Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT 84112, USA.
Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT 84112, USA.
Curr Biol. 2020 Dec 7;30(23):4606-4618.e4. doi: 10.1016/j.cub.2020.09.002. Epub 2020 Oct 1.
Dopamine (DA)-producing neurons are critically involved in the production of motor behaviors in multiple circuits that are conserved from basal vertebrates to mammals. Although there is increasing evidence that DA neurons in the hypothalamus play a locomotor role, their precise contributions to behavior and the circuit mechanisms by which they are achieved remain unclear. Here, we demonstrate that tyrosine-hydroxylase-2-expressing (th2+) DA neurons in the zebrafish hypothalamus fire phasic bursts of activity to acutely promote swimming and modulate audiomotor behaviors on fast timescales. Their anatomy and physiology reveal two distinct functional DA modules within the hypothalamus. The first comprises an interconnected set of cerebrospinal-fluid-contacting DA nuclei surrounding the 3 ventricle, which lack distal projections outside of the hypothalamus and influence locomotion through unknown means. The second includes neurons in the preoptic nucleus, which send long-range projections to targets throughout the brain, including the mid- and hindbrain, where they activate premotor circuits involved in swimming and sensorimotor integration. These data suggest a broad regulation of motor behavior by DA neurons within multiple hypothalamic nuclei and elucidate a novel functional mechanism for the preoptic DA neurons in the initiation of movement.
多巴胺（DA）产生神经元在多个从基础脊椎动物到哺乳动物都保守的回路中对运动行为的产生至关重要。尽管越来越多的证据表明下丘脑的 DA 神经元在运动中发挥作用，但它们对行为的精确贡献以及实现这些贡献的回路机制仍不清楚。在这里，我们证明斑马鱼下丘脑表达酪氨酸羟化酶-2（th2+）的 DA 神经元会发出突发的活动爆发，以在快速时间尺度上急性促进游泳，并调节听觉运动行为。它们的解剖结构和生理学揭示了下丘脑内两个不同的功能 DA 模块。第一个由一组相互连接的围绕第三脑室的脑脊液接触 DA 核组成，这些核在外周没有远距离投射，其通过未知的方式影响运动。第二个包括视前核中的神经元，它们向大脑中的各个目标发送长程投射，包括中脑和后脑，在那里它们激活参与游泳和感觉运动整合的运动前回路。这些数据表明，多个下丘脑核内的 DA 神经元对运动行为有广泛的调节作用，并阐明了视前 DA 神经元在运动启动中的一个新的功能机制。
