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前庭眼反射（aVOR）的重要背景。最大增益变化发生在适应位置，并且随着头部远离该位置而减小。重力依赖适应的频谱分量也被调谐到适应的频率。提出了一项研究，以确定这种适应的重力和频率依赖方面的警觉猴前庭核的细胞基础。重力依赖适应的频率特性将首先被研究，以确定在一个频率的适应如何影响适应在很宽的频率范围和头部取向。这将为研究中枢前庭神经元耳石极化向量的通道-眼传导和重定向的适应性变化奠定基础。这些研究将包括：1）研究前庭神经核中耳石-管会聚神经元的耳石极化向量在重力依赖性适应中的变化。2)调查如何适应性变化的耳石重定向和在特定频率的耳道-耳石会聚神经元的耳道-眼转导相关的时空收敛（STC）的特点的单位。初步研究表明，当重力依赖性适应诱导在一个特定的频率，耳石会聚神经元开发STC的特点，也调谐到适应的频率。3)确定FTN和PVP神经元如何编码重力依赖性适应。4)将这些发现与神经元网络模型联系起来，这将成为这项研究的基础。重力依赖的适应是一个时空过程，编码在耳道-耳石会聚单位的STC特征中。进一步提出前庭核中的仅前庭神经元（vestibular-only，VO）通过绒球向絮状靶神经元（floccular target neurons，FTN）和直接向编码重力依赖性适应的位置-前庭暂停（position-vestibular-pause，PVP）细胞传递这种信息，从而确定前庭眼反射对重力依赖性适应的神经机制。这可能提供一种新的方法来解释前庭系统病变后通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.