Scientists restore movements to paralysed limbs
Scientists restored movements in monkeys whose arms were temporarily anaesthetised
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Thursday, 16, Oct 2008 01:42
For the first time scientists have demonstrated that a direct artificial connection from the brain to the muscles can restore voluntary movement in animals whose arms have been temporarily anaesthetised.
The authors of the study, published in the journal Nature today, claim the results could have positive implications for those suffering from spinal cord injures and paralysing neurological diseases.
"This study demonstrates a novel approach to restoring movement through neuroprosthetic devices, one that would link a person's brain to the activation of individual muscles in a paralyzed limb to produce natural control and movements," said Joseph Pancrazio, from the National Institute of Neurological Disorders and Stroke.
In the study, the researchers trained monkeys to control the activity of single nerve cells in the motor cortex, an area of the brain that controls voluntary movements, and detected neuronal activity using a type of brain-computer interface.
Electrodes implanted in the motor cortex of the monkeys were then connected via external circuitry to a computer. The neural activity led to movements of a cursor, as monkeys played a target practice game.
During their tests, the researchers temporarily paralysed the monkey's wrist muscles using a local aesthetic to block nerve conduction.
They then converted the activity in the monkey's brain to electrical stimulation delivered to the paralysed wrist muscles. The monkeys continued to play the target practice game, but the cursor movements were now being driven by actual wrist movements - demonstrating that they had regained the ability to control the otherwise paralysed wrist.
Other techniques for restoring physical currently being developed include the use of robotic limbs.
"A robotic arm would be better for someone whose physical arm has been lost or if the muscles have atrophied, but if you have an arm whose muscles can be stimulated, a person can learn to reactivate them with this technology," said Eberhard Fetz, from the University of Washington in Seattle.
In today's report the authors also claim they discovered that any motor cortex cell, regardless of whether it had been previously associated with wrist movement, was capable of stimulating muscle activity.
"This finding greatly expands the potential number of neurons that could control signals for brain-computer interfaces and also illustrates the flexibility of the motor cortex," the authors declared.