Wireless Tech Enables Paralyzed Monkey to Walk Again

11:30 minutes

A Swiss research team reported in Nature this week that they wired a monkey to walk again on a leg that had been paralyzed, a mere six days after the paralyzing spinal cord injury. The treatment? A brain-computer interface connecting the monkey’s motor cortex to an electrical stimulation device on the spine. With the device, signals from the brain are translated to pulses on the spine, giving the limbs instructions to move despite the interruption of signals in the spine itself.

A rhesus monkey, the same species that was given the ability to walk again, thanks to a spinal cord implant. Credit: Shutterstock
A rhesus monkey, the same species that was given the ability to walk again, thanks to a spinal cord implant. Credit: Shutterstock

The study marks an advance in using interfaces for lower limb rehabilitation, and lead researcher Gregoire Courtine has speculated that humans could be testing such an interface within 10 years. In the meantime, other researchers who deal with spinal cord injuries are already advancing clinical trials in humans for other techniques.

What could the future hold for patients with spinal cord injuries? What are the obstacles? Two researchers—Susan Harkema at the University of Louisville, and Bolu Ajiboye at Case Western Reserve University—discuss their work and the frontiers of rehabilitation technology.

Segment Guests

Susan Harkema

Susan Harkema is research director of the Frazier Rehab Institute at the Kentucky Spinal Cord Injury Research Center at the University of Louisville in Louisville, Kentucky.

Bolu Ajiboye

Bolu Ajiboye is an assistant professor of biomedical engineering at Case Western Reserve University in Cleveland, Ohio.

Segment Transcript

IRA FLATOW: This is Science Friday. I’m Ira Flatow. This Veteran’s Day there is hopeful news about spinal cord injury research. A Swiss research team describes a paralyzed monkey walking again with help from an implant connecting its brain to a device that applies electrical pulses to its spine. One researcher says it could be 10 years or less before we could offer human patients something similar as therapy. Meanwhile, other researchers have been working on similar brain-controlled technology for upper-body rehabilitation and also electrical stimulation systems without brain-computer interfaces, all for helping paralyzed people use their legs and regain other functions.

A couple of those researchers join me now. Susan Harkema is a professor of neurological surgery at the University of Louisville in Louisville, Kentucky. Welcome to Science Friday.

SUSAN HARKEMA: It’s great to be back. Thanks for having me.

IRA FLATOW: You’re welcome. And Bolu Ajiboye is assistant professor of biomedical engineering at Case Western Reserve University. He joins us from Cleveland. Welcome to Science Friday, Dr. Ajiboye.

BOLU AJIBOYE: Thank you. Thank you for having me.

IRA FLATOW: Let’s talk about this new research first. Susan Harkema, can you describe for us how the monkeys could walk again, what this brain computer interface was?

SUSAN HARKEMA: It’s been known for a long time that mammals with support to their spinal cord, with stimulation, or applying drugs can regain locomotion when their spinal cord is transected. In this case, they just took one pathway away– the corticospinal pathway– that’s thought to be important for movement. But what’s new about this is they recorded signals from the brain and they used wireless technology to send those signals after they had cut the spinal cord and then tell the other piece of technology to send signals to help the paralyzed part of the body reactivate to stop. So what they did is took knowledge that was already known and put it together in a unique way.

IRA FLATOW: Dr. Ajiboye, what excites you about this?

BOLU AJIBOYE: Well, I think the research itself is quite novel, quite interesting. As Dr. Harkema mentioned, they’re using a brain-computer interface to create stimulation or to control stimulation. It does suggest that in a person with a thoracic-level spinal cord injury you may be able to do something similar. A lot of the technology that they used is already approved for human use. There are some caveats to the research, I believe– the necessity of a brain-computer interface for restoring locomotion. But overall, I think scientifically it’s very interesting.

IRA FLATOW: Now, I know that your work looks at brain interface technology, but for rehabilitating upper limbs. Where does that research currently stand?

BOLU AJIBOYE: Yes. So I work in a collaboration with a number of universities around the country in a clinical trial called BrainGate. And the goal of the BrainGate clinical trial is to use brain-computer interface technology and connect it with functional electrical stimulation technology to restore hand and arm movements to persons with high-level spinal cord injury. We currently have one participant enrolled in Cleveland. And we are at this point working on connecting those two systems.

Functional electrical stimulation has been around for decades. It was pioneered at Case Western by Dr. Hunter Peckham and Dr. Robert Kirsch. It actually became a commercial product in the mid 90s. There was a product available to persons with cervical-level five spinal cord injury to restore hand grasping. We are now trying to connect that technology– that implantable technology– to an implanted brain-computer interface to restore both reaching and grasping to somebody with high-cervical spinal cord injury.

IRA FLATOW: Dr. Harkema, what’s the difference between that and what you are working on?

SUSAN HARKEMA: Well, what we have been focusing on is related to the stimulation in the current paper of the human spinal cord. So we’re using current technology to activate the spinal cord networks for walking, for standing, and for voluntary movement in very severely paralyzed humans. And what’s very exciting is that bringing the scientists and the technology together is enabling us to make pretty significant advances in all those areas.

In addition, while we’ve been studying walking and standing and moving voluntarily, we found that other conditions, such as cardiovascular deficits, respiratory, poor blood flow, lots of other secondary conditions– bowel and bladder– seem to be positively affected by this stimulation. So this is a time where we’re starting to understand the complexity of the nervous system, being able to exploit that. And if we work hand-in-hand with developing the technology, I think that we can see some great advances in recovery after paralysis for people with spinal cord injury.

So we started out with locomotion. We’re still working on that. We have been working on that for several years now but are also branching out to many other areas that affect people with paralysis today.

IRA FLATOW: I’ll ask this to both of you. Do you find that these newer technologies, the fact that you can stimulate the nerve endings below the spinal cord injury, that it might help make connections better and to have them regrow back partially themselves?

SUSAN HARKEMA: Well, I think that there’s not evidence that it’s going to enable them to regrow. But I think that there’s so much plasticity in the nervous system that it is able to take advantage of the system that still exists. And I think that was really not well understood until now.

But what’s important is with regeneration techniques that are also advancing, coupling these two could be extraordinary because you wouldn’t need to have a regeneration technique that would completely regenerate the nervous system. Maybe it would only need to regenerate a small percentage of fibers and you couple it with this technology and get pretty tremendous recovery. So I think multiple strategies together will ultimately be the answer.

BOLU AJIBOYE: And maybe I’ll add to that. I think that we as scientists just need to be a bit careful about some of the claims that we make. So obviously this paper and the work that we’re talking about is not claiming that we are fully regenerating the spinal cord. Our particular approach is to essentially circumvent the spinal cord– to basically be able to take those cortical signals that are generated in the brain, circumvent the spinal cord, and create the necessary stimulation patterns to create the same movements that would occur if the spinal cord were intact.

IRA FLATOW: I mentioned that there were some scientists saying we might see new research applied to patients within 10 years. Do you both think that’s possible?

SUSAN HARKEMA: Well, I think there’s many unknowns. To translate something to the human– there’s a lot of stakeholders who have to work together. There’s a lot of unknowns. And so I think I would be really cautious in trying to put a timeline on it. But what I think is exciting about it is that there’s been many scientific breakthroughs. So the path is known on how to get there. So bringing the technology that is known out there together with the scientists I think could really accelerate that.

IRA FLATOW: Mm-hmm. Two years ago, we talked to you after your team used electrical pulses in the spine to help two men move their legs voluntarily after years of paralysis. What’s happened since then? Have we seen advances since then? Have you had other successes?

SUSAN HARKEMA: We have. We’ve now implanted 10 individuals. And we have seen very similar results in varying degrees both in the ability to move voluntarily and stand. So that is very positive in that we can reproduce those results. We still need, as I have mentioned several times, we need to couple that with the technology to make it useful in the home and community. So that’s one of the areas of research we’re working very hard on.

And we also have a grant where we’re looking at the cardiovascular function. And we’re working towards actually doing a very large cohort of 36 patients where we will be looking at the secondary conditions, cardiovascular function, and we’re hoping that that’s something that might be translated pretty quickly because we’ve seen results with that with the existing technology. So yes, I think this is a very promising area that many scientific groups are working on. It is very positive. And we’re very excited where the path is going.

IRA FLATOW: Dr. Ajiboye, we heard about this being a breakthrough, this trial with the monkeys, because it uses wireless technology which has to carry a lot of data for this to work, right? When you look at the future of the brain-computer interfaces, what do we still need to improve on here?

BOLU AJIBOYE: Well, so first and foremost, I think the wireless technology is a breakthrough and it is necessary for a clinical translation. In our current clinical trial, participants have a percutaneous pedestal, or a pedestal which goes through the skull, and they are connected to our recording devices. For them to being able to use these systems on a regular basis, we need a system which allows us to perform 24/7 recording and that’s wireless. So that’s definitely a breakthrough.

There needs to be a number of technological advances in terms of the interface. We need to make sure that the interfaces are robust, that they’re able to outlive the patients, they’re able to record high fidelity and robust neural signals for long periods of time so that just like they did in the paper, we can have confidence in the information that we extract from the neural signals related to movement.

We also need the ability to record from large numbers of neurons. Most of the current work– my work included, the work in the paper– are fairly limited in terms of the number of neurons you’re able to record from simultaneously. We need to be able to record, I believe, from thousands, tens of thousands of neurons simultaneously so that we can begin to think about controlling high-dimensional systems– so in the case of reaching and grasping– to be able to control the shoulder, the elbow, the hand, the wrist, all the fingers together. We need high-dimensional recordings that allow us to control these high-dimensional systems.

IRA FLATOW: Dr. Bolu Ajiboye, assistant professor of biomedical engineering at Case Western Reserve. Dr. Susan Harkema, professor of neurological surgery at the University of Louisville. Thank you both for taking time to be with us today.

BOLU AJIBOYE: Thank you.

IRA FLATOW: –good weekend.

SUSAN HARKEMA: Thank you very much.

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