The University of Richmond rats wowed the world in 2019 with their ability to drive miniature cars. Now, they're part of a groundbreaking project that explores how environmental enrichment shapes the brain -- and could ultimately help solve human mental health problems.
"It draws people's attention to the intelligence and ability to learn of these animals," says Kelly Lambert, director of the university's behavioral neuroscience lab, who tries to keep a healthy scientific distance from her rodents by not giving them the name of the stroke of colored marker applied to their tails.
One of the great failures of modern medicine, for Kelly Lambert, is its inability to cure these mental pathologies with the help of drugs, even though the pharmaceutical companies are reaping profits in this field.
These drug approaches are increasingly called into question, after the publication in July of a major study questioning the theory according to which a chemical imbalance, in particular a lack of serotonin, would cause depression.
- "Workers" and "annuitants" -
Instead, Kelly Lambert sees behavioral therapy as a key to treating the mind, hence the study of small mammals.
"Our brains transform from the womb to the grave," she says, explaining that having an active life -- one way or another -- can affect the ability to make a depression.
In a previous experiment, she had divided a group of rats into "workers", who had to make an effort to obtain a reward - in this case digging in a pile of soil - and "annuitants", a control group at who were given the treats without consideration.
When faced with stressful tasks, the group of workers persisted longer than those conditioned to remain in a state that psychologists refer to as “learned helplessness”.
And when they had to swim, the workers had a hormonal reaction indicating greater emotional resilience.
Rats that learned to drive also showed greater emotional tenacity and reduced levels of stress, which may be related to the satisfaction of learning new skills, according to Kelly Lambert.
“They make paths in nature that they take all the time and we wanted to see if they were able to maintain this excellent sense of direction in a vehicle”, explains researcher Olivia Harding.
The learning curve was not easy: the rats first had to flick their snouts on the controls, before the scientists discovered that they preferred to stand on their hind legs and use their front ones to drive.
Even when their car was in an unusual position, with its back to the treat, the rodents managed to steer their vehicle the right way and reach the treat, evidence of advanced cognitive ability.
Today's pilots, "Black Tail" and "Multicolored Tail", show "anticipation" by fidgeting at the arrival of humans, pacing and trying to scale the walls of their cages .
Just like humans, not all rats have the same interests: while some seem to enjoy driving itself, others only do it for the rewards and a third group don't even bother.
- Cage vs nature -
Female rats have long been ignored by scientists who, believing that their four-day menstrual cycle could alter research results, have thus deprived themselves of in-depth knowledge about them.
A phenomenon that Kelly Lambert has worked to combat in her own experiments, and the conditions for receiving federal research funds in the United States now encourage people to follow her example.
The boss of the behavioral neuroscience laboratory understood early in her career that studying rats living in "unenriched" cages, that is to say, devoid of obstacle courses and activities, did not have much of interest, such as the study of confined and isolated humans.
Rats raised in enriched cages, for example, were much more successful in driving a vehicle than the others.
His most recent work found that wild rats had larger brains than lab rats, more neurons, bigger spleens to better fight disease, and much higher stress levels.
Which leads to a philosophical question: are we closer to lab rats, to those locked in enriched cages, or to those that live in the wild?
"I feel a little closer to the rat supplied in the lab than to the wild rat", laughs Kelly Lambert.
Wild rats, which must daily scavenge for food and avoid predators, a behavior similar to that of our ancestors, may have a thing or two to teach us about mental toughness.