Dopaminergic neurons mediate male Drosophila courtship motivational state

Motivational states are important determinants of behavior. In Drosophila melanogaster, courtship behavior is robust and crucial for species continuation. However, the motivation of courtship behavior remains unexplored. We first find the phenomenon that courtship behavior is modulated by motivational state. A male fly courts another male fly when it first courts a decapitated female fly, however, male-male courtship behavior rarely occurs under normal conditions. Therefore, in this phenomenon, the male fly's courtship motivational state is induced by its exposure to female flies. Blocking dopaminergic neurons synaptic transmission by expressing Tetanus toxin light chain (TNTe) decreases motivational state induced male-male courtship behavior without affecting male-female courtship behavior. Vision cues are another key component in sexually driven Drosophila male-male courtship behavior. Here, we identify a base theory that the inner motivational state could eventually decide Drosophila behavior.