Yates B J, Goto T, Bolton P S
Laboratory of Neurophysiology, Rockefeller University, New York, NY 10021.
Brain Res. 1993 Jan 22;601(1-2):255-64. doi: 10.1016/0006-8993(93)91718-8.
To investigate the neural substrate of vestibulo-sympathetic reflexes, we studied the responses of neurons in the rostral ventrolateral medulla (RVLM) of decerebrate cats to natural stimulation of the labyrinth in vertical and horizontal planes. The RVLM is a major source of excitatory inputs to sympathetic preganglionic neurons. The animals used in these studies were baroreceptor-denervated and vagotomized and had a cervical spinal transection so that inputs from tilt-sensitive receptors outside of the labyrinth did not influence the units we recorded. Of the 38 neurons whose type of vertical vestibular inputs could be classified, the majority (27) received signals mainly from otolith organs. Only 4 of the neurons received inputs predominantly from vertical semicircular canals, and 7 were classified as having convergent inputs from otoliths and canals that were spatially aligned (2 cells) or misaligned (5 cells). In addition, only 2 of 68 neurons tested responded to sinusoidal horizontal rotations in a manner typical of brainstem neurons that receive inputs from the horizontal semicircular canals. Thus, the vestibular inputs to the RVLM appear to come mainly from otolith receptors. In labyrinthectomized cats, we were unable to locate neurons with responses to tilt similar to those of cells recorded in labyrinth-intact cats, confirming that the responses attributed to vertical vestibular inputs were produced by signals from the labyrinth. In animals whose semicircular canals had been rendered dysfunctional by plugging, we only recorded responses similar to those of neurons classified as having mainly otolith inputs in canal-intact animals, indicating that the dynamic behavior of these cells does not depend upon canal inputs. The presence of otolith inputs to the RVLM is consistent with the hypothesis that this region mediates vestibulo-sympathetic reflexes involved in correcting posturally-related changes in blood pressure.
为了研究前庭交感反射的神经基础，我们研究了去大脑猫延髓头端腹外侧区（RVLM）神经元对垂直和水平平面内迷路自然刺激的反应。RVLM是交感神经节前神经元兴奋性输入的主要来源。这些研究中使用的动物已去除压力感受器神经支配并切断迷走神经，且进行了颈髓横断，以使来自迷路外倾斜敏感感受器的输入不会影响我们记录的神经元。在38个可分类垂直前庭输入类型的神经元中，大多数（27个）主要接收来自耳石器官的信号。只有4个神经元主要接收来自垂直半规管的输入，7个被分类为具有来自耳石和半规管的汇聚输入，这些输入在空间上是对齐的（2个细胞）或不对齐的（5个细胞）。此外，在68个测试的神经元中，只有2个以典型的接收来自水平半规管输入的脑干神经元的方式对正弦水平旋转做出反应。因此，RVLM的前庭输入似乎主要来自耳石感受器。在迷路切除的猫中，我们无法找到对倾斜的反应与迷路完整猫中记录的细胞相似的神经元，这证实了归因于垂直前庭输入的反应是由来自迷路的信号产生的。在通过堵塞使半规管功能失调的动物中，我们只记录到了与在半规管完整动物中被分类为主要具有耳石输入的神经元相似的反应，这表明这些细胞的动态行为不依赖于半规管输入。RVLM存在耳石输入与该区域介导参与纠正与姿势相关的血压变化的前庭交感反射的假设一致。
