Bilateral processing of vestibular responses revealed by injecting lidocaine into the eighth cranial nerve in vitro.
Bilateral processing of vestibular responses revealed by injecting lidocaine into the eighth cranial nerve in vitro.
复制标题
通过在体外将利多卡因注射到第八脑神经来揭示前庭反应的双边处理。
DOI：
10.1016/j.brainres.2003.11.043
复制
发表时间：
2004
期刊：
影响因子：
2.9
通讯作者：
Jones,MichaelS
中科院分区：
文献类型：
--
作者：
Ariel,Michael;Fan,TianXing;Jones,MichaelS
在体外龟脑干中，颞骨保持附着的水平头部旋转过程中，记录前庭核（VN）和内侧纵束的细胞外单位反应。根据对同向或反向旋转的反应，分别将单位表征为I型或II型。将利多卡因（0.5%）注射到颅骨内的第八脑神经根中，对头部旋转的单位反应产生快速影响。I型单位的反应减少同侧注射，但增强后对侧注射。另一方面，II型单位的反应增加同侧注射，但减少对侧注射。在大约一半的II型细胞中，伴随着潜在的ipsiversive活动的外观的逆反应的减少。我们的研究结果不仅证实，每个第八神经的传入，驱动两个前庭核的同侧兴奋，但也表明，两个神经竞争主导中枢神经元的前庭反应。这些结果可能与推拉前庭模型不一致，在该模型中，每个神经驱动中枢神经元以增强前庭输出的互补响应。另一种模型中，前庭神经元接受双边的兴奋，兴奋性输入的拮抗在contraversive运动的交叉抑制。
Extracellular unit responses were recorded from the vestibular nucleus (VN) and medial longitudinal fasciculus during horizontal head rotation of an in vitro turtle brainstem in which the temporal bones remained attached. Units were characterized as type I or type II based on the responses to ipsiversive or contraversive rotation, respectively. Lidocaine injections (0.5–2 μl of 0.5%) into the root of the eighth cranial nerve within the cranium caused rapid effects on unit responses to head rotation. Responses of type I units were reduced by ipsilateral injection but enhanced following contralateral injection. On the other hand, type II units had their responses increased by ipsilateral injections yet decreased by contralateral injections. In approximately half of the type II cells, decrease of the contraversive response was accompanied by the appearance of latent ipsiversive activity. Our findings not only confirm that each eighth nerve has afferents that drive ipsiversive excitation of both vestibular nuclei but also suggest that both nerves compete to dominate a central neuron's vestibular response. These results may be inconsistent with the push–pull vestibular model in which each nerve drives the central neuron with a complementary response that enhances the vestibular output. An alternate model is described in which vestibular neurons receive bilateral excitation, and that excitatory input is antagonized by crossed inhibition during contraversive motion.