[Effect of various periods of social isolation of juvenile rats on the level of their intraspecies aggression at a sexually mature age].

Isolation of male outbred white rats from the same age rats at 12-30 and 15-30 days of postnatal life increases their aggressiveness in pubertal age and causes a change of aggressive reactions spectrum towards the decrease of attacks and increase of threats in relation to intruders. These changes in the ontogenetic formation of rats aggressive behaviour are not compensated by the experience of rats social intercourse in the period 30-70th days. A hypothesis is made about the existence of sensitive period of rats aggressive behaviour formation with the approximate limits 15th-30th days of postnatal life during which under the influence of contacts with rats of the same age prerequisites are created for consolidation of various agonistic reactions in resultant act of mature aggression.