Rats may be able to dream just like humans

The ability to get lost in thought and drift into daydreams may not be unique to humans. In a study published in the new issue of the journal Science, it was discovered that rats can think about objects and places that are not in front of them.

Imagining places far from our current location is part of both memory and the ability to visualize potential future scenarios. If animals possess this ability, they may be exhibiting a form of imagination similar to our own species.

EVEN IF THE BODY IS STATIONARY, THOUGHTS CAN BE IN A DISTANT REGION

According to details featured in Populer Science Turkey, Chongxi Lai, an engineer, neuroscientist, and co-author of the paper working at the Howard Hughes Medical Institute, says, “Rats can indeed activate the representations of places in the environment without going there.” “Even if the physical body is stationary, their spatial thoughts can travel to a very distant region.”

Lai and a research team working at the Maryland – Howard Hughes Medical Institute designed a series of experiments to learn more about this, aiming to see if rats could use their thoughts to imagine going to a specific place or moving a distant object.

A new brain-machine interface and virtual reality system for rats.

In this experiment, a rat uses this system to reach a target by simply thinking about the place it wants to reach. According to the rules of the system, the physical movement the rat makes does not affect the rat's position in the virtual environment. The rat can only control where it goes by controlling its hippocampal brain activity. To explain in more detail, in this system, the animal moved virtually toward the ‘decoded location’ represented by hippocampal activity.

When humans and rodents experience certain events or visit certain places, specific neural activity patterns are activated in their hippocampal regions. This region of the brain, which is responsible for spatial memory, stores the mental map of the rat's world.

The region is also used to recall past events and imagine future situations. To recall memories, specific patterns associated with places and events are generated in the hippocampus. While it has been shown that chimpanzees have the ability to pretend to do something, scientists are still trying to figure out how chimpanzees and other non-human animals think.

The research team developed a real-time “thought detector” to look inside a rat's brain and see these patterns. The system measures neural activity and translates what it means using a brain-machine interface (BMI).

The BMI established a connection between the electrical activity occurring in the rat's hippocampus and the animal's position in a 360-degree virtual reality scene. Thus, the researchers had the opportunity to see if a rat could trigger hippocampal activity and think about a location in the virtual scene without actually going there.

DECODING BRAIN SIGNALS

With the activation of the BMI, the researchers worked to decode the brain signals in the rats. As the rat navigated the virtual scene in the experiment, they built a “thought dictionary” of what brain activity patterns looked like.

For this, a virtual reality system was used for the rat. As the rat walked on a spherical treadmill, its movements were translated onto a 360-degree screen. When it reached its target, the rat was rewarded.

While the rat was walking on the treadmill, the BMI system recorded the activity taking place in the hippocampus. The research team observed which neurons were activated as the rat navigated the virtual scene to reach each target. These signals showed the research team what was happening in the hippocampus