Cerebellar nodulectomy impairs spatial memory of vestibular and optokinetic stimulation in rabbits
Cerebellar nodulectomy impairs spatial memory of vestibular and optokinetic stimulation in rabbits
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DOI：
10.1152/jn.00528.2001
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发表时间：
2002-02-01
影响因子：
2.5
通讯作者：
Yakhnitsa, V
中科院分区：
文献类型：
--
作者：
Barmack, NH;Errico, P;Yakhnitsa, V
用自然前庭刺激和视动刺激研究了小脑小结在兔眼反射运动调节和调节中的可能作用。手术抽吸法破坏悬垂小结和悬垂叶9d。在前庭正弦刺激时，测量切除结节前后的垂直和水平前庭眼反射(VVOR、HVOR)。虽然切除结节对HVOR的增益(G(HVOR)=眼球运动峰值速度/头部峰值速度)没有影响，但VVOR的增益(G(VVOR))有所降低。测量单眼正弦视动刺激(OKS)对纵轴和垂直轴的垂直和水平视动反射增益(G(VOKR)，(GHOKR))。结节切除术后，G(VOKR)或G(Hokr)均无下降。长期的双眼OKs被用来产生持续数小时的视动性后震颤，Okan II。在诱导Okan II后，对兔进行静态俯仰和侧滚，以确定变化的前庭环境对Okan II平面和速度的影响。在静态俯仰时，Okan II慢相保持与地水平方向一致。对于正常和切除结节的兔子来说，情况也是如此。在静态滚动过程中，正常兔的OKAN II保持与地水平对齐。在去结节兔的静态滚动过程中，Okan II慢相出现向心性垂直漂移。我们观察了相互冲突的垂直OKs暴露10-30分钟后G(VVOR)的抑制和恢复。这种前庭-视动冲突降低了正常和结节切除兔的G(VVOR)。冲突OKs手术前后G(VVOR)恢复的时间进程相同。在正常兔中，出现Okan II速度峰值的头部俯仰角与长期OKS过程中维持的头部俯仰角相对应。如果在长期OKS中头部保持“上倾”或“下倾”方向，随后测量的Okan II峰值速度出现在相同的方向上。对于切除结节的兔则不是这样，它们在头部俯仰角的Okan II峰值速度独立于长期OKS期间的峰值速度。我们认为，结节参与了代偿性反射运动的调节。结节也会影响先前视动和前庭刺激所产生的“记忆”头部在空间中的位置。
Natural vestibular and optokinetic stimulation were used to investigate the possible role of the cerebellar nodulus in the regulation and modification of reflexive eye movements in rabbits. The nodulus and folium 9d of the uvula were destroyed by surgical aspiration. Before and after nodulectomy the vertical and horizontal vestibuloocular reflexes (VVOR, HVOR) were measured during sinusoidal vestibular stimulation about the longitudinal (roll) and vertical (yaw) axes. Although the gain of the HVOR (G(HVOR) = peak eye movement velocity/peak head velocity) was not affected by the nodulectomy, the gain of the VVOR (G(VVOR)) was reduced. The gains of the vertical and horizontal optokinetic reflexes (G(VOKR), (GHOKR)) were measured during monocular, sinusoidal optokinetic stimulation (OKS) about the longitudinal and vertical axes. Following nodulectomy, there was no reduction in G(VOKR) or G(HOKR). Long-term binocular OKS was used to generate optokinetic afternystagmus, OKAN II, that lasts for hours. After OKAN II was induced, rabbits were subjected to static pitch and roll, to determine how the plane and velocity of OKAN II is influenced by a changing vestibular environment. During static pitch, OKAN II slow phase remained aligned with earth-horizontal. This was true for normal and nodulectomized rabbits. During static roll, OKAN II remained aligned with earth-horizontal in normal rabbits. During static roll in nodulectomized rabbits, OKAN II slow phase developed a centripetal vertical drift. We examined the suppression and recovery of G(VVOR) following exposure to conflicting vertical OKS for 10-30 min. This vestibular-optokinetic conflict reduced G(VVOR) in both normal and nodulectomized rabbits. The time course of recovery of G(VVOR) after conflicting OKS was the same before and after nodulectomy. In normal rabbits, the head pitch angle, at which peak OKAN II velocity occurred, corresponded to the head pitch angle maintained during long-term OKS. If the head was maintained in a "pitched-up" or "pitched-down" orientation during long-term OKS, the subsequently measured OKAN II peak velocity occurred at the same orientation. This was not true for nodulectomized rabbits, who had OKAN II peak velocities at head pitch angles independent of those maintained during long-term OKS. We conclude that the nodulus participates in the regulation of compensatory reflexive movements. The nodulus also influences "remembered" head position in space derived from previous optokinetic and vestibular stimulation.