We rely on electric pulses flowing from neuron to neuron in our brains. To understand which pathways of neurons are responsible for particular actions or emotions, neuroscientists want to learn how electrical messages move through a network of neurons. Until recently, however, they have lacked the necessary tools to do so.

Assistant Professor of Chemistry and Molecular and Cell Biology Evan Miller is developing new technologies to measure electrical changes in the brain using voltage reporters. Voltage reporters are electrically-sensitive proteins that change color in response to a firing neuron, allowing scientists to visually detect the movement of electricity through connected neurons.

As a graduate student in Miller’s lab, Dr. Parker Deal engineered a new type of voltage reporter, nicknamed RhoVR, suitable for tracing electrical changes in the brain. It is brighter and responds faster than other voltage reporters, and it works well with twophoton microscopy. As Deal explains, twophoton microscopes can penetrate through several layers of brain tissue, which allows researchers to study neurons buried deep in the brain. Additionally, RhoVR can target specific neurons. By tethering RhoVR to a protein that is only produced in a specific subset of neurons, researchers can be certain that they are only measuring electrical activity in cells they care about.

Only neurons (left baseline image) containing RhoVR become fluorescent upon application of voltage (right image). Image Design: Alexandra Ramsey.

As the technology improves, voltage reporters are becoming a popular way to measure electrical signaling in neurons. Their application brings us closer to understanding exactly what happens in our brains whenever we feel gloomy or take a walk.

This article is part of the Spring 2020 issue.