Department of Biological Science, Program in Neuroscience, The Florida State University, Tallahassee, Florida; and.
Am J Physiol Regul Integr Comp Physiol. 2013 Oct 1;305(7):R793-803. doi: 10.1152/ajpregu.00549.2012. Epub 2013 May 29.
High-strength static magnetic fields (>7 tesla) perturb the vestibular system causing dizziness, nystagmus, and nausea in humans; and head motion, locomotor circling, conditioned taste aversion, and c-Fos induction in brain stem vestibular nuclei in rodents. To determine the role of head orientation, mice were exposed for 15 min within a 14.1-tesla magnet at six different angles (mice oriented parallel to the field with the head toward B+ at 0°; or pitched rostrally down at 45°, 90°, 90° sideways, 135°, and 180°), followed by a 2-min swimming test. Additional mice were exposed at 0°, 90°, and 180° and processed for c-Fos immunohistochemistry. Magnetic field exposure induced circular swimming that was maximal at 0° and 180° but attenuated at 45° and 135°. Mice exposed at 0° and 45° swam counterclockwise, whereas mice exposed at 135° and 180° swam clockwise. Mice exposed at 90° (with their rostral-caudal axis perpendicular to the magnetic field) did not swim differently than controls. In parallel, exposure at 0° and 180° induced c-Fos in vestibular nuclei with left-right asymmetries that were reversed at 0° vs. 180°. No significant c-Fos was induced after 90° exposure. Thus, the optimal orientation for magnetic field effects is the rostral-caudal axis parallel to the field, such that the horizontal canal and utricle are also parallel to the field. These results have mechanistic implications for modeling magnetic field interactions with the vestibular apparatus of the inner ear (e.g., the model of Roberts et al. of an induced Lorenz force causing horizontal canal cupula deflection).
高强度静磁场（>7 特斯拉）会扰乱前庭系统，导致人类出现头晕、眼球震颤和恶心；而在啮齿动物的脑干前庭核中，会引起头部运动、运动性转圈、条件性味觉厌恶和 c-Fos 诱导。为了确定头部方向的作用，将小鼠在 14.1 特斯拉磁体中以六种不同的角度暴露 15 分钟（当小鼠头部朝向 B+时，与磁场平行定向，0°；或向前倾斜 45°、90°、90°侧向、135°和 180°），然后进行 2 分钟游泳测试。另外一些小鼠在 0°、90°和 180°下暴露，并进行 c-Fos 免疫组织化学处理。磁场暴露会引起圆形游泳，在 0°和 180°时最大，但在 45°和 135°时减弱。在 0°和 45°下暴露的小鼠逆时针游泳，而在 135°和 180°下暴露的小鼠顺时针游泳。在 90°（其头尾部轴垂直于磁场）下暴露的小鼠与对照组相比游泳方式没有不同。同时，在 0°和 180°下暴露会引起前庭核中的 c-Fos，其左右不对称性在 0°与 180°之间反转。90°暴露后没有引起明显的 c-Fos。因此，磁场效应的最佳定向是头尾部轴与磁场平行，使得水平半规管和耳石器也与磁场平行。这些结果对模拟磁场与内耳前庭器官的相互作用具有机制意义（例如，罗伯茨等人的模型，即诱导的洛伦兹力导致水平半规管壶腹偏转）。
