Relationships among cardiovascular, muscular, and oxytocin responses during human sexual activity.

To determine the psychophysiological correlates of hormonal response during sexual activity, systolic blood pressure (SBP), anal electromyography (EMG), and anal photoplethysmography (APG) were monitored continuously throughout testing in 13 women and 10 men. Each subject completed two or more tests of self-stimulation to 5 min beyond orgasm. Blood samples were obtained continuously for measurement of oxytocin (OT) levels. In both men and women, very high positive correlations were observed between the percentage change in levels from baseline through orgasm of: OT and SBP; OT and EMG intensity prior to and during orgasm; APG and EMG. The number of anal contractions and duration of orgasm were also highly correlated. Two patterns of orgasm were defined by the presence or absence of a quiescent period between orgasmic contractions. EMG and APG amplitudes correlated with the pattern of orgasm. Subjective orgasm intensity correlated significantly with increased levels of OT in multiorgasmic women only. The positive correlations between measures are consistent with a possible functional role for OT in human sexual response.

The emission and elicitation of mouse ultrasonic vocalizations: the effects of age, sex and gonadal status.

Subject' mice of varying gonadal status (castrate males; intact or neonatally gonadectomized females and males) were paired for 3-min with intact 'stimulus' females and ultrasonic vocalizations were monitored. Vocalization patterns from home cages differed from the test pairings. The results suggested that the age, experience and gonadal status of the subject influenced the vocalizations from the pair. As the source of ultrasonic calls from these vocally intact pairs could not be individually identified, the 'subjects' were paired with a range of ultrasonically silent (inferior laryngeal nerve-transected) stimulus animals. Vocalizations were detected from all combinations of animals. Gonadally intact females were most effective in eliciting ultrasonic vocalizations from the subjects and gonadally intact males were least effective. The responses of castrate males were lower than from intact males. Anesthetized adults of either sex elicited only poor vocalization responses from other adults. Ultrasonic calls have often previously been studied using vocally intact 'subject' and 'stimulus' animals: the present results confirm the difficulty of establishing who is who in such situations.

Long-term monitoring of mouse ultrasonic vocalizations.

The temporal pattern of ultrasonic vocalizations by mice in an undisturbed 'home' environment can now be assessed using a system based on amplitude discrimination. Within a chosen frequency band, vocalizations of sufficient intensity are detected by an amplitude discriminator. The output from a pulse generator is sent to a microcomputer which records the time of the incoming event. The system has been validated for monitoring ultrasonic vocalizations in the mouse.