Grob Robin, Fleischmann Pauline N, Grübel Kornelia, Wehner Rüdiger, Rössler Wolfgang
Behavioral Physiology and Sociobiology (Zoology II), Biozentrum, University of Würzburg, Würzburg, Germany.
Brain Research Institute, University of Zürich, Zürich, Switzerland.
Front Behav Neurosci. 2017 Nov 14;11:226. doi: 10.3389/fnbeh.2017.00226. eCollection 2017.
Central place foragers are faced with the challenge to learn the position of their nest entrance in its surroundings, in order to find their way back home every time they go out to search for food. To acquire navigational information at the beginning of their foraging career, performs learning walks during the transition from interior worker to forager. These small loops around the nest entrance are repeatedly interrupted by strikingly accurate back turns during which the ants stop and precisely gaze back to the nest entrance-presumably to learn the landmark panorama of the nest surroundings. However, as at this point the complete navigational toolkit is not yet available, the ants are in need of a reference system for the compass component of the path integrator to align their nest entrance-directed gazes. In order to find this directional reference system, we systematically manipulated the skylight information received by ants during learning walks in their natural habitat, as it has been previously suggested that the celestial compass, as part of the path integrator, might provide such a reference system. High-speed video analyses of distinct learning walk elements revealed that even exclusion from the skylight polarization pattern, UV-light spectrum and the position of the sun did not alter the accuracy of the look back to the nest behavior. We therefore conclude that uses a different reference system to initially align their gaze directions. However, a comparison of neuroanatomical changes in the central complex and the mushroom bodies before and after learning walks revealed that exposure to UV light together with a naturally changing polarization pattern was essential to induce neuroplasticity in these high-order sensory integration centers of the ant brain. This suggests a crucial role of celestial information, in particular a changing polarization pattern, in initially calibrating the celestial compass system.
中心地觅食者面临着一项挑战，即要了解其巢穴入口在周围环境中的位置，以便每次外出觅食后都能找到回家的路。为了在觅食生涯开始时获取导航信息，工蚁在从内勤工蚁转变为觅食者的过程中会进行学习行走。这些围绕巢穴入口的小环线会被极其精确的向后转弯反复打断，在此期间蚂蚁会停下来并精确地回头看向巢穴入口——大概是为了学习巢穴周围环境的地标全景。然而，由于此时完整的导航工具包尚未具备，蚂蚁需要一个路径积分器罗盘组件的参考系统，以校准它们朝向巢穴入口的视线。为了找到这个方向参考系统，我们系统地操控了蚂蚁在自然栖息地学习行走期间接收到的天窗信息，因为此前有人提出，作为路径积分器一部分的天体罗盘可能会提供这样一个参考系统。对不同学习行走元素的高速视频分析表明，即使排除天窗偏振模式、紫外光谱和太阳位置等因素，也不会改变回头看向巢穴行为的准确性。因此，我们得出结论，蚂蚁使用不同的参考系统来初步校准它们的视线方向。然而，对学习行走前后中央复合体和蘑菇体神经解剖学变化的比较表明，暴露在紫外线下以及自然变化的偏振模式对于在蚂蚁大脑这些高阶感觉整合中心诱导神经可塑性至关重要。这表明天体信息，特别是变化的偏振模式，在最初校准天体罗盘系统中起着关键作用。
