Interdisciplinary team maps the vestibular system of a zebrafish

A team of University of Queensland optical physicists and neuroscientists has used optical tweezers, or focused beams of light, to investigate how the brain of a zebrafish reacts to gravity and motion. 

The method, previously published in Nature Communicationsand awarded a 2018 Australian Museum Eureka prize, has demonstrated that optical tweezers can simulate movements and acceleration. 

School of Biomedical Sciences researcher Associate Professor Ethan Scott said the vestibular system – which governs balance and spatial orientation – was crucial to survival, but the nerve circuits processing that information had not previously been revealed.

“We needed a way to activate the vestibular system without the animal moving," he said. 

“By tricking the animal into thinking it's moving while the brain remains stationary, we used advanced microscopy to study the cells and circuits across the brain responsible for motion processing for the first time.”

Researcher Dr Itia Favre-Bulle said the team targeted an infrared laser toward the otoliths, or ear stones, of larval zebrafish. 

”Optical trapping was the perfect solution as it uses light to apply forces on transparent objects.

"From a technical standpoint, this is exciting because these are the largest and most optically complex objects that have been manipulated with optical trapping,” she said.

“The technique was effective even though the targets were deep within a living animal."

The team also identified the vestibular neuronal network using calcium imaging and image processing. 

By scanning the whole brain with light sheets and performing fluorescence imaging, the researchers identified every neuron that was involved in sensing movement by tracking its activity.

"Using a series of algorithms and high performance computing, we could then discern patterns of activity across the brain,” Dr Favre-Bulle said. 

“This gives us the first brain-wide map of the neurons that form the vestibular system.”

The research article, “Cellular-Resolution Imaging of Vestibular Processing across the Larval Zebrafish Brain”, is published in the journal Current Biology.

The team also includes EQUS Chief Investigator and School of Maths and Physics Professor Halina Rubinsztein Dunlop and Dr Gilles Vanwalleghemfrom School of Biomedical Sciences.

Media: Ethan Scott, ethan.scott@uq.edu.au, 0432 798 207