Rats are smart little critters. They can use tools, recognize emotion in their buddies’ faces and, famously, navigate mazes. Now, a study published in Behavioral Brain Research has highlighted yet another rat skill: driving tiny cars to retrieve tasty Froot Loops.
A team of researchers led by Kelly Lambert, a behavioral neuroscientist at the University of Richmond, spent weeks teaching rats to drive a hand-made “rodent operated vehicle." The sight of a rat zipping around in a little car is pretty neat to behold, but the scientists were more interested in what the experiment can tell us about the animals’ ability to learn complex tasks—and the resulting implications for the study of human neurological diseases and psychiatric illnesses.
Though previous research has shown that rats are capable of performing a variety of different tasks—like pressing bars and recognizing objects—these studies “capture a narrow window of animal cognition,” writes Alice Klein of New Scientist. So Lambert and her colleagues set about giving the rodents a more complex task.
They made a “car” out of a clear plastic food container attached to an aluminum plate, fitted with a set of wheels. Three copper bars on the aluminum plate let the rats “steer” the car; when they placed their paws on the bars, the rodents completed an electrical circuit that propelled the ROV, either to the left, right, or straight ahead. Releasing the bar would stop the car’s movement.
Next, the researchers tested their contraption on two groups of rats. One had been reared in standard lab conditions, the other in an “enriched environment” with plenty of toys, ladders and wood chips for mental stimulation, according to CNN’s Scottie Andrew. The idea was to provide some of the rodent subjects with a home that more closely resembles their natural habitat. As the study authors explain, “Environmental enrichment has been shown to affect rat learning performance in spatial tasks, as well as enhance hippocampal complexity and emotional resilience.”
During the training process, the researchers would dangle Froot Loops in front of the rats, dispensing the snacks if the furry drivers steered the car to the right spot. The distances that the rats had to drive increased as the training progressed.
As the researchers suspected, rats raised in an enriched environment “demonstrated more robust learning in driving performance,” and their interest in the car persisted even in the absence of food rewards, suggesting that the “enriched animals may have developed a more engaged reward system throughout training.” But the fact that the rodents could complete the task at all is impressive, and significant. Rats are known to be skilled navigators—one study, for instance, found that the animals are able to intermittently drive a car on a circular track—but the new study shows that they can control a vehicle in complex ways, steering a car in different directions in pursuit of a tasty snack.
What’s more, driving seemed to relax the rats. The researchers analyzed the animals’ feces to measure corticosterone, a stress hormone, and dehydroepiandrosterone, which is secreted in response to stress and, in humans, has been shown to improve moods. In all of the animals involved in the experiment, the ratio of dehydroepiandrosterone to corticosterone increased with training. This in turn may suggest that, much like humans, rats derive satisfaction from honing a new skill. “In humans, we call this self-efficacy or agency,” Lambert tells Klein.
Learning more about the types of activities that bolster “self-efficacy” is important for the study of psychiatric conditions. As Lambert explains in an interview with CNN’s Andrew, “Anything that reduces stress can build resilience against the onset of mental illness.”
The new research also indicates that complex tests can and perhaps should be deployed when using rats as a model for studying various illnesses. Rodent driving tests, for instance, could shed insight into the ways that Parkison’s disease impacts motor and spatial skills, Lambert tells Klein.
“I do believe that rats are smarter than most people perceive them to be,” she adds, “and that most animals are smarter in unique ways than we think.”