Researchers have created a non-intruding technology that detects when nerve cells fire based on changes in shape. The method can be used to observe nerve activity in light-accessible parts of the body, such as the eye. It will allow doctors to quantitatively examine visual function at the cellular level.
The study appears in the journal Light: Science and Applications. National Eye Institute supported this research. Researchers conducted this study at Stanford University, Palo Alto, California.
What will the new technique do?
When nerves fire, there’s an alteration in the electric potential (trans-membrane voltage) in the observed cell. Present techniques for examining nerve activity are intruding. They need electrodes attached around the inserted nerves or fluorescent markers into the cell.
However, this new technique takes benefit of a side-effect of that alteration in voltage. As the nerve cell fires, the cell’s membrane transiently becomes a little hard. It rounds the cell’s configuration. Interferometric (phase) imaging can identify this alteration. It analyzes alterations in the passing light or the reflection from the surface across the cell.
What did the researchers do?
They designed an interferometric microscope with a high-end camera that collects 50,000 frames per second. This speed is critical because the alterations in cell integrity are light. So, there is a very weak signal in contrast to the noise in the photos. With high-speed imaging, the researchers can integrate 50 frames together in components.
It cancels out the noise and amplifies the sharpness of the signal. They also made a state-of-the-art algorithm that would identify informative areas (i.e. the parts of the cells that are the most active) and amplify the signal even more.
This nanometer-scale shape alteration is very hard to vie. However, it is visible through ultrafast quantitative phase imaging. Researchers used a dish of engineered cells to fire like neurons. The researchers contrasted their technique to the previous, electrode-based measurements of neurons firing. The electrodes evaluated electric signals were the same as the recordings from their microscope.
The goal of the project
The goal is to imply this technique to identify signals passing through the optic nerve. It can also detect signals from individual nerve cells present in the retina. Direct evaluation of nerves in the eye will help scientists plan and examine new therapies to rejuvenate visual function. The target in this grant was the establishment of the core facts.
These include the speed and ability of the cells to move during an action potential. Another fact is devising the perfect technical strategies for the system that humans may imply. This study will be solid evidence for studying mechanical effects in firing cells.
The research team will acknowledge how to imply this method with optical coherence tomography. This tomography is a type of imaging technology normally used to visualize the retina of the eye.
Scientists can potentially use non-intruding, optical, neural picking methods in human eyes. These developments are promising for studying retinal diseases in human on a cellular scale. It also builds up new pathways to examine treatments to cure them.