Mice go ‘loopy’ amid cramped tedium of extraterrestrial mission

SPACE travel sends mice “loopy” – quite literally – scientists have discovered, in findings that could have implications for humans.

Nasa sent 20 female mice to the International Space Station (ISS) for 37 days, the equivalent of a three-and-ahalf-year mission for humans, and discovered the animals soon displayed a bizarre “race-tracking” behaviour, sprinting around their cage walls. The scientists were hoping to understand how exposure to a weightless space environment affects animals over a long period.

They found that the mice initially engaged in normal behaviours such as feeding, self-grooming and huddling together.

But, around day seven, the younger mice started running around the walls of their habitat in a strange circling behaviour. And within days, all the other mice had joined in. The scientists speculated that the mice may have craved greater levels of exercise in microgravity, or were attempting to stimulate the balance function of their ears, which does not work in weightlessness.

But the researchers could not rule out the possibility that it was “abnormal repetitive behaviour” triggered by the impact of weightlessness in response to being bored or living in cramped conditions.

Such repetitive behaviours are usually only seen in animals when they are living in poor welfare conditions, such as small cages without anything to enrich their experience.

Birds, for example, are known to pace, while carnivores will bite the bars on their cages, primates will rock and parrots have been known to selfharm.

Writing in the journal Scientific Reports, Dr April Ronca, of the Nasa Ames Research Centre in California, said: “Space flight involves exposure to microgravity, radiation, isolation, confinement, increased CO2, and other factors that may culminate in stress and pose potential health risks for astronauts.” She added: “Animal studies are needed to establish a deeper understanding of molecular, cellular, and organismal responses that can inform crew health during lengthy space flight missions.

“The unique circling behaviour emerged during the second mission quarter and progressed from a relatively solitary behaviour to a highly coordinated group activity.”

Dr Ronca added: “Circling could represent the emergence of stereotyped motor behaviour or abnormal repetitive behaviours.”