Mushroom body output neurons encode valence and guide memory-based action selection in Drosophila.
Mushroom body output neurons encode valence and guide memory-based action selection in Drosophila.
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DOI：
10.7554/elife.04580
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发表时间：
2014-12-23
期刊：
影响因子：
7.7
通讯作者：
Rubin GM
中科院分区：
文献类型：
--
作者：
Aso Y;Sitaraman D;Ichinose T;Kaun KR;Vogt K;Belliart-Guérin G;Plaçais PY;Robie AA;Yamagata N;Schnaitmann C;Rowell WJ;Johnston RM;Ngo TT;Chen N;Korff W;Nitabach MN;Heberlein U;Preat T;Branson KM;Tanimoto H;Rubin GM
动物区分刺激，学习它们的预测价值，并利用这些知识来修改它们的行为。在果蝇中，蘑菇体（MB）在这些过程中起着关键作用。感觉刺激由2000个Kenyon细胞稀疏地表示，这些细胞汇聚到21种类型的34个输出神经元（MBON）上。我们研究了MBON在几个联想学习任务和睡眠调节中的作用，揭示了信息流被分离到不同的通道的程度，并提出了多层MBON网络可能的作用。我们还表明，MBON的光遗传学激活可以根据细胞类型诱导果蝇的排斥或吸引。MBON扰动的行为效应是组合的，表明MBON系综共同代表价态。我们建议，局部，刺激特异性多巴胺能调制选择性地改变MBON网络内的平衡，这些刺激。我们的研究结果表明，价编码的MBON合奏偏见记忆为基础的行动选择。http://dx.doi.org/10.7554/eLife.04580.001动物的生存取决于它对环境做出适当反应的能力，接近发出奖励信号的刺激，避免任何警告潜在威胁的刺激。在果蝇中，这种行为需要大脑中称为蘑菇体的区域的活动，该区域处理感官信息并使用该信息来影响对刺激的反应。阿索等人最近绘制了果蝇蘑菇体的整体图。这项工作表明，蘑菇体包含21种不同类型的输出神经元。在这项工作的基础上，阿索等人开始研究这种回路如何使苍蝇学会将刺激（如气味）与结果（如食物的存在）联系起来。两种互补的技术--使用分子遗传学来阻断神经元的活动，以及使用光来激活神经元（一种称为光遗传学的技术）--被用来研究蘑菇体中输出神经元所扮演的角色。结果显示，不同的输出细胞群必须被激活苍蝇避免，而不是接近气味。此外，相同的输出神经元用于避免与惩罚相关的气味和颜色。总之，这些结果表明，输出细胞不编码刺激的身份：相反，它们发出信号，是否应该接近或避免刺激。输出细胞还调节苍蝇的睡眠量，这与蘑菇体在调节苍蝇的内部状态方面具有更广泛的作用是一致的。这些实验的结果结合了关于蘑菇体详细结构的新知识，为探索个体回路及其组成细胞水平上的联想学习奠定了基础。考虑到蘑菇体的组织与哺乳动物大脑的组织有很多共同之处，这些研究应该可以深入了解其他物种（包括人类）学习和记忆的基本原理。DOI：http://dx.doi.org/10.7554/eLife.04580.002网站
Animals discriminate stimuli, learn their predictive value and use this knowledge to modify their behavior. In Drosophila, the mushroom body (MB) plays a key role in these processes. Sensory stimuli are sparsely represented by ∼2000 Kenyon cells, which converge onto 34 output neurons (MBONs) of 21 types. We studied the role of MBONs in several associative learning tasks and in sleep regulation, revealing the extent to which information flow is segregated into distinct channels and suggesting possible roles for the multi-layered MBON network. We also show that optogenetic activation of MBONs can, depending on cell type, induce repulsion or attraction in flies. The behavioral effects of MBON perturbation are combinatorial, suggesting that the MBON ensemble collectively represents valence. We propose that local, stimulus-specific dopaminergic modulation selectively alters the balance within the MBON network for those stimuli. Our results suggest that valence encoded by the MBON ensemble biases memory-based action selection. DOI: http://dx.doi.org/10.7554/eLife.04580.001 An animal's survival depends on its ability to respond appropriately to its environment, approaching stimuli that signal rewards and avoiding any that warn of potential threats. In fruit flies, this behavior requires activity in a region of the brain called the mushroom body, which processes sensory information and uses that information to influence responses to stimuli. Aso et al. recently mapped the mushroom body of the fruit fly in its entirety. This work showed, among other things, that the mushroom body contained 21 different types of output neurons. Building on this work, Aso et al. have started to work out how this circuitry enables flies to learn to associate a stimulus, such as an odor, with an outcome, such as the presence of food. Two complementary techniques—the use of molecular genetics to block neuronal activity, and the use of light to activate neurons (a technique called optogenetics)—were employed to study the roles performed by the output neurons in the mushroom body. Results revealed that distinct groups of output cells must be activated for flies to avoid—as opposed to approach—odors. Moreover, the same output neurons are used to avoid both odors and colors that have been associated with punishment. Together, these results indicate that the output cells do not encode the identity of stimuli: rather, they signal whether a stimulus should be approached or avoided. The output cells also regulate the amount of sleep taken by the fly, which is consistent with the mushroom body having a broader role in regulating the fly's internal state. The results of these experiments—combined with new knowledge about the detailed structure of the mushroom body—lay the foundations for new studies that explore associative learning at the level of individual circuits and their component cells. Given that the organization of the mushroom body has much in common with that of the mammalian brain, these studies should provide insights into the fundamental principles that underpin learning and memory in other species, including humans. DOI: http://dx.doi.org/10.7554/eLife.04580.002