Imagination. It is undoubtedly one of the most remarkable qualities bestowed upon humans. And today, researchers from the Howard Hughes Medical Institute (HHMI, USA) reveal in the pages of the journal Science that we are not the only animals endowed with this gift. Rats, too, can exhibit imagination.
A Rat’s Thought Detector
Nine years ago, HHMI teams started working on the creation of a system to comprehend what animals think, which is where the story of this incredible discovery began. A kind of real-time “thought detector” capable of measuring neuronal activity and translating its meaning is a feat in itself.
At the heart of the system is a brain-machine interface (BMI) that establishes a link between the electrical activity of the rat’s hippocampus and its position in a virtual reality setting. The hippocampus was chosen because it is the brain region responsible for spatial memory. It’s where the mental maps that allow us to recall past events and imagine future scenarios are stored. Through the BMI, the researchers hoped to determine whether a rat could voluntarily activate its hippocampus, thinking about a place without physically going there, essentially imagining going to a place.
Rats Can Imagine Movement
To achieve this, a “rat’s thought dictionary” had to be developed. A dictionary that would decode the recorded brain signals. To associate signals with activity, the researchers had the rat walk on a treadmill, translating its movements into virtual reality while recording everything.
Once the protocol was in place, the researchers could translate the rat’s hippocampal activity into movement in virtual reality. They observed that the rat uses its thoughts to navigate toward a reward by first contemplating where it needs to go. This is similar to what we do when we imagine going grocery shopping and visualize the places we will pass on the way before leaving our house.
Following a similar pattern, the researchers then allowed the rat to move an object to a location through the power of imagination by controlling the activity in its hippocampus.
Studies on Rats That Could Benefit Humans
Thus, the work of HHMI researchers demonstrates that rats can control their hippocampal activity with precision and flexibility, much like humans. Rats are also capable of maintaining this hippocampal activity, keeping their thoughts in one place for several seconds. This may seem lengthy, given the possibly mistaken belief scientists have about a rat’s attention span.
Rats, like humans, possess a certain form of imagination. This is already a remarkable revelation in itself. But the researchers go even further. With this achievement, they hope to leverage their “thought detector” to design new prosthetic devices.