Wystrach Antoine, Schwarz Sebastian, Graham Paul, Cheng Ken
Centre de Recherches sur la Cognition Animale, CNRS, Université Paul Sabatier, 31062, Toulouse, France.
School of Life Sciences, University of Sussex, John Maynard Smith Building, Falmer, Brighton, Sussex, BN1 9QG, UK.
Anim Cogn. 2019 Mar;22(2):213-222. doi: 10.1007/s10071-019-01236-7. Epub 2019 Jan 25.
Ants are expert navigators, keeping track of the vector to home as they travel, through path integration, and using terrestrial panoramas in view-based navigation. Although insect learning has been much studied, the learning processes in navigation have not received much attention. Here, we investigate in desert ants (Melophorus bagoti) the effects of repeating a well-travelled and familiar route segment without success. We find that re-running a homeward route without entering the nest impacted subsequent trips. Over trips, ants showed more meandering from side to side and more scanning behaviour, in which the ant stopped and turned, rotating to a range of directions. In repeatedly re-running their familiar route, ants eventually gave up heading in the nestward direction as defined by visual cues and turned to walk in the opposite direction. Further manipulations showed that the extent and rate of this path degradation depend on (1) the length of the vector accumulated in the direction opposite to the food-to-nest direction, (2) the specific visual experience of the repeated segment of the route that the ants were forced to re-run, and (3) the visual panorama: paths are more degraded in an open panorama, compared with a visually cluttered scene. The results show that ants dynamically modulate the weighting given to route memories, and that fits well with the recent models, suggesting that the mushroom bodies provide a substrate for the reinforcement learning of views for navigation.
蚂蚁是专业的导航者，它们在行进过程中通过路径积分追踪回家的方向，并在基于视图的导航中利用地面全景。尽管昆虫学习已得到大量研究，但导航中的学习过程却未受到太多关注。在此，我们研究了沙漠蚂蚁（巴氏美澳蚁）重复走过一条熟悉的路线段却未成功返回蚁巢的影响。我们发现，在未进入蚁巢的情况下重新走过一条回家的路线会影响后续行程。在多次行程中，蚂蚁表现出更多的左右迂回以及更多的扫描行为，即蚂蚁会停下来转身，转向一系列不同方向。在反复重新走过它们熟悉的路线时，蚂蚁最终放弃了按照视觉线索所定义的朝向蚁巢的方向行进，转而朝相反方向行走。进一步的实验表明，这种路径退化的程度和速度取决于：（1）在与食物到蚁巢方向相反的方向上积累的向量长度；（2）蚂蚁被迫重新走过的路线重复段的特定视觉体验；（3）视觉全景：与视觉杂乱的场景相比，在开阔全景中路径退化更严重。结果表明，蚂蚁会动态调整赋予路线记忆的权重，这与最近的模型非常契合，表明蘑菇体为导航视图的强化学习提供了一个基础。
