Bilateral postsynaptic actions of pyramidal tract and reticulospinal neurons on feline erector spinae motoneurons.
Bilateral postsynaptic actions of pyramidal tract and reticulospinal neurons on feline erector spinae motoneurons.
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DOI：
10.1523/jneurosci.4859-09.2010
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发表时间：
2010-01-20
期刊：
影响因子：
--
通讯作者：
Jankowska E
中科院分区：
文献类型：
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作者：
Galea MP;Hammar I;Nilsson E;Jankowska E
躯干肌肉是重要的姿势调整与自愿运动，但很少有人做了分析机制，这些肌肉的脊髓上控制在细胞水平上。因此，本研究旨在探讨锥体束（PT）神经元对延髓运动神经元的输入。的腰最长肌的竖脊肌，并分析在何种程度上是由网状脊髓（RS）神经元中继。从运动神经元的细胞内记录被用来评估的影响，电刺激的延髓锥体和RS神经元的轴突下降的内侧纵束（MLF）。结果表明，同侧和对侧PT均能诱发相似的突触活动，包括双突触和三突触的EPSP以及三突触的IPSP。在同一运动神经元中，刺激MLF可诱发单突触和双突触的EPSP以及双突触或三突触的IPSP。所有的短潜伏期PSP的PT起源被取消了横断的MLF，而他们仍然横断后的PT纤维在脊髓水平。因此，RS神经元可能是最直接的PT动作的主要中继神经元。最长肌然而，更长的潜伏期IPSP后，MLF或PT脊髓损伤和同侧或对侧脊髓半切后，表明PT行动也介导同侧和/或对侧位于脊髓中间神经元。因此，PT刺激的双侧效应提供了一种解释，为什么PT神经元单侧损伤（例如中风）后的躯干运动受损程度低于四肢运动。
Trunk muscles are important for postural adjustments associated with voluntary movements but little has been done to analyse mechanisms of supraspinal control of these muscles at a cellular level. The present study therefore aimed to investigate the input from pyramidal tract (PT) neurons to motoneurons of the m. longissimus lumborum of the erector spinae and to analyse to what extent it is relayed by reticulospinal (RS) neurons. Intracellular records from motoneurons were used to evaluate effects of electrical stimulation of medullary pyramids and of axons of RS neurons descending in the medial longitudinal fasciculus (MLF). The results revealed that similar synaptic actions were evoked from the ipsilateral and contralateral PTs, including disynaptic and trisynaptic EPSPs and trisynaptic IPSPs. Stimulation of the MLF evoked monosynaptic and disynaptic EPSPs and disynaptic or trisynaptic IPSPs in the same motoneurons. All short latency PSPs of PT origin were abolished by transection of the MLF, while they remained after transection of PT fibers at a spinal level. Hence, RS neurons might serve as the main relay neurons of the most direct PT actions on m. longissimus. However, longer latency IPSPs remaining after MLF or PT spinal lesions and after ipsilateral or contralateral hemisection of spinal cord indicate that PT actions are also mediated by ipsilaterally and/or contralaterally located spinal interneurons. The bilateral effects of PT stimulation thereby provide an explanation why trunk movements after unilateral injuries of PT neurons (e.g. stroke) are impaired to a lesser degree than movements of the extremities.