Neuroanatomical divergence between two substrains of C57BL/6J inbred mice entails differential radial-maze learning.

Compared to the parental strain C57BL/6J, male mice from the mutated substrain C57BL/6JNmg show smaller hippocampal intra- and infrapyramidal mossy fiber projections and a correlated inability to master a simple spatial radial-maze task. Possibly, these two substrains differ for only one single gene, making them a valuable model to investigate the physiological pathways leading from genotype to neurobehavioral phenotype.