Geometry-based navigation in the dark: Layout symmetry facilitates spatial learning in the house cricket, Acheta domesticus, in the absence of visual cues

Abstract

The capacity to navigate by layout geometry has been widely recognized as a robust navigational strategy. It was reported in various species, albeit most studies were performed with vision-based paradigms. In the presented study, we aimed to investigate layout symmetry-based navigation in the house cricket, Acheta domesticus, in the absence of visual cues. For this purpose, we used a non-visual paradigm modeled on the Tennessee Williams setup. We also verified the inaccessibility of visual cues for tested insects using antennal positioning reflex towards looming stimulus and by testing the performance of blinded crickets. In the main experiment, we tested the crickets capacity to learn to find a cool spot positioned centrally in heated arenas of different shapes (i.e., circular, square, triangular, and asymmetric quadrilateral). We found that the symmetry of the arena significantly facilitates crickets learning to find the cool spot, indicated by the increase of time spent on the cool spot and decrease of the latency of locating it in subsequent trials. To investigate possible mechanisms utilized by crickets during the experiment, we analyzed insects approach paths to the spot. The trajectories were grouped in four distinct clusters corresponding to both heuristic and directed strategies of approaching the target, with the dominance of a semi-directed strategy (thigmotactic phase preceding direct navigation to the target). Against these results, we discuss the possibility of insects navigation by using a non-visual space representation and possible limitations of navigation capacities in such conditions in relation to multimodally-guided navigation.