Habituation of male sexual arousal: effects of attentional focus

Three experiments are reported demonstrating that levels of penile tumescence and subjective sexual arousal are greater when men employ participant-oriented rather than spectator-oriented attentional focus while viewing an erotic film segment. Under each instructional set, there was a reduction in sexual arousal during repeated erotic stimulation. As sexual arousal habituated, the men reported feeling less absorbed during erotic stimulation. When these associated changes in attentional focus (absorption) were partialled out through analysis of covariance, sexual arousal remained relatively stable over trials, suggesting that sexual arousal is less likely to habituate if attentional focus remains constant during repeated erotic stimulation. Further directions for studying associations between habituation of sexual arousal and cognitive processing are discussed.     

There are differences in cerebral activation between females in distinct menstrual phases during viewing of erotic stimuli: a fMRI study

There is evidence that men experience more sexual arousal than women but also that women in mid-luteal phase experience more sexual arousal than women outside this phase. Recently, a few functional brain imaging studies have tackled the issue of gender differences as pertaining to reactions to erotica. The question of whether or not gender differences in reactions to erotica are maintained with women in different phases has not yet been answered from a functional brain imaging perspective. In order to examine this issue, functional MRI was performed in 22 male and 22 female volunteers. Subjects viewed erotic film excerpts alternating with emotionally neutral excerpts in a standard block-design paradigm. Arousal to erotic stimuli was evaluated using standard rating scales after scanning. Two-sample t-test with uncorrected P<0.001 values for a priori determined region of interests involved in processing of erotic stimuli and with corrected P<0.05 revealed gender differences: Comparing women in mid-luteal phase and during their menses, superior activation was revealed for women in mid-luteal phase in the anterior cingulate, left insula, and orbitofrontal cortex. A superior activation for men was found in the left thalamus, the bilateral amygdala, the anterior cingulate, the bilateral orbitofrontal, bilateral parahippocampal, and insular regions, which were maintained at a corrected P in the amygdala, the insula, and thalamus. There were no areas of significant superior activation for women neither in mid-luteal phase nor during their menses. Our results indicate that there are differences between women in the two cycle times in cerebral activity during viewing of erotic stimuli. Furthermore, gender differences with women in mid-luteal phases are similar to those in females outside the mid-luteal phase.     

The time course of pupil dilation evoked by visual sexual stimuli: Exploring the underlying ANS mechanisms

The early processing of visual sexual stimuli shows signs of automaticity. Moreover, there is evidence for sex‐specific patterns in cognitive and physiological responding to erotica. However, little is known about the time course of rapid pupillary responses to sexual stimuli and their correspondence with other measures of autonomic activity in women and men. To study pupil dilation as an implicit measure of sexual arousal at various stages of picture processing, we presented 35 heterosexual participants with pictures showing either erotic couples or single (male/female) erotic nudes, contrasted with people involved in everyday situations. Brightness‐adjusted grayscale pictures were shown for a duration of 2,500 ms within the central visual field, alternating with perceptually matched patches. Left pupil diameter was recorded at 500 Hz using a video‐based eye tracker. Skin conductance and heart rate were coregistered and correlated with latent components of pupil dilation (dissociated by temporal PCA). Whereas stimulus‐evoked changes in pupil size indicated virtually no initial constriction, a rapid effect of appetence emerged (dilation to erotica within 500 ms). Responses at early stages of processing were remarkably consistent across both sexes. In contrast, later phases of pupil dilation, subjective ratings, and skin conductance responses showed a sex‐specific pattern. Moreover, evidence for an association of early‐onset pupil dilation and heart rate acceleration was found, suggestive of parasympathetic inhibition, whereas the late component was mainly related to sympathetically mediated skin conductance. Taken together, our results indicate that different temporal components of pupil responses to erotic stimuli may reflect divergent underlying neural mechanisms.     

The Relationship Between Sexual Arousal Experience and Genital Response

In studies of sexuality, there has been a wide divergence in findings concerning the correlation between the subjective and genital measurements of sexual arousal. The present study is aimed at helping clarify this situation by examining the role of certain factors involved in determining the subjective-genital correlation. Thus, the following study was designed to (1) employ a methodology aimed at improving the correlation between the subjective and genital measurements of arousal in women, and (2) determine the effect of attending to bodily cues upon the subjective-genital relationship. To accomplish this end, 36 female subjects were separated into two experimental groups and one control group. The experimental groups were given instructions suggesting that they attend to either genital or non-genital body signals of sexual arousal while viewing a series of 10 erotic slides. Subjects in the control group were given no attention instructions. Subjective levels of arousal to the erotic slides were scaled by having subjects set the intensity of sound and light to match their intensity of arousal (cross-modality matching) and by using a rating scale. Genital measures of sexual arousal consisted of measurement of vaginal pulse amplitude. Analyses revealed that group computed correlations were very high and that individually computed subjective-genital correlations were highest in the attention groups. Paying attention to bodily cues has a significant and positive effect on the subjective-genital relationship. Possible explanations for these results are given along with a discussion of the role of methodological variables in influencing the genital-subjective correlation. The finding of high levels of correlation raises doubts on the heretofore made assumption of low subjective-genital correlations for women.     

Sexual arousal patterns of bisexual men revisited

Men who identify themselves as bisexual report feeling sexually aroused by both men and women. However, past research has not demonstrated that such men exhibit substantial genital arousal to both male and female erotic stimuli, suggesting that they identify as bisexual for reasons other than their genital arousal pattern. The purpose of the present study was to examine arousal patterns among bisexual men who were recruited using stringent criteria involving sexual and romantic experience with both men and women in order to increase the likelihood of finding a bisexual arousal pattern. Bisexual men in the present study demonstrated bisexual patterns of both subjective and genital arousal. It remains unclear which pattern is most typical of contemporary bisexual men: the present results supporting a bisexual arousal pattern, or previous results not finding one. In either case, understanding men with bisexual arousal patterns could help illuminate the etiology and development of male sexual orientation.     

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.     

Does dorsolateral prefrontal cortex (DLPFC) activation return to baseline when sexual stimuli cease?: The role of DLPFC in visual sexual stimulation

A fundamental question in human sexuality regards the neural substrate underlying sexually-arousing representations. Lesion and neuroimaging studies suggest that dorsolateral pre-frontal cortex (DLPFC) plays an important role in regulating the processing of visual sexual stimulation. The aim of this Functional Near-Infrared Spectroscopy (fNIRS) study was to explore DLPFC structures involved in the processing of erotic and non-sexual films. fNIRS was used to image the evoked-cerebral blood oxygenation (CBO) response in 15 male and 15 female subjects. Our hypothesis is that a sexual stimulus would produce DLPFC activation during the period of direct stimulus perception ("on" period), and that this activation would continue after stimulus cessation ("off" period). A new paradigm was used to measure the relative oxygenated hemoglobin (oxyHb) concentrations in DLPFC while subjects viewed the two selected stimuli (Roman orgy and a non-sexual film clip), and also immediately following stimulus cessation. Viewing of the non-sexual stimulus produced no overshoot in DLPFC, whereas exposure to the erotic stimulus produced rapidly ascendant overshoot, which became even more pronounced following stimulus cessation. We also report on gender differences in the timing and intensity of DLPFC activation in response to a sexually explicit visual stimulus. We found evidence indicating that men experience greater and more rapid sexual arousal when exposed to erotic stimuli than do women. Our results point out that self-regulation of DLPFC activation is modulated by subjective arousal and that cognitive appraisal of the sexual stimulus (valence) plays a secondary role in this regulation.     

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.     

Determinants of subjective experience of sexual arousal in women: Feedback from genital arousal and erotic stimulus content

Sixty-two women participated in a study designed to explore the association between gential and subjective sexual arousal. Four stimulus conditions were created, designed to evoke differential patterns of genital arousal over time. Subjects were instructed to report sensations in their genitalia while being exposed to the same erotic stimulus on repeated trials or to a series of varying erotic stimuli. Detection of genital arousal was facilitated by the occurrence of changes in genital arousal over trials. That is, genital and subjective sexual arousal were linearly related in conditions that resulted in large differences in genital arousal over trails, whereas such a relation was absent in conditions in which genital arousal levels remained relatively constant. In women, peripheral feedback from consciously detected genital arousal seems to be a relatively unimportant determinant of subjective sexual arousal.     

Are Females More Responsive to Emotional Stimuli? A Neurophysiological Study Across Arousal and Valence Dimensions

Men and women seem to process emotions and react to them differently. Yet, few neurophysiological studies have systematically investigated gender differences in emotional processing. Here, we studied gender differences using Event Related Potentials (ERPs) and Skin Conductance Responses (SCR) recorded from participants who passively viewed emotional pictures selected from the International Affective Picture System (IAPS). The arousal and valence dimension of the stimuli were manipulated orthogonally. The peak amplitude and peak latency of ERP components and SCR were analyzed separately, and the scalp topographies of significant ERP differences were documented. Females responded with enhanced negative components (N100 and N200), in comparison to males, especially to the unpleasant visual stimuli, whereas both genders responded faster to high arousing or unpleasant stimuli. Scalp topographies revealed more pronounced gender differences on central and left hemisphere areas. Our results suggest a difference in the way emotional stimuli are processed by genders: unpleasant and high arousing stimuli evoke greater ERP amplitudes in women relatively to men. It also seems that unpleasant or high arousing stimuli are temporally prioritized during visual processing by both genders.     

ERP responses to sexual cues among young women attracted to men

Previous event-related potential (ERP) studies reported larger N170, P3, and late positive potential (LPP) amplitudes to sexual than nonsexual stimuli. These ERPs may not be specifically sensitive to processing sexual cues, however, because the sexual stimuli included information beyond sexual cues (e.g., faces, bodies, social interaction) to a greater extent than comparison stimuli. We investigated ERPs to stimuli that focused on sexual and nonsexual body regions, in different states of readiness for activity, to elucidate neural responses involved in processing sexual cues. Forty cisgender, primarily white, undergraduate women who were attracted to men (M_age = 18.6, SD = 0.9) viewed images that varied by male body part (penis, arm) and activity state (rest, poised for activity). Participants viewed 40 images per category (flaccid penises, erect penises, outstretched arms, bent arms). Electroencephalography (EEG) was recorded using a 128-channel net, time-locked to the onset of each image. Using a whole-head cluster-mass approach, we found that the P3 was sensitive to sexual readiness—P3 amplitudes were larger to erect than flaccid penises, but not to bent than outstretched arms. The N170 and LPP components did not show evidence of similarly specific responses to sexual readiness, revealing potential dissociation of different neural processes commonly elicited in response to more complex sexual stimuli. An additional novel finding was that an anterior N270-400 was sensitive to sexual readiness. Findings clarify the brain's rapid responses to sexual stimuli, setting the stage for future research aimed at better understanding the neurocognitive processes that contribute to the coordination of sexual arousal.     

Physiological and Subjective Sexual Arousal in Pre- and Postmenopausal Women and Postmenopausal Women Taking Replacement Therapy

Twenty premenopausal, 14 postmenopausal, and 14 postmenopausal women receiving replacement estrogen therapy were studied to determine whether differences in hormone status were associated with differences in physiological and subjective sexual responses. All subjects viewed a neutral, an erotic, and a second neutral videotape while photoplethysmographic vaginal pulse amplitude was continuously recorded. Self-report ratings of sexual arousal and affective response were collected. Serum levels of testosterone, estradiol, estrone, and luteinizing hormone were obtained. The three groups did not differ in either average or maximum vaginal pulse amplitude to the videotapes nor in latency of sexual response. The postmenopausal women not taking replacement estrogen reported significantly less vaginal lubrication in response to the erotic videotape than the higher estrogen premenopausal and replacement hormone groups. Estradiol level was significantly correlated with ratings of vaginal lubrication in response to the erotic videotape but not with vaginal pulse amplitude. Results thus suggest that estrogen is important in maintaining vaginal lubrication and the perception of sexual arousal but not in determining vaginal vasocongestion.     

Event-related potentials as asymmetry indices of lateralized cognitive processes during music and verbal tasks

The present study replicates and extends earlier findings by using event-related potentials (ERPs) as a means of providing information about differential hemispheric engagement in cognitive processing. ERPs were recorded from T3, T4, T5 and T6 in response to task-irrelevant tone pips superimposed on white noise, on music and on verbal passages, which are thought to differentially activate the two hemispheres. The latencies and amplitudes of three peaks (N1, P2 and N2) were obtained in 37 women. Task-related ERP asymmetries were found only for the peak amplitude of N2 recorded at posterior-temporal scalp areas, whereas at the anterior-temporal recording, there were no interactional effects. The hemisphere assumed to be most engaged in task processing showed a smaller N2 peak amplitude to tone pips at the posterior-temporal scalp area than the hypothesized unengaged hemisphere. A result common to the three peaks in the ERP was that peak latencies were longer in the music than in the noise condition. Finally, the posterior-temporal areas produced longer N2 peak latencies in verbal and even more in music conditions compared to white noise conditions. No differences in latencies were found between hemispheres during the ongoing cognitive tasks.     

Sex differences in memory of emotional images: a behavioral and electrophysiological investigation

Current research suggests that emotional responses differ between men and women. Sex differences regarding emotional effects on memory have been recently studied through brain imaging techniques. However, the majority of investigations have often neglected to balance the variable of emotional intensity (arousal) across pleasant and unpleasant pictures. Additionally, men and women were often mixed or studied separately. The current study aims at comparing men and women's electrophysiological responses related to emotional memory of photographic material. These responses were measured using Event Related brain Potentials (ERP) in response to a task of episodic memory of emotional images. The frontal N200, the parietal P300 and the central LPC were compared in 17 men and 17 women matched for age, social economic status, education and intelligence. Behavioral results showed that, in men, reaction times were modulated by valence, whereas for women, reaction times were mainly modulated by arousal. Accuracy was affected by both emotional valence and arousal, but only in women. ERP analyses revealed that emotional valence influenced earlier time components (frontal N200 and parietal P300), whereas arousal influenced memory in the later time component (central LPC). Moreover, sex differences, mediated by valence and arousal, were found in ERP responses at different times in the processing stream.     

Women with hypoactive sexual desire disorder compared to normal females: a functional magnetic resonance imaging study

Lack of sexual interest is the most common sexual complaint among women. However, factors affecting sexual desire in women have rarely been studied. While the role of the brain in integrating the sensory, attentional, motivational, and motor aspects of sexual response is commonly acknowledged as important, little is known about specific patterns of brain activation and sexual interest or response, particularly among women. We compared 20 females with no history of sexual dysfunction (NHSD) to 16 women with hypoactive sexual desire disorder (HSDD) in a functional magnetic resonance imaging (fMRI) study that included assessment of subjective sexual arousal, peripheral sexual response using a vaginal photoplethysmograph (VPP), as well as brain activation across three time points. Video stimuli included erotic, sports, and relaxing segments. Subjective arousal to erotic stimuli was significantly greater in NHSD participants compared with HSDD. In the erotic-sports contrast, NHSD women showed significantly greater activation in the bilateral entorhinal cortex than HSDD women. In the same contrast, HSDD females demonstrated higher activation than NHSD females in the medial frontal gyrus (Brodmann area (BA) 10), right inferior frontal gyrus (BA 47) and bilateral putamen. There were no between group differences in VPP-correlated brain activation and peripheral sexual response was not significantly associated with either subjective sexual response or brain activation patterns. Findings were consistent across the three experimental sessions. The results suggest differences between women with NHSD and HSDD in encoding arousing stimuli, retrieval of past erotic experiences, or both. The findings of greater activation in BA 10 and BA 47 among women with HSDD suggest that this group allocated significantly more attention to monitoring and/or evaluating their responses than NHSD participants, which may interfere with normal sexual response.     

Event-related brain potentials and affective responses to threat in spider/snake-phobic and non-phobic subjects.

We investigated cortical responses and valence/arousal ratings of spider phobic, snake phobic, and healthy subjects while they were processing feared, fear-relevant, emotional neutral, and pleasant stimuli. Results revealed significantly larger amplitudes of late ERP components (P3 and late positive complex, LPC) but not of early components (N1, P2, N2) in phobics when subjects were processing feared stimuli. This fear-associated increase of amplitudes of late ERP components in phobic subjects was maximal at centro-parietal and occipital brain sites. Furthermore, phobics but not controls rated feared stimuli to be more negative and arousing than fear-relevant, emotional neutral, and pleasant stimuli. Since late ERP components and valence/arousal ratings were only significantly increased when phobic subjects but not when healthy controls were processing feared stimuli, the present data suggest that P3 and LPC amplitudes represent useful neural correlates of the emotional significance and meaning of stimuli.     

A Psychophysiological Exploration of Sexual Arousal Patterns in Females and Males

Fifty-nine female and 39 male undergraduates completed 3 sessions of a psychophysiological study on sexual arousal. Subjects were assigned to one of six experimental groups. Subjects within each group were exposed to a series of four audio-tapes, and were asked to fantasize before and after the tape series. Tapes varied in their erotic and romantic content, and two sex role dimensions were also varied across tapes. Dependent measures included scaled subjective reports, genital pulse amplitude and blood volume responses, heart rate, and finger pulse amplitude. Erotic contents were significantly more sexually arousing than nonerotic contents for both sexes. Romantic content did not significantly enhance the facilitation of sexual arousal. Nontraditional sex roles were significantly more arousing for females, with a similar nonsignificant trend for males. There were significant correlations between genital pulse amplitude and subjective reports of arousal; however, for females the genital blood volume measure showed less reliable agreement with subjective report. Genital pulse amplitude was the most reliable and precise indicator of arousal and accounted for the most variance across conditions. No significant changes occurred on the heart rate and finger pulse amplitude measures. Although subjects were able to become aroused by fantasy alone, listening to erotic tapes did not facilitate their ability to be sexually aroused during fantasy.     

Effect of sleep deprivation on NREM sleep ERPs and related activity at sleep onset.

This research assessed the impact of one night of sleep deprivation on the amplitudes of NREM-sleep event-related potentials (NREM ERPs) and on the frequency of occurrence of related electroencephalogram activity including sleep spindles, arousals, K-complexes, and vertex sharp waves (VSWs). The NREM ERPs identified included P220, N350, P450, N550 and P900. During a pre-deprivation night, ten subjects took two 20-min naps separated by a 20-min break at their normal bedtime. Brief tones were presented at three intensity levels (60, 75 and 90 dB) with a 5-s interstimulus interval. Following these naps, subjects were kept awake until their normal bedtime the following day. At that time, they repeated the two-nap procedure. The ERPs obtained for each tone and wake/sleep state for pre- and post-deprivation conditions were analyzed using repeated measures statistical procedures. As anticipated, NREM ERP amplitudes recorded both pre- and post-deprivation increased with tone intensity and with approaching sleep. Also, sleep deprivation was associated with more rapid sleep onset, reduced arousability, and greater spindle production. While sleep deprivation had no effect on the amplitude of P220. Post-deprivation amplitudes of N350, N550 and P900 were greater, especially following the 90-dB tone. There was a corresponding increase in VSWs and K-complexes. These findings are inconsistent with the view that NREM ERPs reflect arousal. The underlying mechanism(s) may facilitate initiation and maintenance of sleep.     

The relationship between women's subjective and physiological sexual arousal

Previous literature presents discordant results on the relationship between physiological and subjective sexual arousal in women. In this study, the use of hierarchical linear modeling (HLM) revealed a significant concordance between continuous measures of physiological and subjective sexual arousal as assessed during exposure to erotic stimuli in a laboratory setting. We propose that past studies that have found little or no association between the two measures may have been in part limited by the methodology and statistical analyses employed.