Division of Cerebral Circuitry, National Institute for Physiological Sciences, Okazaki. 444-8787, Japan.
Sci Rep. 2011;1:89. doi: 10.1038/srep00089. Epub 2011 Sep 13.
Dendritic trees influence synaptic integration and neuronal excitability, yet appear to develop in rather arbitrary patterns. Using electron microscopy and serial reconstructions, we analyzed the dendritic trees of four morphologically distinct neocortical interneuron subtypes to reveal two underlying organizational principles common to all. First, cross-sectional areas at any given point within a dendrite were proportional to the summed length of all dendritic segments distal to that point. Consistent with this observation, total cross-sectional area was almost perfectly conserved at bifurcation points. Second, dendritic cross-sections became progressively more elliptical at more proximal, larger diameter, dendritic locations. Finally, computer simulations revealed that these conserved morphological features limit distance dependent filtering of somatic EPSPs and facilitate distribution of somatic depolarization into all dendritic compartments. Because these features were shared by all interneurons studied, they may represent common organizational principles underlying the otherwise diverse morphology of dendritic trees.
树突的形态影响着突触的整合和神经元的兴奋性，但它们的发育模式似乎相当随意。本研究利用电子显微镜和连续重建技术，分析了四种形态独特的皮质中间神经元亚型的树突，揭示了所有中间神经元共有的两种基本组织原则。首先，树突上任意一点的横截面积与该点远端所有树突段的总长度成正比。与这一观察结果一致的是，在分叉点，总横截面积几乎可以完美地保持不变。其次，树突的横截面积在更靠近近端、更大直径的位置变得越来越椭圆。最后，计算机模拟表明，这些保守的形态特征限制了躯体 EPSP 的距离依赖性滤波，并有助于将躯体去极化分布到所有树突隔室。由于这些特征被所有研究的中间神经元所共有，它们可能代表了树突形态多样性背后的共同组织原则。
