Grantyn A, Grantyn R, Gaunitz U, Robiné K P
Exp Brain Res. 1980;39(1):49-61. doi: 10.1007/BF00237069.
The paramedian pontine and bulbar tegmentum was explored by microstimulation to outline the sites of origin of direct excitatory and inhibitory inputs to lateral rectus (LR) and medial rectus (MR) motoneurons (MNs). In order to avoid activation of fibers of passage and axon reflexes originating outside the stimulation sites, experiments were carried out 4--22 days after brain stem transections causing degeneration of vestibulo-ocular pathways. Additionally, in some experiments the paramedian tegmentum was isolated from the contralateral side by midline transections. Mapping of stimulus sites from which monosynaptic EPSPs and IPSPs were elicited brought out the following preoculomotor reticular regions: 1. LR-MNs received monosynaptic IPSPs from the contralateral reticular formation corresponding to Nucl. reticularis points caudalis (R.p.c.) and the rostral part of Nucl. reticularis gigantocellularis (R.gc.). 2. Monosynaptic inhibitory input to MR-MNs could only be demonstrated after degeneration of excitatory pathways ascending from the internuclear neurons of the VIth nucleus and from the ipsilateral vestibular nuclei. Monosynaptic IPSPs originated in the ipsilateral dorso-medial tegmentum through the entire extent of the Nucl. reticularis pontis oralis and rostral R.p.c. including the region of the ipsilateral VIth nucleus. 3. Monosynaptic excitation of LR-MNs was induced by stimulation of the ipsilateral R.p.c. and the rostral half of the paramedian bulbar tegmentum (R.gc.). 4. The sites from which monosynaptic EPSPs were evoked in MR-MNs were confined to the contralateral VIth nucleus and its immediate vicinity. No evidence could be obtained for direct excitatory inputs to MR-MNs from the ipsilateral paramedian tegmentum. It is concluded that the paramedian rhombencephalic reticular formation contains four pools of premotor neurons related to coordination of conjugate horizontal eye movements. Two of them are excitatory for LR- and MR-MNs with ipsilateral ON-directions, the other two mediate reciprocal inhibition of the antagonistic motor nuclei.
通过微刺激探索脑桥旁正中及延髓被盖，以勾勒出直接兴奋性和抑制性输入到外直肌（LR）和内直肌（MR）运动神经元（MNs）的起源部位。为避免激活刺激部位以外的传导纤维和轴突反射，实验在脑干横断4 - 22天后进行，脑干横断导致前庭眼通路退变。此外，在一些实验中，通过中线横断将旁正中被盖与对侧分离。绘制引发单突触兴奋性突触后电位（EPSPs）和抑制性突触后电位（IPSPs）的刺激部位图，揭示了以下动眼神经前网状区域：1. LR - MNs从对侧网状结构接受单突触IPSPs，对应于尾侧网状核（R.p.c.）和巨细胞网状核（R.gc.）的头侧部分。2. 只有在来自第六核间神经元和同侧前庭核的兴奋性通路退变后，才能证明对MR - MNs的单突触抑制性输入。单突触IPSPs起源于同侧背内侧被盖，贯穿脑桥嘴侧网状核和头侧R.p.c.的整个范围，包括同侧第六核区域。3. 刺激同侧R.p.c.和旁正中延髓被盖的头侧半（R.gc.）可诱导LR - MNs的单突触兴奋。4. 在MR - MNs中引发单突触EPSPs的部位局限于对侧第六核及其紧邻区域。未获得来自同侧旁正中被盖对MR - MNs直接兴奋性输入的证据。结论是，菱形脑桥旁正中网状结构包含四组与共轭水平眼运动协调相关的运动前神经元池。其中两组对具有同侧ON方向的LR - 和MR - MNs起兴奋作用，另外两组介导拮抗运动核的相互抑制。
