Jacob Segil, PhD, an instructor in the engineering plus program at University of Colorado Boulder as well as research health care scientist with the Rocky Mountain regional V.A. Medical Center, talks about the use of neural interfaces to restore the sense of touch for people with upper limb amputation.
So, you’re working with taking prosthetics to a new level where you give them the sense of touch – we’ve done some stories where they have the sensation of whether they’re holding the coffee cup or not. But now you’re taking it to the study of embodiment. How important is that?
SEGIL: Good, what we’re doing here is trying to study embodiment in particular. So, this is not only the idea of tactile sensation like forces against your hands when you’re holding your coffee. But also, the idea of that artificial device becoming incorporated into your body. And so it becomes a psychometric sort of topic where not only is the sensation a part of it but there’s also this idea of agency, which is your ability to control the limb. And when you loop all those things together then we think we can elicit more embodiment so that the device becomes a part of the person.
And this bases all from the idea that feelings and everything start in the brain. It’s not in the limb. So, if you can control the brain you can control the limb?
SEGIL: Yes. We plug into the peripheral nervous system. So, it’s literally the wires in our bodies are the peripheral nerves. That means coming out of the brain, out of the spinal cord are these wires that used to send information from the hand to the brain. And after amputation the wires are still there. So, if we plug into those wires and send the right electric signals, our nerves are electric, we can trick the brain into thinking or feeling the hand that isn’t there anymore.
And like one of the reasons you know that these nerves are still there is because a lot of people have a lot of pain in an amputee and even phantom pain?
SEGIL: Yeah definitely so phantom limb pain is a neurological disorder after amputation where the nerves that have been severed can cause pain from the limb that isn’t there. It’s a horrible condition. It affects a large majority of amputees. The work that we’re doing anecdotally has shown effects on phantom limb pain. It improves it because we’re giving the brain what it wants. We’re stimulating the nerves and eliciting feeling. So anecdotally the type of peripheral nerve stimulation that we’re providing has seen benefits for the few people we’ve been working with. And we think it’s because we’re giving the brain what it wants. So, it’s receiving more physiologically appropriate signals from the peripheral nervous system. And then to the body—that’s enjoyable, right? That’s what the brain is expecting. And so, the pain is replaced with a more physiological sensation.
So could you kind of go through how you use sensation to make it part of your body again?
SEGIL: So, this is not my work. This is our collaborators at Case Western Reserve University and the Cleveland V.A. Medical Center. Dr. Dustin Tyler and his team have developed a peripheral nerve interface. That means it’s an implanted device. It’s a cuff, that actually surrounds the nerve and it can stimulate the nerve with an electric signal. They’ve figured out the secret sauce meaning the way in which we should stimulate, send electricity into the body, so that the brain understands it as sensation, as tactile sensation. The biggest breakthroughs in Dr. Tyler’s work in my opinion had to do with their human trials where they were able to show that over a long period time, meaning years, that the sensations were stable and that they were physiologically appropriate. Now, we have this whole new realm to study, which is what I’m interested in, in embodiment and the way in which we can use that interface to help incorporate that artificial device into the body.
And where are you now in embodiment?
SEGIL: We’re way at the beginning. We know that people embody artificial devices all the time. You know the classic example is a person who’s blind using a cane. That device is embodied. It’s a tool that the person uses.
Tell me more about how we’re already using things that are embodied for helping us, right? Like blind people are using a cane.
SEGIL: We can embody tools to some degree without the need for these neural interfaces and the sensory restoration we can provide. The classic example is someone who’s blind using a cane. That tool, right, is embodied somewhat. It’s part of that person’s ability to navigate the world. And so, we could measure some amount of embodiment of that tool. Of course, I don’t believe the prosthetic hands that we’re using today are incorporated the way our intact limbs are. I know where my body starts and ends because of the sensory information my brain is getting. That’s why you know like on a cold day when your fingers get numb and you start looking for your car keys in your bag. It’s hard to do. Your fingers with the lack of that sensory information become less and less embodied and effectively become more and more like tools as opposed to a part of your physiological system.
So, is that what’s happening?
SEGIL: Yes. I think in the field of upper limb and lower limb prosthetic design we haven’t been able to tackle about half of the problem, though the half we’ve been working on is the motor control. That means the actuation of these devices to allow for the movements and the function of the limb to be restored but.
So, is this neural interfacing the start of a whole new approach to prosthetics?
SEGIL: I think it’s about half the problem. So, our field is focused on the motor control. That means the actuation of these different hands and limbs. And we know physiologically it’s half the problem. The need for sensation is important not only for the function of the device right. You can do things with sensation that you can’t do without, the example of you know your fingers going numb in the wintertime is an example of that. But we also think that the psychological effects of a limb that’s embodied, meaning that it becomes a part of the person, will be even larger. The majority of amputees today don’t use a prosthetic device. They just get by without. And we’re very able as people as humans to adapt. And that’s why our field hasn’t overcome that challenge.
So how do you plan to solve these challenges?
SEGIL: I think solving the sensory restoration problem will provide functional benefits but more importantly psychological to people with amputation. That limb, that tool will all of a sudden be more and more incorporated into their body. They will feel more attached to that device and all of a sudden the psychological benefits will improve, and we’ll see better functional outcomes.
As far as embodiment go, can you kind of explain how that works? It’s an implant that goes in the body?
SEGIL: The embodiment refers to this psychological phenomenon. The neural interface is an implanted device. So, in surgery, it’s cuffed. It’s wrapped around the nerves. The nerves are like strands of spaghetti. And then in this case it’s the flat interface nerve electrode, which sandwiches the nerve and then on the inside of the cuff it has electrodes that can stimulate.
Where would that be implanted let’s say if you had the lower part of your right arm?
SEGIL: In a transradial amputee there are three nerves that we can cuff, the medial, ulnar, and radial nerves. They come in right off your shoulder and we can implant those in the upper arm. Then there are percutaneous wires. That means we have wires coming out of the body that we can plug into.
And what does that allow you to tell that you have these wires coming out of the body? What do you do with those?
SEGIL: So those wires allow us to stimulate those three different nerves across many different electrode sites and we can effectively map out the sensations for that transradial amputee. We have maps produced by our collaborators at Case Western of areas of sensation of the hand that’s missing. The media electrode site number seven creates a sensation of pressure on the index. Or the ulnar electrode site number six creates pressure along the ulnar border. And so, then we can play with those sites and stimulate accordingly to recreate the sensation that you would feel during activities of daily living.
Now are you already in clinical trials with your work?
SEGIL: I’m an engineer, so I build stuff. And our collaborators at Case Western are in clinical trials. They have subjects, at this point there are four people in the world with that technology, all based out of Cleveland and I work with those subjects to run these types of experiments. So, the clinical trial is ongoing and there are larger ones planned in order to help and promote this idea.
I mean what’s it like for you working on something like this, especially with the wars we’ve been in lately, amputation is something that’s quite common? You could be solving a problem that helps hundreds of thousands, millions of people.
SEGIL: It’s all very meaningful. The best part of my job is when we’re working with our subjects. Those are people with amputation. For the most part I’m right inside of engineering lab building Equipment. But those days are always the best. And our field is fortunate in that there isn’t a huge population of people that have amputation compared to a lot of other medical pathologies. But for that smaller pool of people, let’s call it a hundred thousand in the US, the restoration of any part of that limb that was lost has a big impact as you can imagine. I also work with people with partial hand amputation. So, we have a startup company doing prosthetic fingers. And right we’re talking digits alone, but in terms of volume, they’re not as big as some other types of amputation. But the psychological, the improvement in these patients lives is amazing. They go back to work. They can hold hands. They can play with their children. And the experiences that I have when we get to take stuff from our lab, from these bench top sort of engineering projects into the clinical realm are always the best days of my work.
Now that’s not always the case for engineers. They usually don’t get to see the final result being used right? You hand it off and somebody takes it and goes?
SEGIL: Yeah so I mean I’ve been fortunate in that my interests and my research have been on this translational border where we’re working directly with clinicians solving clinical problems that they’re facing and then the CU Boulder ecosystem is very proficient at promoting these entrepreneurial ventures. I’ve been part of several now where we’ve been able to translate and commercialize our ideas. And in my mind, it should be a central focus of our academic institutions of taking that knowledge and that expertise and making sure it reaches the market, reaches people. As opposed to just our favorite journal publications.
Do you mind if I ask what your startup is called?
SEGIL: Point designs is the one I was referring to. That one is at CU and it’s a collaboration with Richard Weir in bioengineering, Steve Huddle bioengineering and Levin Sliker is our CEO. He’s a graduate of are mechanical engineering program here.
Interview conducted by Ivanhoe Broadcast News.
END OF INTERVIEW
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