Passive avoidance learning in the toad Bufo arenarum.

PUDDINGTON, M. M. & MUZIO, R.N.

Buenos Aires

Congreso; XIVth Biannual Meeting of the International Society for Comparative Psychology.; 2008

International Society for Comparative Psychology (ISCP, USA)

During a passive avoidance procedure animals must inhibit a response to avoid an aversive stimulus. This kind of learning has been widely studied in mammals, but little is known in others vertebrates groups. Our work presents a passive avoidance procedure in the toad Bufo arenarum for comparative studies. Toads were trained in a one-way shuttle box with two compartments, one lighted and another one dark. Animals began each trial in the lighted compartment. When they moved to the dark compartment, an aversive stimulus (NaCl saline solution, 800mM) was delivered. This stimulus was used since they produce dehydration, and lost of weight. A control group was also trained with a saline solution of lower concentration (300mM), which produces neither gain nor lost of weight. Results showed that toads are able to inhibit its response in order to avoid an unpleasant event. Preliminary data of another experiment with lesioned animals in the striatum (homologous area of the amygdala of mammals) are shown, suggesting a central role of that region in this learning. Since amphibians have no neocortex, the use of this animal model constitutes a tool in the identification of basic components of this learning in absence of a strong cortical modulation.