Sleep remains a major mystery of biology, with little understood about its basic function. One of the most commonly proposed functions of sleep is the consolidation of memory 1 – 3 . However, as conditions such as starvation require the organism to be awake and active 4 , the ability to switch to a memory consolidation mechanism that is not contingent on sleep may confer an evolutionary advantage. Here we identify an adaptive circuit-based mechanism that enables Drosophila to form sleep-dependent and sleep-independent memory. Flies fed after appetitive conditioning needed increased sleep for memory consolidation, but flies starved after training did not require sleep to form memories. Memory in fed flies is mediated by the anterior–posterior α′/β′ neurons of the mushroom body, while memory under starvation is mediated by medial α′/β′ neurons. Sleep-dependent and sleep-independent memory rely on distinct dopaminergic neurons and corresponding mushroom body output neurons. However, sleep and memory are coupled such that mushroom body neurons required for sleep-dependent memory also promote sleep. Flies lacking Neuropeptide F display sleep-dependent memory even when starved, suggesting that circuit selection is determined by hunger. This plasticity in memory circuits enables flies to retain essential information in changing environments. Hunger status in a fly is shown to drive either sleep-dependent or sleep-independent memory formation through different mushroom body circuits.

中文翻译：

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食物的可用性决定了记忆巩固中睡眠的需要

睡眠仍然是生物学的一个主要谜团，对其基本功能知之甚少。最常见的睡眠功能之一是巩固记忆 1-3。然而，由于饥饿等条件要求有机体保持清醒和活跃 4 ，切换到不依赖于睡眠的记忆巩固机制的能力可能会带来进化优势。在这里，我们确定了一种基于自适应电路的机制，使果蝇能够形成依赖睡眠和不依赖睡眠的记忆。食欲调节后喂食的果蝇需要增加睡眠来巩固记忆，但训练后饥饿的果蝇不需要睡眠来形成记忆。进食果蝇的记忆是由蘑菇体的前后α'/β'神经元介导的，而饥饿下的记忆是由内侧α'/β'神经元介导的。依赖睡眠和不依赖睡眠的记忆依赖于不同的多巴胺能神经元和相应的蘑菇体输出神经元。然而，睡眠和记忆是耦合的，因此依赖睡眠的记忆所需的蘑菇体神经元也能促进睡眠。缺乏神经肽 F 的果蝇即使在饥饿时也会表现出依赖睡眠的记忆，这表明回路选择是由饥饿决定的。记忆电路的这种可塑性使苍蝇能够在不断变化的环境中保留基本信息。果蝇的饥饿状态显示通过不同的蘑菇体回路驱动依赖睡眠或不依赖睡眠的记忆形成。睡眠和记忆是耦合的，因此睡眠依赖性记忆所需的蘑菇体神经元也能促进睡眠。缺乏神经肽 F 的果蝇即使在饥饿时也会表现出依赖睡眠的记忆，这表明回路选择是由饥饿决定的。记忆电路的这种可塑性使苍蝇能够在不断变化的环境中保留基本信息。果蝇的饥饿状态显示通过不同的蘑菇体回路驱动依赖睡眠或不依赖睡眠的记忆形成。睡眠和记忆是耦合的，因此睡眠依赖性记忆所需的蘑菇体神经元也能促进睡眠。缺乏神经肽 F 的果蝇即使在饥饿时也会表现出依赖睡眠的记忆，这表明回路选择是由饥饿决定的。记忆电路的这种可塑性使苍蝇能够在不断变化的环境中保留基本信息。果蝇的饥饿状态显示通过不同的蘑菇体回路驱动依赖睡眠或不依赖睡眠的记忆形成。