Ono S, Kushiro K, Zakir M, Meng H, Sato H, Uchino Y
Department of Physiology, Tokyo Medical University, Japan.
Exp Brain Res. 2000 Sep;134(1):1-8. doi: 10.1007/s002210000424.
Properties of otolith inputs to vestibulocerebellar neurons were investigated in 14 adult cats. In the vestibular nuclei, we recorded single-unit activities that responded orthodromically after stimulation of the utricular and/or saccular nerves and antidromically after stimulation of the cerebellum (uvula-nodulus and anterior vermis). Descending axonal projections to the spinal cord were also examined by antidromic stimulation of the caudal end of the C1 segment. Forty-seven otolith-activated neurons that projected to the uvula-nodulus were recorded. Thirteen (28%) of the 47 neurons received convergent inputs from the utriculus and sacculus. The remaining 34 (72%) vestibular neurons were non-convergent neurons: 18 (38%) received utricular input alone, and 16 (34%) received saccular input alone. Most (35/47) vestibulocerebellar neurons were located in the descending vestibular nucleus and only one of these projected to the spinal cord. Seven of the 47 vestibulocerebellar neurons were located in the lateral vestibular nucleus and most of these neurons projected to the spinal cord. The remaining neurons were located in group X (two neurons) and the superior vestibular nucleus (three neurons). In a different series of experiments, 37 otolith-activated vestibular neurons were tested to determine whether they projected to the uvula-nodulus and/or the anterior vermis. Nineteen of the 37 neurons projected to the anterior vermis, 13/37 projected to the uvula-nodulus, and 5/37 projected to both. The utricular and/or saccular nerve-activated vestibulocerebellar neurons projected to not only the uvulanodulus, but also to the anterior vermis. In summary, the results of this study showed that vestibular neurons receiving inputs from the utriculus and/or sacculus projected to the cerebellar cortex. This indirect otolith-cerebellar pathway terminated both in the anterior lobe and in the uvula/nodulus.
在14只成年猫中研究了前庭小脑神经元的耳石输入特性。在前庭核中，我们记录了单单位活动，这些活动在刺激椭圆囊和/或球囊神经后出现顺向反应，在刺激小脑（蚓垂-小结和前蚓部）后出现逆向反应。通过对C1节段尾端的逆向刺激，还检查了向下投射到脊髓的轴突投射。记录了47个投射到蚓垂-小结的耳石激活神经元。47个神经元中有13个（28%）接受了来自椭圆囊和球囊的汇聚输入。其余34个（72%）前庭神经元是非汇聚神经元：18个（38%）仅接受椭圆囊输入，16个（34%）仅接受球囊输入。大多数（35/47）前庭小脑神经元位于下行前庭核，其中只有一个投射到脊髓。47个前庭小脑神经元中有7个位于外侧前庭核，这些神经元中的大多数投射到脊髓。其余神经元位于X组（2个神经元）和前庭上核（3个神经元）。在另一系列实验中，对37个耳石激活的前庭神经元进行了测试，以确定它们是否投射到蚓垂-小结和/或前蚓部。37个神经元中有19个投射到前蚓部，13/37投射到蚓垂-小结，5/37投射到两者。椭圆囊和/或球囊神经激活的前庭小脑神经元不仅投射到蚓垂-小结，还投射到前蚓部。总之，本研究结果表明，接受来自椭圆囊和/或球囊输入的前庭神经元投射到小脑皮质。这条间接的耳石-小脑通路在前叶和蚓垂/小结均有终止。
