Functional analysis of premotor neurons in the brain stem during orienting movement ; neural responses to gaze perturbation.

本研究旨在探讨警觉猫的上级丘（SC）和扫视相关运动前区在凝视扫视中的作用。训练动物在黑暗中获得记忆引导的凝视转移。头部连接到与摩擦离合器连接的轴上，这使我们能够在受控的时间段（10 ms-400 ms）内对头部进行控制。一个刹车使头部在发作后不久就不能动了。眼扫视停止后不久，头部速度下降到零，并在随后的时间内，头部固定，眼睛保持不动的轨道。制动诱导的头部减速开始与眼速变为零（即凝视平台开始）之间的平均时间为48.5ms ± 19.2ms。制动器释放后，头部恢复其运动，眼球反向旋转补偿初始头部运动，以稳定凝视，导致凝视平台。在平台期之后，矫正性眼扫视与头部运动一起被触发。 关于我们 离子。没有纠正扫视，头释放之前，曾经见过。因此，这些结果表明，猫实际上补偿刹车引起的凝视扰动。我们首先探索了SC的运动地图使用电刺激。然后，我们记录了凝视扫视相关神经元（GSRN）在地图上的中间层和深层在凝视扰动。我们还记录了活动的丘固定神经元（SCFNs）在固定区的吻侧SC。活动的SC神经元反映凝视扰动轨迹，并不相关的眼睛和头部的速度。这两个单元都编码注视位置误差，即目标和当前注视位置之间的距离。GSRN的轴突投射到展神经核的腹侧部。SCFN投射到脑桥中缝核，即全能神经元（OPNs）所在的位置。部分SCFN有轴突侧支投射到更远的尾侧区域。接下来，我们记录了脑桥中缝核中的OPNs。在凝视过程中，OPN的活性高于SCFN。这种放电与制动引起的凝视平台期的眼球运动有关。然而，SCFN与眼球运动无关。因此，这些结果表明，OPN的活性需要除了SCFN之外的附加输入。少

This study was undertaken to investigate roles of the superior colliculus (SC) and saccade-related premotor areas during gaze saccades in alert cats. The animals were trained to obtain memory guided gaze shifts in darkness. The head is attached to a shaft connected to a friction clutch, which allowed us to immobilize the head for controlled time periods (10 ms-400 ms). A brake immobilized the head shortly after its onset. The eye saccade stopped soon after head velocity declined to zero and, during the ensuing period of head-immobilization, the eye remained immobile in the orbit. The mean time between the onset of the brake-induced head deceleration and when eye velocity became zero (i.e. the onset of the gaze plateau) was 48.5ms ± 19.2ms. Upon brake release the head resumed its movement and an ocular counter-rotation compensated for initial head motion so as to stabilize gaze, resulting in a gaze plateau. After the plateau, a corrective eye saccade was triggered together with head mot … More ion. No corrective saccades, that preceded head-release, were ever seen. Thus, these results showed that cats actually compensated for the brake-induced gaze perturbation.We first explored the SC's motor map using electrical stimulation. Then, we recorded gaze saccade-related neurons (GSRNs) on the map in the intermediate and deep layers during gaze perturbation. We also recorded the activity of collicular fixation neurons (SCFNs) in the fixation zone of the rostral SC. Activity of both the SC neurons reflected gaze perturbation trajectories, and not related to eye and head velocities. Both the cells encoded gaze-position error which is distance between a target and current gaze position. Axons of GSRNs projected to the ventral part of the abducens nucleus. SCFNs projected to the pontine raphe nucleus where the omnipause neurons (OPNs) were located. A part of the SCFNs have axon collaterals projecting to further caudal areas. Next, we recorded OPNs in the pontine raphe nuclei. Activity of OPNs was higher than SCFNs during gaze fixations. The discharges were related to eye movement during brake-induced gaze plateau. However SCFNs were not related to eye movement. Therefore, these results suggest that activity of OPNs requires additive inputs besides SCFNs. Less