Peever J H, Duffin J
Department of Physiology, University of Toronto, Ontario, Canada.
Pflugers Arch. 2001 Sep;442(6):943-51. doi: 10.1007/s004240100621.
The synchronisation of the discharges recorded from left and right phrenic nerves in the adult rat is produced in part by shared excitation from a common premotor neurone population. However, such synchronisation has not been examined for hypoglossal motoneurones in adult rats, or for phrenic and hypoglossal motoneurons in neonatal in vitro preparations. In adult rats, cross-correlograms computed between the inspiratory discharges of the left and right phrenic nerves, and the left and right hypoglossal nerves displayed central peaks with half-amplitude widths of 1.4+/-0.1 and 1.7+/-0.1 ms (mean+/-SE), respectively. We interpret these as evidence for common excitation. However, such central peaks were absent in the same cross-correlograms computed for neonatal in vitro preparations, although central peaks were observed in cross-correlograms computed between the discharges recorded from adjacent phrenic nerve rootlets. We conclude that, in the adult rat, left and right hypoglossal nerve discharges are synchronised by excitation from a common premotor neurone population, as for the phrenic nerves, but this type of synchronisation is undetectable in neonatal in vitro preparations. We speculate that the differences between the adult and neonatal preparations are due to developmental changes in respiratory drive transmission pathways.
成年大鼠左右膈神经记录放电的同步部分是由共同的运动前神经元群的共享兴奋产生的。然而，成年大鼠舌下运动神经元，或新生大鼠体外制备物中的膈神经和舌下运动神经元的这种同步尚未得到研究。在成年大鼠中，计算左、右膈神经吸气放电与左、右舌下神经之间的互相关图，其中心峰的半高宽分别为1.4±0.1和1.7±0.1毫秒（平均值±标准误）。我们将这些解释为共同兴奋的证据。然而，在新生大鼠体外制备物计算的相同互相关图中没有这种中心峰，尽管在相邻膈神经根记录的放电之间计算的互相关图中观察到了中心峰。我们得出结论，在成年大鼠中，左右舌下神经放电如膈神经一样由共同的运动前神经元群的兴奋同步，但这种同步在新生大鼠体外制备物中无法检测到。我们推测成年和新生制备物之间的差异是由于呼吸驱动传导途径的发育变化。
