How fruit flies chase invisible ribbons of smell to get to their source

AI 中文解读

果蝇追踪腐果或伴侣，靠的是闻气味。但自然界的风会让气味变得断断续续，像看不见的烟雾碎片，果蝇得在混乱中判断方向，这对只有针尖大小的大脑来说简直是不可能任务。科学家原本以为它们靠“冲浪加扫描”的本能反射：闻到味就逆风冲，闻不到就左右飞找回来。但洛克菲勒大学团队的最新发现颠覆了这一认知——果蝇的行为远比想象中聪明。研究者给果蝇搭了个“跑步机”，通过虚拟现实控制气味和气流，发现它们能根据气味浓度的细微变化调整飞行路径，像在脑海中构建一张“气味地图”，而不是简单靠条件反射。这项研究的意义在于，它揭示了微型大脑也能执行复杂的计算任务。未来，这些发现或许能启发更灵敏的机器人嗅觉系统，用于搜救、环境监测甚至农业防虫，让机器人在看不见气味的情况下也能精准定位源头，而普通人则能期待更智能的“电子鼻”设备进入日常生活。

A fruit fly hunting a piece of rotting fruit or a mate navigates by smell, following plumes of odor. Out in the wild, turbulent air swirls these plumes into a chaotic, broken landscape—dense chemical filaments laced through long stretches of clean air. A fly trying to find the source gets the smell in stutters, from constantly shifting directions, with no guarantee that a next whiff is coming at all. Scientist had little idea of how fruit flies manage this chaotic signal with a brain the size of a pinhead. For a long time, biologists stood by the “surge and cast” model, which posited that insects solved this with hardwired reflexes. The idea was that, when a fly registers the plume with olfactory neurons in its antennae, it simply flies upwind until it’s gone and then flies side to side attempting to catch it again. But now a team led by Vanessa Ruta, a neuroscientist at the Rockefeller University, has shown that fruit flies do something far more advanced. A treadmill for flies The trouble with the traditional surge and cast model is that it struggles to explain how an insect tracks a meandering plume across long distances. Chemical cues floating in the air in the natural environment are often sparse and unreliable. But those same features make the mechanism behind olfactory navigation notoriously difficult to test. "Odors are invisible," Ruta says, "and often they're carried along by turbulent airflow." We’ve got no way of knowing what the animal is smelling from one moment to the next.Read full article Comments