Tan H S, Collewijn H, Van der Steen J
Department of Physiology I, Faculty of Medicine, Erasmus University Rotterdam, The Netherlands.
Exp Brain Res. 1993;92(3):385-90. doi: 10.1007/BF00229026.
It has been proposed that a common velocity-storage mechanism is responsible for the prolongation of vestibular nystagmus beyond the duration of the change in firing frequency of primary vestibular fibers in response to a step in velocity, and for the production of optokinetic afternystagmus (OKAN). In a previous study, bilateral injection of the aselective cholinergic agonist carbachol in the flocculus shortened the duration of buildup of optokinetic nystagmus (OKN) and the duration of OKAN, suggesting floccular involvement in velocity storage (Tan et al. 1992). In extension to that study of OKN, the present study assesses the effects of floccular carbachol on vestibular nystagmus in response to velocity steps. Our results show that injection of carbachol shortens the duration of vestibular nystagmus from about 13 to about 8 s; a finding which supports a common velocity-storage mechanism for optokinetic and vestibular signals. We propose that the indistinguishable effects of carbachol on OKAN and vestibular nystagmus are due to modification of the transmission of an oculomotor corollary signal, which has been identified electrophysiologically in the flocculus.
有人提出，一种常见的速度存储机制负责将前庭眼震的持续时间延长至超过初级前庭纤维因速度阶跃而产生的放电频率变化的持续时间，并负责产生视动性眼震后效（OKAN）。在先前的一项研究中，在小脑绒球双侧注射非选择性胆碱能激动剂卡巴胆碱缩短了视动性眼震（OKN）的累积持续时间和OKAN的持续时间，提示绒球参与速度存储（Tan等人，1992年）。作为对该OKN研究的扩展，本研究评估了绒球注射卡巴胆碱对速度阶跃引起的前庭眼震的影响。我们的结果表明，注射卡巴胆碱可将前庭眼震的持续时间从约13秒缩短至约8秒；这一发现支持了视动性和前庭信号存在共同速度存储机制的观点。我们提出，卡巴胆碱对OKAN和前庭眼震的不可区分的影响是由于对一种眼球运动伴随信号传递的改变，这种信号已在绒球中通过电生理学方法得到确认。
