A rat's world map could hold the key to curing diseases of the brain

Rats may have a better sense of direction than humans. Researchers are still trying to figure out how

Published September 3, 2022 10:00AM (EDT)

Human brain scan | Laboratory rat (Photo illustration by Salon/Getty Images)
Human brain scan | Laboratory rat (Photo illustration by Salon/Getty Images)

Have you heard the one about the rat who got lost? Probably not, because rats don't need to ask directions. Jokes aside, it is well-established in scientific research circles that rats have an amazing sense of direction — possibly better than humans. In new neuroscience research from Frontiers in Behavioral Neuroscience, authored by Thomas Doublet, Mona Nosrati and Clifford G. Kentros, the research team studied the way that adolescent lab rats navigated. They found that these teenage rats had surprising intuition when it came to navigation: the rats did not need to actually physically explore an environment themselves in order to pick up crucial information about a specific location and how to navigate that space. Rather, they were able to intuit such information in other ways, akin to how a human might read a map in order to create a mental map of a space prior to physically experiencing it.

The Trondheim, Norway-based study at the Norwegian University of Science and Technology found "observer" rats were able to figure out the navigational challenge by watching another rat, called "demonstrator" rats, in the study. These observer rats were then able to successfully demonstrate their navigational knowledge, typically completing the maze challenge at nearly 100% during their first trial. In other words, they were watching and learning navigational skills by observing their rat colleagues.

Rats can learn navigational skills merely from watching each other.

Numerous studies have previously suggested that rats have an innate sense of direction from birth. One study found that the development of a rat's directional abilities start before newborn rat pups open their eyes. Another study led by University of Richmond's Dr. Kelly Lambert even found that lab rats with prompts could "drive" specially made tiny rat cars in order to get food rewards, suggesting that their navigational skills extend beyond walking on their legs.

Given what we already know about rats and navigation skills, what makes this study novel? According to Dr. Clifford G. Kentros, Ph.D, who heads the Norwegian University of Science and Technology Kentros lab, this study revealed that rats can learn navigational skills merely from watching each other, which was not something that was known definitively before. Some rats, like the demonstrator-in-training rats weren't natural learners, however: Kentros notes that it took the demonstrator rats some time to figure out what to do. 

Kentros said, "We trained those rats to be the demonstrators. The next step in their research experiment was using the 'naive' observer rats who were able to watch the demonstrator rats first," Kentros said. But once the observer rats learned, they would nail the correct sequence every time. 

One interesting finding in the study was that observer rats often ended up consistently outperforming the original demonstrator rats.

These latest research findings in this study are unique because, while research scientists believed that rats might have observational learning capabilities, it hadn't been documented this ability in a study on this level. The study focused on how many rats also have deeply entrenched cognitive brain mapping skills. In order words, rats are able to acquire, store, recall, and decode information about spatial environments, including novel or new environments.

In the second phase of the study, the research team injected drugs into the observer rats to ascertain whether the rats' navigational performance would be affected. The study's results suggest that the medication did not affect the rats' observational and navigational abilities or place memory. 

Intriguingly, this rat study also has implications for humans — or more specifically our knowledge of human brains. 

Our internal GPS

As fellow mammals, rats and humans are not too genetically distant: we share a common ancestor that probably lived a mere 65 million years ago. That isn't a long time in evolution — life has been evolving and separating into different species for about 3.7 billion years, give or take — meaning that humans and rats have a lot in common in how our brains and bodies work. 

"Any fool knows that a rat brain and a human brain are different. It takes a Ph.D. in neuroscience to know that they are basically the same," Kentros joked. 

Indeed, the rat navigation study aims to shed some light on how our (human) internal GPS works (vis-a-vis rats). The study authors said that further research is needed to understand the precise mechanism at play, and how these lab rats generate maps in their head.

"There is some evidence that some rats can demonstrate social justice and fairness, and there is documented lab research showing that rats passed up food rewards to assist other rats in distress."

Parsons, a behavioral scientist who specializes in academic research relating to rat pheromones, says serendipitous observational data derived from rat behavior has given him a lot to ponder regarding rats' internal GPS and navigational abilities. Likewise, he says that behavioral scientists have learned much about how rats travel differently: urban wild rats with access to sewers travel farther distances than previously thought. Additionally, male rats tend to travel greater distances than female rats (many of whom are constantly reproducing.) While wild rats are primarily motivated by food sources, there is really limited research on how well wild rats can find their way back to, say, previous food services that are great distances away.

Parsons also issued a paean for rat intelligence.

"There is some evidence that some rats can demonstrate social justice and fairness, and there is documented lab research showing that rats passed up food rewards to assist other rats in distress," Parsons maintained. Notably, much lab research involves male sibling lab rats — meaning that even cutting-edge lab research may have shortcomings compared to those who study wild urban rats. Indeed, lab researchers typically exclude female rats, citing the possibility of hormonal issues skewing test results. Hence, there is a significant research disparity between male rats and female rats, both in the lab and in the wild, Parsons says.

Returning to the topic of direction and navigational skills and lab research, Parsons said he understands why neuroscientists and others have used lab rats, rather than wild rats, in their research. At the same time, he cautions about humane treatment among lab researchers and the pressure to go through lab rats needlessly, redoing already known scientifically-proven research.

Kentros notes that rats are treated very humanely in labs like those housed at the Norwegian University of Science and Technology, and at other reputable research centers. Kentros was born and raised in the United States and completed his graduate studies in neuroscience at Columbia University in New York City. He said he can confidently state the wild urban rats of New York City, for example, have significantly harder lives compared to the average lab rat. 

Want more health and science stories in your inbox? Subscribe to Salon's weekly newsletter The Vulgar Scientist.

Kentros is motivated by altruism and the medical possibilities; and he says that society has a long way to go. Kentros noted that we have so much to learn about brain conditions and diseases — things like memory recall and directional issues that might be present if a patient has Alzheimer's Disease.

 "While I am a big believer in pure science, in the course of trying to figure out how the brain works, my ultimate motivation is helping folks," Kentros said, noting on a personal level that he has family members who have developed dementia.

"The brain is so complicated," Kentros continued. "When it comes to a large number of diseases of the brain, you have to not look at the whole brain, but instead [p]articular circuits of the brain," he said. Kendros explained that specialized neuroscientists tend to research specific circuits or neurons, considering the brain on a micro- level. 

Place cells, Kentros explains, are specific neurons located within the brain's hippocampus that "fire" when an animal (or human) is in a specific environment, called a place location. 

"One of the amazing things about these place cells is that you can record – even eavesdrop – on what each place cell is doing: neuron A fires up in the north and neuron B fires up in the south. They are all kind of unique," he said.

"The question now is whether that stabilizes place cells in rats. That is the thing. What is memory? It is basically the movies that you make with your eyes, ears etc. Your recording of your personal experience. The fact that the animal did not make place cells by observation alone when there was no observation alone. What to do there?"

"That is why we came up the experience in our research experiment," Kentros said. 

Ultimately, wild rats' navigational abilities — and their understanding of how to navigate sewers and urban pathways — is not well understood by current behavioral researchers, according to Michael H. Parsons, a rodent behavior expert, urban field ecologist and visiting research scholar at Fordham University in New York.

Rats on the move

Returning to the implications of the observer-demonstrator rat study, Kentros wants to study spatial cells in lab rats next. Spatial cells, Kentros said, constitute the "movie set" that typifies your life; he noted that the spatial cells are intimately connected to memory. "Can you not remember something without thinking of where it was?" he posed. 

The real surprising implication of the study is how similar we are to rats.

"What this experiment shows us is exactly how much like rats we really are," Kentros says. "This fact that they are so much like us is why we need to [study] them to get after these really complex, really tragic, brain diseases in humans."

By Pamela Appea

Pamela Appea is a New York City-based independent journalist covering health, science and intersectionality. Appea is a 2022 Age Boom Fellow, a program of the Robert N. Butler Columbia Aging Center and the Columbia School of Journalism. She has written for Salon, Glamour, Parents, Wired and other publications. She is currently working on a nonfiction book on gender-based health disparities. Follow her on Twitter at @pamelawritesnyc

MORE FROM Pamela Appea

Related Topics ------------------------------------------

Animal Navigation Neurology Rats Reporting Research