Fachbereich Biologie, Tierphysiologie, Philipps-Universität Marburg, D-35032 Marburg, Germany.
J Insect Physiol. 2010 Aug;56(8):971-9. doi: 10.1016/j.jinsphys.2010.05.011. Epub 2010 May 26.
For spatial orientation and navigation, many insects derive compass information from the polarization pattern of the blue sky. The desert locust Schistocerca gregaria detects polarized light with a specialized dorsal rim area of its compound eye. In the locust brain, polarized-light signals are passed through the anterior optic tract and tubercle to the central complex which most likely serves as an internal sky compass. Here, we suggest that neurons of a second visual pathway, via the accessory medulla and posterior optic tubercle, also provide polarization information to the central complex. Intracellular recordings show that two types of neuron in this posterior pathway are sensitive to polarized light. One cell type connects the dorsal rim area of the medulla with the medulla and accessory medulla, and a second type connects the bilaterally paired posterior optic tubercles. Given the evidence for a role of the accessory medulla as the master clock controlling circadian changes in behavioral activity in flies and cockroaches, our data open the possibility that time-compensated polarized-light signals may reach the central complex via this pathway for time-compensated sky-compass navigation.
对于空间定向和导航，许多昆虫从蓝天的偏振模式中获得罗盘信息。沙漠蝗 Schistocerca gregaria 用其复眼的一个专门的背缘区域来检测偏振光。在蝗虫大脑中，偏振光信号通过前视神经束和神经节传递到中央复合体，中央复合体很可能作为内部天空罗盘。在这里，我们提出，通过附加的 medulla 和后视神经节的第二视觉通路的神经元也为中央复合体提供偏振信息。细胞内记录表明，这个后向通路中的两种类型的神经元对偏振光敏感。一种细胞类型将 medulla 的背缘区域与 medulla 和附加的 medulla 连接起来，第二种类型将双侧成对的后视神经节连接起来。鉴于附加的 medulla 作为控制苍蝇和蟑螂行为活动中昼夜节律变化的主时钟的证据，我们的数据为通过这条通路到达中央复合体的时间补偿偏振光信号用于时间补偿天空罗盘导航提供了可能性。
