Rats Can Use Their Imaginations, Like Humans, In Virtual Reality Experiments

Rats have imaginations – just like humans, suggests a new study.

Experiments on the rodents found they were able to use their minds to perform tasks in virtual reality.

A team of American researchers pioneered a system combining virtual reality and a brain-machine interface that probed the minds of rats.

The scientists discovered that, like us, rats can think about places and objects that aren’t immediately in front of them – by using their imaginations.

The rodents were even found in tests to be able to use their minds to move objects in their virtual realities – much like Jedis in the Star Wars franchise.

The innovative research serves as proof that the minds of rats – and most likely other animals, too – harbor imaginations like ours.

Researchers from the Howard Hughes Medical Institute’s (HHMI) Janelia Research Campus, in Virginia, found that brain activity is activated in rodents, like humans, when they experience places and events.

This neural activity occurs in the hippocampus: an area of the brain responsible for spatial memory.

The new study suggests rats can voluntarily generate these same activity patterns and do so to recall remote locations far away from them.

This ability to imagine locations elsewhere from our current positions is crucial to recalling past events and imagining future possible scenarios.

According to the authors of the groundbreaking study, published in the journal Science, this demonstrates that animals, too, have imaginations.

The researchers project began nearly a decade ago when first author Dr. Chongxi Lai arrived at the Janelia campus and teamed up with Dr. Albert Lee to pursue the idea of testing whether or not animals could think.

The pair worked together to develop a ‘thought detector’ system that could measure neural activity and translate it to understand what animals are thinking.

The system uses a brain-machine interface – or BMI – which provides a direct connection between brain activity and an external device.

This BMI produces a connection between the electrical activity in the rat’s hippocampus – a complex brain structure embedded deep into the temporal lobe – and its position in a 360-degree virtual reality arena.

The hippocampus stores mental maps of the world involved in recalling past events and imagining future scenarios.

Memory recall involves the generation of specific hippocampal activity patterns related to places and events – though no one knew whether animals could voluntarily control this activity until this latest study.

The researcher’s BMI allows them to test whether a rat can activate hippocampal activity to merely think about a location in the arena without physically going there – essentially, to assess whether the animal is able to imagine going to the location.

Once this system was developed, the researchers then had to create what they described as a ‘thought dictionary’ which allowed them to decode the rat’s brain signals.

The dictionary compiles what activity patterns look like when the rat experiences something – in this case, places in the VR arena.

The rat is harnessed into the VR system, where it walks on a spherical treadmill.

The rat’s movements are monitored and translated onto the 360-degree screen, and it is rewarded when it successfully navigates to its goal.

Simultaneously, the BMI system records the rat’s hippocampal activity, and the researchers are able to monitor which neurons are activated when the rat navigates the arena to reach each of its goals.

These signals provide the basis for a real-time hippocampal BMI, with the hippocampal activity in the brain translated into actions on a screen.

The research team next disconnected the treadmill and rewarded the rat for reproducing the hippocampal activity pattern associated with a goal location in a real-life situation.

In this task, named a ‘Jumper’ task after the 2008 film of the same name, the BMI translated the animal’s brain activity into motion on the virtual reality screen.

The rats essentially used their thoughts to navigate towards their rewards by first thinking about where they needed to go in order to receive them – a thought process humans experience regularly.

For example, when we are asked to pick something up at a familiar store, we may imagine the locations we pass along the way before we’ve even left the house.

In the second task – named the “Jedi” task in a nod to the Star Wars films – the rat moves an object to a location by thoughts alone.

The rat is fixed in a virtual place but ‘moves’ an object to a goal in the VR space by controlling its hippocampal activity – much like how a person sitting in their office might imagine taking a cup next to the coffee machine and filling it with coffee.

The researchers then changed the location of the goal, requiring the animal to produce activity patterns associated with the new location.

The team found the rats can precisely and flexibly control their hippocampal activity, in the same way humans do.

The animals are also able to sustain this hippocampal activity, holding their thoughts on a given location for many seconds – a timeframe similar to the one at which humans relive past events or imagine new scenarios.

Dr. Lai, first author of the study, explained: “The rat can indeed activate the representation of places in the environment without going there.

“Even if his physical body is fixed, his spatial thoughts can go to a very remote location.”

Dr. Lee, an HHMI Investigator at Beth Israel Deaconess Medical Center, added: “To imagine is one of the remarkable things that humans can do.

“Now, we have found that animals can do it too, and we found a way to study it.”

The research also demonstrates that BMI can be used to probe hippocampal activity, providing a novel system for studying this important brain region.

Because BMI is increasingly used in prosthetics, this new work also opens up the possibility of designing novel prosthetic devices based on the same principles, according to the authors.

Produced in association with SWNS Talker