Water-maze learning in the mouse correlates with variation in hippocampal morphology

We studied mouse learning performance in a water-maze task in order to explore the relations between heritable structural variation in the hippocampus and spatial learning abilities. Based on previous findings we hypothesized a relation between spatial learning abilities and the size of the intra- and infrapyramidal mossy fiber (iip-MF) terminal field. Factor analysis revealed that learning in this water maze has two components: one related to apparatus-induced activity and one related to maze-learning ability. The size of the iip-MF terminal field covaried negatively with the activity-related component but positively with the spatial-learning component. These findings are in agreement with previous results obtained for shuttle-box learning.