Controlling Your World With a Single Neuron

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mrt scans of a human brain

Your brain is a busy place. How busy? Consider that everyday, 100 billion neurons punch in for work and they’re all linked to one another in trillions upon trillions of ways. You wouldn’t think one or two of them would make any difference, but don’t take your cellular workforce for granted. A new collaborative study by UCLA and the California Institute of Technology (Caltech) shows just how powerful an individual neuron can be — and how that power can be harnessed.

The punch a solitary brain cell packs and the precision with which it fires is not a completely new discovery for scientists. For 20 years, Itzhak Fried, a professor of neurosurgery at UCLA, has been studying how neurons talk to one another, with the help of neurosurgical patients who allowed him to take electrode readings during surgery. Fried, along with Caltech’s Christof Koch, made news in 2005 with their discovery that familiar images seem to be associated with individual brain cells, which fire in recognition when a person sees a face, object or place that the brain has processed before. Clearly, a single neuron cannot do all that recognition work by itself, but it does seem able to set off the more complex series of connections that can. (More on What Goes on Inside the Brain of a Misbehaving Boy?)

In their new study, published in Nature, Fried and Koch went deeper, literally, working with a dozen patients who underwent brain procedures for severe epilepsy. The subjects had electrodes implanted in their brains to pinpoint the sites that triggered their seizures — sites which could then be targeted for  surgery. As long as the electrodes were there anyway, the patients also agreed to allow Fried and Koch to use them to gather data about neuronal firing.

All 12 patients first  selected four images of things that interested them — including the Boston Red Sox, Marilyn Monroe and TV’s Dr. House. Fried and Koch then looked at which neurons fired when the subjects looked at those pictures. Neuronal activity, of course, is merely chemical and electrical activity, which means that when a Boston Red Sox brain cell fires, it can do more than just focus on the team (despite what some true Sox fans might believe). When the Sox-fan patient was hooked up to a computer, for example, and told to think about the image of the Red Sox, the same neuronal stirring was also able to move a cursor on the screen. (More on The Lab Rat: How to Improve Memory in 15 Minutes)

That, in itself, was remarkable — effectively a mind-machine interface. But the patients could do other things as well. When the researchers displayed a target image on the screen in the company of other competing images, the subjects could concentrate on their chosen picture to the point that it grew brighter — while the others grew dimmer. More than simply turning the neuron on and off, they were, in effect, boosting its power so that it was able to shout down other competing ones. The experiment didn’t work all the time, but its success rate — about 70% — more than exceeded chance.

For now the new study is little more than a parlor trick — albeit an extraordinary one. But its implications are huge. For one thing, it provides a better understanding of how the brain operates and of how we, in turn, can control it.

More important, it could provide a whole new level of independence for quadriplegics and other people who have lost mobility. Hands-free computing remains in its relative infancy, limited mostly to often-unreliable voice commands or the painstaking business of tracking eye movements as users select options on a screen. Weaving the brain and the computer together so that a simple thought elicits a response strips out any of those middle steps, putting the mind in direct control of the surroundings. We’re still a long way from perfecting such a brain-machine system — but we are clearly one big step closer than we were.

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