Joshua Singer

Portrait of Joshua Singer

Joshua Singer

Biology Professor & Chair
jhsinger@umd.edu 1210 Biology-Psychology Bldg.
301 405 9784

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, my laboratory studies a specialized group of neurons that compose a retinal circuit called the rod bipolar cell pathway (see figure at right). This pathway functions during night vision, and signaling within it begins when rods absorb light. Rods are the receptive cells that are most sensitive to light: single photons can activate rods and cause very small electrical signals to be generated within them. Electrical signals from rods are propagated first to rod bipolar cells, then to AII amacrine cells (AIIs), and finally to ganglion cells, the neurons that project to the brain.
Signaling within the rod bipolar cell pathway is significant because the circuit is sensitive enough to encode small rod signals generated by single photons and flexible enough to encode much larger rod signals that arise from the widely variable light intensities within ever-changing natural scenes. Thus, the rod bipolar pathway exhibits both sensitivity and a wide operating, or dynamic, range. My laboratory studies two aspects of signaling in the rod bipolar pathway: synaptic transmission from rod bipolar cells to AIIs and processing of rod bipolar cell outputs by AIIs and ganglion cells. We assess synaptic transmission by recording neurons' electrical activity. Recordings are complemented by anatomical and computational analyses and ultimately used to understand features of the retina's responses to visual stimuli. 
From our studies, we hope not only to understand signaling within the rod bipolar pathway but also to generate a broader understanding of how the properties of neurons and their synapses give rise to circuit behavior. Our work is of interest to sensory neuroscientists specifically and to neuroscientists generally: the former because it relates to the coding of sensory information by ribbon synapses and retinal circuits and the latter because it provides an understanding of the basic principles of synaptic communication between neurons and neural circuit function. As well, our work may provide insights that serve as a basis for therapies for human diseases that affect the first stages of visual processing. Such diseases include retinitis pigmentosa and macular degeneration.

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

Teaching

  • BSCI450: Mammalian Systems Physiology
  • BSCI399: Academic credit for research (by permission only)
  • BSCI279: Readings in Physiology (by permission only)

Graduate Program Affiliations

Education

  • Sc.B., Brown University, 1993
  • Ph.D., University of Washington, 1998
  • Postdoctoral Research, NIH, 1998-2004

All Publications 

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BISI Concentration Areas

Physiological Systems

Latest Papers

The Structural and Functional Integrity of Rod Photoreceptor Ribbon Synapses Depends on Redundant Actions of Dynamins 1 and 3

| The Journal of Neuroscience
Author(s): Christin Hanke-Gogokhia, Thomas E. Zapadka, Stella Finkelstein, et. al
UMD Author(s): Joshua Singer

Multiple Calcium Channel Types with Unique Expression Patterns Mediate Retinal Signaling at Bipolar Cell Ribbon Synapses.

| The Journal of neuroscience : the official journal of the Society for Neuroscience
Author(s): Joshua Singer, Zhang G, Liu JB, et. al
UMD Author(s): Joshua Singer

Analysis of Rod/Cone Gap Junctions from the Reconstruction of Mouse Photoreceptor Terminals


Author(s): Munenori Ishibashi, Joyce Keung, Catherine W. Morgans, et. al
UMD Author(s): Joshua Singer

Computational and Molecular Properties of Starburst Amacrine Cell Synapses Differ With Postsynaptic Cell Type.

| Frontiers in cellular neuroscience
Author(s): Joshua Singer, Pottackal J, Singer JH, et. al
UMD Author(s): Joshua Singer

Dendro-somatic synaptic inputs to ganglion cells violate receptive field and connectivity rules in the mammalian retina


Author(s): Miloslav Sedlacek, William N. Grimes, Morgan Musgrove, et. al
UMD Author(s): Joshua Singer

Calmodulin Bidirectionally Regulates Evoked and Spontaneous Neurotransmitter Release at Retinal Ribbon Synapses.

| eNeuro
Author(s): Joshua Singer, Liang CQ, Zhang G, et. al
UMD Author(s): Joshua Singer

Receptoral Mechanisms for Fast Cholinergic Transmission in Direction-Selective Retinal Circuitry.

| Frontiers in cellular neuroscience
Author(s): Joshua Singer, Pottackal J, Singer JH, et. al
UMD Author(s): Joshua Singer

Connectomic analysis reveals an interneuron with an integral role in the retinal circuit for night vision.

| eLife
Author(s): Park SJ, Lieberman EE, Ke JB, et. al
UMD Author(s): Joshua Singer

Functional characterization of retinal ganglion cells using tailored nonlinear modeling.

| Scientific Reports
Author(s): Joshua Singer, Shi Q, Gupta P, et. al
UMD Author(s): Joshua Singer

Voltage-Gated Calcium Channels: Key Players in Sensory Coding in the Retina and the Inner Ear.

| Physiological reviews
Author(s): Joshua Singer, Pangrsic T, Singer JH, et. al
UMD Author(s): Joshua Singer