Neuroelectric Correlates of Human Sexuality: A Review and Meta-Analysis

The standardization of a new Explicit Pornographic Picture Set (EPPS)

Pictures with affective content have been extensively used in scientific studies of emotion and sexuality. However, only a few standardized picture sets have been developed that offer explicit images, with most lacking pornographic pictures depicting diverse sexual practices. This study aimed to fill this gap through developing a standardized affective set of diverse pornographic pictures (masturbation, oral sex, vaginal sex, anal sex, group sex, paraphilia) of same-sex and opposite-sex content, offering dimensional affective ratings of valence, arousal, and dominance, as well as co-elicited discrete emotions (disgust, moral and ethical acceptance). In total, 192 pornographic pictures acquired from online pornography platforms and 24 control IAPS images have been rated by 319 participants (Mage = 22.66, SDage = 4.66) with self-reported same- and opposite-sex sexual attraction. Stimuli were representative of the entire affective space, including positively and negatively perceived pictures. Participants showed differential affective perception of pornographic pictures according to gender and sexual attraction. Differences in affective ratings related to participants' gender and sexual attraction, as well as stimuli content (depicted sexual practices and sexes). From the stimuli set, researchers can select explicit pornographic pictures based on the obtained affective ratings and technical parameters (i.e., pixel size, luminosity, color space, contrast, chromatic complexity, spatial frequency, entropy). The stimuli set may be considered a valid tool of diverse explicit pornographic pictures covering the affective space, in particular, for women and men with same- and opposite-sex sexual attraction. This new explicit pornographic picture set (EPPS) is available to the scientific community for non-commercial use.

Interplay between sexual excitation and inhibition: impact on sexual function and neural correlates of erotic stimulus processing in women

Background

As outlined by the dual control model (DCM), individual differences in the regulation of sexual arousal following sexual stimulation depend on two distinct neurophysiological processes: sexual excitation (SE) and sexual inhibition (SI). Although associations with sexual function, behavior, and cue processing have been demonstrated in previous research, underlying neural correlates remain insufficiently explored. Moreover, interactive effects of SE/SI as proposed by the DCM, as well as factors impacting SE/SI properties, such as the use of oral contraceptives (OCs), have not received adequate attention in existing research.

Methods

90 healthy, sexually active women (n = 51 using OCs, n = 39 naturally cycling) completed an Emotional-Picture-Stroop-Paradigm (EPSP) while a 64-channel EEG was recorded. LPP amplitudes toward erotic and neutral stimuli were consecutively computed as a marker of motivational salience and approach motivation. Additionally, women provided self-reports of SE/SI and sexual function. Moderation analyses were performed to assess interactive effects of SE/SI in predicting LPP amplitudes and sexual function.

Results

Sexual function was negatively associated with SI levels but unrelated to SE. Higher SI was associated with reduced LPP amplitudes in response to erotic stimuli. This negative association was, however, attenuated for women high in SE, suggesting interactive effects of SE/SI. Furthermore, women using OCs reported lower SE compared to naturally cycling women.

Conclusion

The observed findings provide additional psychophysiological evidence supporting the DCM and underscore the relevance of interactive SE/SI effects in stimulus processing and approach motivation. They also highlight the possible impact of OCs on psychosexual variables that warrants further research.

Dark Tetrad personality traits, paraphilic interests, and the role of impulsivity: an EEG-study using a Go/No-Go paradigm

Maladaptive personality traits, such as 'dark personalities' are found to result in a diverse set of negative outcomes, including paraphilic interests and associated (illegal) behaviors. It is however unclear how these are exactly related, and if related, if then only those individuals higher on dark personality traits and higher impulsivity engage in paraphilic behaviors. In the current study, 50 participants were recruited to investigate the relationship between Dark Tetrad personality traits (i.e., narcissism, psychopathy, Machiavellianism and everyday sadism), paraphilic interests (arousal and behavior) and the moderating role of impulsivity. Personality and paraphilic interests were investigated through self-report questionnaires. Impulsivity was measured both through self-reported dysfunctional impulsivity and the P3 event related potential using electroencephalography during the Go/No-Go task (i.e. response inhibition). The results showed that there was a positive association between psychopathy, sadism and paraphilic interests. Whereas everyday sadism was associated with paraphilic (self-reported) arousal, psychopathy was associated with paraphilic behavior. Although P3 amplitude was not associated with paraphilic interests, self-reported dysfunctional impulsivity was associated with paraphilic behavior specifically. However, there was no moderating role of dysfunctional impulsivity and response inhibition (P3) in the relationship between psychopathy and paraphilic behavior. Findings indicate that the relation between specific dark personalities and paraphilic interests may be more complex than initially thought. Nevertheless, risk assessment and intervention approaches for paraphilia and related behavior both may benefit from incorporating Dark Tetrad and impulsivity measurements.

Early adversity and sexual diversity: the importance of self-reported and neurobiological sexual reward sensitivity

Work shows that sexually-diverse individuals face high rates of early life adversity and in turn increased engagement in behavioral outcomes traditionally associated with adversity, such as sexual risk taking. Recent theoretical work suggests that these associations may be attributable to heightened sexual reward sensitivity among adversity-exposed women. We aimed to test these claims using a combination of self-report and EEG measures to test the relationship between early adversity, sexual reward sensitivity (both self-reported and EEG measured) and sexual risk taking in a sexually diverse sample of cis-gender women (N = 208) (Mage = 27.17, SD = 6.36). Results showed that childhood SES predicted self-reported sexual reward sensitivity which in turn predicted numbers of male and female sexual partners. In contrast we found that perceived childhood unpredictability predicted neurobiological sexual reward sensitivity as measured by EEG which in turn predicted male sexual partner number. The results presented here provide support for the notion that heightened sexual reward sensitivity may be a pathway through which early life adversity augments future sexual behavior, and underscores the importance of including greater attention to the dynamics of pleasure and reward in sexual health promotion.

Sex Differences in Sexual Motivation in Humans and Other Mammals: The Role of Conscious and Unconscious Processes

In self-report questionnaires, men report higher scores than women on variables such as desire for sex, frequency of sexual thoughts, number of sex partners, etc. Based on this, men are considered to have a higher level of sexual motivation than women. However, retrospective self-reports may be unsuitable for estimations of the inherent level of sexual motivation. We review data on automatic (unconsciously controlled) responses and measures of implicit motivation during exposure to sexual stimuli. These responses and measures are inaccessible to willful manipulations and make it possible to determine whether the sex difference in answers to questionnaires is replicated when volitional response manipulations are unlikely. We complement the human data with observations from some rodent and non-human primate species. The attentional resources allotted to stimuli with sexual relevance as well as genital responses to such stimuli are similar in men and women. Measures of implicit motivation also fail to detect any sex difference. Finally, the frequency of masturbation is superior in female infants before the age at which social expectations begin to determine behavior. Neither in rodents nor in non-human primates is there any clear-cut evidence for sex differences in motivation. It seems that males and females are similar with regard to the intensity of sexual motivation. The responses to questionnaires may be affected by social learning of sexual scripts and/or the inferior quality of sexual experiences in women, among other things.

Female Affective Perception of Mainstream and Paraphilic Pornography: Associations with Sexual and Psychological Intrapersonal Variables

Understanding affective perceptual processes can further contribute to the explanation of motivation and actions, as well as sexual risk behaviors. Pornography can be considered salient emotional content and is popular, also among females. Yet, the female perspective on pornography has often been overlooked and it remains unclear how individual variables may be associated with the affective perception of pornography and could provide a risk profile. Possible associations between several sexual and psychological intrapersonal variables and the affective perception of various forms of pornography were analyzed from the female perspective. A sample of 231 females (M = 21.87 years; SD = 3.9 years) provided ratings of affective valence, arousal, disgust, and moral and ethical acceptance for mainstream pornographic and paraphilic images of dominance, submission, or sexual violence. Paraphilic pornography was perceived as less pleasant, arousing, and moral and ethically acceptable, but more disgusting compared to mainstream pornography. This was more pronounced among females who had never consumed pornography. Results further suggest that the female affective perception of pornography was associated with the following sexual intrapersonal variables: sexual sensation seeking for physical sensations, erotophilia, lack of sexual control, problematic pornography consumption, and sexual disgust sensitivity. Of the assessed psychological intrapersonal variables, only anxiety was negatively associated with disgust for paraphilic pornography. It is important to further analyze the female affective perception of pornography and associated variables to include them in strategies for prevention and for addressing problematic consequences of the acceptance of specific sexual content and behaviors, especially related to sexualized violence.

Deep Learning in the Identification of Electroencephalogram Sources Associated with Sexual Orientation

INTRODUCTION

It is unclear if sexual orientation is a biological trait that has neurofunctional footprints. With deep learning, the power to classify biological datasets without an a priori selection of features has increased by magnitudes. The aim of this study was to correctly classify resting-state electroencephalogram (EEG) data from males with different sexual orientation using deep learning and to explore techniques to identify the learned distinguishing features.

METHODS

Three cohorts (homosexual men, heterosexual men, and a mixed sex cohort), one pretrained network on sex classification, and one newly trained network for sexual orientation classification were used to classify sex. Further, Grad-CAM methodology and source localization were used to identify the spatiotemporal patterns that were used for differentiation by the networks.

RESULTS

Using a pretrained network for classification of males and females, no differences existed between classification of homosexual and heterosexual males. The newly trained network was able, however, to correctly classify the cohorts with a total accuracy of 83%. The retrograde activation using Grad-CAM technology yielded distinctive functional EEG patterns in the Brodmann area 40 and 1 when combined with Fourier analysis and a source localization.

DISCUSSION

This study shows that electrophysiological trait markers of male sexual orientation can be identified using deep learning. These patterns are different from the differentiating signatures of males and females in a resting-state EEG.

Automaticity of Early Sexual Attention: An Event-Related Potential Study

A promising line of research on forensic assessment of paraphilic sexual interest focuses on behavioral measures of visual attention using sexual stimuli as distractors. The present study combined event-related potentials (ERPs) with behavioral measures to investigate whether detection of a hidden sexual preference can be improved with ERPs. Normal variants of sexual orientation were used for a proof-of-concept investigation. Accordingly, 40 heterosexual and 40 gay men participated in the study. Within each group, half of the participants were instructed to hide their sexual orientation. The results showed that a match between sexual orientation and stimulus delays responses and influences ERP before motor responses. Late ERP components showed higher potential in differentiating hidden sexual preferences than motor responses, thereby showing how ERPs can be used in combination with reaction time measures to potentially facilitate the detection of hidden sexual preferences.

Electrophysiological Evidence of Enhanced Processing of Novel Pornographic Images in Individuals With Tendencies Toward Problematic Internet Pornography Use

Novelty seeking is regarded as a core feature in substance use disorders. However, few studies thus far have investigated this feature in problematic Internet pornography use (PIPU). The main aim of the present study was to examine group differences in electrophysiological activity associated with novelty processing in participants with high tendencies toward PIPU vs. low tendencies using event-related potentials (ERPs). Twenty-seven participants with high tendencies toward PIPU and 25 with low tendencies toward PIPU completed a modified three-stimulus oddball task while electroencephalogram (EEG) was recorded. Participants were instructed to detect neutral target stimuli from distracting stimuli. The distracting stimuli contained a familiar sexual stimulus and a set of novel sexual stimuli. The novel-familiar difference waves were calculated to identify specific group difference in novelty effect. While both groups demonstrated a sustained novelty effect in the late positive potential (LPP) within the 500–800 ms time windows, the novelty effect was greater in the high tendencies toward PIPU group than in the low tendencies toward PIPU group. This result suggests that individuals with high tendencies toward PIPU allocate more attentional resources for novelty processing. Enhanced brain responding to novel sexual stimuli may facilitate pornographic consumption and play an essential role in the development and maintenance of PIPU.

A Case of Female Orgasm Without Genital Stimulation

INTRODUCTION

Orgasm is a complex, multimodal reflex induced typically by genital stimulation. Genitally stimulated orgasms (GSOs) activate excitatory neurochemical pathways in the brain and spinal cord that ultimately stimulate sympathetic outflow and the inhibition of parasympathetic spinal circuits in the lower lumbar cord. However, some women claim to have orgasms spontaneously without genital stimulation.

AIMS

To report the case of a 33-year-old woman who developed the ability to attain and control the duration of a subjective orgasmic state without genital stimulation after tantric training.

METHODS

Blood was taken at weekly intervals before, during, and after spontaneously-induced orgasms that lasted 5 or 10 minutes, or after a 10-minutes period of book reading. Plasma was analyzed using ELISA for luteinizing hormone, follicle stimulating hormone, free testosterone, and prolactin. The woman also provided subjective scores for different types of orgasms using the Mah and Binik (2002) Orgasm Rating Scale (ORS).

RESULTS

Prolactin levels post orgasm increased by 25% and 48%, respectively, after the 5- or 10-minutes non-genitally stimulated orgasm (NGSO), and were still elevated from baseline 30 minutes after orgasm. No changes were observed in FSH or free testosterone. The pattern of sensory, affective, and evaluative orgasm ratings after a 10-minutes NGSO was similar to orgasms induced by clitoral or anal stimulation. Book reading did not result in any change in prolactin.

CONCLUSION

Prolactin surges after orgasm are an objective marker of orgasm quality. The increase in prolactin after her NGSOs indicate that they induce the same physiological changes as GSOs and result from "top-down" processing in the brain. Pfaus JG, Tsarski K, A Case of Female Orgasm Without Genital Stimulation. Sex Med 2022;10:100496.

Neuroticism and Attention Toward Sexual and Non-Sexual Images During an Oddball Task: Evidence from Event-Related Potentials

While previous research has argued that neuroticism is a vulnerability factor for the experience of sexual difficulties, the basic cognitive processes associated with the impact of such a personality trait on the processing of sexually explicit stimuli are less understood. The current study examined the influence of neuroticism on the attentional processes and its neurophysiological correlates during the perception of sexual and non-sexual images. Event-related potentials from 30 women and 28 men were recorded during a modified oddball paradigm in which participants of both sexes visualized stimuli from three different categories (sexual, non-sexual positive, and non-sexual negative), and two arousal levels (high and low arousal). A P1 latency effect was found for female participants, in which high neuroticism was associated with longer latencies for pornographic compared to romantic sexual images. Higher levels of neuroticism were also associated with higher P3 amplitudes for highly arousing images, with both sexual and non-sexual content. Results were interpreted in light of the information processing model of sexual arousal and showed that neuroticism seems to impact both automatic and conscious pathways of processing of sexual stimuli.

MEG reveals preference specific increases of sexual-image-evoked responses in paedophilic sexual offenders and healthy controls

OBJECTIVES

Paedophilic disorder is characterised by sexual attraction towards children. Classification of a counterpart as sexually attractive likely occurs rapidly, and involves both conscious and unconscious attentional and cognitive processes. Magnetoencephalography (MEG) is an imaging method especially well-suited to examine visual and attentional processes triggered by sexual images within the range of milliseconds.

METHODS

We investigated brain responses to sexual images depicting adults (frequent) and children (infrequent stimulus) in seventeen paedophilic patients with a history of child sexual offending (P + CSO) and twenty healthy controls (HC) during a passive visual oddball paradigm. Event-related fields (ERF) were measured to extract the magnetic visual mismatch negativity (vMMNm), and how it relates to the processing of different classes of sexual stimuli.

RESULTS

P + CSO exhibited significantly longer vMMNm latencies (100-180 ms post-stimulus) than HC. Moreover, P + CSO showed widespread increased amplitudes in response to child images starting from P3a and P3b components and lasting up to 400 ms post-stimulus presentation localised in frontal and temporal brain regions.

CONCLUSIONS

This study uncovers the first MEG differences in automatic change detection between P + CSO and HC during the presentation of subliminal sexual images of adults and children, contributing towards a better understanding of the neurobiological processes of P + CSO.