RENEE MONTAGNE, host:
And researchers may now have a better understanding of problems like epilepsy and chronic pain, questions that have baffled the scientific world for decades. The explanation involves a new discovery about how nerve cells communicate. And it's based on the work of a scientist who kept asking basic questions, even as he approached his 100th birthday. NPR's Jon Hamilton has the story.
JON HAMILTON: The scientist's name was Ichiji Tasaki. And he came to the National Institutes of Health in the 1950s. Peter Basser became Tasaki's boss about 10 years ago. He says Tasaki had a sharp mind and strong body, well into his 90s.
Dr. PETER BASSER (National Institute of Child Health and Human Development): He would walk back and forth to his house with his wife, who helped him in the laboratory every day, seven days a week. He was here on the weekends. He was here when it was snowing. He was an amazing man.
HAMILTON: Tasaki was determined to learn everything he could about how nerve cells transmit messages. Meanwhile, a much younger NIH researcher named Doug Fields was trying to understand something odd. Most scientists thought nerve cells only sent messages across a junction known as a synapse. But Fields was doing experiments that suggested nerve cells were communicating with other cells without using a synapse.
Mr. FIELDS: How was that happening? How could you have signaling from neurons to cells that are not neurons when our understanding of how signaling works is all based on synapses? So, that's the mystery.
HAMILTON: Then one day Fields found a clue. He calls up a video on his computer. It shows an axon, the long, slender projection from a nerve cell that carries electrical impulses to the synapse.
Mr. FIELDS: I was playing back a movie of an experiment in the lab in which I had stimulated the axon to fire impulses, and in that recording I saw this -the axon moved. It twitched.
HAMILTON: When Fields saw the twitch, he was puzzled. Then he remembered that not far from his office was a man who could help him understand what he was seeing: Dr. Tasaki.
Mr. FIELDS: Dr. Tasaki had measured these mechanical changes in all kinds of tissue - in the retina, in the skin. He even showed that the whole spinal cord of a frog twitched when an axon fired.
HAMILTON: Dr. Tasaki told Fields that the twitch could be part of a communication system that sends a chemical messenger directly to another cell. And he helped Fields design experiments that would show whether that system existed. One of them used a high-tech microscope equipped with night vision technology. Fields put it in a plywood box he built himself to keep out all light.
Mr. FIELDS: It looks a little bit like a prop for a magician, doesn't it? A black box.
HAMILTON: So, you got the combination of, like, the world's latest technology inside a box you built in your garage.
Mr. FIELDS: It looks kind of crude.
HAMILTON: Fields suspected that when a nerve cell's axon twitches, it opens a channel in the cell membrane and a chemical called ATP escapes. His black box gave him a way to test this idea.
The experiment used a dish containing nerve cells and all but one of the chemicals that allow fireflies to light up the summer sky. The missing chemical was ATP, which was trapped inside each neuron. Fields demonstrates the experiment.
Mr. FIELDS: Stimulate the neuron and if it releases ATP we should see a burst of photons. So, here we go. Stimulate the neuron and there's a burst of photons, meaning ATP has been released.
HAMILTON: Other experiments confirmed that twitching axons were indeed releasing ATP and maybe other neurotransmitters, too - no synapse needed. Fields says this new�system of cell communication does a better job explaining problems like chronic pain and epilepsy. Both involve nerve cells firing when they shouldn't, and studies show that this firing isn't triggered by signals coming across synapses. Doug Fields says it could be triggered by twitching axons releasing ATP.
He says the system also may be involved in controlling blood flow and the formation of myelin insulation around nerves. Peter Basser says even though that's still just speculation, Fields' approach represents a big step forward.
Mr. BASSER: The genius of Doug's work is that he's been able to use this basic research that Dr. Tasaki did and show its biological relevance.
HAMILTON: When Fields finished his paper on ATP, he eagerly walked it over to Dr. Tasaki's office. But he was too late - Dr. Tasaki had died a few weeks earlier at the age of 98. The research based on his work appears in the journal, Science Signaling.
Jon Hamilton, NPR News.
MONTAGNE: At our website, you can watch videos of the neuron experiments and learn more about how our brains work. That's at NPR.org/Science.
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