The development of olfactory conditioned ejaculatory preferences in the male rat II. Parametric manipulation of conditioning session number and duration

We have previously demonstrated that repeated pairing of a neutral odor wit h copulation produces a subsequent conditioned ejaculatory preference (CEP) for females bearing that odor. The present study examines the course of CE P development. In Experiment 1, Long-Evans male rats were allowed access to almond-scented, sexually receptive females for either one, five, or nine c onditioning sessions that were 30 min in duration. Males given five or nine sessions displayed significant CEPs. In Experiment 2, male rats were given a single conditioning session with multiple almond-scented females until e ither a duration (60, 120, 180, or 240 min) or copulatory criterion (two, f our, or six ejaculatory series) was satisfied. Mates that received 120-, 18 0-, or 240-min sessions or four ejaculations displayed significant CEPs; ma les that received two or six ejaculations displayed a trend for CEPs. Analy sis of effect size estimates revealed that the strongest CEPs were produced by 120 min of copulation or four ejaculations. In Experiment 3, males rece iving nine conditioning sessions each 30 min in duration displayed a more e nduring CEP than did males receiving a single conditioning session 240 min in duration. These data suggest that early sexual experiences have particul arly powerful influences on subsequent sexual preferences and that the deve lopment of sexual preferences are influenced by interactions between CS-UCS pairings and motivational variables. (C) 2001 Elsevier Science Inc. All ri ghts reserved.