Our eyes seamlessly tell us about the world around us while in the near dark twilight as well as in the bright noonday sun. That’s over 10 orders of magnitude of light intensities! This is an impressive feat, especially considering that there is no camera currently in existence that operates as well as our eyes! How is our visual system able to function over such a wide dynamic range?
It turns out that this is largely due to adjustments at the first synapse of sight. Understanding those adjustments at the biophysical level was the focus of my dissertation work. I used electrophysiological techniques to record the responses of rod photoreceptors, which capture photons of light, and the cells that rods synapse onto, called rod bipolar cells, when they are stimulated by light. Understanding the fundamental mechanisms of rod vision will ultimately provide insights into how debilitating vision disorders, like night blindness, may be targeted for therapeutic relief.
Ever wonder what grad school is like? Here's a week in my life as a 3rd year graduate student at UCLA!
Griffis KG, Fehlhaber KE, Rieke F, Sampath AP. Light Adaptation of Retinal Rod Bipolar Cells. Journal of Neuroscience. 2023 Jun 14;43(24):4379-89.
Fehlhaber KE, Majumder A, Boyd KK, Griffis KG, Artemyev NO, Fain GL, Sampath AP. A Novel Role for UNC119 as an Enhancer of Synaptic Transmission. International journal of molecular sciences. 2023 Apr 30;24(9):8106.
Wang Y, Fehlhaber KE, Sarria I, Cao Y, Ingram NT, Guerrero-Given D, Throesch B, Baldwin K, Kamasawa N, Ohtsuka T, Sampath AP. The auxiliary calcium channel subunit α2δ4 is required for axonal elaboration, synaptic transmission, and wiring of rod photoreceptors. Neuron. 2017 Mar 22;93(6):1359-74.
Cao Y, Sarria I, Fehlhaber KE, Kamasawa N, Orlandi C, James KN, Hazen JL, Gardner MR, Farzan M, Lee A, Baker S. Mechanism for selective synaptic wiring of rod photoreceptors into the retinal circuitry and its role in vision. Neuron. 2015 Sep 23;87(6):1248-60.