Zebrafish use visual cues and geometric relationships to form a spatial memory

Abstract

Animals use salient cues to navigate in their environment, but their specific cognitive strategies are largely unknown. We developed a conditioned place avoidance paradigm to discover whether and how zebrafish form spatial memories in a Y-shaped maze. Juvenile zebrafish, older than three weeks, learned to avoid the arm of the maze that was cued with a mild electric shock. We found that the fish required distinct visual patterns to develop a conditioned response. Interestingly, individual fish solve this task in different ways: by staying in the safe center of the maze, by preference for one, or both, of the safe patterns, or by mixed strategies. In experiments in which the learned patterns were swapped, rotated or replaced, the animals could transfer the association of safety to a different arm or to a different pattern using either visual cues or location as the conditioned stimulus. These findings show that juvenile zebrafish exhibit several complementary spatial learning modes and pave the way for neurobiological studies of navigational mechanisms in this model species.