In a groundbreaking experiment, a man without his right hand used his brain to pick up a water bottle and a credit card with a bionic hand. The feat was accomplished after years of study at the University of Houston.
The 56-year-old man, whose right hand was amputated, used a high-tech prosthetic hand attached to his stump to grasp the items.
Unlike with other experiments in prosthetics, researchers used non-invasive techniques and did not surgically implant electrodes in the brain. Jose Luis Contreras-Vidal, a neuroscientist and engineer at the university who headed the study, said in an interview with notimpossiblenow.com that the experiment avoided the risk of brain surgery and offered an improvement over another type of neuroprosthetics, myoelectric control. This method isn’t possible for all patients because it requires that nervous system activities related to grasping are working.
Contreras-Vidal calls the experiment a “major advance” in the field of neuroprosthetics. Success came after 14 years of hard work, he says.
The results were published March 30 in Frontiers in Neuroscience in the Neuroprosthetics section. The work was funded by the National Science Foundation.
When the experiment proved successful, Contreras-Vidal said, everybody in the lab clapped.
“This technology has very strong indications for improving the quality of life,” Contreras-Vidal said.
“To my knowledge, this is the first time that it was possible to demonstrate that you can do this from the outside of the brain, You can extract enough information to understand the intent of grasping a specific object and then use that information to control the movement of the hand in time and space,” Contreras-Vidal said.
“One, you can read the brain from the outside and two, you can use that information to communicate directly with machines, including robotic hands.”
Instead of using brain surgery, researchers used caps covered with EEG sensors to measure brain waves. The researchers enlisted five able-bodied, right-handed volunteers (one woman and four men) to wear the 64-channel EEG caps and grasp items. Scientists monitored certain areas of the brain and examined how and where the information about grasping was encoded in its nervous system network. Brain activity was recorded in several areas, including the motor cortex and areas known to be used in action observation and decision making, and occurred between 50 and 90 milliseconds before the hand began to grasp, the university said. That indicated that the brain was predicting the movement, rather than reflecting on it, according to the university.
Information about grasping was encoded in the fluctuations of the EEG signals, Contreras-Vidal says. He compares monitoring the EEG signals to listening to music.
“So we need to listen to the whole brain,” Contreras-Vidal said. “I call this the neuron symphony. You have different players inside the brain responsible for different aspects of intent, different aspects of motion.”
Researchers then trained a computer to interpret the fluctuations in EEG signals and predict hand movement and linked it to a bionic hand. The amputee, attached to an EEG cap, was told to watch the hand moving and think about the motion. Researchers recorded his EEG waves and the hand movements of the other subjects together. Once this was done, the amputee was able to control the hand. This use of a computer is known as brain-machine interface or BMI.
The study marks the first time EEG-based brain machine interface directed the use of a multi-fingered bionic hand.
Contreras-Vidal says the amputee moved with greater ease and dexterity than the subjects of other experiments. He performed 100 trials and was successful in grasping objects 80 percent of the time, but Contreras-Vidal says he is striving for 100 percent accuracy. He said that the study offers hope to spinal-cord-injury and stroke victims and could lead to better and safer prosthetics that don’t require invasive brain surgery.
Fellow scientists applauded Contreras-Vidal’s work. In an email Dr. Cristina Sadowsky, clinical director of the International Center for Spinal Cord Injury at Kennedy Kreiger Institute, which provides research, patient care and community programs, called the work another important step.
“Brain computer interfaces have tantalized the human imagination for decades from simple tasks like turning off a light with a thought to more far reaching scopes, like helping a paralyzed muscle move,” Sadowski said. “This study has made another step towards the latter by interpreting subtle changes in brain waves and translating them into fine motor movements while using a non-invasive approach.”
Future experiments could include force feedback, which is using information gathered from the monitoring of brain activity and directing that information to the prosthesis or exoskeleton, which is worn on the outside of the body by people who are paralyzed. It is also used in rehab for stroke victims and other impaired patients.
Contreras-Vidal, lead author on the paper submitted to Frontiers in Neuroscience, was assisted by graduate students Harshavardhan Ashok Agashe, Andrew Young Paek and Yuhang Zhang.
Top photo courtesy of the University of Houston