MULTISENSORY INTEGRATION OF VESTIBULAR AND MAGNETIC SIGNALS

描述（由申请人提供）：许多动物可以检测和使用地球磁场的方向和导航功能。我们最近在鸽子的前庭脑干中发现了编码磁场方向和强度的细胞（MR细胞）;以及携带前庭线性运动信号的多感觉细胞。我们还描述了一种磁感觉神经通路，该通路包括已知与空间定向和导航任务有关的大脑区域，包括前庭核、背侧丘脑、海马和视觉关联皮层。该项目的主要目标是确定前庭和磁感信号的多感官会聚如何创建编码地理位置和航向信息的神经结构。首先，我们发现MR细胞是空间余弦调谐到磁场方向，因此这些神经元编码一个3D磁场矢量。在目标1中，我们将研究磁场方向调谐是否与世界固定的引力常数有关。我们假设前庭和磁线索的多感觉整合允许MR细胞方向反应在空间上是稳定的，并且不随头部位置而改变。在目标2中，我们将确定MR细胞平移响应是否相对于磁场方向固定，而与头部位置无关。我们假设MR细胞提供磁场坐标中的方向性航向信息。我们最近还发现，滑翔飞行的独特状态增加了前庭神经元对运动的敏感性。在目标3中，我们将确定飞行是否会增加MR细胞的灵敏度，并提供更完整的参考系转换，如目标1和2所述。这些实验将共同揭示建立位置和航向神经表征的基本多感觉整合机制。这些是所有动物行为的重要功能，通常会受到前庭创伤或人类疾病的影响。了解一种新的磁感觉如何通过会聚使用前庭运动线索来创建复杂的信息结构，将为重要的大脑功能提供关键的见解，并使我们更接近 获得新的治疗选择定向障碍疾病。

DESCRIPTION (provided by applicant): Many animals can detect and use the Earth's magnetic field for orientation and navigation functions. We have recently discovered cells in the vestibular brainstem of pigeons that encode the direction and intensity of the magnetic field (MR cells); as well as being multisensory carrying vestibular linear motion signals. We have also characterized a magnetic sense neural pathway that includes regions in the brain known to be involved with spatial orientation and navigation tasks, including the vestibular nuclei, dorsal thalamus, hippocampus, and visual association cortex. The primary goal of the proposed project is to determine how multisensory convergence of vestibular and magnetic sense signals creates neural constructs that encode geopositional and heading direction information. First, we found that MR cells are spatially cosine tuned to magnetic field direction, thus these neurons encode a 3D magnetic field vector. In Aim 1, we will examine whether magnetic directional tuning is referenced to the world-fixed constant of gravity. We hypothesize that multisensory integration of vestibular and magnetic cues allows MR cell directional responses to be spatially stable and not change with head position. In Aim 2, we will determine if MR cell translational responses are fixed relative to the magnetic field direction, independent of head position. We hypothesize that MR cells provide directional heading information in magnetic field coordinates. We recently also discovered that the distinct state of gliding flight increases the sensitivity to motion in vestibuar neurons. In Aim 3, we will determine if flight increases the sensitivity of MR cells and provides for more complete reference frame transformations as outlined in Aims 1 and 2. Together, these experiments will uncover basic multisensory integration mechanisms for building neural representations of position and heading direction. These are vital functions for all animal behavior and are often compromised by vestibular trauma or disease in people. Understanding how a new magnetic sense uses vestibular motion cues through convergence to create complex information constructs will provide key insights into important brain functions and bring us closer to obtaining new treatment options disorientation maladies.