Role of primate flocculus during rapid behavioral modification of vestibuloocular reflex. II. Mossy fiber firing patterns during horizontal head rotation and eye movement.
Role of primate flocculus during rapid behavioral modification of vestibuloocular reflex. II. Mossy fiber firing patterns during horizontal head rotation and eye movement.
复制标题
灵长类絮状在前庭眼反射快速行为改变中的作用。
作者：
S. Lisberger;A. Fuchs
1. 研究人员对警觉的猴子进行了训练，让它们在正弦、水平头部旋转的情况下执行视觉跟踪任务，获得了它们小叶中113条摩苏纤维（MFs）的细胞外记录。本研究的目的是定量比较小叶MFs与可能产生MFs的脑干细胞群和小叶浦肯野细胞（p细胞）的放电特性。根据他们的射击模式，mf被分为两类。前庭MFs的释放与头部速度有关，在某些情况下，也与眼球运动有关。眼动MFs只与眼动的一个或多个组成部分有关。2. 前庭MFs分为三类。只有前庭的MFs （n = 15）在头部旋转时显示出放电速率的调制，但与自发眼动没有关系。前庭+扫视MFs （n = 14）显示头部旋转时射击速率的调制，在数量上类似于仅前庭MFs的调制。此外，在一个或多个方向的扫视过程中，放电速率的暂停会中断前庭调制。前庭+位置MFs （n = 4）在没有前庭刺激的情况下表现出稳定的放电率，与水平眼位线性相关。头部正弦旋转引起的发射速率调制高于或低于由眼睛位置设定的发射速率。3. 在正弦波头部旋转时，前庭MF放电率使头部速度平均增加24度。中频射击速率调制的幅度随着头部旋转频率的增加而增加，从而增加了最大头部速度。由于这些特征与p细胞在抑制VOR时所表现的特征相似，前庭mf可能将p细胞放电速率的头部速度成分传递给小叶。根据来自其他哺乳动物的证据和种群放电特征的定量比较，前庭MFs可能起源于前庭神经和前庭内侧核的细胞。4. 根据他们的放电模式，眼动mf也被细分为三类。突发MFs （n = 14）在扫视前和扫视期间向一个或多个方向发出高频脉冲，但在稳定注视时沉默。爆发-紧张性MFs （n = 53）在扫视前向首选（“开”）方向发射了一阵尖峰，在扫视时向相反（“关”）方向停止发射，并表现出稳定的发射率，随着稳定的目光转向“开”方向而增加。紧张性MFs （n = 13）表现出稳定的放电速率，随着凝视方向的移动而增加，并且在扫视期间放电速率暂停或呈现阶跃变化。5. 在稳定注视期间，64%的强直性和突发性强直性MFs被招募到注视主方向+/- 10度范围内的持续放电。
1. Extracellular recordings were obtained from 113 mossu fibers (MFs) in the flocculus of alert monkeys trained to perform a visual tracking task during sinusoidal, horizontal head rotation. The analysis of MF discharge patterns was designed to allow quantitative comparison of the discharge properties of flocculus MFs with brain stem cell populations from which the MFs might originate and with flocculus Purkinje cells (P-cells). Based on their firing patterns, MFs were divided into two classes. Vestibular MFs discharged in relation to head velocity and, in some cases, also in relation to eye movement. Eye movement MFs discharged only in relation to one or more components of eye movement. 2. Vestibular MFs were subdivided into three classes. Vestibular-only MFs (n = 15) displayed a modulation in firing rate during head rotation but exhibited no relationship to spontaneous eye movements. Vestibular-plus-saccade MFs (n = 14) displayed a modulation in firing rate during head rotation that quantitatively resembled the modulation in vestibular-only MFs. In addition, a pause in firing rate interrupted the vestibular modulation during saccades in one or more directions. Vestibular-plus-position MFs (n = 4) exhibited steady firing rates that were linearly related to horizontal eye position in the absence of vestibular stimulation. Sinusoidal head rotation evoked a modulation ofiring rate above and below the firing rate set by the eye position. 3. during sinusoidal head rotation, vestibular MF firing rate led head velocity by an average of 24 degrees. The amplitude of MF firing-rate modulation increased as a function of the frequency of head rotation and, hence, maximum head velocity. Since these characteristics are similar to those displayed by P-cells during suppression of the VOR, vestibular MFs probably transmit the head velocity component of P-cell firing rate to the flocculus. Based on evidence from other mammals and a quantitative comparison of population discharge characteristics, it is likely that vestibular MFs originate from the vestibular nerve and from cells in the medial vestibular nucleus. 4. Based on their discharge patterns, eye movement MFs were also subdivided into three classes. Burst MFs (n = 14) emitted a high-frequency burst of spikes prior to and during saccades in one or more direction, but were silent during steady fixation. Burst-tonic MFs (n = 53) emitted a burst of spikes prior to saccades in a preferred ("on") direction, ceased firing during saccades in the opposite ("off") direction, and exhibited steady firing rates that increased as steady gaze shifted in the on direction. Tonic MFs (n = 13) displayed steady firing rates that increased as the position of steady gaze shifted in the on direction, and either paused or exhibited step changes in firing rate during saccades. 5. During steady fixation, 64% of tonic and burst-tonic MFs were recruited into maintained firing within +/- 10 degrees of the primary direction of gaze...