Rats can move objects in virtual reality just by thinking of where they want them to go, thanks to an artificial intelligence that reads their intentions in the brain.
A mental map of our local surroundings is stored in a brain region called the hippocampus, which contains neurons called 鈥減lace cells鈥�. These cells fire different patterns of electrical impulses depending on where you are.
However, it has been unclear whether this activity in the hippocampus can be consciously controlled by imagining travelling to relevant locations or recalling places we have been.
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To investigate, at the Howard Hughes Medical Institute in Virginia and his colleagues created a brain-machine interface, which they used to record the electrical activity in the hippocampi of four rats as they ran on top of a spherical treadmill.
The rotation of the ball, which could go in any direction, controlled where the rats were in a 1-square-metre virtual environment projected onto a screen surrounding the animals. On reaching a tall virtual column, the rats were rewarded with a sip of water.
As the tasks proceeded, the researchers trained an AI to learn any links between the brain activity of the rats and the animals鈥� locations in the virtual environment.
Lee and his colleagues then placed the rats on the treadmill, but disconnected it from the projected environment, so the animals couldn鈥檛 get to where they wanted to go by moving the ball. Instead, the AI translated the rats鈥� brain activity to work out their intended destination and take them there in the VR world, so they could get their reward. The technique worked for three of the four rats.
The researchers also trained the rats to move a virtual object to get a reward and, again, the AI could use the brain-machine interface to work out what three of the rats were trying to do and move objects for them in VR.
The findings suggest that rats can recall and imagine moving to remote locations, which changes their brain activity in identifiable ways, say the researchers.
鈥淧revious work has suggested a role for the hippocampus in imagination, but demonstrating this at a cellular level is quite challenging and a major achievement,鈥� says at University College London.
Similar brain-machine interfaces could potentially be used by people with paralysis to control devices that help them move, says Bendor. However, the AI would need to be trained to decode brain signals for any new environment, he says.听
bioRxiv
