Scientists have connected the brains of a pair of animals and allowed them to share sensory information in a major step towards what the researchers call the world's first "organic computer".
The US team fitted two rats with devices called brain-to-brain interfaces that let the animals collaborate on simple tasks to earn rewards, such as a drink of water.
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Led by Miguel Nicolelis, a pioneer of devices that allow paralysed people to control computers and robotic arms with their thoughts, the researchers say their latest work may enable multiple brains to be hooked up to share information.
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The scientists first demonstrated that rats can share, and act on, each other's sensory information by electrically connecting their brains via tiny grids of electrodes that reach into the motor cortex, the brain region that processes movement.
The rats were trained to press a lever when a light went on above it. When they performed the task correctly, they got a drink of water. To test the animals' ability to share brain information, they put the rats in two separate compartments. Only one compartment had a light that came on above the lever. When the rat pressed the lever, an electronic version of its brain activity was sent directly to the other rat's brain. In trials, the second rat responded correctly to the imported brain signals 70% of the time by pressing the lever.
Remarkably, the communication between the rats was two-way. If the receiving rat failed at the task, the first rat was not rewarded with a drink, and appeared to change its behaviour to make the task easier for its partner. In further experiments, the rats collaborated in a task that required them to distinguish between narrow and wide openings using their whiskers.
In the final test, the scientists connected rats on different continents and beamed their brain activity back and forth over the internet. "Even though the animals were on different continents, with the resulting noisy transmission and signal delays, they could still communicate," said Miguel Pais-Vieira, the first author of the study, in a statement. "This tells us that we could create a workable network of animal brains distributed in many different locations."