excerpts from the New York Times, February 8, 2002
Eye Cell Tied to Body Clock Shocks Experts
By SANDRA BLAKESLEE
With the help of three kinds of blind mice and some ugly frogs, scientists have discovered a new class of light-sensing cells in the retina.
The cells, which are different from the rods and cones that enable vision, appear to reset the body's master biological clock each morning and night. The researchers said that while the finding was made in mice, it was certain to hold true for humans, with implications for possible treatment of sleep disorders, jet lag, depression and other maladies involving the body's internal clock.
Dr. Berson said a deeper understanding of the new photoreceptors might lead to novel treatments for disturbances of the body's internal clock. It may turn out that people who have defects in the newly described system could suffer from "time blindness," similar to colorblindness.
Three kinds of blind mice posed the problem. [See how they run.]The first was a mutant mouse that lacked all its rods and 95 percent of its cones. "These animals are blind, yet they are as good at responding to light in setting their daily rhythms as their sighted litter mates," Dr. Foster said.
"I'll never forget the first time we did the experiment," Dr. Berson said. "We gathered around the rig. The cell was sitting in darkness. We hit it with light. Nothing happened for almost a second. Then all of a sudden it began to spike. We went crazy. The missing photoreceptors in the retina and the cells that talk to the clock are one and the same."
Now what?
