Scheme to Let Robot Take Over Brain-Computer Interface

For all this to work, the program must be able not only to correctly discriminate between spikes from different neurons in the same recording but also to retain this information and track a neuron’s spiking patterns over time. The neuron-tracking algorithm was inspired by software the U.S. military uses to track planes, and Wolf expects that his formulas may be useful to other applications in robot and computer vision.

Yu-Chong Tai, a MEMS researcher at Caltech, is designing the hardware that would move the electrodes on a scale of microns. Each electrode in an array would have to connect to a tiny motor on the surface of the brain that would control all its movements. And there’s quite a bit of work left to be done on that. ”The idea of actually putting this in the [human] brain is far off,” says Wolf.

Brain-machine-interface developers are making progress without the ability to keep hold of the signal from a single neuron. ”It’s not yet clear that holding the same neurons, the exact same neurons, is a requirement,” says Lee Hochberg, a neurologist at the Massachusetts General Hospital who works with brain-machine-interface developer Cyberkinetics Neurotechnology Systems, in Foxborough, Mass.

But Wolf argues that a robotic interface could increase the life span of neural prosthetics. No one has yet left an electrode array in a human brain long enough to see how long the connection survives, but there’s wide speculation that the signal will deteriorate as cells from the brain’s immune system gather around the electrode tip and form a signal-blocking scar. A system like the one Wolf proposes would be constantly capable of moving to find better electrical connections when old ones fail.

The algorithms have gotten a few test runs in other labs at Caltech. Grant Mulliken, a neuroscientist at the university who records signals in the posterior parietal cortex of rhesus macaques, has used the algorithm to control a machine, called a microdrive, which most electrophysiologists use to position their electrodes. He began by giving the algorithm control of half his six electrodes. Now, he says, he often uses Wolf’s program to guide all six electrodes before taking over and doing his own fine-tune adjustments.

”I’m very meticulous when doing my experiments. If something doesn’t benefit me, I immediately trash it,” he says. ”I wouldn’t use [the robotic system] if it didn’t work.”