Neural activity (yellow/red) throughout the entire CNS (grey) of a Drosophila larva during fictive backward crawling. The images were acquired with hs-SiMView light-sheet microscopy.

These gifs look pretty amazing for the fiery reds and yellows firing through a ghostly grey body. They’re even more cool when you realize what they depict–scientists have been able to peer through the skin and record all the neural activity of a fruit fly larva’s central nervous system (CNS).

Using advanced imaging called light-sheet microscopy and image processing and analysis, Howard Hughes Medical Institute researchers watched the activation of brain and ventral nerve cord neurons while a larva crawled. This gave them a functional view of how the organism’s nervous system manages motor activity. It’s like a very scaled down version of watching activity ripple through the brain and spinal cord of a walking human. Learn more below.

“It is becoming increasingly clear that to understand how neuronal networks function, it is important to measure neuronal network activity at the system level,” write biologist Philipp Keller and colleagues in a study that appeared last week in the journal Nature Communications. “Our method enables, for the first time, the imaging of activity within the entire CNS of a widely used genetically tractable model organism as it generates multiple fictive behaviors.”

The imaging system they developed was able to take five images of the larva’s CNS every second as it crawled backwards. This speed was important in getting the system’s time resolution down enough to uncover the details of how the CNS works. The activity they recorded within neurons wasn’t the actual electricity the cells use to communicate. Instead, the process involved getting the Drosophila melanogaster larva’s cells to express a calcium indicator that glows when the microscopes sheet of laser light hits it. The presence of the indicator shows that the cell is active.

The work is a continuation of exciting research happening at HHMI’s Janella Research Campus, which is using a new generation of microscopes and techniques to reveal how organisms develop and operate in real time.

“Understanding how the brain works in tight concert with the rest of the CNS hinges upon knowledge of coordinated activity patterns across the whole CNS,” the authors write. “We present a method for measuring activity in an entire, non-transparent CNS with high spatiotemporal resolution…These technologies bring into reach the possibility of recording from every part of a nervous system during behaviors.”

All gifs created from Youtube videos courtesy of Keller et al./Nature Communications.