The team of researchers, led by Carolina Rezaval (University of Birmingham), was interested in finding out more about how decisions are made in the brain when the rewards of courtship may be seen to outweigh the risk of predation. Laurie Cazalé-Debat, a postdoctoral student in Rezaval’s team and joint first author of the study together with biologist Lisa Scheunemann from Freie Universität Berlin, found that simulating the presence of a predator while fruit flies are in the early stages of courtship activated certain visual neurons in the brain that led the flies to immediately halt courtship and engage in defensive responses. However, during the later stages of courtship, when copulation is imminent, the male fruit flies ignored the simulated threat.

In order to assess dopamine production levels in male fruit fly brains as they progress through courtship, the team used a method for tracking neural activity in fruit flies under a two-photon microscope. This showed that the further the flies progressed in their courtship, the more dopamine was produced in their brains and the more the flies’ ability to detect threats was suppressed.

Due to the similarities in the cellular biology of dopamine neurons across species, the team suggests parallels in their findings to other decision-making processes across the animal kingdom, including humans. Dopamine signaling may be a general mechanism that biases sensory perception based on how close the organism is to achieving a specific goal – in this case, mating. David Owald from the Institute for Neurophysiology at Charité – Universitätsmedizin Berlin and his team were also involved in the research, as was Andrew Lin from the University of Sheffield.