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Turning brain cells on with light BY JAMIE TALAN [log in to unmask] April 4, 2007, 8:41 PM EDT Scientists at Stanford University have orchestrated worm brain cells to stop and go, using a beam of light as the baton. Straight from a Dr. Seuss children's book, yellow means stop and blue means go. And the feat of engineering makes nifty magic as well: Shine a blue light and a worm wiggles. Yellow, it is as still as a church mouse. Ultimately, said Dr. Karl Deiss.eroth, an assistant professor of bioengineering and psychiatry at the university, such a technique could be used to control the inner workings of the human brain. Flash a light, for instance, and specific populations of brain cells could be activated. The study appears this week in the journal Nature. The Stanford scientists developed a technique that allows light to control specific cell populations. This discovery was possible thanks to bacteria that live in salt lakes in Egypt. There are cells in these bacteria that are light-sensitive pumps that move salt and chloride in and out of cells. "These pumps, or channels, are very fast at moving these substances around," Deisseroth said. To engineer these light-sensitive cells into neurons in a worm, scientists attach a DNA prompter specific for brain cells that make glutamate, the most common neurotransmitter in the brain. This chemical excites brain cells to fire. Once in the brain, these light-sensitive cells move chloride through the cell. And once they are working within a neuron, scientists use a light to regulate the activity of the cell. These light-sensing cells responde by stopping the neuron from firing (the yellow light). A gene from algae is used to make the brain cells respond to blue light, which makes them turn on. To test their model, German collaborators flashed either a blue or yellow light onto the worms and, depending on the color, they either wiggled or stop moving. The effect was instantaneous. "It's really interesting," said Edward Boyden, an assistant professor at the MIT Media Arts and Sciences Lab who published similar work last month in the science online journal PLOS One. "In the future, controlling the activity patterns of neurons may enable very specific treatments for neurological and psychiatric diseases, with few or no side effects." Deisseroth thinks it's only a matter of time until they can figure out a way to make the technique work in the human brain. The idea is to use light as a treatment to regulate the activity of specific brain cells. The Stanford scientists are beginning studies to see whether they can enhance certain cells in the brain's hippocampus in depressed mice. Subscribe to Newsday home delivery | Article licensing and reprint options ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn