KINGSTON, R.I. – May 19, 2009 – A unique electrode developed for non-invasive use by a University of Rhode Island biomedical engineer is showing promising results in helping to interpret brain signals so paralyzed patients may control their environment. It is also being studied as a means of delivering a stimulus to control epileptic seizures.
Unlike the conventional disk-shaped electrode, the bulls-eye electrode is made up of concentric circles that make it look like a small target.
"Imagine an inner tube sitting in a pool of water. The water in the middle of the tube is calm because the ring flattens out the choppy water around it," explained Walter Besio, URI assistant professor of biomedical engineering. "In a similar way, the concentric circles of the electrode eliminate distractions from other sources and allow us to focus in on exactly the signal we're most interested in."
Initially used for a more accurate detection of cardiac signals, Besio began to test its usefulness in detecting brain waves in an effort to help his brother who had become paralyzed in an automobile accident.
"I wanted to see if the electrode could help us figure out what someone was thinking," he said. "When you think about moving your arm, can we discriminate the signals from the brain to interpret the movement you want to make? It would allow paralyzed individuals to be more independent by letting them use their thoughts to perhaps control a robot or computer or a wheelchair."
In addition to detecting signals from the brain, Besio believes the electrode can be used in a therapeutic manner to administer an electrical stimulus to a precise location in the brain to control epileptic seizures or treat other neurological disorders. He has been awarded a $397,000 grant from the National Institutes of Health to verify his earlier experiments with rats and develop a computer model of this system.
"Some frequencies can cause seizures, while others are therapeutic, so this research will allow us to assess the frequencies and magnitudes that are most beneficial," Besio said. "We hope to use the electrode to detect a neurological disorder like a seizure, and then use the electrode to determine exactly where to apply electrotherapy to counteract the seizure.
"The advantage of performing this non-invasively is that as the seizure focus moves, we can change which electrodes the electrical stimulation is applied to without having to conduct surgery to add more electrodes to the brain," he added.
According to Besio, if a seizure lasts for an extended period of time it can cause brain damage, so a method of turning off the seizure via electrical stimulation should prevent brain damage and provide what he calls "neuro-protection." From his research findings, he believes that a stimulus provided through his electrode could be especially beneficial to those suffering from status epilepticus, a life-threatening condition in which the brain is in a state of persistent seizure and which causes 20,000 to 40,000 deaths each year in the United States.
Besio's NIH grant, along with an additional $15,000 grant from the Rhode Island Foundation, will also be used to determine if the electrical stimulation itself causes any bodily harm, pain or changes in heart rate.
While Besio has already demonstrated that his bulls-eye electrode works for several applications, he can't quite explain why it works.
"We hope to learn more about that with this study," he said. "I think it has something to do with the pattern of stimulation it administers, with how it injects current into the body. Neurons in specific areas of the brain are oriented in a certain direction, and by applying the stimulation in a particular way, it activates certain neurons aligned in one orientation. Conventional electrodes simply stimulate everything in their path."