Functional anatomy of nonspiking interneuron dendrites

用激光共聚焦扫描显微镜系统，用三维形态计量学方法，对克氏原甲鱼腹神经节末梢的感觉和运动前非尖峰中间神经元的结构进行了定量研究。我们还从电生理学角度研究了它们的钝化膜性质，以分析它们的电紧性结构。AL型和PL型两种运动前非尖峰中间神经元的主要树突结构和胞体在神经节中的位置不同，它们在神经束中共享共同的树突野。它们在形态和生理上都不同：PL型细胞表现出更多的分枝，解剖上更长的树突(&lt；3 mm)，更短的时间和长度常数(p&lt；0.05)。因此，在PL-型细胞中，细小树突的总电致伸展长度明显长于AL-型细胞。两者树突的总解剖长度和电紧张性长度无统计学差异(P&gt；0.05)。已鉴定的感觉中间神经元具有较短的膜时间常数和长度常数。对运动前神经元和感觉非棘突中间神经元的形态和电生理特性的比较表明，感觉中粗大的树突(~gt；3 mm)的总解剖长度大于运动前细胞，而时间和长度常数小于运动前细胞(P&lt；0.05)。感觉中间神经元粗、细树突电张力总长度均显著大于运动前细胞(P&lt；0.05)。感觉和运动前非棘波中间神经元在电紧张性结构上的差异似乎反映了它们在控制突触后神经细胞时突触整合的不同方式。

The structure of sensory and premotor nonspiking interneurons in the terminal abdominal ganglion of the crayfich, Procambarus clarkii Girard, has been studied quantitatively by 3-dimensional morphometry, using a confocal laser scanning microscopic system. Their passive membrane properties have also been studied electrophysiologically to analyze their electrotonic structure. Two types of premotor nonspiking interneurons, AL- and PL-types that are characterized by different structure of major dendrites and different location of cell bodies in the ganglion, have been found to share common dendritic field in the neuropil. They are different from each other both morphologically and physiologically : the PL-type cells show a larger number of branching, anatomically longer fine (<3 mm) dendrites and shorter time and length constants (p<0.05). The total electrotonic length of fine dendrites is accordingly significantly longer in PL- than in AL-type cells. The total anatomical and electrotonic lengths of whole dendrites were not statistically different between them (P>0.05). An identified sensory interneuron had significantly shorter membrane time constant and length constant. Comparison of morphological and electrophysiological properties between premotor and sensory nonspiking interneurons has revealed that the total anatomical length of thick dendrites (>3 mm) is greater in the sensory than in premotor cells whereas the time and length constants are smaller in the former (P<0.05). The total electrotonic lengths of both thick and fine dendrites of the sensory interneuron were significantly greater than those of premotor cells (P<0.05). The difference in electrotonic structure between sensory and premotor nonspiking interneurons seems to reflect their different manners of synaptic integration in the control of postsynaptic nerve cells.