Spatial navigation in amphibians: Importance of the medial pallium

MARÍA FLORENCIA DANERI; VERNER PETER BINGMAN; MARÍA INÉS SOTELO; RUBÉN NÉSTOR MUZIO

Montevideo

Congreso; International Congress of Neuroethology; 2016

International Society for Neuroethology

Despite their transformative importance in vertebrate evolution, amphibians are scarcely considered in studies of comparative cognition. Using water as reward, we first trained terrestrial toads, Rhinella arenarum, in two navigational tasks to test whether they could use geometry (Geometry Only task) or visual cues + geometry (Geometry?Feature task) to locate a goal. Subsequent memory-probe trials showed that animals could use both kinds of information to find the goal location and that they preferred geometry when set in conflict. Postmortem cFos IHC showed a higher number of cFos+ cells in the medialpallium (MP) of the trained groups (Geometry Only and Geometry-Feature groups)compared to a Control group with no training. Increased activation of cFos+ cells was also recorded in the lateral and dorsal pallia, but only for the Geometry-Feature group.In a second experiment, we tested the effect of MP lesion on performance in theGeometry-Feature task. Control, Sham and Lesioned animals were trained and tested.MP-lesioned animals displayed more errors on geometry probe tests and a paralleltendency to rely more on the visual cue on conflict probe tests compared to the Control and Sham groups. Our concluson of a medial pallium important for the encoding and use of geometry is in agreement with findings from other vertebrate species such as pigeons and rats.