| Citation | Russell Foster has made fundamental contributions to the field of biological clocks (circadian rhythms) and has discovered a novel photoreceptor in the retina - separate from the rods and cones - that is critical for the pathway whereby light signals at dawn and dusk entrain the central circadian clock. Using transgenic and retinally degenerate mice he dimonstrated that animals lacking rods and cones still have their central clock entrained by light-dark cycles, and went on to localise the photoreceptors in a subset of the retinal ganglion cells which are directly photosensitive. These cells project via the retino-hypothalamic tract to the suprachiasmatic nuclei in the anteriro hypothalamus. He proceeded to measure the action spectrum of these ganglion cells, and subsquently discovered a new opsin-based pigment ( melanopsin ). Separately, he uncovered a paralleel system in the Teleost eye, based upon another new opsin ( VA-opsin ). His earlier research studied non-retinal photoreceptors in the deep brain of birds which are used to regulate seasonal reproduction. |