A month ago, a team of Japanese scientists managed to capture a zebrafish's thoughts on video. Now, you can now watch the entire brain of a larval zebrafish light up as its individual neurons fire.
This work, featured in Nature Methods this week, provides the most complete imaging of single-neuron brain activity in a vertebrate to date. Using light-sheet microscopy, researchers from the Howard Hughes Medical Institute's Janella Farm Research Campus were able to record flashes of brain activity in a fish every 1.3 seconds, showing 80 percent of its 100,000 neurons.
The imaging system developed by study authors Philipp Keller and Misha Ahrens can't distinguish between neurons that fire once and those that fire multiple times in a short period, but it does show how neural activity moves through the brain. It'll hopefully allow researchers to better analyze how regions of the brain work together to coordinate movement or process sensory detail.
Seeing inside the brain of a zebrafish requires genetic engineering to make a protein glow when nerve cells activate. A microscope then shoots sheets of light through the fish's brain, and a detector captures the result. The technique works pretty simply within zebrafish embryos because they're transparent, but would be a little more complex to adapt for mammal brains: surgery would be necessary, and we wouldn't be able to see as much of the brain at once.