Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, United Kingdom.
Neuroscience Institute, University of Sheffield, Sheffield S10 2TN, United Kingdom.
Proc Natl Acad Sci U S A. 2020 Jul 14;117(28):16606-16615. doi: 10.1073/pnas.1921294117. Epub 2020 Jun 29.
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 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.
神经网络的功能需要通过自身平衡的可塑性来维持兴奋和抑制之间的适当平衡。然而，对于完整的中枢大脑在体内的自身平衡机制知之甚少。在这里，我们研究了蘑菇体中的自身平衡可塑性，其中，Kenyon 细胞接收来自嗅觉投射神经元的前馈兴奋和来自前配对侧神经元（APL）的反馈抑制。我们发现，长时间（4 天）人为激活抑制性 APL 会在去除人为抑制后增加 Kenyon 细胞对气味的反应，这表明蘑菇体补偿了过度的抑制。相比之下，对于缺乏抑制（APL 阻断）几乎没有补偿。这种补偿是通过增加 Kenyon 细胞的兴奋和降低 APL 的激活来实现的，对于不同的 Kenyon 细胞亚型有不同的相对贡献。我们的发现确立了果蝇蘑菇体作为体内自身平衡可塑性的模型。
