Chet Moritz

Development of a brain-computer-spinal interface to restore hand and arm function is the name of this talk.

How do we communicate between a neuron and an electrical circuit? How does a thought become a movement? How do we develop a brian-controlled spinal interface to restore limb function after paralysis?

Going to talk about two kinds of studies . . .

Implanted electrodes allow users to control robotic arms. This is where a paralyzed person can use an electrode implanted in her brain to “think” the robotic arm to move a cup to her mouth and set it down again. There’s a woman who’s a quad using the same technique to eat a piece of chocolate. But hey . . . what we really want is to use our own arms, right?

Right. And that’s the focus in his lab. About six years ago they were able to get monkeys to do this. The early form of this technology triggered paralyzed muscles with shoulder shrug. In Chet’s lab they gave monkeys nerve blocks and then triggered muscle stimulation from the brain. They translated brain activity into stimulation of muscles, and the monkeys could play a video game with their paralyzed arms.

So, the did a human trial of a 23 yr old guy with a c injury who was 4 years post. This was done at Battelle and Ohio State. Showing a video. Flexible electrodes attached like bracelets to the guys arm. And then he voluntarily opens and closes his hand. By looking at a computer screen and imagining doing just that.

The room is dead silent. Wow.

We can do better with intraspinal microstimulation instead of brain controlled interfaces.

Why? Why not just use the peripheral muscle?

You get a more natural recruitment order of motor units. It just works better. You get smooth grading of force and fatigue-resistant contractions. You get synergies, so you need fewer electrodes and controllers. They’ve done this in both rats and monkeys. They use micro-amps, a tiny, tiny amount of energy.

It works in chronics. They put 30-micron wires below the lesion. These wires are about half the diameter of a human hair. They record neuron action potentials in the brain to see how they correlate with actual motion. Showing a video of a rat with a paralyzed left front paw. The rat can’t reach a lever and she can’t bear weight on that paw. With the stimulator on, she can easily press the lever but still has some trouble weight-bearing.

They’re going forward with this in more animals, but also working with engineers to build a wireless power coil so there can be a wireless data and power link. Describing the fantastic engineers and statisticians who work in his lab.

So.

Can a circuit like this be used to enhance spared circuits? There’s evidence in the UNinjured system that synaptic connections are built up with this technology. They put electrodes in and stimulated for 7 hours a day for 12 weeks. This isn’t coming from the brain, it’s external. And that rat can reach and grasp.

11 animals stimulated did much better than 11 that weren’t. One of them actually dislodged her wires and some — not all — of the benefit remained.

He’s been working with Phil Horner to see what happens when you add cells into a damaged cord . .. stay tuned.

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