Researchers at the California Institute of Technology (Caltech) have obtained the first recordings of brain-cell activity in an actively flying fruit fly.

The work - by Michael Dickinson, the Esther M. and Abe M. Zarem Professor of Bioengineering, with postdoctoral scholars Gaby Maimon and Andrew Straw - suggests that at least part of the brain of the fruit fly (Drosophila melanogaster) "is in a different and more sensitive state during flight than when the fly is quiescent," Dickinson says.

New research hopes to use these tiny insects to help determine how neurons give rise to complex behavior. This effort is helped by the fact that it is easy to manipulate the genes of fruit flies, but one problem remains: These insects are really, really tiny, which means it is very difficult to record from their brain during active behaviors such as flight."

"Researchers have recorded the neural-cell activity of fruit flies before, but only in restrained preparations - animals that had been stuck or glued down," Dickinson explains. "Gaby was able to develop a preparation where the animal is tethered" - its head clamped into place - "but free to flap its wings." By slicing off a patch of the hard cuticle covering the brain, "we were able to target our electrodes onto genetically marked neurons," he says.

A puff of air was used to spur the flies into flapping their wings, while electrodes measured the activity of the marked neurons and high-speed digital cameras simultaneously recorded the flies' behavior.

"A dye-filled glass electrode (pink) is inserted into a fruit fly's brain. The electrode and the brain are immersed in saline (colored blue in this image). The fly is flapping its wings in tethered flight. (Credit: Gaby Maimon and Michael Dickinson/Caltech)"

Source: California Institute of Technology