PrintJoshua Singer
Assistant Professor
Research Interests and Goals
Generally, I want to understand how the output of a neural circuit reflects the behaviors of the individual synapses and neurons that compose it. The mammalian retina is a model circuit well suited to the study of this issue: it is well-characterized anatomically and physiologically, but the nature of synaptic transmission between its component neurons is understood poorly.
Specifically, I study a retinal microcircuit, the rod bipolar cell pathway, that serves night vision and comprises well-defined interneurons: the rod bipolar cell, the AII amacrine cell, and ON cone bipolar cells. This circuit transfers the output of rod photoreceptors to ganglion cells, the output cells of the retina. My goal is to understand how the physiological properties of its component neurons and synapses allow the circuit to transfer rod photoreceptor output to ganglion cells with the fidelity necessary for vision when photons are scarce and few rods are activated. Currently I am pursuing three related lines of inquiry: 1) what presynaptic factors govern the rate of exocytosis and the time course of transmitter action at rod bipolar cell ribbon synapses; 2) how do postsynaptic membrane properties of AIIs shape rod bipolar output; 3) how is AII output altered as it is transferred to ON cone bipolar cells via electrical synapses?
These questions are addressed largely by electrophysiological recording from retinal neurons in an in vitro slice preparation and complemented by computational analyses. Recently, my investigations have been aided by the use of readily-available transgenic mice in which retinal neurons express eGFP under the control of cell-specific promoters, and I expect that future work will benefit greatly from the use of such experimental animals.
Recent Publications
Original, peer-reviewed research articlesÂ
Cembrowski, MS, Logan, SM, Tian, M, Jia, L, Li, W, Kath, WL, Riecke, H, and Singer, JH (2012) The mechanisms of repetitive spike generation in an axonless retinal interneuron. Cell Reports 1:155-66.
Jarsky, T, Cembrowski M, Logan SM, Kath WL, Riecke H, Demb JB and Singer JH. (2011) A synaptic mechanism for retinal adaptation to luminance and contrast. J. Neurosci. 31(30):11003-11015.
Jarsky, T., Tian, M. and Singer JH (2010) Nanodomain control of exocytosis is responsible for the signaling capability of a retinal ribbon synapse. J. Neurosci. 30(36): 11885-95. (Cited twice by Faculty of 1000.)
Tian, M., Jarsky, T., Murphy, G., Rieke, F., and Singer, JH (2010) Voltage-gated Na channels in AII amacrine cells accelerate scotopic light responses mediated by the rod bipolar cell pathway. J. Neurosci.30: 4650-59.
Fuerst, PG, Bruce, F, Tian, M, Wei, W, Elstrott, J, Feller, MB, Erskine, L, Singer, JH, and Burgess, RW (2009). DSCAM and DSCAML1 Function in Self-Avoidance in Multiple Cell Types in the Developing Mouse Retina. Neuron 64:484-97. (Cited by Faculty of 1000.)
Reviews and Commentaries
Demb, J.B. and Singer JH (2012) Intrinsic properties and functional circuitry of the AII amacrine cell. Vis. Neurosci. 29: 51-60
Singer, JH, Glowatzki, E, Moser, T, Strowbridge, B, Bhandawat, V, and Sampath, AP. (2009) Functional Properties of Synaptic Transmission in Primary Sense Organs. J. Neurosci., 29(41): 12802-6.
Singer, JH (2008) GABA is an endogenous agonist of glycine receptors.Neuron: 57(4): 475-77.
Singer, JH (2007) Multivesicular release and saturation of glutamatergic signaling at retinal ribbon synapses. J. Physiol.
580(1):23-29.
Awards
2011 Research to Prevent Blindness Special Scholar Award for Retinitis Pigmentosa
2007-2009 Alfred P. Sloan Foundation Research Fellowship
2002-2007 NINDS Career Development (K-22) Award
Education
Ph.D, University of Washington, 1998
Neurophysiology Postdoctoral Research, NIH, 1998-2004
