Rats That Drive: How Anticipation and Play Reshape the Brain

By Kelly Lambert, University of Richmond

We began with a plastic cereal tub and a lot of curiosity. After several trial-and-error iterations, my colleagues and I discovered that rats could be taught to move a tiny electrically powered vehicle by manipulating a small wire that acted like a gas pedal. Before long, they were steering with surprising accuracy to reach a Froot Loop reward. The project grew from a makeshift rodent car into a fleet of improved rat-operated vehicles (ROVs) designed with rodent-proof wiring, rugged tires and ergonomic levers by robotics professor John McManus and his students.

Enrichment, learning and motivation

Rats housed in enriched environments—ones that include toys, more space and social companions—learned to drive faster than animals kept in standard cages. That result supports a well-established idea in neuroscience: complex, stimulating surroundings enhance neuroplasticity, the brain’s capacity to change across the lifespan in response to experience.

What surprised us was the intensity of the animals’ motivation. Rats often leapt into the ROV and began working the lever before the vehicle ever moved, as if the act of driving itself were pleasurable. That observation led us to shift our focus from chronic stress and its effects to how positive events—and, importantly, anticipation of those events—shape neural function and behavior.

The "Wait For It" protocol and UPERs

With postdoctoral fellow Kitty Hartvigsen, I developed a protocol designed to amplify anticipation. Drawing on Pavlovian and operant conditioning principles, we introduced controlled delays before rewards. For example, rats waited 15 minutes after a Lego block was placed in their cage before receiving a Froot Loop, experienced brief waits in transport cages before entering their play area (Rat Park), and sometimes had to shell sunflower seeds before eating them.

We called this the Wait For It program and used the term UPERs (unpredictable positive experience responses) to describe animals trained to wait for pleasurable events. Control animals received rewards immediately. After about a month of training, we tested the animals’ cognition, decision-making and behavior and began mapping the neural signatures associated with extended positive experiences.

Behavioral and neural effects

Early results were striking. Rats trained to wait for rewards showed a shift from a more pessimistic cognitive style toward greater optimism on tests designed to probe rodent outlook. They performed better on cognitive tasks and adopted bolder problem-solving strategies. These changes align with the notion I’ve termed "behaviorceuticals": experiences that can alter brain chemistry in ways comparable to pharmaceuticals.

We also noticed a distinctive bodily sign. Some anticipation-trained rats held their tails high with a slight crook at the end—an elevated tail posture reminiscent of a mild Straub tail. This S-shaped curl is classically associated with opioid administration and is linked to dopamine activity; blocking dopamine reduces the behavior. The tail posture suggests natural opiates and dopamine may be engaged when rats anticipate positive experiences, and it highlights how emotional states are expressed across the whole body.

Choice, enjoyment and broader context

To probe whether rats enjoy driving itself, we offered them a choice: a short walk to a Froot Loop or a detour that required driving the ROV to reach the same reward. Two of the three trained rats chose to climb into the car and drive, preferring the journey as well as the destination. This choice implies that the rats derived intrinsic value from the driving experience, not just the treat.

Other researchers have documented positive affect in rodents. Jaak Panksepp’s tickling experiments revealed vocalizations consistent with joy, and classic environmental enrichment studies show that low-stress, desirable settings remodel reward circuits such as the nucleus accumbens. Conversely, stressful environments can expand fear-related zones. Curt Richter’s older (now ethically unacceptable) experiments suggested that experiences like rescue can produce hope-like persistence in rats—reinforcing the idea that expectation and social context influence survival and motivation.

Implications

Our driving-rats project offers a playful but powerful model for studying how anticipation and positive experiences alter behavior and brain chemistry. Anticipation itself appears to amplify reward circuitry—engaging dopamine and endogenous opioid systems—and to promote optimism, cognitive flexibility and persistence. These findings support the broader view that deliberately shaping positive experiences can be a potent tool for improving mental resilience across species.

While much of neuroscience rightly focuses on stress and pathology, these results remind us that pleasure, play and the expectation of good things are central to healthy brain function. Whether through enriched environments, structured delays before rewards, or opportunities for engaging activity, fostering anticipation may be as important as reducing adversity when it comes to shaping adaptive behavior and neural health.

Kelly Lambert is a behavioral neuroscientist at the University of Richmond.