Neurobiology Section, Division of Biological Sciences, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
Nat Commun. 2019 Apr 5;10(1):1560. doi: 10.1038/s41467-019-09346-z.
In the Drosophila antenna, different subtypes of olfactory receptor neurons (ORNs) housed in the same sensory hair (sensillum) can inhibit each other non-synaptically. However, the mechanisms underlying this underexplored form of lateral inhibition remain unclear. Here we use recordings from pairs of sensilla impaled by the same tungsten electrode to demonstrate that direct electrical ("ephaptic") interactions mediate lateral inhibition between ORNs. Intriguingly, within individual sensilla, we find that ephaptic lateral inhibition is asymmetric such that one ORN exerts greater influence onto its neighbor. Serial block-face scanning electron microscopy of genetically identified ORNs and circuit modeling indicate that asymmetric lateral inhibition reflects a surprisingly simple mechanism: the physically larger ORN in a pair corresponds to the dominant neuron in ephaptic interactions. Thus, morphometric differences between compartmentalized ORNs account for highly specialized inhibitory interactions that govern information processing at the earliest stages of olfactory coding.
在果蝇的触角中，同一感觉毛（感器）内的不同亚型嗅觉受体神经元（ORN）可以非突触地相互抑制。然而，这种尚未深入研究的侧抑制形式的机制仍不清楚。在这里，我们使用相同的钨电极刺穿的成对感器的记录来证明，直接的电（“电突触”）相互作用介导了 ORN 之间的侧抑制。有趣的是，在单个感器内，我们发现电突触侧抑制是不对称的，即一个 ORN 对其邻居的影响更大。遗传鉴定的 ORN 的连续块面扫描电子显微镜和电路建模表明，不对称的侧抑制反映了一个惊人的简单机制：一对中物理上更大的 ORN 对应于电突触相互作用中的主导神经元。因此，分隔的 ORN 之间的形态差异解释了高度专业化的抑制相互作用，这些相互作用控制着嗅觉编码的最早阶段的信息处理。
