Spatial reversal learning deficit after medial cortex lesion in turtles.

Many comparative pieces of research support the hypothesis that the medial cortex region of the reptilian forebrain could be homologous to hippocampal formation. Besides, there is some evidence involving this structure in complex spatial learning in a similar manner to hippocampus of mammals and birds. In this experiment we examined effects of medial cortex lesion in reversal learning. Turtles were trained in a spatial and a non-spatial maze procedure and the reversal of these tasks. Data revealed that sham and medial cortex lesioned turtles of both procedures performed well on the initial learning (acquisition). However, during the reversal phase, only the turtles with medial cortex lesion showed impaired performance in the spatial procedure. These results suggest that turtles possess different spatial learning and memory systems in close parallel to those described in other vertebrates, and that medial cortex plays a crucial role in complex place learning.