In the name of science, researchers have successfully turned a group of fruit flies into raging sex maniacs, with the use of laser beams.
While conducting a study on male courtship behavior of fruit flies (Drosophila melanogaster), researchers from the Howard Hughes Medical Institute used a technique called thermogenetics to flip a mental switch that gets fruit flies in the mood for love. The technique involves using lasers to trigger special neurons that affect certain complex behaviors in the flies. The researchers conducting the study wanted to gain a deeper understanding about the specific neural circuits that control complex behavioral mechanisms. The researchers working on the study have named their laser equipment Fly Mind-Altering Device or FlyMAD for short.
"In Drosophila, male courtship is largely innate and consists of a complex series of ordered behaviors that includes orienting, following, tapping, singing (wing extension and vibration), licking, abdomen bending, attempted copulation, copulation, and culminates with ejaculation," said the researchers who conducted the study. "The behaviors prior to copulation convey visual, olfactory, gustatory, auditory, and tactile cues that allow males and females to recognize and evaluate potential mating targets and drive the progression of courtship from one behavior to the next."
In previous studies, scientists have already attempted using light to trigger certain neurons in other organisms such as mice. The process is referred to as optogenetics and this is the first time that such a technique was used in flies. To turn on a fly's mating switch, the scientists modified the neural circuits in flies responsible for managing complex mechanisms such as decision making and courtship by adding a heat sensitive protein called TRPA1. The scientists then shined laser beams on the flies. Since heat from the lasers can penetrate a fly's exoskeleton, researchers were able to activate the necessary neurons to control the fly's behavior.
"Solitary males in which these circuits were activated showed robust levels of nearly all courtship behaviors," said the researchers. "We analyzed these behaviors in both intact and headless males, and also in intact males with a variety of courtship targets."
Once the right neural circuits were activated, the flies started exhibiting courtship behavior. In fact, the flies were so excited that they proceeded to attempt mating with the nearest object, which in this case happened to be a ball of wax.
"A male will not execute these courtship behaviors (especially the later steps) unless he senses a potential mate," said the researchers. "Indeed, throughout the animal kingdom, there is a strong linkage between the percept of a potential mate and the display of male sexual behavior."
Using the same technique on a different set of neurons, the scientists were also able to control a fly's muscular coordination. When the muscular control neural circuits were activated using lasers, the flies began walking backwards. After shutting the lasers down, the flies reverted to their normal behavior. When using lasers on the mating neural circuits however, the effect persisted for about 15 minutes, which seems to indicate that triggering the neural circuits responsible for mating behavior produced more lasting effects. The researchers published their findings in the online journal Nature.