Rats Aren't Smarter Than Mice: A Surprise for Researchers

Rats have long been used as the ideal test subjects of behavioral and neurological study. Mice, on the other hand, are used in things like viral, drug, and even cosmetic testing, as they have been seen as too simple-minded for more complex work. Now, new research has turned this assumption on its head, finding that the rodents are of equal intelligence.

That's at least according to a study recently published in the journal Frontiers in Systems Neuroscience, which questions the wisdom in assuming that rats are more clever than mice.

"Our results demonstrate that mice are an appropriate model for the study of the neural mechanisms underlying adaptive decision-making, and suggest they might be suitable for other cognitive tasks as well," the authors wrote.

They determined this after presenting groups of laboratory-ready rats and mice with the same complex behavioral task.

According to the study, 10 rats and 10 mice were trained to categorize sounds based on their frequency, hitting one of two buttons to indicate if they were hearing a high or low frequency noise. The researchers found that although rats learned to do this task at a faster rate than the mouse group, the rodents appeared to perform equally in more than 300 trials. This indicated an equal understanding of the task at hand, despite its relative complexity. (Scroll to read on...)

Study author Tony Zador recently explained to The Atlantic that he's confident that "anything we could train a rat to do we could train a mouse to do as well."

He argues that the reason rats always seemed more clever than the smaller rodents was because humans have spent more time learning how to properly train them. In fact, that may be one of the factors that resulted in the mice taking longer to learn the study's task.

"Over the course of 100 years people had figured out how to train rats, and that mice aren't rats," Zandor said. "There was no big epiphany, there was no aha! moment. But it was just a series of small optimizations and we got mice to perform pretty much as well as the rats."

And this is pretty big news for the research world. Mice are cheaper and easier to store in labs compared to rats, and according to Zandor and his colleagues, a mouse's brain is actually easier to image using a number of novel techniques. This could make them preferable for some neurological studies currently dominated by rat models.

Co-author Santiago Jaramillo is reportedly moving on to test if mice can be taught to complete complex tasks once reserved for test monkeys -tasks already successfully adapted by rats in recent years.