The need for speed

摘要

Neurons in the retina turn on and off rapidly in response to light. With the discovery of mutations in human genes that mediate this quick turn-off, we have the first picture of its importance in visual perception. Imagine walking out of a dark theatre into a bright and sunny Sunday afternoon. You are momentarily blinded, but your eyes rapidly adjust to the change and you continue on your way. For some people with a rare visual defect, however, this momentary blindness can last for up to ten seconds. A similar, but potentially more dangerous, prolonged blindness occurs when these individuals drive from daylight into a darkened tunnel. Moreover, people with this problem also suffer from difficulties in seeing certain moving objects (such as balls thrown during a sporting event). On page 75 of this issue, Nishiguchi et al. describe a genetic cause of this condition. In so doing, they reveal that visual perception requires rapid deactivation of the light-stimulated responses shown by neurons in theeye.