Properties of mapping induced by fornix damages: Learning and memorizing the radial maze task

A correlational analysis of learning scores and degrees of divergence of the patterns of choice was performed in fornix-damaged, sham-operated, and control rats during the acquisition stage of the radial maze task. The results show that dorsal fornix sections, which initially reduce choice accuracy, induce the parallel adoption of weakly divergent patterns of choice. The positive correlation observed during the course of training between these two dependent variables suggests that fornix-damaged animals learn the task on the basis of specific gathering and processing of information: initial choice of few proximal paths with progressive increases in the number of visited paths under the control of reinforcement determines a correlative increase in the degrees of divergence of the patterns of choice. This observation indicates that mapping in lesioned animals occurs through the progressive introduction of new spatial elements in an initial sectorial exploratory system, whereas sham-operated and control animals immediately process more information on the total configuration of the apparatus. This particular gathering and processing of spatial information could determine specific reference and working memory processes in lesioned animals.