All-Optical Electrophysiology with Microbial Rhodopsins

When: Thursday, October 02, 2014 at 4:00 pm
Where: DA 114
Speaker: Adam Cohen
Organization: Harvard University
Sponsor: Physics Colloquium

In the wild, microbial rhodopsin proteins convert solar energy into
changes in transmembrane voltage, which provide energy and information
for their host.  These proteins have recently attracted much attention
as a means to gain optical control over membrane potential in neurons
and cardiac cells.  We engineered a microbial rhodopsin to run in
reverse: to convert changes in membrane potential into a readily
detectable optical signal.  When expressed in a neuron or a cardiac
myocyte, these voltage-indicating proteins convert electrical action
potentials into visible flashes of fluorescence.  We made movies of
action potential propagation in primary neuronal cultures, in human
induced pluripotent stem cell-derived neurons and cardiomyocytes, and
in zebrafish embryos.  We combined rhodopsin-based voltage indicators
with channelrhodopsin-based neuronal actuators to create an
all-optical electrophysiology system.  We developed computational
techniques to map electrical propagation in neurons at effective
frames rates up to 100,000 frames per second.  The genes, imaging
systems, and analysis software enable studies of electrical dynamics
in cells, tissues, and organisms with an information content and
throughput that greatly exceed the capabilities of electrode-based
devices.

Host: Assistant Professor Meni Wanunu