SYNAPTIC INTEGRATION AND DEVELOPMENT IN COMMAND NEURONS

本研究将探讨胚胎后生长对胚胎生长的影响。 神经元整合并对突触输入做出反应的能力。在.期间 胚胎后发育，大多数神经元阐述新的树突和 轴突分支并增加胞体的大小、长度和 树突的直径以及轴突的长度和直径。 神经元大小的增加应该会减少输入阻力和 增加整个单元的输入电容，也增加 其不同部分的电离子分离。这些变化将会改变 神经元的整合和反应特性，除非 补偿性变化发生在投入的数量和强度上，在他们的 空间和时间分布，以及在性质和分布上 细胞的主动膜和被动膜。 这个项目将研究这个问题，因为它影响到横向巨星(LG) 小龙虾胚胎后生长过程中的中间神经元 幼体1厘米至成体10厘米。LG是一个“指挥神经元”， 尾部翻转逃逸行为，这可以说是 是所有神经回路中最被人理解的。我们建议追踪这一增长 LG和它的机械感官输入来检查这样的建议 神经元生长本身就是LG下降的原因 对阶段性机械感觉刺激的反应性，尽管大幅增加 在细胞接收的传入输入的数量中。我们将决定 传入突触终末在生长过程中如何变化，以及这些 改变成功或失败补偿突触后的生长 手机。最后，我们将检验这样一个假设，即 LG的电子紧张性结构使细胞对触觉做出反应 刺激物的大小与不断增长的尾扇相匹配。

This research will investigate the effects of postembryonic growth on the ability of neurons to integrate and respond to synaptic inputs. During postembryonic development, most neurons elaborate new dendritic and axonal branches and increase the size of the soma, the lengths and diameters of the dendrites, and the length and diameter of the axon. Increases in neuronal size should decrease the input resistance and increase the input capacitance throughout the cell, and also increase the electrotonic separation of its different parts. These changes will alter the integrative and response characteristics of a neuron unless compensatory changes occur in the number and strength of inputs, in their spatial and temporal distribution, and in the nature and distribution of the cell's active and passive membrane. This project will examine this issue as it affects the lateral giant (LG) interneuron of crayfish during postembryonic growth of the animal from a 1 cm juvenile to a 10 cm adult. LG is a "command neuron" for the tailflip escape behavior, and is part of what is arguably the best-understood of all neural circuits. We propose to trace the growth of LG and its mechanosensory inputs to examine the suggestion that neuronal growth itself is responsible for the decline in LG's responsiveness to phasic mechanosensory stimuli, despite great increases in the number of afferent inputs the cell receives. We will determine how afferent synaptic terminals change during growth, and whether these changes succeed or fail to compensate for the growth of the postsynaptic cell. Finally, we will examine the hypothesis that the growth of the LG's electrotonic structure "tunes" the cell to respond to tactile stimuli of a size that matches the growing tailfan.