近日，美国哈佛医学院Rachel I. Wilson小组发现将头部方向信号转化为目标导向转向指令。2024年2月7日，《自然》杂志在线发表了这项成果。

研究人员表示，为了导航，人类必须不断估计前进的方向，并纠正偏离目标的情况。方向估计由头部方向系统中的环形吸引子网络完成。然而，人们并不完全了解方向感是如何用于指导行动的。果蝇连接组分析揭示了连接头部方向系统和运动系统的三个细胞群（PFL3R、PFL3L和PFL2）。

研究人员利用成像、电生理学和导航过程中的化学刺激来展示这些细胞群的功能。每个细胞群都会接收一份头部方向向量的移位拷贝，这样它们的三个参照系就会相对移位约120°。然后，每种细胞类型都会将自己的头部方向向量与共同的目标向量进行比较；具体来说，它们会通过非线性变换来评估这些向量的一致性。然后将所有三种细胞群的输出结合起来，生成运动指令。当果蝇朝向其目标的左侧时，PFL3R细胞会被招募，它们的活动会驱动果蝇向右转；PFL3L则相反。

与此同时，PFL2细胞会提高转向速度，当果蝇的方向远离目标时，它们就会被招募。随着方向误差的增加，PFL2细胞会自适应地增加转向强度，从而有效地控制速度和准确性之间的权衡。总之，这些研究结果表明，通过从以世界为中心的坐标到以身体为中心的坐标的转换，大脑中的空间地图可以与内部目标相结合，从而产生行动指令。

附：英文原文

Title: Transforming a head direction signal into a goal-oriented steering command

Author: Westeinde, Elena A., Kellogg, Emily, Dawson, Paul M., Lu, Jenny, Hamburg, Lydia, Midler, Benjamin, Druckmann, Shaul, Wilson, Rachel I.

Issue&Volume: 2024-02-07

Abstract: To navigate, we must continuously estimate the direction we are headed in, and we must correct deviations from our goal1. Direction estimation is accomplished by ring attractor networks in the head direction system2,3. However, we do not fully understand how the sense of direction is used to guide action. Drosophila connectome analyses4,5 reveal three cell populations (PFL3R, PFL3L and PFL2) that connect the head direction system to the locomotor system. Here we use imaging, electrophysiology and chemogenetic stimulation during navigation to show how these populations function. Each population receives a shifted copy of the head direction vector, such that their three reference frames are shifted approximately 120° relative to each other. Each cell type then compares its own head direction vector with a common goal vector; specifically, it evaluates the congruence of these vectors via a nonlinear transformation. The output of all three cell populations is then combined to generate locomotor commands. PFL3R cells are recruited when the fly is oriented to the left of its goal, and their activity drives rightward turning; the reverse is true for PFL3L. Meanwhile, PFL2 cells increase steering speed, and are recruited when the fly is oriented far from its goal. PFL2 cells adaptively increase the strength of steering as directional error increases, effectively managing the tradeoff between speed and accuracy. Together, our results show how a map of space in the brain can be combined with an internal goal to generate action commands, via a transformation from world-centric coordinates to body-centric coordinates.

DOI: 10.1038/s41586-024-07039-2

Source: https://www.nature.com/articles/s41586-024-07039-2