SCIRP Investigator Vignette

Title: Restoring Sensorimotor Hand Function by Selectively Activating and Recording from Arm Nerves

Investigator: Gregory A. Clark, Ph.D., University of Utah

I had been working for some time now in attempting to restore function after spinal cord injury in preclinical animal models, to reanimate paralyzed muscles, and to restore sensory function by activating the sensory system artificially to replace the capacity that's been lost.

My approach uses a device called the Utah Slanted Electrode Array, and it's variant Utah Electrode Array, that has lots of different electrodes. And these electrodes can talk to subsets of neurons very precisely and very specifically.

So this is one version of the Utah Array; it's the Utah Slanted Electrode Array. It's got electrodes of different lengths; we would put that electrode array into, for example, an arm nerve. And if we stimulate the biological wires, the axons, that are in that arm nerve in a precise way, then we could for example cause the person to be able to do a pinch grip, or a power grip, or to pick up a cup or a fork, and to move their arm so as to be able to feed themselves.

Now if you look carefully you'll see there's another version of it that has electrodes; again 100 electrodes, but they're all the same length. And we would take this device and put it into brain. And we'd record the discharges, determine what the person is thinking about doing but is unable to do because of the spinal cord injury. We could relay that information to our other array which is in the nerve, bypassing the gap in the spinal cord, and we could send those same intentions, if you will, those same neural commands to the appropriate biological wires in the nerve and recreate the hand grasp that the person is thinking about.

This part of the problem has been previously investigated for quite some time, and what we're doing new here is attempting to now reanimate these paralyzed muscles of the hand so as to create complicated hand grasps, and then ultimately once we get that part working, to put these two parts together, to record intent, figure out what type of movement they want to make, and then to generate that movement by stimulating and activating the fibers that would normally drive the muscles of the hand.

In this particular case, we have three electrode arrays; they're in three nerves. Each one of them has 100 electrodes; after we've figured out what each individual electrode does, then we have to figure out the appropriate stimulation pattern so that one could create hand movements.

We've done brain recordings and interpreted them. We've done stimulation through Utah Slanted Electrode Arrays in the nerve to reanimate paralyzed limbs and to re-create complicated coordinated hand grasps. And what we want to do now is to take those two steps, put them together so that it's the actual brain of the individual which is sending out the signals that are used to drive the stimulation pattern that, in turn, will be used to drive the hand grasp that the individual intends - much in the way that the brain would normally do it, but is unable to do it because at the moment that signal is interrupted in the case of an individual with spinal cord injury, due to that spinal cord injury.