“But for years no one knew what cell carried the signal,” says Greg Schwartz, lead investigator and assistant professor of ophthalmology at Northwestern University Feinberg School of Medicine. “We potentially found the key missing link, which is the cell that actually does that task and the neural circuit that enables this important visual function,” he adds.Schwartz called this cell, “ON Delayed retinal ganglion cell (OND RGC),” due to its unusually slow responses to light stimulation. OND RGC is also different from any other cell types- it has a unique sensitivity to the degree of image focus. That is, it responds to large stimuli and responds slowly. Moreover, the dysfunction of this cell may be linked to the amount of time a child spends indoors and away from natural light. The indoor light spectrum has high red/green contrast. This activates a certain clusters of photoreceptors in the human eye, creating a similar artificial contrast image on the retina. It’s likely for the human version of OND RGC to be overstimulated by such patterns, causing the eye to grow too long that retina fails to focus on images, causing nearsighted vision. The longer you stay indoors, the longer the overstimulation of this cell. “This discovery could lead to a new therapeutic target to control myopia,” Schwartz says. Future researches of this could also lead to gene therapy treating blindness and improving the function of artificial retinal prosthetic. Schwartz, G., Mani, A., Circuit Mechanisms of a Retinal Ganglion Cell with Stimulus-Dependent Response Latency and Activation Beyond Its Dendrites, Current Biology (2017). http://dx.doi.org/10.1016/j.cub.2016.12.033
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