Boundary primacy in spatial mapping: evidence from zebrafish (Danio rerio)

The ability to map locations in the surrounding environment is crucial for any navigating animal. Decades of research on mammalian spatial representations suggest that environmental boundaries play a major role in both navigation behavior and hippocampal place coding. Although the capacity for spatial mapping is shared among vertebrates, including birds and fish, it is not yet clear whether such similarities in competence reflect common underlying mechanisms. The present study tests cue specificity in spatial mapping in zebrafish, by probing their use of various visual cues to encode the location of a nearby conspecific. The results suggest that untrained zebrafish, like other vertebrates tested so far, rely primarily on environmental boundaries to compute spatial relationships and, at the same time, use other visible features such as surface markings and freestanding objects as local cues to goal locations. We propose that the pattern of specificity in spontaneous spatial mapping behavior across vertebrates reveals cross- species commonalities in its underlying neural representations.