The retina of the eye is a highly complex structure. This thin membrane of nerve cells detects light entering the eye and converts it to electrical impulses, which are sent through the optic nerve to the brain to interpret what we see.
Finding how this circuitry is interconnected is the goal of research conducted by Greg Field, assistant professor in the Department of Cell and Neurobiology at the Keck School of Medicine of USC. Field recently received a grant from the Whitehall Foundation to help further his work into mapping the connectivity of the mammalian retina for the Zilkha Neurogenetic Institute.
“The retina has layers like those in a cake,” Field explained. “Photoreceptors at the front respond to light, interneurons in the middle process the information and ganglion cells at the back send the information to the brain. My research is really about trying to understand exactly how all, or nearly all, of the types of neurons in the retina are wired to each other.”
To do this, Field and his team place a retina on a bed of electrodes to record ganglion cell impulses and then project an image from a video display onto the cells. This stimulates individual photoreceptors, allowing Field to measure the output of the retina from the retinal ganglion cells.
“We can basically map how each photoreceptor we stimulate is connected to each ganglion cell,” Field said. “This allows us to understand how the architecture of some circuits relates to their function. In retinal degenerative diseases like macular degeneration, photoreceptors begin to die, and so the retina begins to rewire. We’d like to understand that process and identify ways of slowing or reversing it and identify promising therapies.”
The Whitehall Foundation is a not-for-profit corporation that celebrated its 75th year in 2012. The foundation focuses exclusively on assisting basic research in vertebrate (excluding clinical) and invertebrate neurobiology in the United States.
“This grant is helping to fund a graduate student full time for three years, as well as a large portion of the data storage infrastructure required for the study,” Field said. “We collect a tremendous amount of data — from a half to 1 terabyte in one experiment, which equals around 30 terabytes of data in a year. This type of research just wouldn’t be possible without the foundation’s help.”
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