King W M, Zhou W, Tomlinson R D, McConville K M, Page W K, Paige G D, Maxwell J S
University of Mississippi Medical Center, Jackson.
J Vestib Res. 1994 Sep-Oct;4(5):401-8.
Many neurons in oculomotor pathways encode signals related to eye position. For example, motoneurons in the third, fourth, and sixth cranial nuclei discharge at highly regular rates during fixation intervals. During fixations of far targets, their tonic discharge is linearly related to conjugate eye position. Previous studies provided evidence that premotor cells in brainstem pathways also encoded conjugate eye position. McConville et al. (this volume), however, measured eye movements during binocular fixations when the eyes were converged and concluded that the position signal encoded by premotor position-vestibular-pause (PVP) cells in the vestibular nuclei is related to monocular (right or left) eye position rather than to conjugate eye position. This surprising relationship would not have been noticed in earlier studies that measured the movements of only one eye (using a single eye coil) or that measured only the conjugate movements of the two eyes (using bitemporal EOG electrodes). How general a feature of oculomotor signal processing is this finding? In this paper, we re-examine the eye position signal in abducens and oculomotor neurons when the movements of the two eyes are conjugate and when they are disjunctive and therefore disassociated. The data suggest that abducens neurons (AMNs and AINs) and oculomotor neurons (putative medial rectus motoneurons), unlike PVP cells, are not monocular but encode mixtures of right and left eye position signals.
动眼神经通路中的许多神经元编码与眼位相关的信号。例如，第三、第四和第六颅神经核中的运动神经元在注视间隔期间以高度规则的速率放电。在注视远处目标时，它们的紧张性放电与双眼共轭眼位呈线性相关。先前的研究表明，脑干通路中的运动前细胞也编码共轭眼位。然而，麦康维尔等人（本卷）在双眼集合时测量了双眼注视期间的眼动，并得出结论，前庭核中运动前位置 - 前庭 - 暂停（PVP）细胞编码的位置信号与单眼（右或左）眼位有关，而不是与共轭眼位有关。在早期仅测量一只眼睛运动（使用单眼线圈）或仅测量两只眼睛共轭运动（使用双颞部眼电图电极）的研究中，不会注意到这种惊人的关系。这一发现是动眼神经信号处理的一个多么普遍的特征呢？在本文中，我们重新研究了展神经和动眼神经神经元在双眼运动共轭和分离（因此不相关联）时的眼位信号。数据表明，与PVP细胞不同，展神经神经元（AMN和AIN）和动眼神经神经元（假定的内直肌运动神经元）不是单眼的，而是编码右眼和左眼位置信号的混合。
