ИСТИНА

Yaskin V.A. Seasonal modulation of sex differences in hippocampus size and spatial behavior in Sorex // Advances in the biology of shrews III. Syktyvkar, Komi Republic, Russia. September 14-17. Materials of the International Conference. Moscow, KMK. 2010. P. 80. The hippocampus is involved in processing of spatial information on the environment; its size is known to correlate positively with spatial ability. Seasonal modulation of the sex differences in the hippocampus size and spatial behavior was revealed in Sorex araneus and S. minutus. Sexual dimorphism in both the hippocampus size and spatial activity or mobility became distinct (favoring males) in the early spring when sexual maturation of the shrews began. During the breeding season males of S. araneus and S. minutus were found to be significantly more mobile than females. The absolute and relative masses of the male hippocampus were larger by 5–7% (p < 0.05) compared with females in S. araneus. There were no distinctive sex differences in hippocampus size and spatial behavior in nonbreeding season during autumn and winter months. In S. minutus the absolute and relative masses of the hippocampus in adult males were higher by 5–9% (p < 0.05) than in females. In this species some less distinctive sexual differences (favoring males) were found in immatures in the autumn. Sex differences in the structure of hippocampus and spatial behavior are even more likely to be the result of an interaction between genotype and environment, with such interactions mediated by gonadal and adrenal hormones.