Janelia Farm Research Campus, Ashburn, VA 20147, USA.
Curr Opin Neurobiol. 2013 Jun;23(3):353-60. doi: 10.1016/j.conb.2013.04.006. Epub 2013 May 4.
How does an organism's internal state direct its actions? At one moment an animal forages for food with acrobatic feats such as tree climbing and jumping between branches. At another time, it travels along the ground to find water or a mate, exposing itself to predators along the way. These behaviors are costly in terms of energy or physical risk, and the likelihood of performing one set of actions relative to another is strongly modulated by internal state. For example, an animal in energy deficit searches for food and a dehydrated animal looks for water. The crosstalk between physiological state and motivational processes influences behavioral intensity and intent, but the underlying neural circuits are poorly understood. Molecular genetics along with optogenetic and pharmacogenetic tools for perturbing neuron function have enabled cell type-selective dissection of circuits that mediate behavioral responses to physiological state changes. Here, we review recent progress into neural circuit analysis of hunger in the mouse by focusing on a starvation-sensitive neuron population in the hypothalamus that is sufficient to promote voracious eating. We also consider research into the motivational processes that are thought to underlie hunger in order to outline considerations for bridging the gap between homeostatic and motivational neural circuits.
生物体的内部状态如何指导其行动？在某一时刻，动物会进行杂技般的觅食动作，如爬树和在树枝间跳跃。而在另一时刻，它会沿着地面行进，寻找水或伴侣，在此过程中会暴露在捕食者面前。这些行为在能量或身体风险方面代价高昂，并且相对于另一组行为执行的可能性强烈受到内部状态的调节。例如，处于能量亏缺状态的动物会寻找食物，而脱水的动物会寻找水。生理状态和动机过程之间的串扰会影响行为的强度和意图，但潜在的神经回路仍知之甚少。分子遗传学以及用于扰乱神经元功能的光遗传学和药理学工具，使人们能够对介导对生理状态变化的行为反应的回路进行细胞类型选择性剖析。在这里，我们通过关注下丘脑中对饥饿敏感的神经元群体，来回顾近年来对小鼠饥饿的神经回路分析的进展，该群体足以促进贪婪的进食。我们还考虑了与饥饿相关的动机过程的研究，以便概述弥合稳态和动机神经回路之间差距的注意事项。
