NASA will expose between 18 and 28 squirrel monkeys to low dosages of radiation in an attempt to mimic the radioactive levels experienced by astronauts and monitor the physical effects of such exposure. The scientists are particularly interested in the affect it will have on the animals’ nervous system and behaviour. "We realized there was a need for this kind of work," Jack Bergman, a behavioral pharmacologist at Harvard Medical School's McLean Hospital in Boston, told Discovery News. "There's a long-standing commitment on the part of NASA to deep space travel and with that commitment comes a need for knowing what kinds of adverse effects deep space travel might have, what are the risks to astronauts," Bergman said. "That's not been well assessed."