David Copenhagen, PhD


Synaptic Interactions in the Retina: Pathways and Mechanisms

The retina extracts and encodes specific features of the visual scene such as local contrast, color information and movement. As a sensory tissue, the retina displays an extraordinary ability to adapt to ambient light conditions that range over 10 orders of magnitude. Fundamental questions remain as to how the individual neurons are synaptically "wired" to one another via excitatory,glutamatergic and inhibitory, GABAergic and glycinergic, synaptic pathways. One of our principal areas of interest is to identify and characterize the synaptic pathways in the retina. We investigate not only the biophysical attributes of quantal synaptic transmission but also the relationships between function, connectivity, ligand-gated-channels and transporters. We utilize single cell recording, multi-electrode array, CCD imaging and confocal microscopy in these studies. A second principal area we have recently begun investigating is the development of function in the rodent retina. We have shown that dark rearing affects the anatomical and functional development of the retina. We seek to identify how this developmental retinal plasticity is controlled and what molecules are involved. A third area of ongoing research focuses on the regulation of calcium, chloride and pH in retinal neurons. We are particularly interested in the role of calcium, glutamine and glutamate transporters and the roles they play in homeostasis and regulation of synaptic transmission. In these studies we rely primarily on optical imaging using intracellular dyes, but we also use immunological and patch pipette techniques and have been able to understand function more clearly using transgenic mice lines.

Current Projects

1. The effects of visual deprivation on the formation of retinal circuits.
We are investigating what environmental cues control maturation of the ON and OFF pathways. We are also investigating the role of various signaling molecules, such as BDNF and NMDA receptors, in regulating this maturation. We are using molecular and transgenic approaches to answer these questions.

2. Roles of vesicular glutamate transporters in retinal function.
In collaboration with Rob Edwards' lab , we are localizing and characterizing the roles for VGLUT1, VGLUT2 and VGLUT3 in mammalian retina.

3. Calcium regulation and synaptic transmission in retina.
We are investigating how calcium levels are controlled by inhibitory inputs to glutamatergic retinal neurons and the roles of plasma-membrane calcium ATPases and SERCAs in regulating intracellular calcium.

Lab Members

Shawnta Chaney, PhD
Postdoctoral Fellow

Derek Bredl
Associate Specialist

Jan Verweij

Lab Website