Symposium 1

Abstract

Three-months old male mice from nine different inbred mouse strains were tested in two different spatial radial maze tasks: one in which the maze was turned by 45° between trials and one in which the maze was always placed in the same way. Only four out of eight arms contained food rewards, permitting simultaneous assessment of working (WM) and reference memory (RM) in both situations. Turning of the maze significantly decreased performance in a strain-dependent manner. Other animals from the same strains were processed histologically to estimate the strain-specific extents of the hippocampal intra- and infrapyramidal mossy fibre projections (IIPMF). The extents of the IIPMF correlated strongly with both WM and RM if the maze was turned between trials. Similar correlations were only found in the early phases of learning in the other condition. We conclude that the IIPMF are involved in spatial learning and that non-spatial within-maze cues may influence learning performance in some inbred strains.