US scientists have reported successfully training a group of the rodents to drive tiny cars in exchange for bits of Froot Loops cereal, and found that learning the task lowered their stress levels.
Their study not only demonstrates how sophisticated rat brains are, but could one day help in developing new non-pharmaceutical forms of treatment for mental illness, senior author Kelly Lambert of the University of Richmond told AFP on Wednesday.
Lambert said she had long been interested in neuroplasticity – how the brain changes in response to experience and challenges – and particularly wanted to explore how well rats that were housed in more natural settings (enriched environments) performed against those kept in labs.
She and colleagues modified a robot car kit by adding a clear plastic food container to form a driver compartment with an aluminium plate placed on the bottom.
A copper wire was threaded horizontally across the cab to form three bars: left, centre and right.
When a rat placed itself on the aluminium floor and touched the wire, the circuit was complete and the car moved in the direction selected.
Seventeen rats were trained over several months to drive around an arena 150cm by 60cm made of plexiglass.
Writing in the journal Behavioural Brain Research, the researchers said the animals could indeed be taught to drive forward as well as steer in more complex navigational patterns.
As she had suspected, Lambert found that the animals kept in stimuli-rich environments performed far better than their lab rat counterparts, but “it was actually quite shocking to me that they were so much better”.
The rats’ faeces was collected after their trials to test for the stress hormone corticosterone as well as dehydroepiandrosterone, which counters stress.
All rats that underwent training had higher levels dehydroepiandrosterone, indicating a more relaxed state, which could be linked to the satisfaction of gaining mastery over a new skill, referred to as “self-efficacy” or “agency” in humans.
What’s more, rats that drove themselves showed higher levels of dehydroepiandrosterone as compared to those who were merely passengers when a human controlled the vehicle, meaning they were less stressed – something that will be familiar to nervous backseat drivers.