MULTISENSORY INTEGRATION OF VESTIBULAR AND MAGNETIC SIGNALS

描述(申请人提供)：许多动物可以探测并使用地球磁场来定位和导航功能。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)，以及携带前庭直线运动信号的多感觉细胞。我们还描述了一种磁性感觉神经通路，其中包括大脑中已知涉及空间定向和导航任务的区域，包括前庭核、丘脑背侧核、海马体和视觉关联皮质。这项拟议项目的主要目标是确定前庭和磁性感觉信号的多感觉融合如何创建编码地理位置和航向方向信息的神经结构。首先，我们发现MR细胞在空间上与磁场方向是余弦调谐的，因此这些神经元编码一个三维磁场矢量。在目标1中，我们将检查磁方向调谐是否参考世界上固定的重力常数。我们假设，前庭和磁线索的多感觉整合使得MR细胞的方向性反应在空间上是稳定的，并且不会随着头部位置的改变而改变。在目标2中，我们将确定MR单元的平移响应是否相对于磁场方向是固定的，与磁头位置无关。我们假设MR单元在磁场坐标中提供定向航向信息。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，并提供更完整的参照系转换，如目标1和2中所概述的。这些实验将揭示基本的多感觉整合机制，以建立位置和航向的神经表征。这些是所有动物行为的重要功能，经常受到前庭创伤或人类疾病的影响。了解一种新的磁觉如何通过融合使用前庭运动线索来创建复杂的信息结构，将为我们提供对重要大脑功能的关键见解，并使我们更接近 到获得新的治疗选择，迷失方向病。

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.