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Rats acquire knowledge for thirst
All a rat needed to do was think "I could do with a drink" and a drink would appear. In the first experiment in thought power for rodents, US scientists wired up laboratory rats and encouraged them to move a robot arm.The incentive? It was the only way to serve themselves a drink.
John Chapin of the Hahnemann school of medicine in Philadelphia and colleagues demonstrated in animals something already shown in humans: that there are "places" in the brain where specific limb movements happen - and where thoughts about movements also happen. These thoughts are marked by electrical signals, which instruments can detect and which computers can convert into action.
In January scientists in Tubingen in Germany used neural detectors to enable people with "locked-in syndrome" - people practically unable to move a muscle - to choose from letters on a screen by thoughtpower alone, and so to write a message.
The discovery raised hopes of thought-operated computers, wheelchairs and prosthetic limbs. But the question remained: was this something that only a few could do? Or would it be possible for everyone? Did all mammal brains work in the same way?
Dr Chapin and his team report in Nature Neuroscience today that they trained six rats to press a lever which operated an electric robot arm which would deliver water. They monitored electrodes planted in the rat's brains and analysed the patterns of brain activity as the rats worked on the problem. They pinpointed a particular crackle of activity that went with paw movement.
The researchers then disconnected the robot arm from the lever and connected it to the computer system instead. The rat's brain then controlled the robot arm through the electrode and the computer, rather than through the spinal cord and paw muscles. It was, in effect, a paw bypass.
At first, the rats continued to press the lever. But many of them soon learned that they could serve themselves water by brain activity alone, and stopped pressing the lever. The researchers argue that they had learned to alter their brain activity to control the robot arm.
In practice, there could be a long way to go before the technique could help human patients. In practice, too, the rats were only required to move the mechanical drink-server in one dimension; humans normally need to move objects through three dimensions. But the experiment opens up the possibility of eventually controlling prosthetic devices through brainpower alone.