When excited by light, these cells generate electrical signals that initiate the process of vision. The signals generated by each cell type are distinct with respect to their sensitivity to light, speed and adaptation properties and because this is true, the visual system as a whole can perform over a range of 7 orders of magnitude in light intensity with great reliability and accuracy. A major aim of our work is to understand the mechanisms that make the transduction signal so profoundly different in the two types of photoreceptors.
Retinal development is controlled by factors other than strict genetic lineage.
We pursue these studies in the retina of rainbow trout. Teleost fish are unique among vertebrates because their eyes continue to grow throughout the life of the animal. New retinal differentiation occurs continually at the edge of the mature retina. In the PGZ there is a developmental gradient that extends continuously from undifferentiated stem cells at the margin to the fully mature retina more centrally. Thus, in the PGZ at any given moment, time and distance are equivalent and every possible stage of retinal differentiation is present, side by side.