3D Imaging System May Have Applications in ALS Research

A novel system for three-dimensional (3D) imaging of zebrafish may be useful for studying the motor and neuronal deficits linked with amyotrophic lateral sclerosis (ALS), a study suggests.

The system was described in the journal Optica, in the study “Coded-aperture broadband light field imaging using digital micromirror devices.”

Zebrafish are a useful animal model for studying diseases like ALS. Because ALS affects movement, being able to precisely track and measure the movement of fish may be useful for ALS research.

This kind of movement tracking requires imaging systems that can take precise images in 3D space. Broadly, such imaging systems have used light to detect motion, such as in the coded-aperture light field (CALF) system.

But using white light for this kind of experiment can pose problems because white light can be dispersed — broken up into all of the constituent colors of the rainbow — and reduce the resolution of these imaging systems.

In the new study, a research team in Canada solved this problem using digital micromirror devices (DMDs). The researchers’ system uses two DMDs; one disperses the light, and the other reads that dispersed light to generate an image without dispersion. The researchers termed their system DECALF imaging (short for dispersion-eliminated CALF imaging).

“We are the first to use this design to manage the colour dispersion within the entire visible spectrum, which allows us to use white light for this experiment,” Jingdan Liu, PhD, a postdoctoral fellow at Institut national de la recherche scientifique (INRS) and co-author of the study, said in a press release.

After doing various proof-of-concept experiments to ensure that their system worked as intended, the researchers used the DECALF system to track the movements of zebrafish, with or without a mutation in the C9ORF72 gene that models ALS. When the fish were startled by a stream of water, the system was able to capture differences in how the fish moved, based on whether or not they had ALS.

“The normal zebrafish quickly moved away from the site of the startle. In contrast, the [ALS] zebrafish showed slow responses and a limited moving ability due to motor deficits,” the team wrote.

“Altogether, these findings demonstrate the power of DECALF imaging for the behavioral study of disease-model zebrafish,” they added.

Notably, the system could have other imaging-related applications in research, for imaging large things like whole animals, but also for imaging things too small for the naked eye to see.

“We could go even further in the study of this disease by looking at the microscopic scale. Using this innovative imaging approach, we could learn about what is happening in the neural system in normal and disease states in a non-invasive manner,” said Kessen Patten, PhD, a professor at INRS and study co-author.

The team is planning work to further improve and refine the DECALF system.