PHILADELPHIA -- Researchers at MCP Hahnemann University and Duke University have developed a method for recording brain signals onto electrode arrays in laboratory rats that enable the rats to control a robotic arm without any actual muscle movement.
According to the scientists, the achievement demonstrates the likelihood that electrodes may someday be implanted into the brains of humans who have lost limb function, allowing them to control a prosthetic device as they would their own biological limbs. The study is being published in the July 1 issue of Nature Neuroscience.
In experiments, rats were trained to control a robotic arm by pressing a lever to receive a reward. During the rats' lever-pressing, the researchers used arrays of electrodes implanted in the rats' brains to record the simultaneous activity of dozens of neurons in the areas that control muscle movement.
"Identifying which neurons in the brain are responsible for moving the robotic arm was key to our success," said John Chapin, professor of neurobiology and anatomy at MCP Hahnemann University. "Previously, researchers have focused on single neurons in the motor systems. We took a broader look and found that if we could recreate the many signals sent by dozens of neurons at the same time, we could essentially program the movement into the brain."
Once the data were recorded, researchers switched control of the reward from the lever to the implanted electrodes. The rats quickly learned to move the robotic arm to receive the reward solely through brain activity, without actually moving their muscles.
"We were quite surprised that the animals so readily learned that they did not need to actually make the movement to operate the robot; that they only needed to express the brain wave pattern," said Dr. Miguel Nicolelis of Duke University Medical Center, one of the researchers.
"This study breaks new ground in several areas," said Dr. Eberhard Fetz, Department of Physiology and Biophysics, University of Washington School of Medicine, who authored a commentary on the research in the "News and Views" section of Nature Neuroscience. "Unlike comparable studies, this is the first demonstration to prove that simultaneous recordings from large ensembles of neurons can be converted in real time and online to control an external device. Extracting signals directly from the brain to control robotic devices has been a science fiction theme that seems destined to become fact."
Added Chapin, "We believe that we have all the key elements to be able to make this technology one that could, in the not-so-distant future, make a substantial difference in the lives of people who are limited in their physical abilities, but not in their neurological capabilities -- ALS and spinal cord injured patients for instance.
"While there are significant technical obstacles to overcome before we are ready to begin clinical trials on patients, we feel those obstacles are readily surmountable," he said.
William Heetderks, Director of the Neural Prosthesis Program for the National Institutes of Health, said the study has implications for a variety of disabilities.
"The most obvious group is individuals with locked-in syndrome who have no means to communicate," Heetderks said. "Other individuals such as those with cerebral palsy and spinal cord injury might also benefit."
Chapin and Nicolelis were part of a research team that included Karen Moxon and Ronald Markowitz, also of MCP Hahnemann University. Funding for this research was provided by the National Institute of Neurological Disorders and Stroke (NINDS) of the National Institutes of Health (NIH) and from the Office of Naval Research (ONR/DARPA).
Journal
Nature Neuroscience