摘要: The prospect of long-term space travel raises a number of questions about the safety of astronauts asked to venture on prolonged journeys. The problems of microgravity are well known, but the hazards of exposure to radiation are l... 展开 The prospect of long-term space travel raises a number of questions about the safety of astronauts asked to venture on prolonged journeys. The problems of microgravity are well known, but the hazards of exposure to radiation are less understood. Most space travel has involved a few days to many months in low-altitude, equatorial orbits, where the dangers of radiation are lessened by the magnetic field surrounding the earth. Travel to polar or geostationary orbits or travel to the moon or the planets has a far greater radiation hazard. Almost nothing is known about possible risks to behavior and brain function after radiation exposure, such as found after the emission of solar flares or from long-term exposure from galactic cosmic radiation. Exposure to low doses of high-energy iron particles can alter motor behavior. The ability of rats to hang from a wire has been reported to be significantly degraded after exposure to doses as low as 0.5 Gy. In addition, deficits in the ability of acetylcholine to regulate dopamine release in the caudate nucleus (an area in the brain important for motor function) have been found. These results provide further evidence that exposure to heavy particles can degrade motor behavior through an action on dopaminergic mechanisms and that this can occur after doses much lower than those needed for low-LET radiation. Reprints. (edc) 收起