MULTISENSORY INTEGRATION OF VESTIBULAR AND MAGNETIC SIGNALS

描述（由申请人提供）：许多动物可以探测并利用地球磁场进行定位和导航。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）；同时也是多感官传递前庭线性运动信号。我们还描述了一种磁感神经通路，它包括大脑中已知与空间定向和导航任务有关的区域，包括前庭核、丘脑背侧、海马体和视觉关联皮层。该项目的主要目标是确定前庭和磁感信号的多感觉收敛如何产生编码地理位置和方向信息的神经结构。首先，我们发现MR细胞在空间上是余弦调谐到磁场方向的，因此这些神经元编码了一个三维磁场矢量。在目标1中，我们将研究磁定向调谐是否参考了重力的世界固定常数。我们假设前庭和磁信号的多感觉整合使MR细胞的定向反应在空间上稳定，而不随头部位置而改变。在目标2中，我们将确定MR细胞的翻译反应是否相对于磁场方向是固定的，与头部位置无关。我们假设MR细胞在磁场坐标中提供方向航向信息。我们最近还发现，滑翔飞行的独特状态会增加前庭神经元对运动的敏感度。在目标3中，我们将确定飞行是否会增加MR细胞的灵敏度，并提供目标1和目标2中概述的更完整的参考框架转换。总之，这些实验将揭示基本的多感觉整合机制，以建立位置和方向的神经表征。这些是所有动物行为的重要功能，经常因前庭创伤或人类疾病而受损。了解一种新的磁感是如何利用前庭运动线索通过聚合来创造复杂的信息结构的，将为了解重要的大脑功能提供关键的见解，并使我们更接近

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.