Effect of lesions of the medial pallium on the use of visual cues in spatial learning in amphibians.

DANERI, M.F.; CASANAVE E.B.; MUZIO, R.N.

Huerta Grande, Córdoba, 4 al 6

Congreso; I Reunión Conjunta de Neurociencias.; 2009

Soc. Arg. de Investig. en Neurociencias y Taller Arg. de neurociencias

We are analyzing the neural mechanisms that rule the spatial learning, looking for common patterns potentially present in a common ancestor to several classes of vertebrates. It is known that the mammalian hippocampus is an important structure involved in spatial learning; but yet, its function in other vertebrates such as amphibians is unknown. Amphibians have an area supposed to be homologous to the mammalian hippocampus, the medial pallium. The main goal of the present work was to study the implication of this structure in a simple spatial orientation task. Eighteen partially dehydrated toads (Bufo arenarum) were divided in 3 groups: Medial pallium lesioned, Intact and Sham controls. Animals were daily trained in a plus maze for 10 sessions (3 trials per session) for the acquisition of a basic spatial orientation strategy: use of a visual cue to reach a container full of water (this reward was always associated with the visual cue in the maze). Animals of both control groups acquired the spatial orientation, but the lesioned animals never reach the goal. This result suggests that medial pallium is involved in basic spatial orientation strategies in amphibians and, therefore, it is possible that hippocampus and medial pallium be partially functional equivalents.