人脑长期暴露宇宙射线中会导致认知障碍

What happens to an astronaut's brain during a mission to Mars? Nothing good. It's besieged¹ by destructive particles that can forever impair² cognition, according to a UC Irvine radiation oncology study appearing in the May 1 edition of Science Advances. Charles Limoli and colleagues found that exposure to highly energetic charged particles -- much like those found in the galactic cosmic rays that bombard astronauts during extended spaceflights -- cause significant damage to the central nervous system, resulting in cognitive³ impairments.   "This is not positive news for astronauts deployed⁴ on a two- to three-year round trip to Mars," said Limoli, a professor of radiation oncology in UCI's School of Medicine. "Performance decrements, memory deficits⁵, and loss of awareness⁶ and focus during spaceflight may affect mission-critical activities, and exposure to these particles may have long-term adverse⁷ consequences to cognition throughout life."   For the study, rodents⁸ were subjected to charged particle irradiation (fully ionized oxygen and titanium) at the NASA Space Radiation Laboratory at the Brookhaven National Laboratory before being sent back to Limoli's Irvine lab.   The researchers found that exposure to these particles resulted in brain inflammation, which disrupted the transmission of signals among neurons. Imaging revealed how the brain's communication network was impaired⁹ through reductions in the structure of nerve cells called dendrites and spines¹⁰. Additional synaptic alterations¹¹ in combination with the structural¹² changes interfered¹³ with the capability¹⁴ of nerve cells to efficiently¹⁵ transmit electrochemical signals. Furthermore, these differences were parallel to decreased performance on behavioral tasks designed to test learning and memory.