Neural network function requires an appropriate balance of excitation and inhibition to be maintained by homeostatic plasticity. However, little is known about homeostatic mechanisms in the intact central brain in vivo. Here, we study homeostatic plasticity in the Drosophila mushroom body, where Kenyon cells receive feedforward excitation from olfactory projection neurons and feedback inhibition from the anterior paired lateral neuron (APL). We show that prolonged (4-d) artificial activation of the inhibitory APL causes increased Kenyon cell odor responses after the artificial inhibition is removed, suggesting that the mushroom body compensates for excess inhibition. In contrast, there is little compensation for lack of inhibition (blockade of APL). The compensation occurs through a combination of increased excitation of Kenyon cells and decreased activation of APL, with differing relative contributions for different Kenyon cell subtypes. Our findings establish the fly mushroom body as a model for homeostatic plasticity in vivo.

神经网络功能需要通过稳态的可塑性维持激发和抑制的适当平衡。但是，关于完整的中枢活体内体内的稳态机制知之甚少。在这里，我们研究果蝇体内的稳态可塑性蘑菇体，Kenyon细胞在其中接收来自嗅觉投射神经元的前馈刺激，并从前对侧神经元（APL）获得反馈抑制。我们表明，延长（4-d）抑制性APL的人工激活会导致去除人工抑制后，增加Kenyon细胞的气味反应，这表明蘑菇体可以补偿过度的抑制作用。相反，缺乏抑制作用（APL的阻断）的补偿很小。补偿是通过增加Kenyon细胞的兴奋性和降低APL激活的组合而发生的，对于不同的Kenyon细胞亚型具有不同的相对贡献。我们的发现将果蝇菌体确立为体内稳态可塑性的模型。