Context-specific Spatial Adaptation of the VOR

描述（由申请人提供）：重力是通过视觉-前庭不匹配适应角度前庭-眼反射（aVOR）的重要背景。最大的增益变化发生在适应位置，随着头部朝向远离该位置而减少。依赖重力的适应的频谱分量也被调谐到适应的频率。一项研究提出，以确定细胞基础的重力和频率依赖方面的这种适应在前庭核的警觉猴。首先将研究重力依赖适应的频率特征，以确定一个频率的适应如何影响广泛频率和头部方向的适应。这将为研究前庭中枢神经元的管眼转导和耳石极化矢量的适应性变化奠定基础。这些研究将包括：1)表征前庭核内耳石管会聚神经元的耳石极化载体中与重力依赖适应相关的细胞变化。2)研究特定频率下耳石-耳石会聚神经元的耳石重定向和管眼转导的适应性变化与单元时空会聚（STC）特性的关系。初步研究表明，当重力依赖适应以特定频率诱导时，耳石-管道收敛神经元也会产生STC特征，这种特征也会随着适应频率而变化。3)确定FTN和PVP神经元如何编码重力依赖的适应。4)将这些发现与神经元网络模型联系起来，这将构成研究的潜在基础。本文认为重力依赖的适应是一个时空过程，其编码在耳石-耳管汇聚单元的STC特征中。进一步提出，前庭核内的仅前庭神经元（VO）将这一信息通过小叶传递给絮状靶神经元（FTN），并直接传递给编码重力依赖适应的位置-前庭-暂停（PVP）细胞。本研究旨在探讨前庭-眼反射适应对重力依赖性的神经机制。这可能为解释前庭系统病变后经常遇到的平衡和空间定向困难提供了一种新的方法。

DESCRIPTION (provided by applicant): Gravity is an important context for adapting the angular vestibulo-ocular reflex (aVOR) by visual-vestibular mismatch. Maximal gain changes occur in the position of adaptation and decrease, as the head is oriented away from this position. The spectral components of the gravity-dependent adaptation are also tuned to the frequency of adaptation. A study is proposed to determine the cellular basis for the gravity and frequency dependent aspects of this adaptation in the vestibular nuclei of the alert monkey. The frequency characteristics of gravity dependent adaptation will first be studied to determine how adaptation at one frequency affects adaptation over a wide range of frequencies and head orientations. This will lay the groundwork for studying adaptive changes in canal-ocular transduction and reorientation of otolith polarization vectors in central vestibular neurons. Such studies will include: 1) Characterizing the cellular changes associated with gravity-dependent adaptation in the otolith polarization vectors of otolith-canal convergent neurons in the vestibular nuclei. 2) Investigating how adaptive changes in the otolith reorientation and canal-ocular transduction of canal-otolith convergent neurons at a particular frequency are related to the spatio-temporal convergence (STC) characteristics of the unit. Preliminary investigations show that when gravity-dependent adaptation is induced at a specific frequency, the canal-otolith convergent neurons developed STC characteristics that also tuned to the frequency of adaptation. 3) Determine how FTN and PVP neurons code the gravity-dependent adaptation. 4) Tie these findings to a neuronal net model, which will form the underlying basis for the study. It is postulated that gravity- dependent adaptation is a spatio-temporal process, which is encoded in the STC characteristics of canal- otolith convergent units. It is further proposed that vestibular-only (VO) neurons in the vestibular nuclei transmit this information through the flocculus to floccular target neurons (FTN) and directly to position- vestibular-pause (PVP) cells that code gravity dependent adaptation.The proposed research will determine the neural mechanism for the dependence of adaptation of the vestibulo-ocular reflex on gravity. This could provide a new approach to explaining difficulties in balance and spatial orientation commonly encountered after lesions of the vestibular system.