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.
10 Selected Publications:
Click here to view all the publications for this faculty
Sampath AP,Matthews HR,Cornwall MC,Bandarchi J,Fain GL - Light-dependent changes in outer segment free-Ca2+ concentration in salamander cone photoreceptors. - J Gen Physiol [1999] Feb;113(2):267-77 PubMed
Singer JH,Glowatzki E,Moser T,Strowbridge BW,Bhandawat V,Sampath AP - Functional properties of synaptic transmission in primary sense organs. - J Neurosci [2009] Oct 14;29(41):12802-6 PubMed
Miyagishima KJ,Cornwall MC,Sampath AP - Metabolic constraints on the recovery of sensitivity after visual pigment bleaching in retinal rods. - J Gen Physiol [2009] Aug 17;(): PubMed
Cao Y,Masuho I,Okawa H,Xie K,Asami J,Kammermeier PJ,Maddox DM,Furukawa T,Inoue T,Sampath AP,Martemyanov KA - Retina-specific GTPase accelerator RGS11/G beta 5S/R9AP is a constitutive heterotrimer selectively targeted to mGluR6 in ON-bipolar neurons. - J Neurosci [2009] Jul 22;29(29):9301-13 PubMed
Okawa H,Sampath AP,Laughlin SB,Fain GL - ATP consumption by mammalian rod photoreceptors in darkness and in light. - Curr Biol [2008] Dec 23;18(24):1917-21 PubMed
Cao Y,Song H,Okawa H,Sampath AP,Sokolov M,Martemyanov KA - Targeting of RGS7/Gbeta5 to the dendritic tips of ON-bipolar cells is independent of its association with membrane anchor R7BP. - J Neurosci [2008] Oct 8;28(41):10443-9 PubMed
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
|
