NEUROSENSORY MECHANISMS OF ORIENTATION TO GEOMAGNETISM

有证据表明，某些动物会探测到并将自己定位为 地球的磁场。该容量可以在归位的上下文中使用， 例如，寻找配偶和定位食物来源。尽管 用于转换地磁的生物传感装置的存在可以 从不同动物的定向反应推断，目前还没有什么 已知将地磁能量转化为 任何多细胞动物的神经系统。 一种动物被发现了，它有两个不同寻常的特征，它提供了 获得了解物理/生物学基础的机会 对于地磁意义而言。海生裸目软体动物Tritonia Diomedia 对地球磁场的响应通过在何时适当地定向 其他线索不可用。其次，在最近的实验中，对称的 已经在动物的大脑中发现了一对可重新识别的神经元 通过点火来响应环境磁场方向的变化 电脉冲。 在这项建议中，实验描述了在行为，神经元 电路和单个神经元电平，旨在(I)建立 地磁感觉系统在行为水平和内部的调节 适当的可重新识别的神经元，(Ii)进一步追踪神经 将感官输入与相关的运动控制连接起来的电路 使用电生理技术，以及(Iii)确定细胞和 磁能传递的分子水平机制 转化为神经系统信号。

Evidence indicates that certain animals detect and orient themselves to the earth's magnetic field. This capacity may be used in the context of homing, finding mates, and locating food sources, for instance. Although the existence of biosensory apparatus for transducing geomagnetism can be inferred from the orienting responses of diverse animals, little is yet known of the mechanisms of transduction of geomagnetic energy into the nervous system of any multicellular animal. An animal has been found which has two unusual features and which provides an opportunity to achieve an understanding of the physical/biological basis for the geomagnetic sense. The marine nudibranch mollusc, Tritonia diomedia response to the earth's magnetic field by orienting appropriately when other cues are unavailable. Secondly, in recent experiments, a symmetrical pair of re-identifiable neurons in the animal's brain have been found which respond to changes in the direction of the ambient magnetic field by firing electrical impulses. In this proposal, experiments are described at the behavioral, neuronal circuitry, and single neuron level that are designed to (i) establish the tuning of the geomagnetic sensory system at the behavioral level and in appropriate re-identifiable neurons, (ii) trace further the neural circuitry that couples this sensory input to the relevant motor control using electrophysiological techniques, and (iii) determine cellular and molecular level mechanisms underlying the transduction of magnetic energy into nervous system signals.