SACCADIC BURST NEURONS IN THE OCULOMOTOR REGION OF THE FASTIGIAL NUCLEUS OF MACAQUE MONKEYS
SACCADIC BURST NEURONS IN THE OCULOMOTOR REGION OF THE FASTIGIAL NUCLEUS OF MACAQUE MONKEYS
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DOI：
10.1152/jn.1991.65.6.1422
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发表时间：
1991-06-01
影响因子：
2.5
通讯作者：
NODA, H
中科院分区：
文献类型：
--
作者：
OHTSUKA, K;NODA, H
1.观察了3只训练猕猴在视觉引导眼跳过程中顶核区255个神经元的放电。这些神经元的反应也在头部水平旋转和微刺激动眼蠕虫(小叶Vic和Vi)的过程中被检测。102个单位的特点是对视觉引导的扫视进行一连串的射击。根据记录部位重建，其中98例(96.1%)位于顶端动眼区域(FOR)的解剖范围内。在对侧眼跳中，这些神经元表现出在眼跳开始之前的爆发(眼跳前爆发)，而在同侧眼跳中，它们表现出与眼跳结束相关的爆发(晚期眼跳爆发)。因此，它们被命名为扫视爆发神经元。61个突起神经元(62.2%)在微刺激动眼蠕虫时被抑制，电流为10-mU-A。所有的扫视爆发神经元都是自发活动的，不同单位的静息放电频率有很大的差异，从10到50 imp/S。紧张性活动水平与眼位没有明显的相关性。视前阵发在最佳方向(与阵发导联时间、每次阵发尖峰次数和阵发持续时间的最大值相关的方向)的起跳前18.5+/-4.7(SD)ms(n=45)。最佳方向覆盖整个对侧半球，尽管在本样本中水平方向和上斜角方向的发生率略高。眼跳持续时间与眼跳持续时间高度相关(0.85小于或等于r小于或等于0.97)。在每个单元中，晚期跳动脉冲在与最优方向相反的方向上最健壮(非最佳方向)。其发病时间比同侧眼跳完成时间早30.4+/-5.9ms。到眼跳结束的提前时间在不同单位之间是一致的，对于不同大小的眼跳也是恒定的。因此，即使在眼跳持续时间为30ms的眼跳开始之前，晚期的眼跳爆发就已经开始了。与眼跳前爆发不同，其持续时间与眼跳持续时间无关。眼跳爆发神经元的放电率既不与注视时的眼位相关，也不与眼跳前的初始眼位相关。眼位单位和水平头速单位位于FORE的正上方。13个眼位单位位于眼球跳动爆发神经元的吻侧，其中5个单位在刺激Vermal时被抑制。在66个水平头速单位中，16个单位在同侧正弦旋转时增加了放电(类型I)，50个单位在对侧头部旋转时增加了放电(类型II)。它们广泛分布于顶核的吻部和中央部。本研究表明，在视觉引导的眼跳过程中，For对于视觉运动信息的处理是重要的。眼跳爆发神经元表现为放电爆发和晚期眼跳爆发，前者可能调节对侧方向的眼跳持续时间，后者可能在同侧眼跳时起到刹车的作用。这些反应特征表明，小脑输出可能携带了控制眼跳幅度所需的信息。
1. The discharge of 255 neurons in the fastigial nuclei of three trained macaque monkeys was investigated during visually guided saccades. Responses of these neurons were examined also during horizontal head rotation and during microstimulation of the oculomotor vermis (lobules VIc and VII).2. One hundred and two units were characterized by bursts of firing in response to visually guided saccades. Ninety-eight of these (96.1%) were located within the anatomic confines of the fastigial oculomotor region (FOR), on the basis of reconstruction of recording sites. During contralateral saccades, these neurons showed bursts that preceded the onset of saccades (presaccadic burst), whereas, during ipsilateral saccades, they showed bursts associated with the end of saccades (late saccadic burst). They were hence named saccadic burst neurons. Sixty-one saccadic burst neurons (62.2%) were inhibited during microstimulation of the oculomotor vermis with currents < 10-mu-A.3. All saccadic burst neurons were spontaneously active, and the resting firing rate varied considerably among units, ranging from 10 to 50 imp/s. The tonic levels of activity did not correlate significantly with eye position.4. The presaccadic burst started 18.5 +/- 4.7 (SD) ms (n = 45) before the onset of saccades in the optimal direction (the direction associated with the maximum values of burst lead time, number of spikes per burst, and burst duration). Optimal directions covered the entire contralateral hemifield, although there was a slightly higher incidence in both horizontal and upper-oblique directions in the present sample. The duration of the presaccadic burst was highly correlated with the duration of saccade (0.85 less-than-or-equal-to r less-than-or-equal-to 0.97).5. The late saccadic burst was most robust in the direction opposite to the optimal in each unit (the nonoptimal direction). Its onset preceded the completion of ipsilateral saccade by 30.4 +/- 5.9 ms. The lead time to the end of saccade was consistent among different units and was constant also for saccades of various sizes. Thus the late saccadic burst started even before the saccade onset when the saccade duration was < 30 ms. Unlike the presaccadic burst, its duration was not related to the duration of saccade.6. Discharge rates of saccadic burst neurons were correlated neither to eye positions during fixation nor to the initial eye positions before saccades.7. Eye-position units and horizontal head-velocity units were located rostral to the FOR. Thirteen eye-position units were found rostral to the saccadic burst neurons, and 5 of these units were inhibited during vermal stimulation. Of a total of 66 horizontal head-velocity units, 16 units increased discharges during the ipsilateral phase of sinusoidal head rotation (type I), and 50 units increased discharges during contralateral head rotation (type II). They were widely scattered in the rostral and central portions of the fastigial nucleus.8. The present study has shown that the FOR is important for the processing of visuomotor information during visually guided saccades. The saccadic burst neurons showed a burst of firing, which may regulate the duration of a saccade in the contralateral direction, and a late saccadic burst, which may work as a brake during an ipsilateral saccade. These response features indicate that the cerebelllar output may carry the information necessary for controlling the amplitude of saccade.