Male fruit flies tend to overlook physical threats when they become absorbed in courtship and mating activities, according to new findings.
New research indicates that male fruit flies become unaware of physical dangers as they engage more deeply in courtship and sexual activities.
A study conducted by researchers at the University of Birmingham revealed that when male fruit flies chase after a desirable reward—specifically a female fly—they tend to disregard threats like predators.
Published today (28 Aug) in Nature, this study is the first to identify the neural circuits in the flies’ brains that are involved in this decision-making process, highlighting dopamine’s significant role.
Dr. Carolina Rezaval, the lead researcher, stated: “Every day, we make choices that involve weighing opportunities against risks, yet we understand very little about what’s happening in our brains during these moments.”
“By examining which neural pathways are activated in fruit flies’ brains, we learn more about these decision-making processes. As a male fly engages in courtship and is nearing mating, we observe that when a threat appears, it simply does not react to it.”
For their study, the scientists employed two-photon microscopy to observe which neurons in the flies’ brains became active during courtship. They simulated a predator’s presence by introducing artificial threats through light and shadow.
Dr. Laurie Cazale-Debat, a prominent researcher in Rezaval’s team at the University of Birmingham, mentioned: “In the early stages of courtship, the introduction of a threat activated certain visual neurons that interacted with serotonin-regulated neurons, causing the flies to cease courtship and flee.”
“However, as courtship progresses, the rise in dopamine inhibits crucial sensory pathways, diminishing the fly’s ability to react to threats and causing it to concentrate solely on mating.”
Dr. Rezaval elaborated: “An organism must prioritize what’s most significant. Dopamine plays a vital role in this decision-making, and its levels directly correlate with how close the goal is—essentially, how likely success becomes.”
“This sort of motivation is observable in humans as well. Consider climbing a mountain and nearing the peak; if the weather changes and becomes hazardous, you might overlook that danger because you are so near your objective,” said Dr. Lisa Scheunemann, a group lead from Freie Universität Berlin and a key partner in the research.
Dr. Rezaval concluded: “Our findings demonstrate that as courtship continues, dopamine levels rise, serving as a sensory filter that minimizes distractions and aids the animal in concentrating on its objective when it is close to success. We are eager to investigate if this decision-making mechanism is also present in mammals, including humans.”
This research was conducted in partnership with Dr. Lisa Scheunemann (Freie Universität Berlin), Dr. David Owald’s group (Charité – Universitätsmedizin Berlin), and Dr. Andrew Lin’s group (University of Sheffield). It received funding from various organizations such as the Biotechnology and Biological Sciences Research Council, The Leverhulme Trust, Marie Skłodowska-Curie Actions, the German Research Foundation (DFG), the European Research Council, and the Wellcome Trust.
