CORRELATIONS BETWEEN RADIAL-MAZE LEARNING AND STRUCTURAL VARIATIONS OF SEPTUM AND HIPPOCAMPUS IN RODENTS

Large, but non-pathological, individual differences in neuroanatomy of the brain exist in rodents, which have been shown to covary with beha vioral traits. In the present review, we explore the relationship betw een variations in the extent of the intra- and infrapyramidal messy fi ber projection of the hippocampus and spatial and non-spatial learning capacities in mice and rats. Preliminary data concerning anatomical v ariation in the septo-hippocampal cholinergic system and its consequen ces for individual behavior are also presented. We conclude that the h ippocampal intra- and infrapyramidal messy fiber projection is intimat ely involved in the regulation of spatial, but not of non-spatial lear ning capabilities. Although lesion studies have shown that a well-func tioning cholinergic system is a prerequisite for performance in spatia l learning tasks, our preliminary data suggest that individual differe nces in the cholinergic system do not explain individual differences i n learning.