14 DAY TRIAL // It's no longer a secret to anyone that neurons control the physical movements of the human body. But the processes underlying this ability have remained a mystery to experts for many years. A new study throws more light on the issue.
For a long time, researchers have observed that neurons that control motion tend to fire in very chaotic patterns when activated. That is to say, in the time between when you decide to kick something, and the moment you actually do, the nerve cells in your brain behave erratically.
But now, researchers at the Stanford University say that there could be some method to all of this, some higher patterns that nerve cells follow when activating. Their conclusions go against established data.
The group has shown that some neurons in areas of the brain controlling motion actually get activated as if they want to trigger an opposite motion from what a person is trying to do.
For example, if you want to move your leg to the right, some nerve cells may transmit impulses that look as if they want to steer your leg to the left. But these discrepancies are only apparent.
The Stanford team revealed in their new study that contrarian neurons have been “misunderstood” all this time. They simply employ other pathways of getting to the same result as their peers that transmit signals in a straightforward manner.
“A classic idea is that the neurons are coded according to a sort of blueprint, in which each neuron has a movement that it 'prefers',” explains Stanford postdoctoral researcher in electrical engineering, Mark Churchland, who was a part of the research team.
As such, the theory went, certain neurons would be more active than others in certain circumstances. For instance, right-preferring neurons would be more active when you want to move you leg rightwards. But this is not what the team found.
“But what we found is that a neuron could be very active before, say, a rightward movement, but then actually shut down just before the rightward movement,” Churchland explains.
“If you said that the neuron was effectively voting for its preferred movement, you'd say it is voting for moving left at this time and a tenth of a second later it is voting for moving right and a tenth of a second after that it is voting for something else. It would not make any sense at all,” he adds.
The scientist believes that the key to understanding these neurons is looking at them as if they were individual pendulums. In order to make one move right, you first have to pull it to the left.
“It basically comes down to don't think of planning a movement as something that involves creating an explicit blueprint,” Churchland goes on to say.
“Think of it as getting your motor system wound up in just the right way so that when you release it, it does just the right thing,” he concludes.
A paper detailing the findings was published in the November 4 issue of the top science journal Neuron. Funding was provided by the US National Institutes of Health (NIH) and the Burroughs Wellcome Fund Career Awards in the Biomedical Sciences.