Brain Interface Gives Paralysed Patients Freedom to Move
Ben - Imagine not being able to just pick up a glass and have a drink, and instead, having to rely on others to help with this most simple of tasks. This week a brain interface device has allowed a paralysed stroke victim to drink for herself for the first time in 14 years by controlling a robotic arm just using her mind. Professor John Donoghue from Brown University reports on this work in the journal Nature this week and he joins us now. John, thank you ever so much for joining us.
John - Well, thank you. I'm pleased to be here.
Ben - What did you set out to show with this piece of work?
John - Previously, in 2006, we had shown in spinal cord injured patients that they were able to control a cursor on a computer and type or play a video game. But we didn't know whether people with paralysis, like these two people with stroke that we studied, would be able to control something that's as complicated as a robot arm. This was very important because in order to be able to do things for yourself, you have to be able to reach out and grab something; your drink or your morning toast. Otherwise, you're completely dependent on other people. So our test was to see whether people were able to control something this complex.
Ben - So, what is the increase in complexity from controlling a cursor on the screen, through to controlling a robot arm? Is it the extra dimension, the fact that you're working in 3-dimensions instead of just two?
John - Well, it's even more than that because if you want to grab onto something, you have to open and close your hand and you have to do it whenever you want. So, the challenge was to ask this tiny population of cells that we were picking up in the brain to not only be able to move in 3-dimensions, that is, put your hand anywhere you want in space but also to be able to open and close your hand whenever you want it.
Ben - How does the implant technology actually work?
John - We put a tiny sensor about the size of a small pill on the surface of the brain and it has 100 hair thin electrodes that go just into the surface and they pick up these very weak impulses that come out of neurons. The impulses are taken out and transformed into a command signal. So it's a pattern of brain activity that becomes a command signal to run the robot arm.
Ben - So, it's a computer science problem as well as a neuroscience problem, and a technology problem because you need to interpret what's going on in the brain in order to turn that into a reliable signal?
John - Actually, yes. This is a wonderful example of how it's necessary for engineers and clinicians, and neuroscientists, and computer scientists, all to work together in a team to solve the problem of picking up brain signals, transforming them into meaningful control signals, running them through a computer and robotocists of course, we work with robotocists to be able to take that command signal and actually make the robot arm do what the person is thinking.
Ben - I understand that one of your patients had actually had this implant for quite a long time and one of the things that people have been worried about with this sort of work is that the implants would either generate some sort of response, perhaps a local inflammatory response, or they would just fur up or they would break and stop being useful over time. This seems to be really good demonstration that actually, these things have longevity.
John - Well this is very encouraging that an implant in the brain can last a long time, but we have to be very cautious. It's only one person so far. We've had several others that we've studied for nearly a year, but we're concerned that the materials may break down and we began to see certainly evidence of that as one of the problems.
Ben - In particular, your patients have had a brain stem stroke. So they are essentially isolated from their own body. Do you think that the same techniques could work with people suffering from other forms of paralysis, perhaps spinal injury or stroke in another region of the brain?
John - Basically, what a stroke like this does in the brain stem is it disconnects the wires or the fibre pathway that goes from the brain to the spinal cord and then ultimately out to the body. So, for any person who has an intact and functioning brain, this technology could potentially work. So there are millions of people with various forms of paralysis - spinal cord injury, stroke, stroke in other areas other than the brain stem, and a disease like ALS or Lou Gehrig's disease in which the connections in the spinal cord to the muscles die, and then again, break the pathway from thinking about movement to actually making the movement or disconnecting the brain and the body.
Ben - And could we use other parts of the brain as well? So, could we actually have multiple systems running at once, one to control a robotic arm and then perhaps another one to control a wheelchair for example?
John - Could be, just like we have parts of our brain to control our legs and our arms. Of course, it all is coordinated together and we can't run too many things at once or we might get into trouble. But it's very encouraging as we learn more and more about how the brain turns thoughts into actions. We know there are very large networks and many areas involved and all of those are potential candidates. We could tap into the earlier parts of the stream to get additional arm signals or we could go to the leg area for example, perhaps to control a wheelchair or even exoskeletons on the legs of a paralysed person to make their legs move so they could walk.
Ben - And it's obviously wonderful to be able to control a robotic arm, but we have seen other work where they've been using a special type of electronic stimulation to actually make muscles move. Could ultimately this be used to bridge the stroke site, bridge the gap and reconnect muscles to what the brain is thinking? Could we get people controlling their own limbs again?
John - Yes, that's something that we're working on. We're very interested in reanimating the muscles and this is work of Hunter Peckham and Bob Kirsch at Case Western where they've implanted stimulators in the body and it leads to wires that go to the muscles or to the nerves. And when that stimulator goes off, the arm contracts. There are about 600 people that they've implanted that are standing up or moving their arm to some extent as a consequence of this wonderful technology. So we're working with them to try to say, instead of controlling it with an outside switch - so the current people will use a button that someone can push or a switch on their shoulder so if they can wiggle their shoulder, they can make their hand open and close. But now, imagine we could connect Braingate, this brain sensor, take the brain signals and wire them back into this stimulator which then goes to the muscle. So we should have a physical repair for a broken biological system.