We made our first rodent car out of a plastic cereal container. Through trial and error, my colleagues and I discovered that rats could learn to move forward by grasping a small wire that acted like an accelerator pedal. Before long, they were steering with surprising precision to achieve a Froot Loop treat.

As expected, rats housed in enriched environments – provided with toys, space and companions – learned to drive faster than those living in standard cages. This discovery supports the idea that complex environments enhance neuroplasticitythe brain’s ability to change throughout life in response to environmental demands.

After publishing our research, the story of flying rats went viralin the media. The project continues in my lab with new and improved rat-powered vehicles, or ROVs, designed by a robotics professor. John McManus and his students. These upgraded electric ROVs – featuring rat-proof wiring, indestructible tires and ergonomic driving levers – are akin to a rodent version of Tesla’s Cybertruck.

As a neuroscientist who advocates For housing and testing laboratory animals in natural habitats, I found it amusing how far we strayed from my laboratory practices with this project. Rats generally prefer dirt, sticks and stones to plastic objects. Now we made them drive cars.

But humans didn’t evolve to drive either. Even though our ancient ancestors didn’t have a car, they had flexible brains this allowed them to learn new skills – fire, language, stone tools and agriculture. And sometime after the invention of the wheel, humans made cars.

Although cars designed for rats are nowhere near anything they might encounter in the wild, we thought driving was an interesting way to study how rodents learn new skills. Unexpectedly, we found that the rats were extremely motivated for their driving training, often jumping in the car and revving the “lever engine” before their vehicle hit the road. Why was this?

Some rats practicing driving press a lever before their car is placed on the track, as if they are looking forward to the ride ahead of them.

The new destination for joy

Concepts from introductory psychology textbooks took on a new practical dimension in our rodent control laboratory. Building on foundational learning approaches such as operant conditioningwhich reinforces targeted behavior through strategic incentives, we trained the rats step by step in their driver education programs.

Initially, they learned basic movements, like getting into the car and pushing a lever. But with practice, these simple actions evolved into more complex behaviors, like steering the car to a specific destination.

Rats also taught me something profound on a pandemic morning.

It was the summer of 2020, a time marked by emotional isolation for almost everyone on the planet, even lab rats. When I entered the lab, I noticed something unusual: the three drive-trained rats eagerly ran toward the side of the cage, jumping like my dog ​​does when asked if he wants to take a walk.

Had rats always done this, and I just hadn’t noticed? Were they just eager to do a Froot Loop or were they looking forward to the ride itself? Regardless, they seemed to feel something positive – perhaps excitement and anticipation.

Behaviors associated with positive experiences are associated with joy in humans, but what about rats? Did I see anything akin to joy in a rat? Perhaps, given that neuroscience research increasingly suggests that joy and positive emotions play an essential role in the health of human and non-human animals.

With this, my team and I have shifted our focus from topics like how chronic stress influences the brain to how positive events—and the anticipation of those events—shape neuronal functions.

Working with a postdoctoral fellow Kitty HartvigsenI designed a new protocol that used waiting periods to accelerate anticipation before a positive event. Bring Pavlovian packaging In the mix, rats had to wait 15 minutes after a Lego block was placed in their cage before receiving a Froot Loop. They also had to wait a few minutes in their carrier before entering Rat Park, their playground. We also added challenges, like making them shell sunflower seeds before eating them.

It has become our To wait for He research program. We named this new line of study UPER (unpredictable positive experience responses) where rats were trained to expect rewards. In contrast, control rats received their rewards immediately. After about a month of training, we expose the rats to different tests to determine how the expectation of positive experiences affects their learning and behavior. We are currently studying their brains to map the neural imprint of prolonged positive experiences.

Preliminary results suggest that rats that must wait for their rewards show signs of switching from a pessimistic to an optimistic cognitive style in a test designed to measure rodent optimism. They performed better on cognitive tasks and were bolder in their problem-solving strategies. We linked this program to our laboratory’s broader interest in behavioral productsa term I coined to suggest that experiments can change brain chemistry in a similar way to pharmaceuticals.

This research provides further support for how anticipation can reinforce behavior. Previous work with laboratory rats showed that rats pressed a bar to find cocaine – a stimulant that increases dopamine activation – are already experiencing a surge in dopamine because they anticipate a dose of cocaine.

The story of rat tails

It is not only the effects of anticipation on the behavior of rats that have caught our attention. One day, a student noticed something strange: one of the rats in the group trained to expect positive experiences had a straight tail with a curve at the tip, resembling the handle of an umbrella at the tip. ancient.

I had never seen this in my decades of working with rats. By examining the video footage, we found that rats trained to anticipate positive experiences were more likely to hold their tails high than untrained rats. But what exactly did that mean?

Curious, I posted a photo of the behavior on social media. Colleague neuroscientists have identified this as a milder form of what is called Straub’s tailusually observed in rats given the opioid morphine. This S-shaped loop is also linked to dopamine. When dopamine is blocked, Straub’s tail behavior decreases.

Natural forms of opiates and dopamine – key players in brain pathways that decrease pain and enhance reward – appear to be telltale ingredients in the high tails of our anticipation training program. Observing tail posture in rats adds a new layer to our understanding of rat emotional expression, reminding us that emotions are expressed throughout the body.

Although we cannot directly ask rats if they enjoy driving, we designed a behavioral test to assess their motivation to drive. This time, instead of only giving the rats the option of driving to the Froot Loop tree, they could also take a shorter trip on foot – or by paw, in this case.

Surprisingly, two of the three rats chose to take the less efficient route of turning away from the reward and running toward the car to get to their Froot Loop destination. This response suggests that rats enjoy both the journey and the rewarding destination.

Rat lessons to enjoy the journey

We are not the only team studying positive emotions in animals.

Neuroscientist Jaak Pankseppfamously tickled ratsdemonstrating their capacity for joy.

Research has also shown that desirable low-stress environments for rats readjust their brain’s reward circuitslike the nucleus accumbens. When animals are housed in their preferred environment, the area of ​​the nucleus accumbens that responds to appetitive experiences expands. Alternatively, when rats are housed in stressful contexts, the fear-generating areas of their nucleus accumbens expand. It’s as if the brain is a piano that the environment can tune.

Neuroscientist Curt Richter has also argued in favor rats have hope. In one study that would not be licensed today, rats swam in glass cylinders filled with water, eventually drowning from exhaustion if not rescued. Lab rats frequently handled by humans have swum for hours or even days. The wild rats gave up after just a few minutes. However, if wild rats were briefly rescued, their survival time was extended considerably, sometimes by several days. It seemed that being rescued gave the rats hope and energized them.

The Driving Rats project has opened new and unexpected doors in my behavioral neuroscience research lab. While it is essential to study negative emotions such as fear and stress, positive experiences also shape the brain in significant ways.

As animals – human or otherwise – navigate the unpredictability of life, anticipating positive experiences helps them persevere and continue seeking life’s rewards. In a world of immediate gratification, these rats offer insight into the neural principles that guide everyday behavior. Rather than pushing buttons for instant rewards, they remind us that planning, anticipating, and enjoying the ride can be the key to a healthy brain. It’s a lesson for my lab rats taught me well.

Kelly Lambert is a professor of behavioral neuroscience at the University of Richmond. This article is republished from The conversation under a Creative Commons License. Read the original article.