Social-olfactory experience and initiation of copulation in the virgin male rat.

Two experiments examined the role of olfactory sensation for initiation of normal copulatory behavior of mature male rats. Experiment 1 compared copulatory performance of peripherally anosmic social isolates with that of intact isolate controls. The results revealed significantly lower mounting, intromission, and ejaculation frequencies of the anosmic group and suggested that nonolfactory cues attain significance via an associative-learning process. Experiment 2 compared three social isolate groups of mature males with varying sexual experience prior to anosmia. Four 1-hr tests were conducted at 5-day intervals. The results indicated comparable copulatory performance of the experienced groups and absence of copulation by the majority of the nonexperienced group. With a 12-day continuous exposure to intact females, all noncopulators eventually impregnated. The results are discussed with reference to the requirement of social experience for initiation of normal sexual performance in the male rat.