New research shows that humans aren’t the only animal species with imagination: mice are too. This means that other animals can also think about past and future scenarios.
You probably know this: While you’re making your to-do list, you’re already mentally walking to the supermarket, putting laundry in the washing machine, or having that conversation you’re going to have later that day. You’re still sitting in the same chair, but in your head you’re in a completely different place. Until now, it has always been thought that humans are unique in this way of thinking. No other animal can go somewhere else in its mind. After all, this means that animals can think, something only humans can think. But this old idea has now been overturned by a study. Not only humans, but also mice can imagine things.
Researchers discovered this in Janelia Research Park in the United States of America. In their research they introduced mice for the first time Virtual Reality Discover the environment. The mice then had to follow the same routes in their minds.
mental map
The first part of the research aims to get rats to create a kind of map in their heads of the virtual world they have been shown. By looking at which areas of the brain lit up as the mice did this, the researchers were able to “read” where the mice were at that moment. How does this work?
When you come to a new place, you make a kind of map in your head of where it is. The brain also tracks where you are in that room at that moment. In all of these locations and orientations, specific patterns of brain activity arise in the hippocampus, the region responsible for spatial memory. When you come to the same place again later, your brain recognizes it and the same patterns are activated again. Even the memory of the place. By reading brain activity and knowing the codes for what, you can infer where your subject, in this case the mouse, is in his or her mind.
A virtual world
To create that map and see which brain signals correspond to which location, the researchers hooked a mouse into a virtual reality system. In that system, the mouse walked on a spherical treadmill while its movements were translated to a screen that completely surrounded it. At the same time, the researchers recorded the mouse’s brain activity as it navigated through the virtual world. The mouse was also rewarded for this. When he managed to find certain places, he got something delicious.
Walking in thoughts
Once they were properly trained, and thus familiar with the routes the rat would have to take to reach the target locations, the researchers removed the treadmill. From that point on, they rewarded the mouse not if it walked to the right place – after all, that was no longer possible – but if the mouse went to that place in its thoughts. In other words: if the mouse actively repeats the brain activity associated with walking to that target location. To make this visible to the mice, the mice’s brain activity was translated into movement on a virtual reality screen around the mice. Thus the animal can use its thoughts to move to the reward. And it turns out he can.
Thinking about the future
“Our research shows that mice, just like humans, can activate memory of places without actually going there,” says lead author Zhongxi Lai. “Even if his physical body is stuck, his spatial thoughts can travel to far places.” This offers many new ideas. The ability to effectively retrieve and reflect on location-related information is essential for remembering past events and imagining possible future scenarios. Researcher Albert Lee: “Imagination is one of the most remarkable things humans can do, and now we’ve discovered that animals can do it too.”
And they can do it well. Animals can keep their thoughts in one place for several seconds. Around the same time as people reminiscing about past events or imagining new scenarios. Fellow researcher Tim Harris said: “We found it surprising how mice could think about this place in particular, and nowhere else, for a very long period of time.” But he admits: “It may also be due to our naive idea of the attention span of a rat.”
Mind reading in monkeys
Scientists have previously used brain activity to read monkeys’ minds. In that study, the researchers knew what they were going to do before two monkeys moved. By looking at the animals’ brain activity, they discovered exactly what the monkeys were planning to do. The big difference between the studies is that the monkeys did not stimulate brain activity as effectively, as in the study conducted on mice. Researchers can simply “translate” brain activity into what the monkey would do.
There have also been studies in which monkeys actively control devices using their brains, such as research into self-driving wheelchairs. In this case, controlling the wheelchair was a combination of the monkey learning to control the device, and the algorithm in turn trying to understand what the monkey meant.
