Pressler R Todd, Strowbridge Ben W
Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio 44106, USA.
Neuron. 2006 Mar 16;49(6):889-904. doi: 10.1016/j.neuron.2006.02.019.
Inhibitory local circuits in the olfactory bulb play a critical role in determining the firing patterns of output neurons. However, little is known about the circuitry in the major plexiform layers of the olfactory bulb that regulate this output. Here we report the first electrophysiological recordings from Blanes cells, large stellate-shaped interneurons located in the granule cell layer. We find that Blanes cells are GABAergic and generate large I(CAN)-mediated afterdepolarizations following bursts of action potentials. Using paired two-photon guided intracellular recordings, we show that Blanes cells have a presumptive axon and monosynaptically inhibit granule cells. Sensory axon stimulation evokes barrages of EPSPs in Blanes cells that trigger long epochs of persistent spiking; this firing mode was reset by hyperpolarizing membrane potential steps. Persistent firing in Blanes cells may represent a novel mechanism for encoding short-term olfactory information through modulation of tonic inhibitory synaptic input onto bulbar neurons.
嗅球中的抑制性局部回路在决定输出神经元的放电模式中起着关键作用。然而，对于调节这种输出的嗅球主要丛状层中的神经回路，我们却知之甚少。在此，我们报告了对位于颗粒细胞层的大型星状中间神经元——布兰内斯细胞的首次电生理记录。我们发现，布兰内斯细胞是γ-氨基丁酸能的，并且在动作电位爆发后会产生由I(CAN)介导的大的去极化后电位。利用双光子引导的配对细胞内记录，我们表明布兰内斯细胞有一条推测的轴突，并对颗粒细胞进行单突触抑制。感觉轴突刺激在布兰内斯细胞中引发兴奋性突触后电位（EPSP）阵发，从而触发长时间的持续放电；这种放电模式通过超极化膜电位阶跃而重置。布兰内斯细胞中的持续放电可能代表了一种通过调节对球部神经元的紧张性抑制性突触输入来编码短期嗅觉信息的新机制。
