adult animals suffering the same destruction had no such luck (7). What was the difference? Kalil finally determined that young animal brains are awash in chemicals called growth factors, while adult brains have far lower levels (11). He surmised that the abundance of growth factors helps the new brains organize themselves. When damage occurs, the growth factors simply start over and rebuild damaged networks. Adults have fewer growth factors because their brains, although they constantly undergo changes, are, for the most part, completed. All of which led to another question: Would adding extra growth factors prevent permanent damage in adult brains? Soaking tiny sponges with a variety of growth factors, Kalil placed them inside newly damaged brain areas of adult cats. He and his colleagues found that these adult brains acted more like infant brains: Instead of suffering permanent damage, the adult brains repaired themselves. This ability of the brain to rewire itself, grow new parts for damaged cells, and even make new cells-its "plasticity," was thought to be impossible only a few years ago (4). Brain cells, medical students were taught, were hardwired like so many computer transistors. Once they burned out, that was the end. Brain cells certainly could not sprout new communications lines to take over the jobs of nonfunctioning cells, it was said. Nor could they regenerate themselves after being hurt. Moreover, they absolutely could not divide to replenish the brain with new cells. All those "truths" are being tossed out as brain research undergoes a revolution fueled by molecular biology's remarkable ability to reveal the secrets of cells. Scientists now can hunt down and copy genes that govern cell reassembly and harness them for use in repairing damaged brains (3). The power of these tools was stunningly demonstrated with the discovery of a gene called NeuroD, which plays an essential role in the embryonic development of the brain and nervous system (6).