American scientists have come a step closer to discovering a way of ‘curing’ paralysed limbs by creating technology that delivers direct electronic ‘messages’ from the brain to the affected part of the body.
Researchers from the Northwestern University Feinberg School of Medicine managed to send electric signals from the brain to the targeted limb to move, bypassing the damaged spinal cord.
“We are eavesdropping on the natural electrical signals from the brain that tell the arm and hand how to move, and sending those signals directly to the muscles,” said Lee. E. Miller, lead author of the study.
The researchers focused on a ‘paralysed’ hand of a monkey, whose electrical brain and muscle signals were monitored throughout the process.
The lab monkey was given a local anesthetic to block nerve activity at the elbow, causing temporary (and painless) paralysis of the hand. They were also given tiny 'multi-electrode' implants that scientists used to track the electric signals.
When the electrical signals were sent through the body, scientists were able to develop a algorithm (a decoder) that enabled them to record and predict patterns of muscle activity in the monkey – down to the moment the monkey wanted to move a muscle.
Scientists discovered that the monkey’s brain signals were able to control tiny electric currents sent through the body and into its muscles, causing them to contract and therefore allowing the monkey to pick items up using its ‘paralysed’ hand.
Scientists from the study likened this ‘motor learning’, when people relearn the movements that achieve an everyday task.
"The monkey won't use his hand perfectly, but there is a process of motor learning that we think is very similar to the process you go through when you learn to use a new computer mouse or a different tennis racquet. Things are different and you learn to adjust to them," explains Miller.
"We can extract a remarkable amount of information from only 100 neurons, even though there are literally a million neurons involved in making that movement,” Miller said.
“One reason is that these are output neurons that normally send signals to the muscles. Behind these neurons are many others that are making the calculations the brain needs in order to control movement. We are looking at the end result from all those calculations.”
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