Researchers around the world are working to develop technology that facilitates mobility and communication in patients suffering from locked-in syndrome. But what if locked-in patients could manipulate their environments using only their minds? Research collaborators at Massachusetts General Hospital, Brown University, Providence VA Medical Center, Stanford University and Case Western Reserve University have developed the BrainGate2 Neural Interface System, a brain-computer interface (BCI) which allows paralyzed patients suffering from spinal cord injury, stroke and ALS to control computer cursors and robotic limbs by simply thinking about moving their own hands.
“What we’re hoping to do through our BrainGate research is learn how to record from different parts of the brain and to interpret the brain signals that are associated with the intention to move,” explains Leigh Hochberg, MD, PhD, neurologist and neuroengineer at MGH, Brown, and Providence VAMC, and director of the BrainGate pilot clinical trials. The researchers at BrainGate work to decode these brain signals in real time, and translate them into control signals for assistive devices. “Through our research we aim to restore the communication, mobility and independence of people with paralysis or limb loss,” he says.
The BrainGate System consists of a four-by-four millimeter array of electrodes implanted in the motor cortex of the brain. Fine wires connect the array to a titanium plug secured to the skull. When the researchers wish to record from the arrays, they connect the plug to a computer embedded with software that decodes the firing patterns of neurons.
The BrainGate System is in its second round of clinical trials. To date there have been 11 trial participants, and there are currently three active participants—two with ALS and one with a cervical spinal cord injury. Although much of the research involves participants mind-controlling computer cursors, in 2012 the BrainGate team reported that two participants with tetraplegia were able to use the system to reach and grasp real-world targets with a robotic limb. In one instance, BrainGate trial participant Cathy Hutchinson manipulated a robotic arm to take a sip of coffee from a bottle, 15 years after a stroke left her unable to move any of her limbs.
Over the years, the BrainGate research team has succeeded in making the system smoother, faster and more intuitive. “The way that we really know that we’re doing our job right is when we ask our participants what they’re doing to control the cursor and they say that they’re just doing it,” says Hochberg. “That type of ‘imprecise response’ is exactly what someone who is able-bodied would say if we asked them how they were holding a coffee cup or writing with a pen or typing on a keyboard.”
The BrainGate team is also currently working to develop a wireless transmitter that will eliminate the need to hard-wire trial participants to a computer.
The work of the BrainGate researchers is far from over. Hochberg has high hopes for the future, including someday reconnecting brain to limb and thereby allowing paralyzed patients to use their own arm and hand again. In the meanwhile, Hochberg is thankful for the trial participants who have made the BrainGate research possible.
“We have the privilege of working with incredible participants who join us not because they’re hoping to gain any personal benefit, but because they want to help us to test and develop a technology that we all hope will benefit other people with paralysis in the future.”
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