Multisensory control of orientation in tethered flying Drosophila

A longstanding goal of systems neuroscience is to quantitatively describe how the brain integrates sensory cues over time. Here we develop a closed-loop orienting paradigm in Drosophila to study the algorithms by which cues from two modalities are integrated during ongoing behavior. We find that flies exhibit two behaviors when presented simultaneously with an attractive visual stripe and aversive wind cue. First, flies perform a turn sequence where they initially turn away from the wind and but later turn back toward the stripe, suggesting dynamic sensory processing. Second, turns toward the stripe are slowed by the presence of competing wind, suggesting summation of turning drives. We develop a model in which signals each modality are filtered in space and time to generate turn commands, then summed to produce ongoing orienting behavior. This computational framework correctly predicts behavioral dynamics for a range of stimulus intensities and spatial arrangements.

系统神经科学（systems neuroscience）的长期核心目标之一，是定量刻画大脑随时间整合感官线索（sensory cues）的机制。本研究以果蝇（Drosophila）为实验对象，开发了一种闭环定向范式（closed-loop orienting paradigm），用以探究在持续行为过程中，来自两种模态（modality）的线索如何被整合的算法机制。研究发现，当果蝇同时受到具有吸引力的视觉条纹与厌恶性气流刺激时，会表现出两类行为模式：其一，果蝇会执行一系列转向动作——初始阶段避开气流，后续则转向视觉条纹所在方向，这提示存在动态的感官处理过程；其二，在存在竞争性气流的情况下，果蝇朝向视觉条纹的转向动作会被延缓，这表明转向驱动力存在累加效应。本研究构建了一套计算模型，其中各模态的信号会在空间与时间维度上进行滤波以生成转向指令，随后将这些指令进行累加，从而产生持续的定向行为。该计算框架可准确预测不同刺激强度（stimulus intensities）与空间布局（spatial arrangements）下的行为动力学特征。