Geomagnetic Position Fixing

非技术摘要提案编号：9808420 PI：John B.菲利普斯 许多动物可以从很远的地方回到自己的家。 东部红斑蝾螈的归巢方向的研究将调查地球磁场的一个组成部分，磁倾角的空间变化的使用，以推导出归巢中使用的双坐标导航地图的一个坐标。 蝾螈在实验室中对磁倾角微小变化的反应将被用来估计它们家池塘附近的磁倾角局部梯度的特征。 从蝾螈的行为中得出的估计值将与磁倾斜的空间梯度的实际测量值进行比较，以确定该梯度是否被用于导出一个地图坐标。 此外，由于磁倾角是磁场和重力场矢量之间的角度差，因此将进行一系列单独的行为实验，以确定蝾螈重力反应的敏感性。 这些实验将有助于更好地理解地球磁场在动物导航中的作用。 此外，由于从地磁场获得地图信息需要高水平的灵敏度，这些实验将有助于确定生物系统对地磁场变化的灵敏度下限，以及在更一般的水平上，脊椎动物神经系统可以测量物理刺激的精度。

NON-TECHNICAL ABSTRACT Proposal Number: 9808420 PI: John B. Phillips Many species of animals can return to their homes from great distances. Studies of homing orientation by the eastern red- spotted newt Notophthalmus viridescens will investigate the use of spatial variation in one component of the earth's magnetic field, magnetic inclination, to derive one coordinate of a bicoordinate navigational map used in homing. The newts responses to small changes in magnetic inclination in the laboratory will be used to estimate characteristics of the local gradient of magnetic inclination in the vicinity of their home pond. The estimates derived from the newts' behavior will then be compared with actual measured values of the spatial gradient of magnetic inclination to determine whether this gradient is being used to derive one map coordinate. In addition, since magnetic inclination is the angular difference between the magnetic and gravity field vectors, a separate series of behavioral experiments will be carried out to determine the sensitivity of the newt's gravitational responses. The proposed experiments will contribute to a better understanding of the role of the earth's magnetic field in animal navigation. In addition, because of the high level of sensitivity that is required to derive map information from the geomagnetic field, these experiments will help to determine the lower limits of the sensitivity of a biological system to variation in the geomagnetic field and, at a more general level, the precision with which the vertebrate nervous system can measure physical stimuli.