Romantic engagement can bias sensory perception. This ‘love blindness’ reflects a common behavioural principle across organisms: favouring pursuit of a coveted reward over potential risks¹. In the case of animal courtship, such sensory biases may support reproductive success but can also expose individuals to danger, such as predation^2,3. However, how neural networks balance the trade-off between risk and reward is unknown. Here we discover a dopamine-governed filter mechanism in male Drosophila that reduces threat perception as courtship progresses. We show that during early courtship stages, threat-activated visual neurons inhibit central courtship nodes via specific serotonergic neurons. This serotonergic inhibition prompts flies to abort courtship when they see imminent danger. However, as flies advance in the courtship process, the dopaminergic filter system reduces visual threat responses, shifting the balance from survival to mating. By recording neural activity from males as they approach mating, we demonstrate that progress in courtship is registered as dopaminergic activity levels ramping up. This dopamine signalling inhibits the visual threat detection pathway via Dop2R receptors, allowing male flies to focus on courtship when they are close to copulation. Thus, dopamine signalling biases sensory perception based on perceived goal proximity, to prioritize between competing behaviours.

浪漫的订婚会使感官知觉产生偏差。这种“爱盲”反映了各种生物体的共同行为原则：喜欢追求令人垂涎的回报而不是潜在的风险¹。在动物求偶的情况下，这种感官偏差可能支持繁殖成功，但也可能使个体面临危险，例如捕食^2,3。然而，神经网络如何平衡风险和回报之间的权衡尚不清楚。在这里，我们在雄性果蝇中发现了一种由多巴胺控制的过滤机制，随着求偶的进行，它会减少威胁感知。我们表明，在早期求爱阶段，威胁激活的视觉神经元通过特定的 5-羟色胺能神经元抑制中央求爱节点。这种血清素能抑制会促使果蝇在看到迫在眉睫的危险时中止求偶。然而，随着果蝇在求偶过程中的进展，多巴胺能过滤系统减少了视觉威胁反应，将平衡从生存转变为交配。通过记录雄性接近交配时的神经活动，我们证明求偶的进展记录为多巴胺能活动水平的上升。这种多巴胺信号传导通过 Dop2R 受体抑制视觉威胁检测途径，使雄性果蝇在接近交配时能够专注于求偶。因此，多巴胺信号传导根据感知到的目标接近度来偏倚感官知觉，以优先考虑竞争行为之间的优先级。