A PHYSIOLOGICAL STUDY OF VESTIBULAR AND PREPOSITUS-HYPOGLOSSI NEURONS PROJECTING TO THE ABDUCENS NUCLEUS IN THE ALERT CAT
A PHYSIOLOGICAL STUDY OF VESTIBULAR AND PREPOSITUS-HYPOGLOSSI NEURONS PROJECTING TO THE ABDUCENS NUCLEUS IN THE ALERT CAT
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DOI：
10.1113/jphysiol.1992.sp019433
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发表时间：
1992-12-01
影响因子：
5.5
通讯作者：
DELGADOGARCIA, JM
中科院分区：
文献类型：
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作者：
ESCUDERO, M;DELACRUZ, RR;DELGADOGARCIA, JM
1.在警觉猫上记录前庭和前置舌下肌（PH）神经元投射到展神经核（ABD）的放电特征，以确定ABD神经元水平眼位信号的来源.根据神经元相对于ABD核的位置、从ABD核的逆向激活、用尖峰触发平均技术在ABD核中诱导的突触场电位以及它们在自发和前庭诱导的眼球运动期间的活动对神经元进行分类.投射到ABD核的前庭神经元位于前庭内侧核的头端。对侧ABD神经元兴奋，对同侧ABD神经元抑制。这两种类型的前庭前运动神经元表现出发射率弱相关的眼睛的位置，增加对侧的方向上的眼睛固定，并减少同侧固定。眼睛注视期间的位置敏感度为（平均值+/- S.D.）1.8兴奋性神经元放电频率为± 0.9 s-1 deg-1，抑制性神经元放电频率为2.2 ± 1.3 s-1 deg-1。他们的反应在扫视在关闭的方向的特点是暂停，虽然定义不太明确，偶尔出现在扫视的方向。Eve速度敏感性在自发性扫视的方向上是0.17 +/- 6.15尖峰s-1度-1秒-1兴奋性神经元和0.15 +/- 0.07尖峰s-1度-1秒-1抑制性前庭神经元。在0.2 Hz的正弦头部刺激期间，前庭神经元表现出1型放电率，兴奋性神经元的眼位相位超前为86.0 +/- 14.1度，抑制性神经元的眼位相位超前为80.2 +/- 12.5度。前庭刺激时的位置敏感度与自发性眼球运动的值没有显著差异。然而.头旋转时前庭前运动神经元的速度敏感性（兴奋性神经元为1.6 +/-0.2峰s-1 deg-1 s-1，抑制性神经元为1.5 +/-0.3峰s-1 deg-1 s-1）显著高于自发性运动.投射到ABD核的PH神经元位于核的头端三分之一。 这些神经元在同侧ABD核上具有兴奋性，而在对侧ABD核上具有抑制性。 其放电频率主要与眼位有关，随同侧眼外展眼位的增加而增加，随内收眼位的增加而减少。 眼位置敏感性分别为8.2 +/- 2.9和7.9 +/- 2.9尖峰s-1度-1兴奋性和抑制性神经元。 在眼睛固定的放电率的变化低于所示的启动子前庭神经元。 在扫视过程中，运动前PH神经元表现出较低的眼速敏感性（兴奋组为0.15 +/- 0.21，抑制组为0.32 +/- 0.28尖峰s-1 deg-1 s-1），相关系数较低。在前庭窦刺激期间，这些神经元为II型，在0.2 Hz时分别显示11.3 +/- 4.1和13.0 +/- 4.5度的相位导联。前庭窦刺激期间的Eve位置敏感性与自发性眼球运动期间所示的相似。在前庭刺激期间，它们对兴奋性和抑制性神经元的速度敏感性分别为1.0 +/- 0.7和0.8 +/- 0.3个尖峰s-1 dec-1 s-1。我们认为PH核是产生ABD运动神经元和核间神经元的Eve位置信号的主要核团。此外。前庭神经元中存在的弱位置信号可能是与眼睛位置信号产生不直接相关的必然放电的结果。本文还提出了PH核产生位置信号的可能性。
1. Vestibular and prepositus hypoglossi (PH) neurones projecting to the abducens (ABD) nucleus were recorded in the alert cat. Their discharge characteristics were analysed to ascertain the origin of the horizontal eye position signal present in ABD neurones.2. Neurones were classified according to: their location with respect to the ABD nucleus; their antidromic activation from the ABD nucleus; the synaptic field potential they induced in the ABD nucleus with the spike-triggered averaging technique; and their activity during spontaneous and vestibularly induced eye movements.3. Vestibular neurones projecting to the ABD nucleus were located in the rostral medial vestibular nucleus. They were excitatory on the contralateral and inhibitory on the ipsilateral ABD neurones. Both types of premotor vestibular neurone showed a firing rate weakly related to eye position, increasing for eye fixations in the contralateral on-direction, and decreasing with ipsilateral fixation. Position sensitivity during eye fixations was (means +/- S.D.) 1.8 +/- 0.9 spikes s-1 deg-1 for excitatory neurones and 2.2 +/- 1.3 spikes s-1 deg-1 for inhibitory neurones, Firing rate exhibited a high variability during eye fixations. Their responses during saccades in the off-direction were characterized by a pause that, although less defined, was occasionally present during saccades in the on-direction. Eve velocity sensitivity during spontaneous saccades in the on-direction was 0.17 +/- 6.15 spikes s-1 deg-1 s-1 for excitatory neurones and 0.15 +/- 0.07 spikes s-1 deg-1 s-1 for inhibitory vestibular neurones. During sinusoidal head stimulation at 0.2 Hz, vestibular neurones showed a type 1 discharge rate with a phase lead over eye position of 86.0 +/- 14.1 deg for excitatory and 80.2 +/- 12.5 deg for inhibitory neurones. Position sensitivity during vestibular stimulation did not differ significantly from values obtained for spontaneous eye movements. However. the velocity sensitivity of premotor vestibular neurones during head rotation was significantly higher (1.6 +/- 0.2 spikes s-1 deg-1 s-1 for excitatory and 1.5 +/- 0.3 spikes s-1 deg-1 s-1 for inhibitory neurones) than during spontaneous eve movements.4. PH neurones projecting to the ABD nucleus were located in the rostral one-third third of the nucleus. These neurones were excitatory on the ipsilateral and inhibitory on the contralateral ABD nucleus. Their firing rates were correlated mainly with eye position, increasing for abducting eye positions of the ipsilateral eye and decreasing with adduction movements. Eye position sensitivities were 8.2 +/- 2.9 and 7.9 +/- 2.9 spikes s-1 deg-1 for excitatory and inhibitory neurones, respectively. Variability of the firing rate during eye fixations was lower than that shown by promoter vestibular neurones. During saccades, premotor PH neurones showed low eye velocity sensitivity (0.15 +/- 0.21 for the excitatory and 0.32 +/- 0.28 spikes s-1 deg-1 s-1 for the inhibitory group) with low coefficients of correlation. During vestibular sinusoidal stimulation these neurones were type II and showed phase leads of 11.3 +/- 4.1 and 13.0 +/- 4.5 deg, respectively at 0.2 Hz. Eve position sensitivity during vestibular sinusoidal stimulation was similar to that shown during spontaneous eye movements. Their velocity sensitivities during vestibular stimulation were 1.0 +/- 0.7 and 0.8 +/- 0.3 spikes s-1 dec-1 s-1 for excitatory and inhibitory neurones, respectively.5. It is proposed that the PH nucleus is responsible for the generation of the eve position signal present in ABD motoneurones and internuclear neurones. Furthermore. the weak position signal present in vestibular neurones is probably the result of a corollary discharge not directly related to eye position signal generation. A suggestion of how eve position signal is generated in the PH nucleus is also presented.