Vestibulo-cerebellar contribution to spatial adaptation

描述(申请人提供)：我们提出了三个研究领域，以了解前庭小脑的回路如何利用前庭信息来调节浦肯野细胞的简单棘波(SS)输出，以及这一输出如何有助于行为适应改变前庭的方向：1)将前庭信息传递到下橄榄的回路。延髓旁核(PSOL)向下橄榄的两个亚核--β核和背内侧细胞柱(DMCC)传递前庭信号。单侧损毁PSOL减少但不能消除对侧悬垂-结节中前庭调节的攀升纤维反应(CFRs)，这意味着另一条通向下橄榄的突触前前庭通路。Y基团可能是这种替代途径的起源。我们将结合逆行和正交线示踪器与单个Y群神经元的记录来确定它们携带的前庭和视动信号的类型。2)结节内CFR-SS的前庭可塑性，了解浦肯野细胞上爬行纤维和平行纤维之间的相互作用对于了解小脑是至关重要的。相互作用会带来短期或长期的后果。我们将在体内对平行和攀爬的纤维进行电刺激，这样它们的相互作用就可以用已知的前庭电路来解释。从β核中已知的半规管区域发出的攀援纤维，将与来自单个垂直半规管的平行纤维凌空相互作用。这些相互作用应该揭示攀升的纤维形态如何反映在浦肯野细胞的输出中。3)行为学评价悬垂结节在动态控制前庭-眼反射空间定向中的作用。兔绕纵轴旋转可调节先前诱发的视动性后震颤(Okan II)的速度和方向。眼球震颤速度降低的意义以及结节对眼球速度改变的可能贡献尚不清楚。我们认为，头部倾斜会导致眼球震颤速度的降低，从而降低所有与感知到的垂直方向或先前“记忆”的方向相冲突的眼睛反射的增益。我们将测量当兔头的方向导致眼球震颤在两侧悬垂结节破坏前后以不同的角度在眼眶内执行时，慢相速度的变化。

DESCRIPTION (provided by applicant): We propose three areas of investigation to understand how the circuitry of the vestibulocerebellum uses vestibular information to modify the simple spike (SS) output of Purkinje cells and how this output contributes to behavioral adaptation to altered vestibular orientation: 1) Circuitry transmitting vestibular information to inferior olive. The parasolitary nucleus (Psol) conveys vestibular signals to the beta-nucleus and dorsomedial cell column (dmcc), two subnuclei of the inferior olive. Unilateral lesions of Psol reduce, but do not eliminate vestibularly-modulated climbing fiber responses (CFRs) in the contralateral uvula-nodulus, implying an alternative presynaptic vestibular pathway to the inferior olive. The Y-group may be the origin of this alternative pathway. We will combine retrograde and orthograde tracers with recordings from single Y-group neurons to determine the types of vestibular and optokinetic signals carried by them. 2) Conjunctive CFR-SS vestibular plasticity in the nodulus, understanding interactions between climbing and parallel fibers on Purkinje cells is critical to understanding the cerebellum. Interactions occur with short- or long-term consequences. We will electrically stimulate parallel and climbing fibers in vivo so that their interactions can be interpreted in terms of known vestibular circuitry. A climbing fiber volley from a known semicircular canal zone in the beta-nucleus, will be interacted with a parallel fiber volley from a single vertical semicircular canal. These interactions should reveal how climbing fiber topography is reflected in Purkinje cell output. 3) Behavioral evaluation of the role of the uvula-nodulus in the dynamic control of vestibule-ocular reflex orientation in space. Rotation of rabbits about a longitudinal axis modulates the velocity and orientation of a previously induced optokinetic afternystagmus (OKAN II). The significance of decreases in nystagmus velocity and the possible contribution of the nodulus to modification of eye velocity are poorly understood. We suggest that head tilt induces a reduction in nystagmus velocity to reduce the gain of all eye reflexes that conflict perceived vertical orientation or a previously "remembered" orientation. We will measure changes in slow phase velocity when the orientation of the rabbit's head causes nystagmus to be executed at different angles within the orbit before and after bilateral destruction of the uvula-nodulus.