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Profound and life-altering
Ataxia comes from two Greek words – a, meaning without, and taxis, meaning order. An estimated 150,000 Americans suffer from the condition, according to the National Ataxia Foundation, and they include men and women, young and old, and members of every racial and ethnic group.
Often hereditary, ataxia is a set of symptoms that result from disease, defects or damage to the cerebellum. It afflicts fingers, hands, legs, balance, speech and eye movements, and it is degenerative. From slurred speech and unsteady balance, patients typically progress to the point at which the simplest tasks require the utmost will power.
Many types of ataxia, including Loya’s, do not shorten a person’s life, says Ying, who has worked a decade with ataxia patients. But ataxia in all its forms alters life profoundly.
“Ataxia is socially very isolating. Ataxia patients can’t speak well and they can’t move around. They spend a lot of time on the Internet, but may have difficulty typing.”
BCI technology promises to restore some social life by helping ataxia patients perform activities that can be interfaced with a computer, says Ying. These could include operating a wheelchair or using prosthetic limbs. But scientists must first improve their ability to interpret and harness brain signals.
That endeavor is daunting. The brain’s 100 billion cells make thousands of connections with each other every second. To probe this activity with 64 electrodes, says Thakor, is like asking space aliens who know nothing of human beings to observe the earth and summarize all of its intelligent life from 64 orbiting satellites.
But electrodes placed on the functioning part of the sensory and motor cortex would allow scientists to capture the cortical signature, says Thakor. Humans could then learn to control the signals in this region of the brain by modulating the frequency of those signals, much as a soprano renders an aria by modulating the pitch of her voice.
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One question yet to be answered, says Ying, is whether ataxia patients can control their brain signals as well as normal people. Can they perform as well on the cursor-target exercise and other brain signal tests? Ying is correlating those test results with MRI scans to determine if anatomical clues might predict the ability of Loya and other ataxia patients to master BCI technology.
The research team is also planning a set of experiments to measure the impact of feedback on the transmission of brain signals. The team will implant electrodes on the cortices of epilepsy patients undergoing surgery for seizures. The electrodes will enable the researchers to obtain a “neural signature” by recording the brain signals that are generated when a postsurgery patient performs a routine task. The goal is to observe how that signature changes with and without visual feedback.
“We will ask the person to close his eyes and reach for an object,” says Kothare. “Without the benefit of visual feedback, the person will have to rely on force feedback, along with the memory of the position of the object, to accomplish the task. Then we will tell the person to open his eyes and reach for the object. We will watch the progress of the person’s arm toward the object while we measure the neural signals being emitted.
“Our hypothesis is that the signals generated by the brain during each of these scenarios will be different. This hypothesis has never been tested in an experiment. We hope to understand how neural signals change as feedback occurs.”
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“Any way I can”
Back in Johns Hopkins’ neuroengineering lab, Roy Loya has completed the two-hour brain signal exam. After seven years of MRIs, movement studies, gait testing and cognitive exams, this has been Loya’s first trial with BCI technology. In addition to the cursor-target test, he has also attempted to modulate his brain waves by thinking calm or agitated thoughts. The day has been a qualified success. Loya did well for an hour, then tired. And the researchers need to work on the signal-processing software and refine an algorithm to achieve a better balance between left and right hand.
Loya’s handshake is firm as he says good-bye to the researchers, and his face is alert. He begins to reminisce, moving his hands alongside his neck to improve control over his vocal cords. His words rumble out, each the product of great effort. But he makes himself understood.
As a young man, Loya completed a bachelor’s degree in aeronautical engineering from Princeton. He went to law school at the University of Maryland and at Georgetown. He practiced tax law for 20 years and traveled to 70 countries on six continents. He earned a pilot’s license and flew the Douglas DC-3, a propeller-driven transport plane used in World War II.
Loya did not notice his first symptom of ataxia until eight years ago, when air-traffic controllers began having trouble understanding his speech. Now he has one goal.
“I have always loved science. I want to help these people any way I can.”
