Science / Medicine : ‘Little Movie’ Provides Scientists New Insights Into Brain Cells
Scientists have developed a technique that, for the first time, allows them to “make a little movie” to observe activity by brain cells as it occurs.
“We’ve been able to make a little movie, in essence, of electrical activity in a small piece of brain,” said John Kauer, a neuroscientist at the Tufts University School of Medicine and New England Medical Center in Boston.
“The movie is essentially a real-time movie of what goes on in this little piece of tissue,” said Kauer, who described the new technique in the cover story of the current issue of the British science journal Nature.
The new technique should help scientists study the brain to determine how a variety of functions work, such as the sense of smell, hearing and sight and even learning and memory.
Although much more research is needed, the method could also be used to help study, diagnose and treat brain diseases, including Alzheimer’s disease, Parkinson’s disease, epilepsy and brain tumors, he said.
Small Electrical Impulses
Brain cells communicate in part through small electrical impulses. Scientists are limited to studying electrical activity in the brain one cell at a time by painstakingly inserting tiny electrodes into individual cells and measuring their response to stimuli. But even the most primitive brain activity involves large numbers of cells.
The new technique involves the use of special voltage-sensitive dyes that accumulate inside brain cells and emit light when they are stimulated by the electrical activity produced when a cell becomes active.
The researchers have tested the method on a tiny part of a salamander’s brain that controls the sense of smell. They drilled a small hole into the living, anesthetized salamander’s skull and poured a dye into the brain.
The dye was then illuminated with green light. When the nerves that activate the smell part of the brain were stimulated with an electric shock, the researchers filmed the exposed brain with a high-resolution video camera through a microscope. Cells that were activated emitted red light.
The images were then fed into a computer, which analyzed and enhanced them and fed the images to a color monitor, which allowed the scientists to watch the response of some 16,000 sites on the brain tissue simultaneously, Kauer said.
“We knew what individual cells did, but up to now how they all worked together was unknown. This enables us to look at global ensemble activity,” said Kauer, an associate professor of neurosurgery, anatomy and cell biology.
The method could be used to study how sight works by filming the brain while the eye is exposed to light or how hearing works by filming that part of the brain while a tone is made.
More study is needed before the technique can be tested on humans because researchers are uncertain whether the dyes are toxic.
