For the first time ever, researchers have visually recorded the brain activity of an intact animal engaging in natural behavior. A team of Japanese researchers accomplished the feat by genetically inserting a very sensitive fluorescent probe into specific neurons within the brains of zebrafish larvae. When the scientists exposed their swimming subjects to food items (free-swimming paramecia) or dots on screens placed before the fish’s eyes, they could trace the cascade of calcium ion signals traversing the nerve fibers in their brains. The results were published in Current Biology last week (January 31).
“In the future, we can interpret an animal’s behavior, including learning and memory, fear, joy, or anger, based on the activity of particular combinations of neurons,” senior author Koichi Kawakami of Japan's National Institute of Genetics said in a statement. “We can make the invisible visible.”
He added that the new method could also be able to screen chemicals for their effects on neuronal activity in the brain. “This has the potential to shorten the long processes for the development of new psychiatric medications,” Kawakami said.
Muto et al., “Real-time visualization of neuronal activity during perception,” Current Biology, doi: 10.1016/j.cub.2012.12.040, 2013.