ROLE OF THE CAUDAL FASTIGIAL NUCLEUS IN SACCADE GENERATION .1. NEURONAL DISCHARGE PATTERNS
ROLE OF THE CAUDAL FASTIGIAL NUCLEUS IN SACCADE GENERATION .1. NEURONAL DISCHARGE PATTERNS
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DOI：
10.1152/jn.1993.70.5.1723
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发表时间：
1993-11-01
影响因子：
2.5
通讯作者：
STRAUBE, A
中科院分区：
文献类型：
--
作者：
FUCHS, AF;ROBINSON, FR;STRAUBE, A
1.人类和非人类灵长类动物中病变的影响涉及小脑对快速眼球运动的控制，即，扫视为了研究这种控制的神经基质，我们记录了猴子追踪一个小的跳跃光点时小脑顶核输出细胞的放电模式。在小脑顶核尾侧，神经元向一个或多个方向放电。所有的都表现出爆发。有些人还表现出一个扫视相关的暂停射击之前或之后扫视大于约3-5度。37%的人只释放了一次爆发，44%的人在某些方向的爆发前也表现出停顿，19%的人在某些方向的扫视相关爆发后也停顿了。虽然许多细胞在扫视间隔期间稳定放电，但很少有细胞表现出放电率与眼睛位置之间的稳健关系。作为方向选择性的测量，我们绘制了作为扫视方向的函数的爆发提前时间，用于类似的（10度）径向幅度的扫视。在20个神经元中，17个最早爆发对侧扫视和1个向上扫视;另外2个对方向几乎没有依赖性。在仅在水平方向上测试的19个额外单元中，18个对于对侧扫视较早地爆发。对于对侧扫视，爆发平均比所有大小的扫视提前至少7.7 ms。对于同侧扫视，爆发平均先于小扫视10.3 ms。然而，随着同侧扫视尺寸的增加，爆发相对于扫视开始开始越来越晚，因此，平均而言，它总是发生在20度扫视开始之后，但远在扫视结束之前。许多高峰眼跳相关的单位表现出增加的数量与眼跳的大小和突发持续时间与眼跳持续时间在一个或多个方向。对于任一关系，最高的平均相关系数范围为0.6至0.65。一般来说，对侧眼跳的平均相关系数和斜率略大。纯爆发神经元并没有表现出更好的平均相关性比神经元，也暂停。对于在扫视之前或之后也暂停的神经元，有一个微弱的趋势，即暂停持续时间随着较大扫视的持续时间而增加。我们测试了眼睛位置对13个细胞单位放电的影响，要求猴子从不同的起始位置进行10度同侧和对侧扫视。八个神经元表现出明确的质的差异，无论是突发特性，伴随的停顿，或不同的起始位置的眼间稳定放电率的存在。然而，13个细胞中只有2个细胞表现出至少1个爆发参数和起始位置之间的相关系数为0.8或更高;另外7个细胞至少有1个系数超过0.4。当我们将扫视分为离心运动和向心运动时，与起始位置的相关性并没有得到改善.与扫视相关的小脑顶神经元放电绝不是机器式的。对于某些单位，相同大小和起始位置的扫视伴随着频率和持续时间差异很大的爆发。此外，警觉性和/或注意力似乎会影响扫视反应。然而，我们的数据表明，小脑顶核参与帮助加速对侧扫视和帮助减速同侧的。如果这是真的，小脑顶核的病变应该会导致对侧扫视变为低距离扫视，而同侧扫视变为高距离扫视。在论文中报道的顶核的药理学失活就产生了这样的缺陷。
1. The effects of lesions in both human and nonhuman primates have implicated the cerebellum in the control of rapid eye movements, i.e., saccades. To examine the neural substrate of this control, we recorded the discharge patterns of cerebellar output cells in the fastigial nucleus while monkeys tracked a small, jumping spot of light.2. In the caudal fastigial nucleus, neurons discharged for saccades in one or several directions. All exhibited a burst. Some also exhibited a saccade-related pause in firing either before or after saccades greater than approximately 3-5-degrees. Thirty-seven percent discharged only a burst, 44% also exhibited a pause before bursts in certain directions, and 19% also paused after the saccade-related burst in certain directions. Although many cells discharged steadily during intersaccadic intervals, few exhibited a robust relation between firing rate and eye position.3. As a measure of directional selectivity, we plotted the burst lead time as a function of saccade direction for saccades of similar (10-degrees) radial amplitudes. Of 20 neurons tested, 17 burst earliest for contralateral saccades and 1 for upward saccades; 2 others showed little dependence on direction. Of 19 additional units tested only in the horizontal direction, 18 burst earlier for contralateral saccades.4. For contralateral saccades the burst preceded saccades of all sizes by at least 7.7 ms on average. For ipsilateral saccades, the burst preceded small saccades by an average of 10.3 ms. However, as ipsilateral saccade size increased, the burst began later and later relative to saccade onset so that, on average, it always occurred after the onset of 20-degrees saccades but well before the saccade ended.5. Many fastigial saccade-related units showed increases in the number of spikes with saccade size and in burst duration with saccade duration in one or more directions. For either relation the highest average correlation coefficients ranged from 0.6 to 0.65. In general, the average correlation coefficients and slopes for either relation were slightly larger for contralateral saccades. Pure burst neurons did not display better average correlations than neurons that also paused. For neurons that also paused either before or after saccades, there was a weak tendency for pause duration to increase with the duration of larger saccades.6. We tested the effect of eye position on unit discharge in 13 cells by requiring the monkey to make 10-degrees ipsilateral and contralateral saccades from a variety of starting positions. Eight of the neurons exhibited clear qualitative differences in either the burst characteristics, the presence of an accompanying pause, or the intersaccadic steady firing rate for different starting positions. However, only 2 of the 13 exhibited at least 1 correlation coefficient between burst parameters and starting position of 0.8 or more; 7 additional cells had at least 1 coefficient in excess of 0.4. The correlations with starting position did not improve when we sorted saccades into centrifugal and centripetal movements.7. The saccade-related discharge of fastigial neurons was anything but machinelike. For some units, saccades of the same size and starting position were accompanied by bursts of widely differing frequencies and durations. In addition, alertness and/or attention appeared to affect the saccadic responses.8. Nevertheless, our data suggest that the fastigial nucleus is involved in helping to accelerate contralateral saccades and in helping to decelerate ipsilateral ones. If this is true, lesions of the fastigial nucleus should cause contralateral saccades to become hypometric and ipsilateral saccades to become hypermetric. The pharmacological inactivations of the fastigial nucleus reported in the companion paper produced just such deficits.