Spatial navigation in amphibians: Importance of the medial pallium

SOTELO, M. I., DANERI, M. F., BINGMAN, V. P. & MUZIO, R. N.

Montevideo

Congreso; XII Congress of the International Society for Neuroethology (ICN2016); 2016

International Society for Neuroethology

Although of crucial importance in vertebrate evolution, amphibians are rarely considered in studies of comparative cognition. Previously, we demonstrated in a goal location task that toads can use both boundary geometry and visual features to navigate, but they preferentially use geometry. Briefly, using water as reward, we first trained two groups of the toad Rhinella arenarum in a Geometry-Only task and Geometry?Feature task. In the former task, experimental toads, partially dehydrated, were trained to find water in a rectangular arena with no predictive information available other than the arena?s boundary geometry. In the latter task, the toads were trained in the same rectangular arena, but with a colored panel placed on one of the walls. We then analyzed the neural activity associated with performance of the two tasks by mapping c-Fos/IEG immunostaining. Results showed that the Medial Pallium, presumptive homologue of the mammalian hippocampus, displayed increased activity in animals that were trained in both tasks when compared to a control group with no prior training. The findings resemble those found in other vertebrate groups suggesting a conserved role of hippocampal homologues in boundary geometry-guided, spatial cognition. We also found that the Dorsal Pallium and Lateral Pallium were differentially activated only when visual features could be used for locating the goal (Geometry?Feature group), suggesting a role of these forebrain regions in feature-guided behavior.