FUNCTION OF THE EFFERENT VESTIBULAR SYSTEM

前庭器官具有丰富的传出神经支配，起源于脑干。本研究的长期目标是了解前庭传出系统（EVS）在前庭信息处理中的功能。本研究有三个具体目的：1)确定巴比妥酸麻醉栗鼠不同传入成分的电激活对几个传入组的影响。这个问题最初是在近20年前研究的。有必要通过考虑最近关于传入和传出通路组织的发现来更新结果，因为最近的一项研究表明，EVS刺激对传入增益的影响可能比之前怀疑的要多。本研究提供了有关EVS功能的基本背景信息。2)通过比较急性和慢性传入放电对消除传出神经支配或对侧迷路的影响，研究潜在的长期或营养性传出影响。神经活性肽和代谢受体的存在，以及对电刺激反应的某些特征表明，EVS施加了这样的影响，但这个问题以前没有得到解决。3)确定导致传出神经元放电的条件和传入传递中传入介导的变化。记录将来自前庭神经传入和脑干内的传出神经元，在警觉的松鼠猴的水平平面上自由移动它们的头。对于两组神经元，将比较对主动和被动头部运动的反应。将探讨传出神经从颈部、其他本体感受器或几个前庭器官获得输入的可能性。一些关于前庭输入到EVS的信息最好在急性制剂中获得；这些实验将在不记性的龙猫身上进行。

Vestibular organs are provided with a rich efferent innervation, originating in the brain stem. The long-term objective of this study is to understand the function of the efferent vestibular system (EVS) in the processing of vestibular information. There are three specific aims: 1) To determine the effects of electrical activation of different efferent contingents on the several afferent groups in the barbiturate- anesthetized chinchilla. The problem was originally investigated almost 20 years ago. There is a need to update results by taking into account recent findings on the organization on afferent and efferent pathways, as a recent suggestions that EVS stimulation may have more heterogeneous influence on afferent gain than had been suspected. This study provides essential background information concerning the function of the EVS. 2) To study potential long-term or trophic efferent influences by comparing the acute and chronic effects on afferent discharge on eliminating the efferent innervation or the contralateral labyrinth. The presence of neuroactive peptides and metabotrophic receptors, as well as certain features of the response to electrical stimulation suggests that the EVS exerts such an influence, yet the problem has not been previously addressed. 3) To determine the conditions leading to the discharge of efferent neurons and to efferent-mediated changes in afferent transmission. Recordings will be made from vestibular-nerve afferents and from efferent neurons within the brain stem in alert squirrel monkeys free to move their heads in a horizontal plane. For both groups of neurons, responses to active and passive head movements will be compared. The possibility that efferents get inputs from the neck, from other proprioceptors or from several vestibular organs will be explored. Some information on vestibular inputs to the EVS are best obtained in acute preparations; these experiments will be done in decerebrate chinchillas.