Nitish Thakor of Biomedical Engineering
on developing a new prosthetic arm and
inspiring other innovations:
What led to your work on neuroprostheses?
THAKOR: When I came to Hopkins 25 years ago, I was interested in deciphering heart rhythms, research that was relevant to pacemaker technology. Then about 10 to 15 years ago, my clinical collaborators brought to my attention the very interesting and challenging problem of monitoring brain injury patients. I felt that detecting the changes in brain rhythms, using novel signal analysis methods I had developed, might help doctors more objectively detect or treat different injuries.
Then two years ago, the Defense Advanced Research Project Agency solicited a program to “revolutionize” prosthetics. The Johns Hopkins Applied Physics Lab won the competition, and I got involved with the idea of using my expertise at analyzing brain rhythms to control prosthetics.
When might a next-generation prosthesis become available?
THAKOR: We have the proof of principle. But other factors besides the science will determine how long it takes: How long will it take to test the technology in patients? When will the Food and Drug Administration approve the technology? Will a company want to make it? Will insurance companies cover the cost? There are a lot of questions.
There is also the possibility of building a reduced and simpler version of this prosthesis. A fully neurally controlled, 22-degrees-of-freedom prosthesis is a breakthrough—a moonshot. But a reduced and simpler version, controlled by residual muscle signals, would be useful for below-the-elbow amputees. Then we can come to people who may have lost hands or fingers. The numbers in that category are quite large.
What other innovations might spin off from this research?
THAKOR: The brain-machine interface would be useful in stroke rehabilitation or managing phantom limb pain. There is interest in creating exoskeletons that would augment human capability, whether due to limb or muscle loss and atrophy, or to achieve more super-human capability, for example, lifting weights. And, interestingly, there is a lot of interest now in gaming—games controlled using brain-machine interface.
What have your study volunteers, specifically the amputees, said about this concept?
THAKOR: They’ve found it doesn’t take long to learn to control the virtual hand or mechanical hand using the muscle signals. Some can do it within minutes. Using brain waves to control simple functions, such as opening and closing of the prosthetic hand, is also easily demonstrated. However, the patients have taught us that it’s not just what the prosthesis can do. Other factors, like the cosmetics or weight of the arm, are important. Some people say they simply want an arm that looks like a human arm, while others support the very advanced research on novel and futuristic prostheses.