McCloskey Richard J, Fouad Anthony D, Churgin Matthew A, Fang-Yen Christopher
Department of Bioengineering, School of Engineering and Applied Sciences, University of Pennsylvania, Philadelphia, Pennsylvania; and.
Department of Bioengineering, School of Engineering and Applied Sciences, University of Pennsylvania, Philadelphia, Pennsylvania; and
J Neurophysiol. 2017 May 1;117(5):1911-1934. doi: 10.1152/jn.00555.2016. Epub 2017 Feb 22.
Animals optimize survival and reproduction in part through control of behavioral states, which depend on an organism's internal and external environments. In the nematode a variety of behavioral states have been described, including roaming, dwelling, quiescence, and episodic swimming. These states have been considered in isolation under varied experimental conditions, making it difficult to establish a unified picture of how they are regulated. Using long-term imaging, we examined episodic behavioral states under varied mechanical and nutritional environments. We found that animals alternate between high-activity (active) and low-activity (sedentary) episodes in any mechanical environment, while the incidence of episodes and their behavioral composition depend on food levels. During active episodes, worms primarily roam, as characterized by continuous whole body movement. During sedentary episodes, animals exhibit dwelling (slower movements confined to the anterior half of the body) and quiescence (a complete lack of movement). Roaming, dwelling, and quiescent states are manifest not only through locomotory characteristics but also in pharyngeal pumping (feeding) and in egg-laying behaviors. Next, we analyzed the genetic basis of behavioral states. We found that modulation of behavioral states depends on neuropeptides and insulin-like signaling in the nervous system. Sensory neurons and the Foraging homolog EGL-4 regulate behavior through control of active/sedentary episodes. Optogenetic stimulation of dopaminergic and serotonergic neurons induced dwelling, implicating dopamine as a dwell-promoting neurotransmitter. Our findings provide a more unified description of behavioral states and suggest that perception of nutrition is a conserved mechanism for regulating animal behavior. One strategy by which animals adapt to their internal states and external environments is by adopting behavioral states. The roundworm is an attractive model for investigating how behavioral states are genetically and neuronally controlled. Here we describe the hierarchical organization of behavioral states characterized by locomotory activity, feeding, and egg-laying. We show that decisions to engage in these behaviors are controlled by the nervous system through insulin-like signaling and the perception of food.
动物通过控制行为状态来部分优化生存和繁殖，行为状态取决于生物体的内部和外部环境。在线虫中，已经描述了多种行为状态，包括漫游、栖息、静止和间歇性游泳。这些状态在不同的实验条件下被单独考虑，因此难以建立它们如何被调节的统一图景。我们使用长期成像技术，在不同的机械和营养环境下研究了间歇性行为状态。我们发现，在任何机械环境中，动物都会在高活动（活跃）和低活动（久坐）阶段之间交替，而阶段的发生率及其行为组成取决于食物水平。在活跃阶段，蠕虫主要进行漫游，其特征是全身持续运动。在久坐阶段，动物表现出栖息（局限于身体前半部分的较慢运动）和静止（完全没有运动）。漫游、栖息和静止状态不仅通过运动特征表现出来，还体现在咽部抽吸（进食）和产卵行为中。接下来，我们分析了行为状态的遗传基础。我们发现行为状态的调节依赖于神经系统中的神经肽和胰岛素样信号传导。感觉神经元和觅食同源物EGL-4通过控制活跃/久坐阶段来调节行为。对多巴胺能和5-羟色胺能神经元的光遗传学刺激诱导了栖息，这表明多巴胺是一种促进栖息的神经递质。我们的研究结果对行为状态提供了更统一的描述，并表明对营养的感知是调节动物行为的一种保守机制。动物适应其内部状态和外部环境的一种策略是采用行为状态。蛔虫是研究行为状态如何在基因和神经水平上被控制的一个有吸引力的模型。在这里，我们描述了以运动活动、进食和产卵为特征的行为状态的层次组织。我们表明，参与这些行为的决定是由神经系统通过胰岛素样信号传导和对食物的感知来控制的。
