Systems Neurobiology, Department II of Biology, Ludwig-Maximilians-Universität München, 82152 Martinsried, Germany; Neurophysiology, Institute of Zoology, Universität Regensburg, 93040 Regensburg, Germany.
Computational Neuroscience, Department II of Biology, Ludwig-Maximilians-Universität München, 82152 Martinsried, Germany.
Neuron. 2015 Feb 4;85(3):590-601. doi: 10.1016/j.neuron.2014.12.051. Epub 2015 Jan 22.
Neuronal dendritic spines have been speculated to function as independent computational units, yet evidence for active electrical computation in spines is scarce. Here we show that strictly local voltage-gated sodium channel (Nav) activation can occur during excitatory postsynaptic potentials in the spines of olfactory bulb granule cells, which we mimic and detect via combined two-photon uncaging of glutamate and calcium imaging in conjunction with whole-cell recordings. We find that local Nav activation boosts calcium entry into spines through high-voltage-activated calcium channels and accelerates postsynaptic somatic depolarization, without affecting NMDA receptor-mediated signaling. Hence, Nav-mediated boosting promotes rapid output from the reciprocal granule cell spine onto the lateral mitral cell dendrite and thus can speed up recurrent inhibition. This striking example of electrical compartmentalization both adds to the understanding of olfactory network processing and broadens the general view of spine function.
神经元树突棘被推测具有作为独立计算单元的功能，但在棘突中进行主动电计算的证据很少。在这里，我们表明，在嗅球颗粒细胞的树突棘中的兴奋性突触后电位期间，可以发生严格的局部电压门控钠通道（Nav）激活，我们通过联合使用双光子光解谷氨酸和钙成像以及全细胞记录来模拟和检测这种激活。我们发现，局部 Nav 激活通过高电压激活钙通道增加钙进入棘突，并加速突触后体去极化，而不影响 NMDA 受体介导的信号转导。因此，Nav 介导的增强促进了来自反向颗粒细胞棘突到外侧僧帽细胞树突的快速输出，从而可以加速复发性抑制。这种电分隔的显著例子不仅增加了对嗅觉网络处理的理解，而且拓宽了对棘突功能的一般看法。
