Spatial Cognition in Teleost Fish: Strategies and Mechanisms

SIMPLE SUMMARY: The study of the neurobiological basis of spatial cognition has been demonstrated to be one of the most exciting, successful, and productive research fields in neuroscience. An enormous number of experimental results on the brain mechanisms of navigation have been obtained over several decades and a number of theories and detailed mechanistic computational models have been developed to account for these data obtained mainly in mammals and birds. Recently, the use of teleost fish species as animal models in neurobiology has exponentially increased, nicely complementing the use of traditional mammalian models in basic and translational neuroscience research. Comparative neurobiological research has shown that teleost fish can use a variety of navigational strategies that closely resemble those described in mammals and birds. Although some of these similarities could indicate evolutionary convergence shaped by common environmental constraints and survival requirements, at least some of these strategies seem to be based on conserved neural substrata likely shared with land vertebrates, suggesting that these strategies and their neurobiological basis could have appeared very early on during vertebrate evolution. ABSTRACT: Teleost fish have been traditionally considered primitive vertebrates compared to mammals and birds in regard to brain complexity and behavioral functions. However, an increasing amount of evidence suggests that teleosts show advanced cognitive capabilities including spatial navigation skills that parallel those of land vertebrates. Teleost fish rely on a multiplicity of sensory cues and can use a variety of spatial strategies for navigation, ranging from relatively simple body-centered orientation responses to allocentric or “external world-centered” navigation, likely based on map-like relational memory representations of the environment. These distinct spatial strategies are based on separate brain mechanisms. For example, a crucial brain center for egocentric orientation in teleost fish is the optic tectum, which can be considered an essential hub in a wider brain network responsible for the generation of egocentrically referenced actions in space. In contrast, other brain centers, such as the dorsolateral telencephalic pallium of teleost fish, considered homologue to the hippocampal pallium of land vertebrates, seem to be crucial for allocentric navigation based on map-like spatial memory. Such hypothetical relational memory representations endow fish’s spatial behavior with considerable navigational flexibility, allowing them, for example, to perform shortcuts and detours.