Meseke Maurice, Evers Jan Felix, Duch Carsten
School of Life Sciences, Arizona State University, Tempe AZ 85287, USA.
J Neurophysiol. 2009 Jul;102(1):41-58. doi: 10.1152/jn.90899.2008. Epub 2009 Apr 22.
During nervous system development, different classes of neurons obtain different dendritic architectures, each of which receives a large number of input synapses. However, it is not clear whether synaptic inputs are targeted to specific regions within a dendritic tree and whether dendritic tree geometry and subdendritic synapse distributions might be optimized to support proper neuronal input-output computations. This study uses an insect model where structure and function of an individually identifiable neuron, motoneuron 5 (MN5), are changed while it develops from a slow larval crawling into a fast adult flight motoneuron during metamorphosis. This allows for relating postembryonic dendritic remodeling of an individual motoneuron to developmental changes in behavioral function. Dendritic architecture of MN5 is analyzed by three-dimensional geometric reconstructions and quantitative co-localization analysis to address the distribution of synaptic terminals. Postembryonic development of MN5 comprises distinct changes in dendritic shape and in the subdendritic distribution of GABAergic input synapses onto MN5. Subdendritic synapse targeting is not a consequence of neuropil structure but must rely on specific subdendritic recognition mechanisms. Passive multicompartment simulations indicate that postembryonic changes in dendritic architecture and in subdendritic input synapse distributions may tune the passive computational properties of MN5 toward stage-specific behavioral requirements.
在神经系统发育过程中，不同类型的神经元具有不同的树突结构，每种结构都接收大量的输入突触。然而，尚不清楚突触输入是否靶向树突树内的特定区域，以及树突树的几何形状和树突亚结构突触分布是否可能经过优化以支持适当的神经元输入-输出计算。本研究使用一种昆虫模型，在变态过程中，一个可单独识别的神经元运动神经元5（MN5）从缓慢的幼虫爬行状态发育为快速的成虫飞行运动神经元时，其结构和功能会发生变化。这使得能够将单个运动神经元的胚后树突重塑与行为功能的发育变化联系起来。通过三维几何重建和定量共定位分析来分析MN5的树突结构，以研究突触终末的分布。MN5的胚后发育包括树突形状以及MN5上GABA能输入突触的树突亚结构分布的明显变化。树突亚结构突触靶向不是神经纤维网结构的结果，而是必须依赖于特定的树突亚结构识别机制。被动多室模拟表明，树突结构和树突亚结构输入突触分布的胚后变化可能会使MN5的被动计算特性适应特定阶段的行为需求。
