Rats love driving tiny cars, even when they don’t get treats
Rats that learn to drive are more able to cope with stress. That might sound like the fever-dream of a former scientist-turned-car writer, but it’s actually one of the results of a new study from the University of Richmond. The aim of the research was to see what effect the environment a rat was raised in had on its ability to learn new tasks. Although that kind of thing has been studied in the past, the tests haven’t been particularly complicated. Anyone who has spent time around rats will know they’re actually quite resourceful. So the team, led by Professor Kelly Lambert, came up this time with something a little more involved than navigating a maze: driving.
If you’re going to teach rats to drive, first you need to build them a car (or Rat Operated Vehicle). The chassis and powertrain came from a robot car kit, and a transparent plastic food container provided the body. Explaining the idea of a steering wheel and pedals to rats was probably too difficult, so the controls were three copper wires stretched across an opening cut out of the front of the bodywork and an aluminum plate on the floor. When a rat stood on the plate and gripped a copper bar, a circuit was completed and the motors engaged; one bar made the car turn to the left, one made it turn to the right, and the third made it go straight ahead.
If proof were needed that many existing psychology tests are too simple, rats did not take long to learn how to drive. The driving was conducted in a closed-off arena (1.5m x 0.6m x 0.5m) where the goal was to drive over to a food treat. Three five-minute sessions a week, for eight weeks, was sufficient for the rats to learn how to do it. The placement of the treat and the starting position and orientation of the car varied throughout, so the rats had more of a challenge each time. At the end of the experiment, each rat went through a series of trials, conducted a day or two apart, where they were allowed to drive around the arena but without any food treats to see if they were only doing it for the food.
The subjects were 11 male rats, five of whom lived together in a large cage with multiple surface levels and objects to play with, and six who lived together in pairs in standard laboratory rat cages. Although both groups of rats learned to drive the car, the ones that lived in the enriched environment were quicker to start driving, and they continued to be more interested in driving even when there was no reward on offer beyond the thrill of the wind in one’s fur.
The researchers also collected each rat’s droppings at various points during the study to analyze them for metabolites of corticosterone and dehydroepiandrosterone, a pair of hormones. The ratio of these two hormones can show how stressed an animal is, and it changed in a pattern consistent with emotional resilience in all the rats over the course of the study. However, there was no significant difference between the enriched environment and the control group in this regard, which may well mean that the four-month process of teaching the rats to drive was itself a positive enriching environment.
Serious scientists usually refrain from imputing any further emotion onto research animals, but I’m no longer a serious scientist, so I’m happy saying that learning to drive made the rats more well-adjusted. And the study has further value; these complex activities may be more useful tests in rat models of neuropsychiatry than those in current use.