Lab rats don’t have the easiest of lives but now Japanese scientists have added to their burden by putting a robotic bully in their midst.
The mechanical menace was designed to harass the rodents by chasing them around a cage before rearing up. However, this seemingly pointless study does have a serious purpose.
Mice and rats are often used as models to test treatments for human conditions including drugs for mental disorders. But that left scientists with the perplexing question, how do you depress a rat?
Up till now, they have relied on stressful physical activities such as forced swimming, giving them electric shocks or severing their sense of smell.
But scientists from Wakeda University in Japan, came up with the novel approach of creating a machine that could induce social stress, which is a common trigger for depression.
The team studied rat behaviour before creating a model that was capable to mimicking actions such as chasing, rearing, grooming and mounting.
The robot, called WR-3, moves on two wheels and has a mechanical skeleton allowing basic movements. Its shape and size were comparable to a typical white adult male rat.
The researchers timed how long it took rats to make certain moves, such as rearing up on hind legs and then programmed the robot to match them.
Early tests revealed that the robot could successfully interact with lab rats.
The researchers then performed a study on two groups of 12 rats, to see if WR-3 could induce depression. This was based on the assumption that a stressed rat would move around less.
Rats in group A was constantly harassed by their robot counterpart, while rats in group B were attacked intermittently or when they moved.
The team, led by Hiroyuki Ishii, found the deepest depression was triggered when a rat was constantly harassed in its youth and then attacked now and then as an adult.
It is not clear how closely the rodent reactions predict those of humans placed under stress, but the team said it was a subject worthy of further research.
They next plan to see if these ‘mental disorder‘ rats become more socially active after receiving particular anti-depressants. They have already developed a more sophisticated rat model called WR-4.
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