Alapakkam P. Sampath


Associate Professor
Department of Physiology & Biophysics
Zilkha Neurogenetic Institute
Keck School of Medicine
Co-Associate Director, Neurosciences Graduate Program

Research Topics

  • Cellular Neurobiology
  • Signal Transduction
  • Vision Research
  • Rod and Cone Phototransduction
  • G-Protein Coupled Signaling Pathways
  • Retinal Physiology and Signal Processing.

Research Images

Research Overview

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.

We are ultimately interested in the causal relationship between retinal physiology and behavior for rod-mediated vision. 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.