Does the Menstrual Cycle Play a Role in Sexual Arousal?

Menstrual cycle effects on erotic arousability were tested in 13 women aged 20–28. Vaginal blood volume and pulse amplitude were measured with a light emitting diode photoplethysmograph, labial temperature was measured by a small thermistor, and subject self-report of arousal was estimated on a 7-point Likert scale in response to audio erotic tapes and fantasy over five different phases of the menstrual cycle. Pre-session levels of blood volume and labial temperature showed no important changes across the cycle, but pooled blood volume, pulsatile blood volume and labial temperature reliably demonstrated sexual arousal during tape and fantasy sessions. Repeated measures analyses of variance and covariance of physiological change scores from baseline and subjective ratings failed to demonstrate that significant changes in self-reports, vaginal blood volume, vaginal pulse amplitude, or labial temperature occurred as a function of menstrual cycle phase. This study provides objective physiological evidence that there appears to be no one phase in the menstrual cycle during which women are more sexually arousable to erotic stimuli as detected by these physiological measures.     

An in vivo comparison of two circumferential penile strain gauges: The introduction of a new calibration method

This study assessed the comparability of two types of penile strain gauges using both a circular and a newly developed oval calibration device. A group of 25 sexually functional participants places both an electromechanical and an indium/gallium-in-rubber strain gauge on the penis and viewed an erotic film. The electromechanical gauge as calibrated on the circular device resulted in greater penile circumference changes than the indium/gallium-in-rubber gauge. Mean circumference changes were not different for the two strain gauges when the oval calibration device was used. The use of an oval calibration device improves ecological validity of calibration of penile strain gauges. Standard inclusion of this method in studies on male sexual response will increase comparability of research findings.     

Abdominal Temperature Changes During Male Sexual Arousal

The present study explored the feasibility of using temperature measurement from a non-genital location to assess sexual arousal. Based upon analyses conducted with thermographic techniques, it was hypothesized that abdominal skin cooling would occur during sexual arousal. In 2 sessions, 6 male subjects were shown low, moderate, and high arousing erotic films. Simultaneous measures of abdominal temperature, penile circumference, and subjective arousal were taken. Results indicate that while decreases in skin temperature were seen during arousal, thermister data did not correlate well with tumescence or subjective arousal ratings. It would appear that thermography and temperature measurement might be most fruitfully employed to explore basic physiological processes involved in sexual arousal, since continuous temperature measures do not appear sensitive enough for use in typical sex research paradigms.     

Sex differences in concordance rates between auditory event‐related potentials and subjective sexual arousal

Much research indicates men show a greater concordance between subjective and genital sexual arousal than do women. We investigated the relationship between subjective sexual arousal and brain activation in men and women. Subjective sexual arousal and auditory N1 and P3b ERP amplitudes were measured while 38 participants viewed erotic and non‐erotic films. Most notably, there was a significant correlation between N1 amplitude and sexual arousal in men; for women, there was a significant correlation between the P3b amplitude and sexual arousal. ERP amplitudes were inversely associated with reported arousal, suggesting that sexual arousal interferes with early tone processing for men, and with later tone processing for women. Lastly, for women, pornography/erotica consumption was negatively correlated with P3b amplitudes, suggesting that women who consume more pornography/erotica may also show greater attention to erotic films.     

Penile Anatomy and Hypotheses of Erectile Function in the American Alligator (Alligator mississippiensis): Muscular Eversion and Elastic Retraction

The intromittent organs of most amniotes contain variable‐volume hydrostatic skeletons that are stored in a flexible state and inflate with fluid before or during copulation. However, the penis in male crocodilians is notable because its shaft does not seem to change either its shape or bending stiffness as blood enters its vascular spaces before copulation. Here I report that crocodilians may have evolved a mechanism for penile shaft erection that does not require inflation and detumescence. Dissections of the cloaca in sexually mature male American alligators (Alligator mississippiensis) show that the cross section of the proximal shaft of the alligator penis contains dense collagenous tissues that do not significantly change shape when fluid is added to the central vascular space. The large amount of collagen in the wall and central space of the alligator penis stiffen the structure so it can be simply everted for copulation and rapidly retracted at its completion. Because no muscles insert directly onto the penis, eversion and retraction must be produced indirectly. My results suggest that the contraction of paired levator cloacae muscles around the anterior end of the cloaca rotates the penis out of the cloacal opening and strains the ligamentum rami that connect the base of the penis to the ischia. When the cloacal muscles relax, the elastic recoil of the ligamentum rami can return the penis to its original position inside the cloaca. Anat Rec, 296:488–494, 2013. © 2013 Wiley Periodicals, Inc.     

Physiological and psychological stress reactivity in chronic tinnitus

Several models of tinnitus maintenance emphasize the importance of cognitive, emotional and psychophysiological processes. These factors contribute to distress in patients with decompensated tinnitus symptoms. We investigated whether tinnitus patients show increased physiological levels of arousal, more intense stress reactivity patterns and exaggerated psychological strain compared to healthy controls. Seventy tinnitus patients and 55 healthy controls underwent various stress tests. Muscular reactivity and peripheral arousal as well as strain ratings were assessed. Tinnitus patients reported significantly more strain during stress tests compared to healthy controls. Few physiological reactivity patterns differed significantly between the two groups. The physiological data thus only partly supported a hyperreactivity hypothesis. Strain reports and physiological data were only marginally correlated. Tinnitus patients show maladaptive appraisal processes during stress exposure, yet physiological reactivity is only slightly affected. Treatment programs for patients with decompensated tinnitus symptoms should account for appraisal processes and coping mechanisms in stressful situations.     

Facial Electromyography: A Measure of Affective Processes During Sexual Arousal

Forty female volunteers participated in a study to investigate whether facial EMGs could be used as measures of affect during sexual arousal. Audiotaped narratives were used to induce the following affect-sexual states: 1) pleasant affect + sexual arousal, 2) unpleasant affect + sexual arousal, 3) pleasant affect + no sexual arousal, and 4) unpleasant affect + no sexual arousal. EMG activity was recorded bilaterally from the corrugator and zygomatic muscle regions. Corrugator muscle activity was significantly greater in response to the unpleasant stimulus conditions. This relationship held for both the non-sexual and sexual conditions, suggesting that corrugator muscle activity may provide a reliable index of negative affect during sexual arousal. Zygomatic activity was significantly greater during the sexual as compared to the non-sexual stimuli, but did not increase as a function of pleasant affect. Greater left than right corrugator muscle activity was observed in response to the sexual stimuli. Left muscle superiority was also noted for zygomatic muscle activity, in response to the sexual unpleasant stimulus. Issues related to the interpretation of lateralized muscle activity are discussed.     

On the function of groaning and hyperventilation during sexual intercourse: intensification of sexual experience by altering brain metabolism through hypocapnia

Sexual arousal is accompanied by some typical physiological reaction patterns. Another typical feature of sexual intercourse is involuntary sound production implying in its more intense forms acceleration of breathing (hyperventilation). Up to now no study examined spCO2 during intense sexual intercourse, but there is evidence that some degree of hyperventilation with its physiological consequences may often be induced during sexual intercourse. This article discusses implications of hyperventilation during sexual intercourse for alterations of consciousness and subjective experience in the light of recent studies of brain metabolic changes during states of hyperventilation. Groaning and hyperventilation are interpreted in this context as a psychophysiological mechanism to deepen states of sexual trance.     

Physiological Assessment of Sexual Arousal in Women

The purpose of this investigation was to validate the use of vaginal photoplethysmography along with six other physiological measures for the assessment of sexual arousal in women. Six women in counterbalanced order were presented control, dysphoric, and sexually arousing videotapes. Subjective ratings revealed that subjects experienced moderate levels of sexual and anxiety arousal during the videotapes, and comprehension quizzing at the end of the experiment showed that subjects attended to the content. Heart rate, heart rate variability, and skin conductance response failed to discriminate between any of the videotapes. In order from highest to lowest sensitivity, vaginal blood volume, skin conductance, systolic and diastolic blood pressure, and forehead temperature showed significant increases during the erotic videotape. Though sensitive, skin conductance appeared to he unreliable. Areas for further research were identified.     

Effects of fragrance on female sexual arousal and mood across the menstrual cycle

The effects of fragrance on sexual response in women were investigated using subjective and physiological measures of sexual arousal and of mood. Responses were obtained from female participants in three different fragrance conditions (female fragrance, male fragrance, and a "blank" or neutral substance), as they viewed erotic and sexually neutral films, and fantasized about sexual situations. Each woman was tested twice: during the midfollicular and periovulatory phases of her menstrual cycle. Menstrual cycle phase effects were apparent; self-report data indicated greater sexual arousal and more positive mood during the periovulatory than during the follicular phase. Results demonstrated a positive effect of the male fragrance on genital arousal during erotic fantasy, but this finding was apparent only during the follicular phase testing session. This effect did not appear to be mediated by any effects of fragrance on mood.     

Effects of androstenol on human sexual arousal

The hypothesis that 5-alpha-androst-16-en-3 alpha-ol increases the sexual arousal of the human female was examined. This substance is produced by the male and has been suggested to be a possible human pheromone. Groups of female subjects were asked to read either a neutral or a sexually-arousing passage in the presence of either androstenol or a placebo. Although sexual arousal was clearly manipulated by the experimental conditions, there was no evidence that androstenol influenced sexual feelings.     

Uncovering category specificity of genital sexual arousal in women: The critical role of analytic technique

Based on analytic techniques that collapse data into a single average value, it has been reported that women lack category specificity and show genital sexual arousal to a large range of sexual stimuli including those that both match and do not match their self‐reported sexual interests. These findings may be a methodological artifact of the way in which data are analyzed. This study examined whether using an analytic technique that models data over time would yield different results. Across two studies, heterosexual (N = 19) and lesbian (N = 14) women viewed erotic films featuring heterosexual, lesbian, and gay male couples, respectively, as their physiological sexual arousal was assessed with vaginal photoplethysmography. Data analysis with traditional methods comparing average genital arousal between films failed to detect specificity of genital arousal for either group. When data were analyzed with smoothing regression splines and a within‐subjects approach, both heterosexual and lesbian women demonstrated different patterns of genital sexual arousal to the different types of erotic films, suggesting that sophisticated statistical techniques may be necessary to more fully understand women's genital sexual arousal response. Heterosexual women showed category‐specific genital sexual arousal. Lesbian women showed higher arousal to the heterosexual film than the other films. However, within subjects, lesbian women showed significantly different arousal responses suggesting that lesbian women's genital arousal discriminates between different categories of stimuli at the individual level. Implications for the future use of vaginal photoplethysmography as a diagnostic tool of sexual preferences in clinical and forensic settings are discussed.     

Mediation of the mating induced increase in accessory reproductive organ size of male rats

Accessory reproductive organs were larger in mated than in unmated male rats. Following castration and hormone replacement therapy, only the perineal muscle and penis weight increased as a result of mating, therefore separate physiological processes are proposed to account for increases in these and accessory glands. The number of glans penis papillae was not affected by mating. Males which mated during the first opportunity provided did not have larger organs than those which did not, and males not mating despite repeated opportunity were found not to differ in organ size from socially isolated males. Mating latency was a function both of previous sexual experience and size of the secretory glands. Although 3 intromissions at 4 day intervals was sufficient stimulation to increase organ size, attempts to induce growth by mimicry of vaginal stimulation were unsuccessful, as were attempts to block the effect of intromission by glans penis anesthesia.     

A sex difference in features that elicit genital response

Previous research suggests that women's genital arousal is an automatic response to sexual stimuli, whereas men's genital arousal is dependent upon stimulus features specific to their sexual interests. In this study, we tested the hypothesis that a nonhuman sexual stimulus would elicit a genital response in women but not in men. Eighteen heterosexual women and 18 heterosexual men viewed seven sexual film stimuli, six human films and one nonhuman primate film, while measurements of genital and subjective sexual arousal were recorded. Women showed small increases in genital arousal to the nonhuman stimulus and large increases in genital arousal to both human male and female stimuli. Men did not show any genital arousal to the nonhuman stimulus and demonstrated a category-specific pattern of arousal to the human stimuli that corresponded to their stated sexual orientation. These results suggest that stimulus features necessary to evoke genital arousal are much less specific in women than in men.     

Sexual dysfunction before antidepressant therapy in major depression

BACKGROUND: Decreased sexual interest and function both occur as a consequence of antidepressant medication use, and are especially associated with serotonin reuptake inhibitors (SRIs). However, few investigators have reported the base rate for disturbances in sexual desire, arousal and orgasm or ejaculation in patients with major depression (MD) prior to antidepressant treatment. The purpose of this report is to define the frequency of sexual dysfunction (SD) in 134 patients with MD and examine the relationship between SD and demographic, clinical and personality variables. METHOD: A consecutive series of 55 male and 79 female MD patients diagnosed by SCID-DSM IV assessment completed a series of psychometric measures including a Sexual Function Questionnaire, which asked about change in sexual interest and function as well as sexual activity during the preceding month. RESULTS: Only 50% of women and 75% of men reported sexual activity during the preceding month. Over 40% of men and 50% of women reported decreased sexual interest. Reduced levels of arousal were more common in both men and women (40-50%) than ejaculatory or orgasm difficulties (15-20%). In women, problems with arousal and orgasm correlated with higher neuroticism and lower extraversion. There was no relationship between SD and personality measures in men. While age at onset of depression and number of prior episodes showed a modest correlation with SD measures, there were no correlations with severity of depression or specific symptoms clusters. LIMITATIONS AND CONCLUSIONS: Although limited by a relatively small sample of drug free patients with MD, and by the absence of a non-depressed comparison sample, these results emphasize the importance of factors beyond specific drug effects in the assessment of antidepressant related sexual dysfunction.     

Urinary Acid Phosphatase Secretion Under Different Arousal Conditions

Seventy-three undergraduate males were randomly assigned to five different conditions, sexual, anxiety, aggressive, and laughter arousals and a control group, as a test of the hypothesis that urinary acid phosphatase is a specific indicator of sexual arousal. Pre- and post-arousal urine samples were analyzed for the amount of urinary acid phosphatase (AP) present, and significant increases occurred only in the sexual arousal condition. Both general and specific elements of arousal as well as a possible link between sexual arousal and anxiety are discussed. These findings support earlier results of studies in this area.     

Psychoendocrine response to sexual arousal in human males

The hypothesis is tested that luteinizing hormone (LH) and follicle stimulating hormone (FSH( may be released from the anterior pituitary in response to a psychological state of sexual arousal. LH levels in 10 male volunteers were found to be higher after viewing a sexually arousing film than after a control film. The magnitude of LH response was found to be positively correlated with the subjective evaluation of sexual arousal. FSH levels tended in the same direction bu the predominant and unexpected finding for this hormone was that levels were consistently lower during the first session, when anxiety was high, and higher during the second session, when anxiety was less, whether control or stimulus film had been shown. This study is analogous to those demonstrating the responsiveness of other anterior pituitary hormones to specific psychological states.     

A novel mouse model for assessment of male sexual function

A novel model to evaluate erectile, ejaculatory, and sexual behavior patterns in conscious mouse is presented. Corpus spongiosum of the penis (CSP) pressure was recorded by using telemetry and was correlated with erectile activity (penile elongations, cups, flips) during reflex induction and spontaneous erections in freely moving mice. CSP pressure was also recorded during mating tests (mounts, intromissions with erections, ejaculations), as well as non-contact tests with estrous female mice. Erectile events were quantified in four sexual contexts (spontaneous erections, spinal reflexes, in mating and non-contact tests). The data demonstrate that CSP pressure monitoring is a valid technique for assessment of sexual function in freely moving mice.     

Fluctuations in brain temperature during sexual interaction in male rats: an approach for evaluating neural activity underlying motivated behavior

Since metabolic activity is accompanied by heat release, measurement of brain temperatures offers a method for assessing behavior-associated changes in neural activity. To explore this possibility, we monitored local brain (nucleus accumbens, medial-preoptic hypothalamus, and hippocampus) and body (temporal muscle) temperature in an experienced male rat during sexual behavior with a sexually receptive female. Placement of the female into a neighboring compartment increased the male's temperature and additional increases occurred when rats were allowed to see and partially interact with the female through a Plexiglas barrier with dime-size holes. The temperature increase was robust (1.5-2.0 degrees C), faster in all brain areas than in muscle, and peaked (38-39 degrees C) when the barrier was removed and full interaction was allowed. As the male repeatedly mounted and achieved intromission with the female, temperature further increased, peaking at ejaculation (+0.2-0.4 degrees C). Following ejaculation, the temperature abruptly dropped, until sexual interest and interaction resumed. These biphasic temperature fluctuations were generally similar in each recording location, but all brain sites (particularly, nucleus accumbens and medial-preoptic hypothalamus) showed more profound changes than the muscle.These data generally match single-unit and other physiological findings, suggesting that male sexual behavior is accompanied by sustained and generalized neural activation. This activation is triggered by sexually relevant stimuli (arousal), maintained during repeated mounts and intromissions, and peaked at ejaculation. These findings suggest brain temperature fluctuations not only as a sensitive index of functional neural activation, but as a powerful factor affecting various neural functions and an important part of brain mechanisms underlying motivated behavior.