When the arena was covered with a circularly polarizing filter, eliminating natural linear polarization light patterns, the flies did not shift their heading significantly in response to arena rotations.
The results indicate Drosophila has the ability to coordinate eye and brain functions for rudimentary navigation using light polarization patterns, the researchers concluded. The flies are able to hold a straighter course under normal polarization patterns than they can when those patterns are shifted.
The next step in the research is to try to determine why the flies select a particular heading.
"It's been very hard to study these processes because animals such as butterflies and locusts used in previous studies are not standard lab models," Dickinson said. "We know something about the processes, but not that much."
Demonstrating that fruit flies can navigate using cues from natural skylight makes it easier to use genetics research to better understand the complex capability and exactly how it is implemented in the brain.
For millennia, seafarers have depended on the sun to know their position in the world, but often the sun is not visible. Polarization vision solves that problem, Dickinson said, because if there's even a small patch of clear sky in a fruit fly's very broad range of view then the natural light patterns can provide location information.
He noted that fruit flies "achieve remarkable functionality" with limited resources in their brains. There are 300,000 neurons in a fruit fly's brain, and it would take 300,000 fruit flies to reach the equivalent number of neurons in the human brain.
"A lot of our research is focusing on how the fruit fly brain is multitasking in space and time to achieve remarkable effects," Dickinson said.
|Contact: Vince Stricherz|
University of Washington