Rol of the hippocampus and homologue structures in a simple spatial orientation task.

MUZIO; DANERI

Christchurch, New Zealand.

Congreso; XIIIth Biannual Meeting of the International Society for Comparative Psychology.; 2006

International Society for Comparative Psychology.

Spatial orientation capability, a condition probably appeared early in evolution, is assume to be very important for survival. Mammals are able to build cognitive maps of the environment (hippocampus dependent capability) or to use basic orientation strategies (hippocampus independent capability). It is believed that the structural homologue of the mammal’s hippocampus, the medial pallium, is responsible for spatial orientation in amphibians. The implication of amphibian’s medial pallium in a simple rule spatial orientation task was studied. Adult male toads (Bufo arenarum) were divided in 3 groups: medial pallium lesion, intact and sham control. Animals were daily trained 3 trials per session in a plus maze for 20 sessions until the acquisition of a basic spatial orientation strategy: turn on the same direction (reward was always found turning on a certain constant direction in the maze). Lesioned animals showed impaired performance during acquisition of the orientation task, while animals of control groups acquired the orientation response. This result suggests that, contrary to the observed in mammal’s hippocampus, the medial pallium is responsible for basic spatial orientation strategies in amphibians. Thus, hippocampus and medial pallium seem to be not fully functional homologue structures.