Fouke Kaitlyn E, He Zichen, Loring Matthew D, Naumann Eva A
Department of Neurobiology, Duke University School of Medicine, Durham, NC 27710, USA.
Department of Neurobiology, Duke University School of Medicine, Durham, NC 27710, USA; Department of Psychology and Neuroscience, Duke University, Durham, NC 27710, USA.
Curr Biol. 2025 May 19;35(10):2457-2466.e4. doi: 10.1016/j.cub.2025.04.027. Epub 2025 May 2.
Many animals respond to sensory cues with species-specific coordinated movements. A universal visually guided behavior is the optomotor response (OMR), which stabilizes the body by following optic flow induced by displacements in currents. While the brain-wide OMR circuits in zebrafish (Danio rerio) have been characterized, the homologous neural functions across teleost species with different ecological niches, such as Danionella cerebrum, remain largely unexplored. Here, we directly compare larval zebrafish and D. cerebrum to uncover the neural mechanisms underlying the natural variation of visuomotor coordination. Closed-loop behavioral tracking during visual stimulation revealed that D. cerebrum follow optic flow by swimming continuously, punctuated with sharp directional turns, in contrast to the burst-and-glide locomotion of zebrafish. Although D. cerebrum swim at higher average speeds, they lack the direction-dependent velocity modulation observed in zebrafish. Two-photon calcium imaging and tail tracking showed that both species exhibit direction-selective encoding in putative homologous regions, with D. cerebrum containing more monocular neurons. D. cerebrum sustain significantly longer directed swims across all stimuli than zebrafish, with zebrafish reducing tail movement duration in response to oblique, turn-inducing stimuli. While locomotion-associated neurons in D. cerebrum display more prolonged activity than zebrafish, lateralized turn-associated neural activity in the hindbrain suggests a shared neural circuit architecture that independently controls movement vigor and direction. These findings highlight the diversity in visuomotor strategies among teleost species with shared circuit motifs, establishing a framework for unraveling the neural mechanisms driving continuous and discrete locomotion.
许多动物会通过特定物种的协调运动对感官线索做出反应。一种普遍的视觉引导行为是视动反应（OMR），它通过跟随水流位移引起的光流来稳定身体。虽然斑马鱼（Danio rerio）全脑范围的OMR回路已被表征，但在具有不同生态位的硬骨鱼物种中，如大脑丹尼奥鱼（Danionella cerebrum），同源神经功能在很大程度上仍未被探索。在这里，我们直接比较斑马鱼幼体和大脑丹尼奥鱼，以揭示视觉运动协调自然变异背后的神经机制。视觉刺激期间的闭环行为跟踪显示，与斑马鱼的爆发式和滑行式运动不同，大脑丹尼奥鱼通过持续游泳并伴有急剧的方向转变来跟随光流。尽管大脑丹尼奥鱼的平均游泳速度更高，但它们缺乏在斑马鱼中观察到的方向依赖性速度调制。双光子钙成像和尾巴跟踪表明，这两个物种在假定的同源区域均表现出方向选择性编码，大脑丹尼奥鱼含有更多的单眼神经元。在所有刺激下，大脑丹尼奥鱼的定向游泳持续时间明显比斑马鱼长，斑马鱼会因倾斜的、诱导转弯的刺激而缩短尾巴运动持续时间。虽然大脑丹尼奥鱼中与运动相关的神经元活动比斑马鱼持续时间更长，但后脑的侧向转弯相关神经活动表明存在一个共享的神经回路结构，该结构独立控制运动活力和方向。这些发现突出了具有共享回路基序的硬骨鱼物种之间视觉运动策略的多样性，为揭示驱动连续和离散运动的神经机制建立了一个框架。
