Kept moist, fruit flies can live for up to a day without their heads. Cell biologists at Yale University are taking advantage of this biological oddity to see how neural circuits process information. Using flashes of unfocused laser light, the scientists are making genetically altered headless fruit flies walk, jump, flap their wings, and fly.
“Normally the brain sends a signal down to the thoracic ganglion, which in turn signals to the muscles, and that initiates jumping and flight,” lead researcher Gero Miesenböck says. “If we cut the heads off those flies, they lack the normal input to this circuit” and stop moving. Photons from the laser light act like nerve impulses. When Miesenböck shines laser light on his decapitated insects, “the headless bodies actually take off and fly away.” He has also shown the same method will work on flies that still have their heads.
The point isn’t to create a swarm of programmable insects, he says, but to understand how complex neuronal circuits process information. Before now, scientists could only manipulate neurons directly and invasively by stimulating them with electrodes. That method was clumsy; it limited scientists’ ability to study interconnected nerve networks. Miesenböck’s legion of headless flies presents a novel solution. The researchers hope that applying their technique to higher-order animals like mice will shed light on how neural networks tackle tougher tasks.