Shang Yuhua, Claridge-Chang Adam, Sjulson Lucas, Pypaert Marc, Miesenböck Gero
Department of Cell Biology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA.
Cell. 2007 Feb 9;128(3):601-12. doi: 10.1016/j.cell.2006.12.034.
Conflicting views exist of how circuits of the antennal lobe, the insect equivalent of the olfactory bulb, translate input from olfactory receptor neurons (ORNs) into projection-neuron (PN) output. Synaptic connections between ORNs and PNs are one-to-one, yet PNs are more broadly tuned to odors than ORNs. The basis for this difference in receptive range remains unknown. Analyzing a Drosophila mutant lacking ORN input to one glomerulus, we show that some of the apparent complexity in the antennal lobe's output arises from lateral, interglomerular excitation of PNs. We describe a previously unidentified population of cholinergic local neurons (LNs) with multiglomerular processes. These excitatory LNs respond broadly to odors but exhibit little glomerular specificity in their synaptic output, suggesting that PNs are driven by a combination of glomerulus-specific ORN afferents and diffuse LN excitation. Lateral excitation may boost PN signals and enhance their transmission to third-order neurons in a mechanism akin to stochastic resonance.
对于触角叶（昆虫的嗅球等价物）的神经回路如何将来自嗅觉受体神经元（ORN）的输入转化为投射神经元（PN）输出，存在相互矛盾的观点。ORN与PN之间的突触连接是一对一的，但PN对气味的调谐比ORN更广泛。这种感受范围差异的基础仍然未知。通过分析一个缺失向一个嗅觉小球输入ORN的果蝇突变体，我们发现触角叶输出中一些明显的复杂性源于PN的侧向、小球间兴奋。我们描述了一群以前未被识别的具有多小球突起的胆碱能局部神经元（LN）。这些兴奋性LN对气味有广泛反应，但在其突触输出中表现出很少的小球特异性，这表明PN由小球特异性ORN传入和弥散性LN兴奋共同驱动。侧向兴奋可能会增强PN信号，并以类似于随机共振的机制增强其向三级神经元的传递。
