Context-specific Spatial Adaptation of the VOR

描述(由申请人提供)：重力是通过视觉-前庭不匹配来适应角状前庭-眼反射(AVOR)的一个重要背景。最大的增益变化发生在适应和减小的位置，因为头部朝向远离这个位置。依赖重力的适应的频谱分量也根据适应的频率进行调整。有人建议进行一项研究，以确定警觉猴子前庭核团这种适应的重力和频率依赖方面的细胞学基础。首先将研究重力依赖适应的频率特性，以确定一个频率的适应如何影响广泛频率和头部方位的适应。这将为研究耳道-眼传导的适应性变化和前庭中央神经元耳石极化向量的重新定位奠定基础。这些研究将包括：1)在前庭核团内耳石-管会聚神经元的耳石极化向量中表征与重力依赖适应相关的细胞变化。2)研究耳石汇聚神经元在特定频率下耳石重定向和通道-眼转导的适应性变化与该单位的时空会聚(STC)特征之间的关系。初步研究表明，当以特定频率诱导重力依赖适应时，耳石管会聚神经元发展出与适应频率相适应的STC特征。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，这将构成研究的基本基础。假设重力相关适应是一个时空过程，这一过程编码在耳道-耳石会聚单元的STC特性中。进一步提出，前庭核团中的仅前庭神经元(VO)通过小叶将这一信息传递给绒毛状靶神经元(FTN)，并直接传递到编码重力依赖适应的位置-前庭-暂停(PVP)细胞。这可以提供一种新的方法来解释前庭系统损伤后经常遇到的平衡和空间定向困难。

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.