Alapakkam P. Sampath Assistant Professor Physiology & Biophysics Zilkha Neurogenetic Institute Keck School of Medicine

Education:
BA 1994 Molecular & Cell Biology (Genetics) - University of California, Berkeley
PhD 1999 Physiological Science - University of California, Los Angeles

Postdoctoral Research Fellowship:
1999-2001 Stanford University, California
2002-2004 University of Washington

Started at USC: 2005

Research Topics: Cellular Neurobiology, Physiology, Signal Transduction, Vision Research

Research Description

The Sampath laboratory is interested in understanding the molecular mechanisms underlying early visual processing to gain insight into the following questions. (1) How are G-protein-coupled signaling pathways in the retina controlled, and what are their functional properties? (2) How do these signaling pathways contribute to vision at low light levels? (3) How do alterations in retinal physiology influence visually guided behavior?

To answer these questions we use electrophysiological and optical techniques to measure the light-evoked activity of neurons in the retina. We are interested in rod and cone phototransduction, in particular how these photoreceptors achieve such different response properties despite having similar G-protein signaling pathways. In addition, we are interested in how the second order retinal cells , the bipolar cells, interpret the rod and cone signals and ultimately how these signals are encoded at the retinal output, the ganglion cells. By following the light responses in each of these neurons we can gain insights into how light-evoked signals are procesed by the retina.

More recently we have begun to investigate correlations between retinal physiology and behavior for low light level vision (in collaboration with Jim Hurley, Universtiy of Washington). We use a water maze to characterize visual threshold in transgenic mice with altered retinal protein expression. Our goal is to correlate the physiological properties of the retina with changes in visually guided behavior. This work will provide insights into how the retina shapes signals that are functionally relevant for vision.

Selected Publications

Okawa H, Sampath AP. - Optimization of Single-Photon Response Transmission at the Rod-to-Rod Bipolar Synapse. - Physiology (Bethesda) [ 2007 ] Aug;22:279-86 . PubMed

Dunn FA, Doan T, Sampath AP, Rieke F. - Controlling the gain of rod-mediated signals in the Mammalian retina. - J Neurosci [ 2006 ] Apr 12;26(15):3959-70 . PubMed

Sampath AP, Strissel KJ, Elias R, Arshavsky VY, McGinnis JF, Chen J, Kawamura S, Rieke F, Hurley JB. - Recoverin improves rod-mediated vision by enhancing signal transmission in the mouse retina. - Neuron [ 2005 ] May 5;46(3):413-20 . PubMed

Field GD, Sampath AP, Rieke F. - Retinal processing near absolute threshold: from behavior to mechanism. - Annu Rev Physiol [ 2005 ] 67:491-514 . PubMed

Sampath AP, Rieke F. - Selective transmission of single photon responses by saturation at the rod-to-rod bipolar synapse. - Neuron [ 2004 ] Feb 5;41(3):431-43 . PubMed