15 years after she lost the ability to move her body, Cathy Hutchinson is learning how to use her brain to control a robotic arm.
Today scientists announced in the journal Nature the results of a landmark experiment in which paralyzed subjects were able to control a robotic arm using only their thoughts. The research, after decades of exploration, holds out promise for the future of restoring damaged bodies using robotic prostheses.
Led by researchers at Brown University, the Department of Veterans Affairs, and Massachusetts General Hospital, the study--known as BrainGate--utilized a device called the BrainGate Neural Interface System, implanted directly into the motor cortex of the participants. Wired to a bank of computers, the system was then able to decode their brain's neural signals for movement and translate them into robotic movement. "This work is a critical step," John Donoghue, the neuroscientist who developed BrainGate, said in a statement announcing the research, "toward realizing the long-term goal of creating a neurotechnology that will restore movement, control, and independence to people with paralysis or limb loss."
The two subjects--a 58-year-old woman identified as subject S3 and a 65-year-old man designated as T2, both with tetraplegia--were first able to control a cursor on a screen by thinking about its movement. They then graduated to an advanced humanoid robotic arm made by the German space agency DLR and an advanced prosthetic made by New Hampshire-based DEKA Research. When the subjects concentrated on moving the robotic appendages, their brain supplied the signals for their intent, BrainGate captured those signals, and the robotic limbs responded in turn.
The paper reports that both participants were able to "perform three-dimensional reach and grasp movements," including touching targets and grabbing a bottle. Perhaps most extraordinarily, however, "one of the study participants, implanted with the sensor five years earlier, also used a robotic arm to drink coffee from a bottle."
In the paper, that subject is S3, the female participant. Her real name is Cathy Hutchinson, and this is her story.
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The first thing Cathy Hutchinson became aware of upon waking from three weeks in the quiet of a coma, 16 years ago, was the rhythmic alternation of surge then draw: whoosh, hiss, whoosh, hiss. As the contours of a room began to resolve before her eyes, she discovered the source of the sounds--a ventilator machine beside her bed. Her eyes followed the curve of a plastic tube issuing from the noisy box until it disappeared under her chin, entering her body through the opening in her throat left by a tracheotomy. When she tried to raise her head, she discovered that she could not. No amount of effort allowed her to lift her hand or flex her feet.
Her last memories were of feeling sick, of passing out as her 18-year-old son, Brian, helped her up the stairs to her bedroom, of waking briefly on the rough carpet of the hallway, unable to move. She was 43, a healthy nonsmoker, single mother of two, post office employee.
On that spring day in 1996, it took doctors nearly 12 hours following Brian's emergency call to discover that Cathy had suffered a catastrophic brain-stem stroke. The brain stem is located at the base of the skull, a small region of primitive structures crucial to survival. It governs the critical functions of breathing, swallowing, blood-pressure regulation, and consciousness and conducts all messages between the brain and the spinal cord.
A brain-stem stroke is the sort of medical event that can result in death immediately or soon thereafter. But in Cathy, who was young and in otherwise good health, the stroke disconnected her brain from the descending motor tracts of her brain stem--the neural pathways carrying instructions to her muscles--leaving her "locked in," not only quadriplegic but also unable to speak. The ascending tracts, which carry sensory information from body to brain, remained intact, allowing her the experience of pain, itch, heat, and cold but not the possibility of addressing them. She had a sensate, lucid mind incapable of action.