Characterizing Disease with the Retinal Code
This project’s aim is to understand the extent to which signaling by retinal ganglion cells (RGCs) is affected by degeneration. Rod photoreceptor death is a form of retinal degeneration that alters the wiring of the retina and can eventually leads to blindness. As the retina loses the ability to transmit visual scenes to the brain, there are changes in the signaling across the light spectrum that the human eye detects. A potential measure for visual signaling is the information content that the RGCs sends through their action potentials and the precision with which they send those messages. Shannon’s mutual information provides an entropy based estimation of information, which can be applied to biological systems. The information metric, however, did not show a change with greater degeneration in this setting. Fano factor measurements of the spike trains showed that neurons exhibited greater variability in spike frequencies with greater degeneration. Thus, degeneration affects the spike train precision but does not affect the amount of information sent to the brain.