Uchino Y
Department of Physiology, Tokyo Medical College, Japan.
Acta Otolaryngol Suppl. 1997;528:49-51.
Intracellular recordings from ipsilateral and contralateral neck extensor and flexor motoneurons were studied to determine the connections between the utricular nerve and neck motoneurons and between saccular nerves and neck motoneurons in cats. Stimulating electrodes were placed within the left utricular nerve or saccular nerve. Electrical stimulation of the utricular nerve evoked excitatory postsynaptic potentials (EPSPs) with disynaptic latency in almost all ipsilateral extensor motoneurons and disynaptic EPSPs in all ipsilateral flexor motoneurons. In contralateral extensor and flexor motoneurons, the initial response to utricular stimulation was usually inhibitory postsynaptic potentials (IPSPs) with trisynaptic linkage. Thus, the utriculo-neck connectivities essentially differentiated between the left and right side. In response to stimulation of the saccular nerve, the initial response in bilateral extensor motoneurons ws EPSPs. Ipsilateral projections were always disynaptic; contralateral projections could be di- or trisynaptic. IPSPs were evoked in almost all bilateral flexor motoneurons with di- or trisynaptic latencies. The sacculo-neck motoneuron relationship thus has a qualitatively, bilaterally symmetric organization with regard to flexors and extensors.
研究了猫同侧和对侧颈部伸肌与屈肌运动神经元的细胞内记录，以确定椭圆囊神经与颈部运动神经元之间以及球囊神经与颈部运动神经元之间的联系。刺激电极置于左侧椭圆囊神经或球囊神经内。椭圆囊神经的电刺激在几乎所有同侧伸肌运动神经元中诱发具有双突触潜伏期的兴奋性突触后电位（EPSP），在所有同侧屈肌运动神经元中诱发双突触EPSP。在对侧伸肌和屈肌运动神经元中，对椭圆囊刺激的初始反应通常是具有三突触联系的抑制性突触后电位（IPSP）。因此，椭圆囊与颈部的连接在左右两侧基本不同。对球囊神经刺激的反应中，双侧伸肌运动神经元的初始反应是EPSP。同侧投射总是双突触的；对侧投射可能是双突触或三突触的。几乎所有双侧屈肌运动神经元都以双突触或三突触潜伏期诱发IPSP。因此，就屈肌和伸肌而言，球囊与颈部运动神经元的关系在质量上具有双侧对称的组织。
