Yuste R, Gutnick M J, Saar D, Delaney K R, Tank D W
Biological Computation Research Department, AT&T Bell Laboratories, Murray Hill, New Jersey 07974.
Neuron. 1994 Jul;13(1):23-43. doi: 10.1016/0896-6273(94)90457-x.
Apical dendrites constitute a prominent feature of the microcircuitry in the neocortex, yet their function is poorly understood. Using fura-2 imaging of layer 5 pyramidal neurons from slices of rat somatosensory cortex, we have investigated the Ca2+ influx into dendrites under intracellular, antidromic, synaptic, and receptor-agonist stimulation. We find three spatial patterns of Ca2+ accumulations: an apical band in the apical dendrite approximately 500 microns from the soma, an accumulation restricted to the basal dendrites, soma, and proximal apical dendrite, and a combination of both of these. We show that the apical band can be activated antidromically and synaptically and that, under blocked Na+ and K+ conductances, it generates Ca2+ spikes. Thus, the apical band may serve as a dendritic trigger zone for regenerative Ca2+ spikes or as a current amplifier for distal synaptic events. Our results suggest that the distal apical dendrite should be considered a separate functional compartment from the rest of the cell.
顶端树突是新皮质微电路的一个显著特征，但其功能却鲜为人知。我们利用对大鼠体感皮层切片中第5层锥体神经元进行的fura-2成像，研究了在细胞内、逆向、突触和受体激动剂刺激下钙离子流入树突的情况。我们发现了三种钙离子积累的空间模式：一种位于距胞体约500微米的顶端树突中的顶端带，一种局限于基底树突、胞体和近端顶端树突的积累，以及这两种情况的组合。我们表明，顶端带可通过逆向和突触方式激活，并且在钠电导和钾电导被阻断的情况下，它会产生钙离子峰电位。因此，顶端带可能作为再生性钙离子峰电位的树突触发区，或者作为远端突触事件的电流放大器。我们的结果表明，远端顶端树突应被视为与细胞其他部分分开的功能区室。
