March 2005

Implanting Hope

Continued from page 4

By David Ewing Duncan

The Color of Thought
At Brown University, I met computer expert Michael Black, an alumnus of the famed Xerox Palo Alto Research Center in California. Black is best known for trying to devise machines that can see, although he has also done research on brain-computer interfaces. Black was quickly sold on the possible benefits of Braingate and took on the task of creating improved algorithms for deciphering neuronal spikes. In theory, better deciphering would allow finer motor control. He showed me some charts with colored pixels that he developed to visualize what happens when a neuron fires. Each chart depicts a neuron's activity across a range of hand motions. The chart is blue where the neuron is inactive and shaded purple, orange, and then red where it becomes excited and spikes rapidly. (For example, a blue field with a bright red patch in the upper right corner means that this neuron becomes active when the monkey's hand moves up and to the right.) These grids tell Black the firing patterns of a neuron, which he can model to tell a computer that a given thought command is occurring and that it should take the appropriate action. The key to creating these models, he says, is the amazing tendency of brain neurons to fire in relatively consistent patterns -- consistent enough that a computer can accurately interpret them.

In a building across Brown's campus, I talked to another member of Donoghue's team, Arto Nurmikko, a Finnish electrical engineer and physicist known for his discoveries in laser optics and semiconductors. He and Donoghue are working to simplify Braingate and replace the titanium pedestal and the bulky hardware of the prototype with a much smaller internal system that would connect the implant to a hair-thin fiber-optic cable that would run under the skin of the patient. The ­fiber-optic cable would feed signals from the brain to a processor the size of a cardiac pacemaker, which would be implanted in the chest.

The technology will take a while to ­develop. But Nurmikko says that in this next-generation system, communication between the brain and the machine would be two way, with sensory information from a robotic limb relayed back into the brain, just as in a healthy person. When a patient reaches for a glass of water, for example, such neural feedback would help brain and computer calculate the effort necessary to pick it up.

Waiting for Help
Will these devices improve people's lives? Nagle himself says that Braingate, at least in its current form, is only marginally helpful to him. "This thing was done to see if I could move a cursor with thought," he says, "and I did that in about three minutes." But Nagle forcefully points out that he wasn't doing much of anything before. "I sat here seven days a week with nothing to do, so I said, 'Why not?'"

According to the FDA protocol, the study involving Nagle is to last a year. "I'll have to decide next June if I want to take this out. I'm not sure I will continue on. I may want to wait until they have one that is smaller and easier to use." I ask him if he thinks he'll walk again, and he says that's what he's really waiting for.

David Ewing Duncan's next book, The Geneticist Who Played Hoops with My DNA and Other Masterminds from the Frontiers of Biotech, will be out in May.