Rehabilitation through re-wiring
Steve Perlmutter (left), research assistant professor in physiology and biophysics and WaNPRC researcher, and Eberhard Fetz,UW professor and researcher at WaNPRC discuss their research involving transmission activity in the motor cortex area of the brain to stimulate paralyzed muscles.
Steve Perlmutter (left), research assistant professor in physiology and biophysics and WaNPRC researcher, and Eberhard Fetz,UW professor and researcher at WaNPRC discuss their research involving transmission activity in the motor cortex area of the brain to stimulate paralyzed muscles.Photo by Joshua Bessex
The future of rehabilitation therapy for victims of stroke or spinal-cord injury may lie in a small computer chip — called a neurochip — being developed, in cooperation, by the Washington National Primate Research Center (WaNPRC) and the UW’s College of Engineering.
This chip could repair and ultimately restore function of neurological communication within areas of the brain, and between brain or body activities for people whose neurons have been weakened or damaged in some way. For example, a stroke victim whose mobility has been compromised could receive this implant and, over time, have his brain re-wired by the chip to ensure that a new connection could be made.
Eberhard Fetz, UW professor and researcher at WaNPRC, started researching brain-machine interfaces 10 years ago and has since published several articles about the ability of neurochips to create bidirectional brain computer interfaces.
One study with Chet Moritz, assistant professor in rehabilitation medicine, and Steve Perlmutter, research assistant professor in physiology and biophysics and WaNPRC researcher, looked at the transmission activity in the motor cortex area of the brain to stimulate paralyzed muscles.
In this experiment, a monkey played a video game in which it had to move a cursor into a target range. The nerves in the monkey’s arms were temporarily paralyzed and the monkey was put through the video game again. The monkey learned to control the cursor with stimulation from a motor cortex cell within the brain. The cell activity then stimulated the paralyzed muscles, resulting in new, artificial connections bridging the lost pathway and allowing the monkey to continue playing the game.
Another application of this activity, which is called activity-dependant stimulation, is to strengthen neural connections that already exist -— such as pathways impeded by disease or damage. This was demonstrated in a study in which activity of a cortical neuron triggered stimuli in a neighboring site.
“We’ve now shown that the same phenomena work not only from one cortical site to another, but from a cortical site to the spinal cord,” Fetz said. “If you record the activity of the cortical spinal cell and use the action potential to trigger stimuli in the spinal cord, then after about 22 hours of that [activity], the connection between the cell and its target motor neurons is strengthened.”
Perlmutter is also working on knowing how the chip would be most effective to influence neurons. Perlmutter said the chip would record the baseline of natural activities and then calculate the delivery of signals back into the patient’s nervous system.
“Our approach is to induce plasticity and learning in neural pathways by harnessing or directing the normal processes of activity in nerve cells,” Perlmutter said. “[We] use normal activity … to help direct the learning. Using electrical stimulation we can tell a neuron when to be active and when not to be active, on top of what its normal patterns of activity are.”
Using activity dependent electrical stimulation — which records the signals from the nervous system that tell the scientists what the patient is trying to do — researchers can trigger electrical stimulation to drive activity that is as natural.
The autonomous neurochip would provide the electrical stimulation, which would in turn allow patients to remain mobile and functional in a normal manner instead of being hooked up to electrical wires for clinical treatment.
Despite promising developments from the project, the neurochip is years away from clinical human trials. Engineers of the chip are working on interactivity between the different components and on making the chip bio-compatible.
Brian Otis, associate professor of electrical engineering, is designing the integrated chip that will be used in the automated implant. The encapsulated chip and electrode array must be bio-compatible so the brain tissue won’t reject the chip and cause complications.
There are numerous techniques used to record, process, and influence brain activity, ranging from least accurate and least invasive — such as taking measurements through the scalp — all the way up to extremely accurate and extremely invasive, such as electrodes being surgically inserted into parts of the brain.
The researchers hope to stick to the middle-ground, implanting the chip beneath the skull, but on top of the brain. The chip would be relatively easy to remove, but also have the level of accuracy and ability the scientists require from the tiny machine.
“If this is going to be a long term solution, or a technology this person will walk around with and incorporate into their lives, these wires going through the skin are inconvenient and pose an infection risk, so we really need all this technology to be wireless,” Otis said.
The next step in Otis’ portion of the research is to integrate the chip into the brain-interface platform, but to do this he’ll need cooperation between chip designers, microfabrication experts, and neuroscientists.
Reach reporter Deanna Isaacs at email@example.com. Twitter: @Deanna_Isaacs
Correction: The previous caption misidentified the researchers as Chet Moritz and Steve Perlmutter. The researchers are Steve Perlmutter (left) and Eberhart Fetz.
Please read our Comment policy.