The vestibuloocular reflex of the adult flatfish. II. Vestibulooculomotor connectivity.
The vestibuloocular reflex of the adult flatfish. II. Vestibulooculomotor connectivity.
复制标题
成年比目鱼的前庭眼反射。
DOI：
10.1152/jn.1985.54.4.900
复制
发表时间：
1985
影响因子：
2.5
通讯作者：
Baker,R
中科院分区：
文献类型：
--
作者：
Graf,W;Baker,R
成年比目鱼的外周和中央眼神经组织没有形态学上的基质，足以解释其前庭眼反射系统的适应性变化。适应的必要性是由于在变态期间前庭相对于眼外坐标轴的90度位移而发生的。由于必须假设前庭眼通路的重组（12），因此采用细胞内辣根过氧化物酶方法研究了成年冬比目鱼的电生理学鉴定的次级前庭神经元的位置和终止，重点是水平通道系统。美洲拟鲽垂直管相关神经元的眼靶点与哺乳动物相似。假设兴奋性前管神经元分叉后，主要轴突已越过中线。降分支指向脊髓。升分支经对侧内侧纵束到达眼神经核，止于上级直肌和下斜肌。推测的抑制性后半规管神经元在内侧纵束同侧上行，主要终止于上级直肌和下斜肌分部。水平管神经元表现出明显不同于哺乳动物的特点。观察到两种类型的二级神经元。在第一种情况下，细胞体位于前庭核复合体的前部。轴突越过中线后，在对侧内侧纵束上行。主要终止部位位于眼神经核的下斜肌和上级直肌分支。轴突分支然后再穿过中线，并终止于同侧相同的位置。在第二例中，细胞体位于前庭神经降核。其轴突越过中线，也上升到对侧内侧纵束。主要的终止位点是在trophilar核和下直肌分部的眼神经核。在第一种情况下，轴突分支也重新穿越中线，并终止于相同的运动神经元池同侧。上述靶位点正是预期在代偿性眼球运动期间以相互兴奋-抑制方式使用的靶位点。头向下运动对下水平神经管是兴奋性的，产生上级直肌和下级直肌的收缩以及对抗性的下级直肌和上级直肌的松弛。（400字处截断摘要）
The peripheral and central oculomotor organization of the adult flatfish presents no morphological substrates that suffice to explain adaptive changes in its vestibuloocular reflex system. The necessity for an adaptation occurs because of a 90 degrees displacement of the vestibular with respect to the extraocular coordinate axes during metamorphosis. Since a reorganization of vestibuloocular pathways must be hypothesized (12), the location and termination of electrophysiologically identified secondary vestibular neurons with focus on the horizontal canal system was studied with the intracellular horseradish peroxidase method in adult winter flounders. Pseudopleuronectes americanus. The oculomotor target sites of vertical canal related neurons were similar to those described in mammals. Presumed excitatory anterior canal neurons bifurcated after the main axon had crossed the midline. The descending branch headed toward the spinal cord. The ascending branch reached the oculomotor nucleus via the contralateral medial longitudinal fasciculus and terminated in the superior rectus and inferior oblique subdivisions. Presumed inhibitory posterior canal neurons ascended ipsilaterally in the medial longitudinal fasciculus and terminated mainly in the superior rectus and inferior oblique subdivisions. Horizontal canal neurons exhibited characteristics distinctly different from mammalian ones. Two types of second-order neurons were observed. In the first case, cell bodies were located in the anterior portion of the vestibular nuclear complex. After crossing the midline, the axon ascended in the contralateral medial longitudinal fasciculus. Major termination sites were found in the inferior oblique and superior rectus subdivisions of the oculomotor nucleus. Axonal branches then recrossed the midline and terminated in identical locations on the ipsilateral side. In the second case, cell bodies were located in the descending vestibular nucleus. Their axons crossed the midline and also ascended in the contralateral medial longitudinal fasciculus. Major termination sites were in the trochlear nucleus and in the inferior rectus subdivision of the oculomotor nucleus. As in the first case, axonal branches also recrossed the midline and terminated in identical motoneuron pools on the ipsilateral side. The above target sites were exactly those expected to be used in a reciprocal excitatory-inhibitory fashion during compensatory eye movements. Head-down movement would be excitatory for the lower horizontal canal producing contractions of both superior recti and inferior obliques as well as relaxation of the antagonistic inferior recti and superior obliques.(ABSTRACT TRUNCATED AT 400 WORDS)