Diferente activación neural del Striatum y el Pallium Medial durante el aprendizaje apetitivo y aversivo en sapos (Rhinella arenarum)

PUDDINGTON, MARTIN; DANERI, M. FLORENCIA; MUZIO, RUBEN N.

Chascomús, Buenos Aires

Congreso; XV Jornadas de la Sociedad Argentina de Biología; 2013

Sociedad Argentina de Biología

The Striatum and the Medial Pallium are two amphibians? telencephalic areas considered homologous of the mammals amygdala and hippocampus respectively. The amygdala is one of the main structures implicated in aversive learning and fear expression and the hippocampus was associated with the spatial memory. The functional equivalence hypothesis stands that the function of the structure is conserved between mammals and amphibians. We conducted three different experiments in which animals are trained using appetitive or aversive reinforcement. In all cases toads were previously dehydrated till the 80% of their weight.In experiment 1, animals were trained in a passive avoidance task. They were placed in the illuminated compartment of a shuttle box that had also a dark compartment. As these animals have a preference for darknes, the time that the toads spent in the illuminated compartment was observed, and once they passed to the dark compartment, an aversive stimuli was administrated. In experiment 2, the toads were placed in the starting box of a runway and the time spent to reach the goal box containing dehinized water was measured. In experiment 3 animals were trained in an openfield where four pools were available and only one contained water. Toads were aloud to use a visual key to spacialy orientate and choose the correct pool. In each procedure, after acquisition animals were scarified and brains were processed with the AgNor technique in order to measure Striatum`s and Medial Pallium`s activity. The Striatum showed more activation in the first experiment but not in the others. Medial pallium`s activity was enhanced only in the third experiment. These results were predicted by the functional equivalence hypothesis.