Brain implant that restores touch
Patients with spinal injuries can be robbed of the ability to move or experience sensations from most of their bodies. And while scientists have begun to develop systems to eavesdrop on the brain's motor pathways and turn thoughts into movements - of robots and prosthetic devices - there's still no way to return any sense of touch. Now a team at the University of Pittsburgh have begun a series of experiments using brain implants that can begin to restore some of these sensations as Chris Smith heard from Robert Gaunt.
Robert - When people have a spinal cord injury, and this can happen for many reasons (a common reason is a motor vehicle accident), the connection between the brain and the rest of the body is lost, and if that injury occurs at your neck level, many people end up with paralysed legs and paralysed arms. The brain remains functional and it does its normal thing, it's just that its ability to communicate with the limbs (the hands and arms) is lost.
Chris - How might one try and surmount that problem?
Robert - Well, there's a number of different approaches that people all over the world are taking. One of the things that certainly has a lot of promise; people are actually trying to regenerate and regrow the damaged portion of the spinal cord so that that connection between the brain and the limbs are restored.
The way that we're tackling this problem is to actually implant little tiny wires into different regions of the brain that actually control movement and that are normally responsible for feeling the hand. And so we implant these devices into the brain and by listening to these signals and then actually pumping in information, we hope to be able to reconnect the brain to a device such as a prosthetic limb, or to a computer, computer cursors, things like that.
Chris - Have people not done this before though?
Robert - People actually have. There's been a series of work over a number of years now by a few groups, including our own here at the University of Pittsburgh, where people have been implanting these little grids of wires into the brain and listening to the signals. And people have used those signals to be able to control a robotic arm so that they could reach out and grab objects, but one of the key things that's been missing in that is the ability to feel that object. When you reach out and grab an object with this robotic arm, you can't feel it, you don't know if you're holding it. You can see it but you can't feel it, and so what we're doing now is trying to restore that feeling, that sense of touch, when the robot arm goes out to grab it.
Chris - You've said you send signals into the brain but actually talk me through the nuts and bolts of how you do that physically...
Robert - We know the parts of the brain that are actually normally responsible for processing this information or listening to the signals that normally come from the hand and so what we did in this study is we put these same grids of electrodes into the region of the brain that we know is responsible for normally listening to and processing information that comes from the hand. So what we do here is actually use little tiny electrical pulses, and these little electrical pulses make these neurons become active. And when these cells become active, the person that we're working with can perceive touch coming from that part of the hand that that part of the brain is responsible for.
Chris - So you actually did this in a spinal injury patient?
Robert - That's right. We've been working with the person injured about ten years before we did the implant and we've had these implants in place now for about a year and a half and so, when we stimulate, he feels as though sensations are coming from his own hand.
Chris - What sorts of sensations does he say he "feels" when you do this?
Robert - That's a great question and it's turned out to be a really interesting part of the study. The types of things that the person we're working with will say is that he feels sensations of pressure, occasionally he'll say it feels like light touch; he also says things like electrical or buzzing. But really what we show here is that when you do provide these stimulus strains it feels as though it is your own hand being touched. We've got a lot of work to do on making that feel more natural in some cases, but it really sort of lays the groundwork for showing that these sensations can actually be provided through a direct interface with the brain where we actually go in and sort of tickle these neurons with a little bit of electrical stimulation.
Chris - And how does the patient take to this - does he feel a bit strange feeling that he's feeling his body doing things which it's not doing?
Robert - He has used all sorts of different words and phrases to describe this sensation and sometimes he will say that it does feel strange. It's hard to describe what it feels like to have this part of your hand touched or stimulated that you haven't felt in a decade but he's able to understand those sensations very naturally. So he knows exactly if it's his pinkie finger that's being touched or his index finger that's being touched.