London, Oct 16 : Experimenting with monkeys, scientists have shown that the primates could successfully move paralysed limbs via brain implant with mobile electrodes.
Such artificial re-routing of brain may pave the way towards helping paralysed people in regaining the use of their limbs.
Previous studies have shown that monkeys could be trained to move robotic arms using signals routed from electrodes in their brains. This was done by decoding tens of neurons working simultaneously at a time to replicate actions such as grasping, and required considerable computing power.
In the new research, a team led by Chet Moritz at the University of Washington in Seattle, used similar signals to send direct electrical stimulation to a paralysed muscle, by using just one neuron.
For the study, the researchers first implanted some electrodes in the motor cortex of two macaque monkeys. All the electrodes picked up signals from a single neuron, and the signals in turn were routed through an external circuit to a computer.
The monkeys were trained to move a cursor on screen using only their brain activity, while the neuronal signals controlled the cursor.
Later, the researcher temporarily paralysed the monkeys' wrist muscles by using a local anaesthetic. Then, in order to deliver electrical stimulation to the wrist muscles, the signals were re-routed from the electrodes.
The researchers discovered that the monkeys could control their previously paralysed limbs using the same brain activity.
In fact, the monkeys learnt to do this in less than an hour.
However, the previous function of the neuron doesn't affect if it can be trained to move a particular muscle.
"All neurons could be used equally well, regardless of whether that neuron was originally related to the activity of these muscles. This dramatically expands the potential population of neurons that could be used to control a neural prosthesis," Nature quoted Moritz, as saying.
However, he said that clinical treatments using the technology is still far off, and the long-term electrode implants needed are not yet practical for human subjects.
The study is published in Nature.