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Potential Project Description for 2011-12

 

Title: Neuron classification related to light sensitivity in eyes
Domain Expert: Jay Demas (Physics, Neuroscience)

Retinal ganglion cells (RGCs) are the output neurons of the retina and send their axons to a host of targets in the brain. Retinas have about 100,000 RGCs. There are estimated to be between 10 and 20 different subclasses of RGCs, each of which processes and transmits different information. One subclass of RGCs is directly sensitive to light, responding even in the absence of rod and cone photoreceptors. These RGCs are called intrinsically photosensitive RGCs (ipRGCs) and express melanopsin, a protein that allows them to respond to light. There are roughly 1,000 ipRGCs in each retina. ipRGCs signal mean light levels to the brain, controlling pupil constriction and setting the phase of our circadian rhythm. However, ipRGCs themselves are not a single class of cells. There are at least two different types of ipRGCs. The statistical task will be to look at the responses of ipRGCs to a series of light stimuli and classify them based on their response types. Once armed with a rigorous classification scheme, we will analyze data from mutant mice to see if certain subclasses of ipRGCs are affected by the mutation while others are not.