Hypothalamic neuron responses in the vestibulo-autonomic reflex with special reference to the cerebellar nucleus and brainstem

刺激上级和外侧泡胫神经核（VN），下丘脑后（PH）神经元兴奋性反应，而不是内侧和下方VN刺激。PH和下丘脑室旁核（PVN）的神经元对热刺激有兴奋或抑制反应，对侧或同侧迷路神经元的兴奋/抑制反应模式相似。前庭神经切断或前庭神经鞘切除后，上述反应几乎消失，提示上述反应起源于前庭。静脉输注H_2和H_2阻滞剂可使上述反应减弱、消失或逆转。提示组胺能系统参与了前庭信息的传递。PH神经元的自发放电在旋转开始后逐渐发生变化，这种变化甚至在旋转结束后仍持续数分钟。热刺激引起血压下降，这种变化与室旁核神经元的活动变化有关。虽然电破坏小脑顶核对BP变化的影响很小，但电破坏下丘脑几乎完全消除了对热量刺激的BP变化。这意味着从前庭大肌经脑干网状结构到下丘脑的听觉传导通路在前庭自主神经反射中具有关键作用。迷走神经背核的神经元对同侧或对侧的热刺激均表现兴奋。

Posterior hypothalamic (PH)neurons responded excitatory in response to superior and lateral vesutibular nuclei(VN)stimulation and not to medial and inferior VN stimulation. The neurons in the PH and hypothalamic paraventricular nucleus(PVN) responded either excitatory or inhibitory to caloric stimulstion, and the individual neurons excitaion/inhibition response pattern was ssimilar when stimulated with either hot or cold water and on either the contralateral or ipsilateral labyrinth. These responses were almost disappeared after sectioning the vestibular nerve or labyrinthectomy, suggesting that the above responses were vestibular in origin. Furthermore, these responses were diminished, disappeared or reversed by intravenous H_2 and H_2 blocker infusion. This indicates that the histaminergic systemparticipates in the vestibular information transduction in the brain. The spontaneous discharge of PH neurons gradually changed after the rotation began and these changes lasted for several minutes even after the rotation ended. Caloric stimulation produced a decrease in blood pressure (BP)and this change was related to the activity change of PVN neurons. Although electric destruction of the fastigial nucleus in the cerebellum produced little effect on the BP change, electric destruction of the hypothalamus almost totally abolished the BP change in responses to the caloric stimulation. This means that the acsending pathway from the vestibularcleus to the hypothalamus via the brainstem reticular formation has a crucial role in the vestibulo-sutonomic reflex., The neurons in the dorsal nucleus of the vagus showed mainly excitation in response to either ipsilateral or contralateral caloric stimulation.