Laboratory of Molecular Biology, National Institute of Mental Health, NIH, Bethesda, Maryland 20892, USA.
J Neurosci. 2012 Jan 18;32(3):880-9. doi: 10.1523/JNEUROSCI.3707-11.2012.
The neural circuits that mediate behavioral choices must not only weigh internal demands and environmental circumstances, but also select and implement specific actions, including associated visceral or neuroendocrine functions. Coordinating these multiple processes suggests considerable complexity. As a consequence, even circuits that support simple behavioral decisions remain poorly understood. Here we show that the environmentally sensitive wing expansion decision of adult fruit flies is coordinated by a single pair of neuromodulatory neurons with command-like function. Targeted suppression of these neurons using the Split Gal4 system abrogates the fly's ability to expand its wings in the face of environmental challenges, while stimulating them forces expansion by coordinately activating both motor and neuroendocrine outputs. The arbitration and implementation of the wing expansion decision by this neuronal pair may illustrate a general strategy by which neuromodulatory neurons orchestrate behavior. Interestingly, the decision network exhibits a plasticity that is unmasked under conducive environmental conditions in flies lacking the function of the command-like neuromodulatory neurons. Such flies can often expand their wings using a motor program distinct from that of wild-type animals and controls. This compensatory program may be the vestige of an ancestral, environmentally insensitive program used for wing expansion that existed before the evolution of the environmentally adaptive program currently used by Drosophila and other cyclorrhaphan flies.
介导行为选择的神经回路不仅必须权衡内部需求和环境情况，还必须选择和实施特定的行动，包括相关的内脏或神经内分泌功能。协调这些多个过程表明存在相当大的复杂性。因此，即使支持简单行为决策的回路仍然知之甚少。在这里，我们表明，成年果蝇对环境敏感的翅膀扩张决策是由一对具有指挥功能的神经调质神经元协调的。使用 Split Gal4 系统靶向抑制这些神经元会破坏果蝇在面临环境挑战时扩张翅膀的能力，而刺激它们则通过协调激活运动和神经内分泌输出来强制扩张。这个神经元对协调翅膀扩张决策的仲裁和实施可能说明了神经调质神经元协调行为的一般策略。有趣的是，决策网络表现出一种可塑性，在缺乏类似指令的神经调质神经元功能的果蝇中，这种可塑性在有利的环境条件下显现出来。这些苍蝇通常可以使用不同于野生型动物和对照的运动程序来扩张翅膀。这种补偿程序可能是祖先的、对环境不敏感的翅膀扩张程序的残余，该程序存在于当前用于果蝇和其他环裂蝇的环境适应程序进化之前。
