A diverse array of vertebrate species employs the Earth’s magnetic field to assist navigation. Despite compelling behavioral evidence that a magnetic sense exists, the location of the primary sensory cells and the underlying molecular mechanisms remain unknown [1]. To date, most research has focused on a light-dependent radical-pair-based concept and a system that is proposed to rely on biogenic magnetite (Fe₃O₄) [2, 3]. Here, we explore an overlooked hypothesis that predicts that animals detect magnetic fields by electromagnetic induction within the semicircular canals of the inner ear [4]. Employing an assay that relies on the neuronal activity marker C-FOS, we confirm that magnetic exposure results in activation of the caudal vestibular nuclei in pigeons that is independent of light [5]. We show experimentally and by physical calculations that magnetic stimulation can induce electric fields in the pigeon semicircular canals that are within the physiological range of known electroreceptive systems. Drawing on this finding, we report the presence of a splice isoform of a voltage-gated calcium channel (Ca_V1.3) in the pigeon inner ear that has been shown to mediate electroreception in skates and sharks [6]. We propose that pigeons detect magnetic fields by electromagnetic induction within the semicircular canals that is dependent on the presence of apically located voltage-gated cation channels in a population of electrosensory hair cells.

各种各样的脊椎动物物种利用地球磁场来辅助航行。尽管有令人信服的行为证据表明存在磁性，但主要的感觉细胞的位置和潜在的分子机制仍然未知[1]。迄今为止，大多数研究都集中在基于光依赖的自由基对的概念和一种建议依赖于生物磁铁矿（Fe ₃ O ₄）[2，3]。在这里，我们探索了一个被忽略的假设，该假设预测动物通过内耳半圆管内的电磁感应检测磁场[4]。我们使用一种依赖于神经元活性标记C-FOS的测定方法，证实了磁力暴露可导致鸽子的尾前庭核活化，而这与光无关[5]。我们通过实验和通过物理计算表明，磁刺激可以在已知的电感受系统的生理范围内的鸽子半规管中感应电场。根据这一发现，我们报告了电压门控钙通道（Ca _V1.3）被证明可以介导滑冰鞋和鲨鱼的电信号接收[6]。我们建议鸽子通过半圆形管内的电磁感应检测磁场，这取决于在电感应毛细胞中顶端定位的电压门控阳离子通道的存在。