Scientists Spot Eyes' Motion Sensors
Tough-to-detect cells do the job, physicists say
THURSDAY, Oct. 11, 2007 (HealthDay News) -- U.S. scientists say they've identified a type of retinal nerve cell that helps humans, monkeys and apes see motion.
The discovery of this "upsilon cell" may help improve understanding of vision in humans and other primates. The finding, by high-energy physicists at the University of California, Santa Cruz, and neuroscientists at the Salk Institute in La Jolla, Calif., was published in the Oct. 10 issue of the Journal of Neuroscience.
There are only a small number of upsilon cells, which makes them difficult to find when using traditional techniques. The discovery was made using a new detection system -- with 512 electrodes on an area about the size of a pinhead -- inspired by the UCSC scientists' research looking for particles in high-energy-physics collisions.
"This has been a fantastic journey through high-energy physics, neurobiology, technology, and human health," study senior author Alan Litke, adjunct professor of physics at UCSC's Santa Cruz Institute for Particle Physics, said in a prepared statement.
Biologists have identified about 22 distinct types of primate retinal nerve cells but only know the functions of about a half dozen of them.
"People have looked at cell morphology, but that can't tell us in any detail how the cell responds to light," Litke said. "If we're interested in how the retina is processing visual information, we really want to focus a movie on it and see what it reacts to -- to find out if it's seeing color, responding to motion, or whatever it might be doing."
Litke and his colleagues projected simple movies through a microscope lens and onto a patch of retina. As the rod and cone cells picked up the images, they sent electrical signals to different kinds of retinal nerve cells. Further research revealed the presence and distribution of the upsilon cells and their likely role in detecting motion.
The Washington University School of Medicine in St. Louis has more about the eyes.