Tryon Valerie L, Kim Esther U, Zafar Talal J, Unruh April M, Staley Shelly R, Calton Jeffrey L
Department of Psychology, California State University, USA.
Behav Neurosci. 2012 Dec;126(6):835-44. doi: 10.1037/a0030248. Epub 2012 Oct 1.
Many different species of animals including mole rats, pigeons, and sea turtles are thought to use the magnetic field of the earth for navigational guidance. While laboratory rats are commonly used for navigational research, and brain networks have been described in these animals that presumably mediate accurate spatial navigation, little has been done to determine the role of the geomagnetic field in these brain networks and in the navigational behavior of these animals. In Experiment 1, anterior thalamic head direction (HD) cells were recorded in female Long-Evans rats while they foraged in an environment subjected to an experimentally generated magnetic field of earth-strength intensity, the polarity of which could be shifted from one session to another. Despite previous work that has shown that the preferred direction of HD cells can be controlled by the position of familiar landmarks in a recording environment, the directional signal of HD cells was not influenced by the polarity of the magnetic field in the enclosure. Because this finding could be attributed to the animal being insensitive or inattentive to the magnetic field, in Experiment 2, rats were trained in a choice maze task dependent on the ability of the animals to sense the polarity of the experimentally controlled magnetic field. Over the course of 28 days of training, performance failed to improve to a level above chance, providing evidence that the spatial behavior of laboratory rats (and the associated HD network) is insensitive to the polarity of the geomagnetic field.
包括裸鼹鼠、鸽子和海龟在内的许多不同种类的动物都被认为利用地球磁场进行导航。虽然实验室大鼠常用于导航研究，并且已经描述了这些动物中可能介导精确空间导航的脑网络，但在确定地磁场在这些脑网络以及这些动物的导航行为中的作用方面，几乎没有做过什么工作。在实验1中，在雌性Long-Evans大鼠在一个受到实验产生的地磁场强度的磁场环境中觅食时，记录了丘脑前头部方向（HD）细胞，该磁场的极性可以在不同的实验时段之间切换。尽管之前的研究表明，HD细胞的偏好方向可以由记录环境中熟悉地标物的位置控制，但HD细胞的方向信号不受封闭环境中磁场极性的影响。由于这一发现可能归因于动物对地磁场不敏感或不关注，在实验2中，大鼠在一个选择迷宫任务中接受训练，该任务依赖于动物感知实验控制磁场极性的能力。在28天的训练过程中，表现未能提高到高于随机水平，这证明实验室大鼠的空间行为（以及相关的HD网络）对地磁场的极性不敏感。
