[The features of the hippocampal structure as a neuroanatomical basis for differences in behavior]

Neuromorphological and behavioural studies have been made on several strains of mice (C57B1, DBA/2, SEC) and on the spiny mouse Acomys cahirinus. It was shown that animals with different genotypes differ by the size of fascia dentata and by the extension of the pyramidal layer in CA3 field of the hippocamp. Animals with a higher learning capacity exhibited smaller layer of granular cells in the fascia dentata, which may be due to a lower density of neurones in this region. Terminals of the mossy fibers--the axons of granular cells--were found mainly on the apical dendrites of the pyramidal cells in CA3 field. On the contrary, in animals with lower capacities to learning, mossy fiber terminals were observed mainly on the basal dendrites of the pyramidal cells, the extent of the granular layer in these animals being significantly larger.