The human sexual response cycle: brain imaging evidence linking sex to other pleasures

Cross-sex shifts in two brain imaging phenotypes and their relation to polygenic scores for same-sex sexual behavior: A study of 18,645 individuals from the UK Biobank

Genetic and hormonal factors have been suggested to influence human sexual orientation. Previous studied proposed brain differences related to sexual orientation and that these follow cross-sex shifted patterns. However, the neurobiological correlates of sexual orientation and how genetic factors relate to brain structural variation remains largely unexplored. Using the largest neuroimaging-genetics dataset available on same-sex sexual behavior (SSB) (n = 18,645), we employed a data-driven multivariate classification algorithm (PLS) on magnetic resonance imaging data from two imaging modalities to extract brain covariance patterns related to sex. Through analyses of latent variables, we tested for SSB-related cross-sex shifts in such patterns. Using genotype data, polygenic scores reflecting the genetic predisposition for SSB were computed and tested for associations with neuroimaging outcomes. Patterns important for classifying between males and females were less pronounced in non-heterosexuals. Predominantly in non-heterosexual females, multivariate brain patterns as represented by latent variables were shifted toward the opposite sex. Complementary univariate analyses revealed region specific SSB-related differences in both males and females. Polygenic scores for SSB were associated with volume of lateral occipital and temporo-occipital cortices. The present large-scale study demonstrates multivariate neuroanatomical correlates of SSB, and tentatively suggests that genetic factors related to SSB may contribute to structural variation in certain brain structures. These findings support a neurobiological basis to the differences in human sexuality.

The Impact of Psychosis on Sexual Functioning: A Systematic Review

BACKGROUND

Sexual dysfunction among psychotic patients is highly prevalent. However, most research has focused on antipsychotic side effects on sexual functioning.

AIM

To provide evidence by means of a systematic review of the literature about the impact of psychosis on sexual functioning among unmedicated patients.

METHODS

Systematic search of MEDLINE (PubMed), Scopus, and Google Scholar for studies that reported sexual functioning among psychotic patients, who were drug-naïve or drug-free for at least 3 weeks before the study. Studies were published in English language between January 1994 and October 2019. We used the approach recommended by PRISMA, and the selection process was carried out by 2 reviewers.

OUTCOMES

The outcome measures were sexual function and sexual dysfunctions.

RESULTS

A total of 734 articles were obtained, 658 were obtained after duplicates were removed, 612 were excluded after reading the title and abstract, and 46 were included for a complete review of the articles. 5 papers were finally included. A total of 770 cases were included in the systematic review. The prevalence of sexual dysfunction in psychosis varied from 16.8% to 70% and in ultra-high state was 50%. It is noteworthy that those ultra-high-risk (prodromal) patients who develop psychosis had higher rates of sexual impairment. Therefore, we found higher rates of sexual dysfunction among untreated patients, both psychotic and ultra-high risk patients, than healthy controls.

CLINICAL IMPLICATIONS

The assessment of sexual behavior should be a part of routine psychiatric examination not only in psychotic but also in ultra-high-risk patients.

STRENGTHS & LIMITATIONS

This is the first systematic review about the impact of psychosis on sexual functioning among unmedicated patients. However, scarce and heterogeneous studies were identified.

CONCLUSIONS

Impaired sexual functioning is common in the onset of psychosis (or during ultra-high-risk state) and prior to the beginning of treatment. This suggests that psychotic symptoms and sexual dysfunction may have common etiological pathways at the psychosocial and neurobiological levels. Vargas-Cáceres S, Cera N, Nobre P, et al. The Impact of Psychosis on Sexual Functioning: A Systematic Review. J Sex Med 2021;18:457-466.

Periodontitis, erectile dysfunction, reproductive hormones, and semen quality: A systematic review

BACKGROUND

There is increasing evidence that periodontitis may affect male sexual health (MSH) (erectile function, production of sex hormones, and semen quality). However, a limited number of clinical studies demonstrate the association between MSH and periodontitis.

OBJECTIVES

The aim of this study was to explore the relationship between periodontitis and MSF.

MATERIALS AND METHODS

A comprehensive systematic review of the published literature in MEDLINE, PubMed, Scopus, Cochrane, EMBASE, and Web of Science databases from the earliest available online indexing year until October 2020 was performed, in accordance with the PRISMA guidelines. Keywords related to periodontitis were combined with words describing MSH.

RESULT

A total of 19 studies were included and discussed in the systematic review. The number of study participants ranged from 53 to 197,136 individuals, aged between 18 and 95 years (mean age, 41.2 years). Six studies did not report the age of the participants. Out of nine studies, eight found a significant association between erectile dysfunction (ED) and periodontitis. Only three studies evaluated the association between sex hormone levels and periodontitis, and two of these studies showed that patients with periodontitis are expected to exhibit higher levels of testosterone. Finally, out of five studies, two demonstrated a significant association between semen quality and periodontitis.

DISCUSSION

The findings in this review were limited by the quality and the few available studies. Results from the observational studies might have been affected by recall bias and confounded by cofactors.

CONCLUSION

The results of this systematic review revealed a significant association between periodontitis and ED, although the responsible mechanisms remain unclear. The potential associations between sex hormone levels, semen quality, and periodontitis are yet to be demonstrated. In order to improve patient management, dentists and physicians need to be aware of the association between male sexual health problems and periodontitis.

Sexuality in Ultra-High Risk for Psychosis and First-Episode Psychosis. A Systematic Review of Literature

A considerable body of literature reports that individuals with psychotic disorders often suffer from sexual dysfunctions (SDs), with these representing a major unmet need. Long-term antipsychotic drug treatment may be the main cause for SDs in psychotic patients, through a plethora of different mechanisms, including prolactin dyscrasia, histamine-mediated sedation, and serotonin-induced sexual demotivation. However, a few pieces of evidence treat sexuality in patients at risk or the onset of psychosis. For this purpose, we systematically reviewed literature of the last 10 years in order to investigate sexuality in ultra-high risk (UHR) for psychosis and first-episode psychosis (FEP). We included in our review 34 articles fitting our research criteria on SDs in UHR and FEP. Evidence of SDs in the transition from UHR to FEP emerges through the selected studies. In FEP, sexuality is affected by the severity of the psychotic symptoms and, in some cases, by the iatrogenic effects of psychopharmacological treatment. Further experimental and clinical studies should systematically investigate the role of sexual functioning in the transition from UHR to FEP and, consequently, clarify whether or not SDs could be considered a possible marker for the onset of psychosis in at-risk populations. Moreover, psychiatrists and clinical psychologists should take into consideration the role of sexual life in young people with prodromal mental symptoms or at the onset of psychosis. Focusing on a thorough sexual evaluation might be a major challenge that could break down barriers of mental health promotion among young people with schizophrenia-spectrum disorders and therefore achieve better clinical outcomes.

The role of anterior and posterior insula in male genital response and in visual attention: an exploratory multimodal fMRI study

Several studies highlighted the role of insula on several functions and in sexual behavior. This exploratory study examines the relationships among genital responses, brain responses, and eye movements, to disentangle the role played by the anterior and posterior insula during different stages of male sexual response and during visual attention to sexual stimuli. In 19 healthy men, fMRI, eye movement, and penile tumescence data were collected during a visual sexual stimulation task. After a whole-brain analysis comparing neutral and sexual clips and confirming a role for the bilateral insulae, we selected two bilateral seed regions in anterior and posterior insula for functional connectivity analysis. Single-ROI-GLMs were run for the FC target regions. Single-ROI-GLMs were performed based on areas to which participants fixate: “Faces”, “Genitals,” and “Background” with the contrast “Genitals > Faces”. Single-ROI-GLMs with baseline, onset, and sustained PT response for the sexual clips were performed. We found stronger effects for the posterior than the anterior insula. In the target regions of the posterior insula, we found three different pathways: the first involved in visual attention, onset of erection, and sustained erection; the second involved only in the onset of erection, and the third limited to sustained erection.

Brain Functional Biomarkers Distinguishing Premature Ejaculation From Anejaculation by ALFF: A Resting-State fMRI Study

INTRODUCTION

Premature ejaculation (PE) and anejaculation (AJ) are 2 opposite disorders of male ejaculatory dysfunction. Recent studies have demonstrated that the process of ejaculation is mediated by certain neural circuits in the brain. However, different mechanisms between PE and AJ are still unclear.

AIM

Therefore, we used resting-state functional magnetic resonance imaging (fMRI) to explore the underlying neural mechanisms in patients with PE and AJ by measuring the amplitude of low-frequency fluctuations (ALFF).

METHODS

Resting-state fMRI data were acquired in 17 PE, 20 AJ patients and 23 matched healthy controls (HC).

MAIN OUTCOME MEASURE

Differences of ALFF values among the 3 groups were compared. We also explored the correlations between brain regions showing altered ALFF values and scores of Premature Ejaculation Diagnostic Tool (PEDT) in the PE group.

RESULTS

There were widespread differences of ALFF values among the 3 groups, which included left anterior cingulate gyrus, precentral and postcentral gyrus, paracentral lobule, superior temporal gyrus, calcarine fissure, putamen; right postcentral gyrus, paracentral lobule, middle temporal gyrus, putamen. Compared with HC, PE patients had greater ALFF in the right inferior frontal gyrus (opercular part), AJ patients had greater ALFF in the left postcentral gyrus. In addition, PE patients exhibited greater ALFF in the left Rolandic operculum, anterior cingulate gyrus, inferior frontal gyrus (orbital part), putamen, and right putamen when compared with AJ patients, as well as decreased ALFF in the right postcentral gyrus. Moreover, positive correlations were found between ALFF of left postcentral gyrus, inferior frontal gyrus (orbital part), right inferior frontal gyrus (opercular part), and PEDT scores.

CLINICAL IMPLICATIONS

The differences in central pathophysiological mechanisms between PE and AJ might be useful for improving the clinical diagnosis of ejaculation dysfunction.

STRENGTH & LIMITATIONS

Our results showed that the method of fMRI could identify the differences of ALFF between PE and AJ and that these alterations in ALFF were related to clinical function. However, this was a relatively small sample study, and further multimodal neuroimaging studies with large samples were needed.

CONCLUSION

The findings demonstrated that altered ALFF of frontal, parietal cortex, and putamen might help distinguish premature ejaculation from anejaculation. Abnormal function of these brain regions might play a critical role in the physiopathology of ejaculatory dysfunction of patients. Chen J, Yang J, Huang X, et al. Brain Functional Biomarkers Distinguishing Premature Ejaculation From Anejaculation by ALFF: A Resting-State fMRI Study. J Sex Med 2020;17:2331-2340.

The Influence of Sexual Arousal on Self-Reported Sexual Willingness and Automatic Approach to Models of Low, Medium, and High Prior Attractiveness

Anecdotal evidence suggests that sexual attraction is flexible, and that high levels of sexual arousal can promote sexual willingness and approach tendencies toward a priori low attractive mates. This experimental study tested whether heightened sexual arousal can lower the threshold for sexual willingness and automatic approach tendencies toward potential sex partners of low and medium attractiveness. Heterosexual male (n =54) and female (n =61) participants were randomly assigned to a sexual arousal or control condition. Approach tendencies were indexed using a reaction time task. Sexual willingness was indexed using participant ratings of willingness to kiss and to consider having sex with same- and other-sex models of low, medium, and high attractiveness. Overall, participants showed stronger approach to models of high and medium than of low attractiveness. Sexual arousal weakened this differential responding but did not result in a robust increase of approach toward less attractive other-sex or same-sex models. Sexual willingness toward less attractive models was not affected by sexual arousal. Independent of condition, women reported greater sexual willingness toward same-sex models. The current pattern of findings does not support the notion that sexual arousal promotes automatic approach and sexual willingness to a broader array of sex partners.

The role of dopaminergic and serotonergic transmission in the processing of primary and monetary reward

Natural rewards such as erotic stimuli activate common neural pathways with monetary rewards. In human studies, the manipulation of dopamine and serotonin play an important role in the processing of monetary rewards with less understood on its role on erotic stimuli. In this study, we investigate the neuromodulatory effects of dopaminergic and serotonergic transmission in the processing of erotic versus monetary visual stimuli. We scanned one hundred and two (N = 102) healthy volunteers using functional magnetic resonance imaging while performing a modified version of the well-validated monetary incentive delay task consisting of erotic, monetary and neutral visual stimuli. We show a role for enhanced central dopamine and lowered central serotonin levels in increasing activity in the right caudate and left anterior insula during anticipation of erotic relative to monetary rewards in healthy controls. We further show differential activation in the anticipation of natural versus monetary rewards with the former associated with ventromesial and dorsomesial activity and the latter with dorsal cingulate, striatal and anterior insular activity. These findings are consistent with preclinical and clinical findings of a role for dopaminergic and serotonergic mechanisms in the processing of natural rewards. Our study provides further insights into the neural substrates underlying reward processing for natural primary erotic rewards and yields importance for the neurochemical systems of addictive disorders including gambling disorder.

Brain Cortical Complexity and Subcortical Morphometrics in Lifelong Premature Ejaculation

Premature ejaculation (PE) is the most common male sexual dysfunction. The brain disturbances that cause this disorder remain poorly understood. This study aimed to investigate how the morphology of cortical and subcortical brain structures differed in PE, how these morphologic differences were associated with severity measures of PE, such as intravaginal ejaculatory latency time (IELT), and how these cortical and subcortical structures were causally connected through mediation analysis. Anatomical MRI scans were acquired from 39 male participants, 23 with PE (28.78 ± 4.32 years), and 16 without PE (27.88 ± 3.65 years). We used a subcortical analysis package within FSL to perform subcortical shape segmentation and statistical analysis. The PE group was compared with the normal control (NC) group in the shapes of 15 subcortical structures with general linear models [p < 0.05, family-wise error (FWE)-corrected]. We analyzed the cortical complexity revealed by the gyrification index using the Computational Anatomy Toolbox (CAT12). Vertex-wise shape analyses revealed outward shape deformations (expansions) in the left hippocampus and bilateral thalamus. Gyrification index analyses revealed that the right orbital frontal cortex and the right nucleus accumbens had greater complexity in PE patients. The shape deformations were positively correlated with the IELTs in the NC group, while this relationship was interrupted in the PE group. PE is associated with outward deformations of the subcortical surfaces and more complexity of the cortical structures. These morphological differences may be the basis of the brain functional alterations underlying PE.

Exploring the clinical profile of problematic pornography use

BACKGROUND

Although problematic pornography use (PPU) will soon be diagnosable through the International Classification for Diseases, 11th revision, its clinical profile remains contentious. The current study assessed whether PPU may be characterized by various symptoms sometimes observed among online recovery forums that currently lack empirical assessment, such as heightened cognitive-affective issues following pornography use and sexual dysfunction with partners as a result of escalating use.

METHOD

Cross-sectional surveys were completed by male PPUs (N = 138, mean age = 31.75 years, standard deviation = 10.72) recruited via online recovery communities and Amazon Mechanical Turk. Multiple regression analysis was performed using the Problematic Pornography Use Scale as the dependent variable and variables of interest (Arizona Sexual Experiences Scales modified for partnered sex and pornography use, Brunel Mood Scale, Social Interaction Anxiety Scale, and the Tolerance subscale from the Problematic Pornography Consumption Scale) and potential confounders (eg, comorbid psychopathology) as independent variables.

RESULTS

Current levels of pornography use, indicators of tolerance and escalation, greater sexual functioning with pornography, and psychological distress were uniquely associated with PPU severity, while cognitive-affective issues after pornography use, impulsivity and compulsivity were not. Although sexual dysfunction did not predict PPU severity, nearly half the sample indicated sexual dysfunction with intimate partners.

CONCLUSIONS

The present findings suggest that PPU may be characterized by tolerance and escalation (as per substance addiction models), greater sexual responsivity toward pornography, and psychological distress. Meanwhile, the high rate of partnered sexual dysfunction observed suggests that PPU might be somewhat separable from other forms of compulsive sexual behavior.

Subjective reward value of visual sexual stimuli is coded in human striatum and orbitofrontal cortex

Human neuroimaging research suggests the existence of one core network for the subjective valuation of rewards, including the striatum and orbitofrontal cortex. However, there is little research on the neural representation of subjective reward values of visual sexual stimuli (VSS) and on the role of these subjective valuations in the development of related addictive behaviors. Here, we investigate how neural reactivity to VSS is connected to individual preference using functional magnetic resonance imaging (fMRI). During the fMRI scan, 72 men viewed different VSS film clips. Ratings regarding valence and sexual arousal were collected and used as parametric modulators in the fMRI analysis. Subjects also filled out questionnaires on self-reported symptoms of problematic pornography use (PPU). Firstly, we found that neural reactivity towards VSS clips in the nucleus accumbens, caudate nucleus and orbitofrontal cortex was positively correlated with individual ratings of the respective VSS in all subjects. Second, the strength of the association between neural activity and sexual arousal ratings was positively correlated with self-reported symptoms of PPU. The first result suggests a precise appraisal of VSS according to individual preferences in established reward valuation regions. Secondly, stronger neural differentiation based on preference in participants with more PPU symptoms indicates an increased importance of VSS/preference fit in these individuals. This heightened correspondence between individual liking and neural activity may facilitate PPU development by increased signaling of incentive salience, thus boosting motivation to seek out and respond to these preferred stimuli.

An insight-related neural reward signal

Moments of insight, a phenomenon of creative cognition in which an idea suddenly emerges into awareness as an "Aha!" are often reported to be affectively positive experiences. We tested the hypothesis that problem-solving by insight is accompanied by neural reward processing. We recorded high-density EEGs while participants solved a series of anagrams. For each solution, they reported whether the answer had occurred to them as a sudden insight or whether they had derived it deliberately and incrementally (i.e., "analytically'). Afterwards, they filled out a questionnaire that measures general dispositional reward sensitivity. We computed the time-frequency representations of the EEGs for trials with insight (I) solutions and trials with analytic (A) solutions and subtracted them to obtain an I-A time-frequency representation for each electrode. Statistical Parametric Mapping (SPM) analyses tested for significant I-A and reward-sensitivity effects. SPM revealed the time, frequency, and scalp locations of several I ​> ​A effects. No A ​> ​I effect was observed. The primary neural correlate of insight was a burst of (I ​> ​A) gamma-band oscillatory activity over prefrontal cortex approximately 500 ​ms before participants pressed a button to indicate that they had solved the problem. We correlated the I-A time-frequency representation with reward sensitivity to discover insight-related effects that were modulated by reward sensitivity. This revealed a separate anterior prefrontal burst of gamma-band activity, approximately 100 ​ms after the primary I-A insight effect, which we interpreted to be an insight-related reward signal. This interpretation was supported by source reconstruction showing that this signal was generated in part by orbitofrontal cortex, a region associated with reward learning and hedonically pleasurable experiences such as food, positive social experiences, addictive drugs, and orgasm. These findings support the notion that for many people insight is rewarding. Additionally, these results may explain why many people choose to engage in insight-generating recreational and vocational activities such as solving puzzles, reading murder mysteries, creating inventions, or doing research. This insight-related reward signal may be a manifestation of an evolutionarily adaptive mechanism for the reinforcement of exploration, problem solving, and creative cognition.

Neural Responses to Sexual Stimuli in Heterosexual and Homosexual Men and Women: Men's Responses Are More Specific

Patterns of genital arousal in response to gendered sexual stimuli (i.e., sexual stimuli presenting members of only one sex at a time) are more predictive of men's than of women's sexual orientations. Additional lines of evidence may shed light on the nature of these differences. We measured neural activation in homosexual and heterosexual men and women using fMRI while they viewed three kinds of gendered sexual stimuli: pictures of nude individuals, pictures of same-sex couples interacting, and videos of individuals self-stimulating. The primary neural region of interest was the ventral striatum (VS), an area of central importance for reward processing. For all three kinds of stimuli and for both VS activation and self-report, men's responses were more closely related to their sexual orientations compared with women's. Furthermore, men showed a much greater tendency to respond more positively to stimuli featuring one sex than to stimuli featuring the other sex, leading to higher correlations among men's responses as well as higher correlations between men's responses and their sexual orientations. Whole-brain analyses identified several other regions showing a similar pattern to the VS, and none showed an opposite pattern. Because fMRI is measured identically in men and women, our results provide the most direct evidence to date that men's sexual arousal patterns are more gender specific than women's.

Neuroanatomy and function of human sexual behavior: A neglected or unknown issue?

INTRODUCTION

Sexual desire, arousal, and orgasm are mediated by complex, yet still not fully understood, interactions of the somatic and autonomic nervous systems operating at the central and peripheral levels. Disruption of endocrine, neural, or vascular response, caused by aging, medical illness, neurological diseases, surgery, or drugs, can lead to sexual dysfunctions, thus significantly affecting patients' quality of life.

PURPOSE

This narrative review aims at characterizing the involvement of the central nervous system in human sexual behavior.

METHODS

A literature search was conducted using PubMed in its entirety up to June 2018, analyzing the studies dealing with the neurobiological and neurophysiological basis of human sexuality.

RESULTS

Sexual behavior is regulated by both subcortical structures, such as the hypothalamus, brainstem, and spinal cord, and several cortical brain areas acting as an orchestra to finely adjust this primitive, complex, and versatile behavior. At the central level, dopaminergic and serotonergic systems appear to play a significant role in various factors of sexual response, although adrenergic, cholinergic, and other neuropeptide transmitter systems may contribute as well.

CONCLUSIONS

Providing healthcare professionals with information concerning sexual behavior may overcome useless and sometimes dangerous barriers and improve patient management, since sexual well-being is considered one of the most important aspects of one's quality of life.

Premature Ejaculation: Aetiology and Treatment Strategies

Premature ejaculation (PE) is a highly prevalent male sexual dysfunction that is often neglected, presenting a currently unmet therapeutic need. The classification of PE has historically been varied and at times ambiguous, contributing to inaccurate prevalence estimates. This review uses the International Society for Sexual Medicine (ISSM) definition of PE, which includes reduced ejaculatory latency, lack of control and associated negative personal consequences. Patient assessment and management options differ depending on the classification of PE and it is the role of the clinician to appropriately classify patients and be aware of the correct management strategies. This review provides an overall background of PE in terms of classification and underlying physiology, patient assessment and management strategies along with the scientific rationale for treatment. Patients with lifelong and acquired PE are most likely to benefit from combination therapy of pharmacological treatment in the form of selective serotonin re-uptake inhibitor dapoxetine, psychosexual behavioural therapy and psychological therapy.

Glutamate Afferents From the Medial Prefrontal Cortex Mediate Nucleus Accumbens Activation by Female Sexual Behavior

Low levels of desire and arousal are the primary sexual dysfunctions in women, necessitating neurobiological studies of sexual motivation in female animal models. As the mesocorticolimbic system is a primary neural circuit underlying sexual motivation, the goal of this study was to test the hypothesis that medial prefrontal cortex (mPFC) glutamate mediates sexual behavior activation of the nucleus accumbens. Glutamatergic neurons in the mPFC were activated by sex behavior, and these sex-activated cells shown to project to the nucleus accumbens. During sexual interactions with the male, glutamate transients recorded in the nucleus accumbens of female hamsters were specifically associated with the receipt of intromissions from the male. Further, inhibition of the mPFC during sex significantly decreased nucleus accumbens activation. Glutamatergic medial prefrontal cortical input to the nucleus accumbens mediates the activity in the nucleus accumbens during female sexual behavior. These results offer novel insights into the neurobiology of the motivational control of female sexual behavior and provide attractive avenues for pursuing target-specific and clinically-relevant therapies for sexual dysfunction in women.

Mixed Emotions: An Incentive Motivational Model of Sexual Deviance

Sexual offending behavior is a complex and multifaceted phenomenon. Most existing etiological models describe sexual offending behavior as a variant of offending behavior and mostly include factors referring to disinhibition and sexual deviance. In this article, we argue that there is additional value in describing sexual offending behavior as sexual behavior in terms of an incentive model of sexual motivation. The model describes sexual arousal as an emotion, triggered by a competent stimulus signaling potential reward, and comparable to other emotions coupled with strong bodily reactions. Consequently, we describe sexual offending behavior in terms of this new model with emphasis on the development of deviant sexual interests and preferences. Summarized, the model states that because sexual arousal itself is an emotion, there is a bidirectional relationship between sexual self-regulation and emotional self-regulation. Not only can sex be used to regulate emotional states (i.e., sexual coping), emotions can also be used, consciously or automatically, to regulate sexual arousal (i.e., sexual deviance). Preliminary support for the model is drawn from studies in the field of sex offender research as well as sexology and motivation research.

Modeling Human Sexual Motivation in Rodents: Some Caveats

Sexual behavior is activated by motivation. An overwhelming majority of experimental studies of the intricacies of sexual motivation has been performed in rodents, most of them in rats. Sometimes it is desirable to generalize results obtained in this species to other species, particularly the human. It is hoped that studies of the neurobiology of rodent sexual behavior may shed light on the central nervous mechanisms operating in the human, and the search for efficient pharmacological treatments of human sexual dysfunctions relies partly on studies performed in rodents. Then the issue of generalizability of the rodent data to the human becomes crucial. We emphasize the importance of distinguishing between copulatory acts, behavior involving the genitals, and the preceding event, the establishment of physical contact with a potential mate. Comparisons between the structure of copulatory behavior in rats and humans show abysmal differences, but there may be some similarity in the underlying mechanisms. The endocrine control of sex behavior is shortly mentioned, and we also compare the effects of the few drugs known to affect both rodent and human copulatory behavior. The stimuli activating sexual motivation, often called desire in the human literature, are examined, and the sexual approach behaviors in rats and humans are compared. There is a striking similarity between these species in how these behaviors respond to drugs. It is then shown that the intensity of sexual approach is unrelated to the intensity of copulatory behavior. Even though the approach is a requisite for copulation, an activity that requires at least two individuals in close physical contact, these two aspects of sexuality do not covary. This is similar to the role of the testosterone in men and male rats: although the hormone is needed for sex behavior, there is no correlation between serum testosterone concentration and the intensity of copulation. It is also pointed out that human sexual behavior is mostly determined by social conventions, whereas this is not the case in rats and other rodents. It is concluded that some observations in rats can be generalized to the human, but extreme caution must be exercised.

No Sex Difference Found: Cues of Sexual Stimuli Activate the Reward System in both Sexes

Sexually explicit material (SEM) is increasingly used in western societies. One reason for this high usage might be the rewarding property of SEM demonstrated in many brain imaging studies showing an activation of the reward system during the presentation of SEM. It is not yet well understood why women use SEM to a remarkably lesser extent than men. Maybe men react stronger to stimuli - so called SEM cues -, which signal the presentation of SEM and are therefore more vulnerable to use SEM than women. Therefore, the present study aimed at investigating the sex specific neural correlates towards SEM and SEM cues. We were further interested in whether person characteristics as trait sexual motivation, extent of SEM use in the last month, and age at onset of goal-oriented SEM use affect the neural responses to SEM and SEM cues. The trials of the fMRI experiment consisted of an expectation phase with SEM or neutral cues and a presentation phase with SEM or neutral stimuli, respectively. Analyses showed that the reward circuitry was activated by SEM, but also by SEM cues. There were some sex differences in hemodynamic responses to SEM during the presentation phase, but not during the expectation phase to SEM cues in any of the regions of interest. The influence of the investigated person characteristics was only small if existent. The results suggest that sex specific cue processing cannot explain sex differences in the use of SEM.

Neural substrates of sexual arousal are not sex dependent

Neuroimaging studies suggest differences in the underlying biology of sexual arousal associated with sex and sexual orientation, yet their findings are conflicting. Following a thorough statistical review of all significant neuroimaging studies, we offer strong quantitative evidence that the neuronal response to visual sexual stimuli, contrary to the widely accepted view, is independent of biological sex. Both men and women show increased activation in many cortical and subcortical brain regions thought to be involved in the response to visual sexual stimuli, while the limited sex differences that have been found and reported previously refer to subjective rating of the content.

Sexual arousal is a dynamical, highly coordinated neurophysiological process that is often induced by visual stimuli. Numerous studies have proposed that the cognitive processing stage of responding to sexual stimuli is the first stage, in which sex differences occur, and the divergence between men and women has been attributed to differences in the concerted activity of neural networks. The present comprehensive metaanalysis challenges this hypothesis and provides robust quantitative evidence that the neuronal circuitries activated by visual sexual stimuli are independent of biological sex. Sixty-one functional magnetic resonance imaging studies (1,850 individuals) that presented erotic visual stimuli to men and women of different sexual orientation were identified. Coordinate-based activation likelihood estimation was used to conduct metaanalyses. Sensitivity and clustering analyses of averaged neuronal response patterns were performed to investigate robustness of the findings. In contrast to neutral stimuli, sexual pictures and videos induce significant activations in brain regions, including insula, middle occipital, anterior cingulate and fusiform gyrus, amygdala, striatum, pulvinar, and substantia nigra. Cluster analysis suggests stimulus type as the most, and biological sex as the least, predictor for classification. Contrast analysis further shows no significant sex-specific differences within groups. Systematic review of sex differences in gray matter volume of brain regions associated with sexual arousal (3,723 adults) did not show any causal relationship between structural features and functional response to visual sexual stimuli. The neural basis of sexual arousal in humans is associated with sexual orientation yet, contrary to the widely accepted view, is not different between women and men.

Weight Loss in Women Taking Flibanserin for Hypoactive Sexual Desire Disorder (HSDD): Insights Into Potential Mechanisms

INTRODUCTION

Flibanserin, a multifunctional serotonin receptor agonist and antagonist, is currently approved in the United States and Canada for the treatment of acquired, generalized hypoactive sexual desire disorder (HSDD) in premenopausal women. A post hoc analysis of HSDD clinical trial data found that flibanserin treatment was associated with statistically significant weight loss relative to placebo, even though study patients were not selected for being overweight/obese and were provided no expectation for weight reduction or interventions intended to promote weight loss.

AIM

To understand possible mechanisms by which flibanserin may produce weight loss.

METHODS

A literature review was performed using Medline database for relevant publications on the mechanisms of action by which flibanserin may provide weight loss and the links between sexual function and weight management.

MAIN OUTCOME MEASURES

Examination of (i) biopsychosocial factors regulating sexual desire, food intake, and weight regulation; (ii) clinical pharmacology of flibanserin; (iii) neurobiology of brain reward circuitry; and (iv) identification of possible mechanisms common to flibanserin and weight loss.

RESULTS

Based on flibanserin clinical trial data, there was no consistent correlation between weight loss and improvement in sexual function, as assessed by HSDD outcome measures. Nausea, a common adverse event associated with flibanserin use, also did not appear to be a contributing factor to weight loss. Hypothetical links between flibanserin treatment and weight loss include modulation of peripheral 5-HT_2A receptors and factors such as improved mood and improved sleep.

CONCLUSION

Mechanisms of flibanserin-induced weight loss have not been well characterized but may involve indirect beneficial effects on peripheral 5-HT_2A receptors and central regulation of mood and sleep. Future research may better elucidate the links between sexual function and weight management and the mechanism(s) by which flibanserin use may result in weight loss. Simon JA, Kingsberg SA, Goldstein I, et al. Weight Loss in Women Taking Flibanserin for Hypoactive Sexual Desire Disorder (HSDD): Insights into Potential Mechanisms. Sex Med Rev 2019;7:575-586.

Intensity of affective experience is modulated by magnitude of intracranial electrical stimulation in human orbitofrontal, cingulate and insular cortices

The subjective and behavioral effects of intracranial electrical stimulation (iES) have been studied for decades, but there is a knowledge gap regarding the relationship between the magnitude of electric current and the type, intensity and valence of evoked subjective experiences. We report on rare iES data from 18 neurosurgical patients with implanted intracranial electrodes in the orbitofrontal cortex (OFC), the insula (INS) and the anterior portion of cingulate cortex (ACC). ACC stimulation elicited somatic and visceral sensations, whereas OFC stimulation predominantly elicited olfactory and gustatory responses, and INS stimulation elicited a mix of effects involving somatic and visceral sensations, olfaction and gustation. Further, we found striking evidence that the magnitude of electric current delivered intracranially correlated positively with the perceived intensity of subjective experience and the evoked emotional state, a relationship observed across all three regions. Finally, we observed that the majority of reported experiences were negatively valenced and unpleasant, especially those elicited by ACC stimulation. The present study provides novel case studies from the human brain confirming that these structures contribute causally to the creation of affective states and demonstrates a direct relationship between the magnitude of electrical stimulation of these structures and the qualia of elicited subjective experience. Summary: This study provides critical knowledge about the effect of electrical charge magnitude on the intensity of human subjective experiences and emotional states. We shed light on the fundamental relationship between the electrical (physical) state of cortical tissue and the modality and intensity of human (subjective) experience. As electroceutical interventions are increasingly employed to treat neurological and psychiatric disorders, these findings highlight the importance of electrical stimulation magnitude for eliciting specific changes in human subjective experience.

Effect of Sex Hormones on Brain Connectivity Related to Sexual Function in Perimenopausal Women: A Resting-State fMRI Functional Connectivity Study

BACKGROUND

Perimenopause is associated with increased risk of depression, vasomotor symptoms, and sexual dysfunction.

AIMS

To explore the effect of sex hormones on the functional connectivity (FC) of different brain regions related to sexual function in perimenopausal women.

METHODS

32 premenopausal women (mean age, 47.75 ± 1.55 years) and 25 perimenopausal women (mean age, 51.60 ± 1.63 years) underwent sex hormone level measurements and resting-state fMRI.

MAIN OUTCOME MEASURES

Serum levels of sex hormones, including prolactin (PRL), follicle-stimulating hormone (FSH), luteotropic hormone (LH), estradiol (E2), free testosterone (free-T), and progesterone (P), were measured. 10 brain regions related to sexual function were selected according to a meta-analysis, and FCs of the selected regions of interest were calculated as Pearson's correlation coefficient.

RESULTS

Compared with premenopausal women, perimenopausal women showed increased FC between the right area 13 (A13_r) and the right medial superior frontal gyrus (mSFG), between the left dorsal granular insula (dIg_L) and the right superior frontal gyrus (SFG) (Gaussian random field-corrected at the voxel level, P < .001, and cluster level, P < .025). Furthermore, the PRL level was negatively correlated with the FC of A13_R with the right mSFG and the FC of dIg_L with the right SFG.

CLINICAL TRANSLATION

These findings may be applicable to assessing brain dysfunction with FC changes in women approaching menopause.

STRENGTHS & LIMITATIONS

This study is the first to evaluate a direct relationship between sex hormone levels and brain FC changes in women approaching menopause. Sexual function was not assessed, which may weaken the conclusions related to sexual function.

CONCLUSIONS

The results show that women approaching menopause suffered from aberrant intrinsic FC in regions related to sexual function, and reveal a direct relationship between serum sex hormone levels and FC changes related to sexual function. Lu W, Guo W, Cui D, et al. Effect of Sex Hormones on Brain Connectivity Related to Sexual Function in Perimenopausal Women: A Resting-State fMRI Functional Connectivity Study. J Sex Med 2019;16:711-720.

Serotonergic, Dopaminergic, and Noradrenergic Modulation of Erotic Stimulus Processing in the Male Human Brain

Human sexual behavior is mediated by a complex interplay of cerebral and spinal centers, as well as hormonal, peripheral, and autonomic functions. Neuroimaging studies identified central neural signatures of human sexual responses comprising neural emotional, motivational, autonomic, and cognitive components. However, empirical evidence regarding the neuromodulation of these neural signatures of human sexual responses was scarce for decades. Pharmacological functional magnetic resonance imaging (fMRI) provides a valuable tool to examine the interaction between neuromodulator systems and functional network anatomy relevant for human sexual behavior. In addition, this approach enables the examination of potential neural mechanisms regarding treatment-related sexual dysfunction under psychopharmacological agents. In this article, we introduce common neurobiological concepts regarding cerebral sexual responses based on neuroimaging findings and we discuss challenges and findings regarding investigating the neuromodulation of neural sexual stimulus processing. In particular, we summarize findings from our research program investigating how neural correlates of sexual stimulus processing are modulated by serotonergic, dopaminergic, and noradrenergic antidepressant medication in healthy males.

Body Movement Is Associated With Orgasm During Vaginal Intercourse in Women

Very few studies have investigated the relationship between women's ability to experience an orgasm during vaginal intercourse and specific stimulation techniques. We examined two common techniques during vaginal intercourse both with and without simultaneous external clitoral stimulation: (1) body movement, in particular back-and-forth swinging movements of the pelvis and trunk; and (2) precise rubbing of the clitoris with an immobilized body. Structural equation modeling was used to compare the effects of the two stimulation techniques on women's orgasm frequency (N = 1,239). As hypothesized, the frequency of orgasm during vaginal intercourse with simultaneous clitoral stimulation was positively associated with a preference for body movement during arousal. Body movement, as opposed to body immobilization, was also associated with a higher frequency of orgasm during vaginal intercourse without simultaneous clitoral stimulation. We conclude that body movement is associated with more orgasms during vaginal intercourse, whereas precise rubbing of the clitoris with an immobilized body is not associated with more orgasms. Teaching women to move their pelvis and trunk in a swinging back-and-forth movement during vaginal intercourse might therefore facilitate reaching an orgasm, whereas encouraging them to self-stimulate the clitoris might be less helpful if done with an immobilized body.

Positive emotions have a unique capacity to capture attention

Most of the previous research in the area of cognitive psychology or cognitive neuroscience focused on studying negative emotions and argued that the negative emotional stimuli capture attention involuntarily as compared to neutral stimuli. However, in the last decades, researchers started paying attention in studying positive emotions also as positive emotions have evolutionary significance and are essential for many aspects of our life. The theme of this chapter is to present an overview of research in the area of positive emotions, and make a case that positively-valenced stimulus is prioritized over others. Primarily, when attentional resources are not constrained, many studies have shown that similar to negative stimuli, positive stimuli also capture attention automatically irrespective of whether they are relevant or irrelevant to the primary task. It suggests a fundamental prioritization of these stimuli by the cognitive/motivational system. However, when attentional resources are constrained, only positive or high rewarding stimuli win the competition for attentional resources compared to negative or stimuli associated with high punishment. Positive or high rewarding stimuli also receive priority in temporal selection, when attention is constrained. Theoretical implications of these results have been discussed. Possible cognitive and neural mechanisms have been proposed underlying these effects.

The cognitive aspects of sexual intimacy in dementia patients: a neurophysiological review

Changes in higher-order cognitive behaviors such as reward recognition, salience processing, novelty perception, decision-making, emotional contagion, motivation, and empathy may contribute to intimacy dysfunction. Network circuitry underlying these cognitive functions is often activated in sexually intimate behavior. We propose that sexual dysfunction in AD and bvFTD is more nuanced than is commonly believed, and propose how AD and bvFTD atrophy may correlate neuroanatomically to brain regions and networks that contribute to the higher-order cognitive aspects of intimacy. The characterization of sexual intimacy in dementias must be expanded to meet the needs of our dementia patients and their romantic partners.

Diminished fronto-limbic functional connectivity in child sexual offenders

BACKGROUND

Child sexual abuse and neglect have been related to an increased risk for the development of a wide range of behavioral, psychological, and sexual problems and increased rates of suicidal behavior. Contrary to the large amount of research focusing on the negative mental health consequences of child sexual abuse, very little is known about the characteristics of child sexual offenders and the neuronal underpinnings contributing to child sexual offending.

METHODS AND SAMPLE

This study investigates differences in resting state functional connectivity (rs-FC) between non-pedophilic child sexual offenders (N = 20; CSO-P) and matched healthy controls (N = 20; HC) using a seed-based approach. The focus of this investigation of rs-FC in CSO-P was put on prefrontal and limbic regions highly relevant for emotional and behavioral processing.

RESULTS

Results revealed a significant reduction of rs-FC between the right centromedial amygdala and the left dorsolateral prefrontal cortex in child sexual offenders compared to controls.

CONCLUSION & RECOMMENDATIONS

Given that, in the healthy brain, there is a strong top-down inhibitory control of prefrontal over limbic structures, these results suggest that diminished rs-FC between the amygdala and the dorsolateral prefrontal cortex and may foster sexual deviance and sexual offending. A profound understanding of these concepts should contribute to a better understanding of the occurrence of child sexual offending, as well as further development of more differentiated and effective interventions.

Aberrant baseline brain activity in psychogenic erectile dysfunction patients: a resting state fMRI study

Recent neuroimaging studies have elucidated many interesting and promising findings on sexuality regarding the neural underpinnings of both normal and abnormal sexual processes. Psychogenic erectile dysfunction (pED) consists of a major part of male sexual dysfunction in China, but the understanding of the central mechanism of pED is still in its infancy. It is commonly appreciated that pED is a functional disorder, which can be attributed predominantly or exclusively to psychological factors, such as anxiety, depression, loss of self-esteem, and psychosocial stresses. Most previous studies probed the central response in the brain of pED patients using sexual-related stimuli. However, little concern has been given to a more fundamental issue whether the baseline brain activity is altered in pED or not. With rs-fMRI data, the current study aimed to explain the central mechanism behind pED by investigating the alterations in baseline brain activity in patients with pED, as indexed by the amplitude of low-frequency (0.01-0.08 Hz) fluctuation (ALFF). After the psychological screening and urological examination procedure, 26 pED patients and 26 healthy matched controls were enrolled. Our results explicated significantly lower baseline brain activity in the right anterior insula and right orbitofrontal cortex for pED patients (multiple comparison corrected). Additionally, the voxel-wise correlation analysis showed that ALFF of the right anterior insula was correlated with the outcomes of erectile function (multiple comparison corrected). Our results implied there was impaired cognitive and motivational processing of sexual stimuli in pED patients. Our current findings may shed light on the neural pathology underlying pED. We hope that our study has provided a new angle looking into pED research by investigating resting state brain activity. Furthermore, we suggest that the current study may put forward a more subtle conception of insular influence on pED, which may help foster new specific, mechanistic insights.

Neurobiology of male sexual dysfunctions in psychiatric disorders: the cases of depression, anxiety, mania and schizophrenia

While the pathophysiology of several psychiatric disorders has become modestly elucidated in the last decade, comorbid sexual dysfunctions in such patients are frequently left apart from clinical and research interest. We aimed to address the malfunctioning neurocircuitry underlying sexual dysfunctions in depression, anxiety, schizophrenia and mania. We performed a comprehensive literature review, addressing any combination of the topics of "neurobiology"/"neural", "sexual"/"desire"/"arousal"/"orgasm"/"ejaculation" and "depression"/"anxiety"/"schizophrenia"/"mania"/"bipolar". Altered neurotransmitter levels or connectivity in patients are reported in sexual dysfunctions (either desire, arousal, orgasm and ejaculation) and main psychiatric disorders (depression, anxiety, mania and schizophrenia). Neuronal pathways responsible for the occurrence of sexual dysfunctions in psychiatric disorders can be  figured out by overlap  of their acknowledged pathophysiology. However, specific research in that group is scant, so future tailored studies are warranted to elucidate actual mechanisms.

Tendencies toward Internet-pornography-use disorder: Differences in men and women regarding attentional biases to pornographic stimuli

BACKGROUND AND AIMS

Several authors consider Internet-pornography-use disorder (IPD) as addictive disorder. One of the mechanisms that has been intensively studied in substance- and non-substance-use disorders is an enhanced attentional bias toward addiction-related cues. Attentional biases are described as cognitive processes of individual's perception affected by the addiction-related cues caused by the conditioned incentive salience of the cue itself. It is assumed in the I-PACE model that in individuals prone to develop IPD symptoms implicit cognitions as well as cue-reactivity and craving arise and increase within the addiction process.

METHODS

To investigate the role of attentional biases in the development of IPD, we investigated a sample of 174 male and female participants. Attentional bias was measured with the Visual Probe Task, in which participants had to react on arrows appearing after pornographic or neutral pictures. In addition, participants had to indicate their sexual arousal induced by pornographic pictures. Furthermore, tendencies toward IPD were measured using the short-Internetsex Addiction Test.

RESULTS

The results of this study showed a relationship between attentional bias and symptom severity of IPD partially mediated by indicators for cue-reactivity and craving. While men and women generally differ in reaction times due to pornographic pictures, a moderated regression analysis revealed that attentional biases occur independently of sex in the context of IPD symptoms.

DISCUSSION

The results support theoretical assumptions of the I-PACE model regarding the incentive salience of addiction-related cues and are consistent with studies addressing cue-reactivity and craving in substance-use disorders.

Validation of an Event-Level, Male Sexual Pleasure Scale (EMSEXpleasure) Among Condom-Using Men in the U.S

Sexual pleasure is a key determinant of condom use. We developed and validated a male, event-level sexual pleasure scale (EMSEXpleasure) among a sample of condom-using men in the U.S. in order to facilitate improved measurement of sexual pleasure. Based on an expert panel process, a 12-item scale was developed. An online sample of 169 men who have sex with men and 162 men who have sex with women were recruited. Factor analysis yielded a two-factor solution that matched domains identified a priori by the expert panel, general pleasure and condom-specific pleasure, indicating internal validity of the instrument. One item was deleted from the scale due to poor validity performance. The overall EMSEXpleasure scale, and each subscale, had high (> 0.8) Cronbach's alpha coefficients, indicating internal reliability. The scale demonstrated convergent validity, with theoretically related constructs associated both with individual scale items and with scale totals. Overall relationship quality (b 3.0, 95% CI 2.0, 4.0), sexual relationship quality (b 2.9, 95% CI 2.0, 4.0), foreplay quality (b 7.5, 95% CI 2, 13), positive feelings about condoms (b 18.8, 95% CI 15, 23), and erection problems while using condoms (b - 17.9, 95% CI - 22, - 14) were associated with the EMSEXpleasure scale in expected directions. The validated EMSEXpleasure event-level scale may be advantageous for future assessments of the ephemeral experience of sexual pleasure, including clinical trials of condoms and other interventions, because it can be used immediately after sex, potentially limiting recall error.

Music, dance, and other art forms: New insights into the links between hedonia (pleasure) and eudaimonia (well-being)

For Aristotle, the goal of human life was to live well, to flourish, and to ultimately have a good life. These goals can be conceptualized as "eudaimonia," a concept distinct from "hedonia" (pleasure). Many people would argue that the arts play a large role in their well-being and eudaimonia. Music in particular is a culturally ubiquitous phenomenon which brings joy and social bonding to listeners. Research has given insights into how the "sweet anticipation" of music and other art forms can lead to pleasure, but a full understanding of eudaimonia from the arts is still missing. What is clear is that anticipation and prediction are important for extracting meaning from our environment. In fleeting moments this may translate into pleasure, but over longer timescales, it can imbue life with meaning and purpose and lead to eudaimonia. Based on the existing evidence from neuroimaging, we hypothesize that a special network in the brain, the default-mode network, may play a central role in orchestrating eudaimonia, and propose future strategies for exploring these questions further.

Correlates of Sexual Functioning and Relationship Satisfaction Among Men and Women Experiencing Chronic Pain

Background

The aims of the study were to 1) examine the prevalence of sexual functioning difficulties in a chronic pain sample; 2) identify correlates of sexual functioning and relationship satisfaction utilizing pain variables (pain severity and pain interference) and psychological variables (mood, pain-related cognitions, self-efficacy, self-esteem, body-image); and 3) investigate possible sex differences in the correlates of sexual functioning and relationship satisfaction.

Method

Two hundred sixty-nine participants were recruited online from chronic pain organizations, websites, social media sites, and discussion forums. Those who met criteria for inclusion were presented with a variety of measures related to pain, sexual functioning, and relationship satisfaction (for those in a relationship), as well as cognitive and affective variables.

Results

Participant mean age was 37 years, and the majority were female, heterosexual, and currently in a relationship. High levels of pain severity and interference from pain, fatigue, depression, anxiety, stress, and body image concerns were reported, along with low levels of self-esteem and pain self-efficacy. In addition, substantial proportions of male (43%) and female (48%) respondents had scores indicative of sexual problems. Exploratory hierarchical regression analyses revealed that, for women, age and relationship satisfaction (which were both treated as covariates) as well as depression emerged as statistically significant correlates of sexual functioning (i.e., women who were older and reported greater levels of depression and less satisfaction with their current relationship indicated poorer sexual functioning). When relationship satisfaction was the criterion measure, age and sexual functioning (again, treated as covariates) and perceived stress emerged as significant (i.e., women who were older, reported poorer sexual functioning, and reported greater perceived stress also indicated being less satisfied with their current relationship). For male participants, age emerged as the only statistically significant correlate of sexual functioning (i.e., older men reported poorer functioning). In terms of relationship satisfaction, self-esteem was the lone significant correlate variable (men who reported lower self-esteem also were less satisfied with their current relationship).

Conclusions

Some sex differences were evident in the variables that predict sexual difficulties and relationship satisfaction among those suffering from chronic pain. Of note is that when psychological variables were considered, pain-specific physical variables (e.g., pain severity and activity limitations) accounted for very little additional variance.

Neural correlates of intimate picture stimuli in females

Jacob et al. (2011) previously reported on intimate picture stimuli for emotion research in females in Psychiatry Research. Difficulties to engage in intimate relations constitute problems of many mental disorders, and intimacy must be differentiated from pure sex drive. Functional neuroimaging is an important tool to understand the pathophysiology of psychiatric disorders. We now studied cerebral activation in response to intimate stimuli in 35 healthy women. Comparison stimuli were taken from the International Affective Picture System. Neuroimaging revealed increased activation in bilateral occipitotemporal, parietal and anterior cingulate cortices extending to the orbitofrontal area. These data reflect cognitive, emotional and motivational compounds congruent with previous neuroimaging data of attachment and long term romantic relationships. Lateral prefrontal, posterior insular regions and the fusiform face area were more active during control images. Our data present a solid basis for use in psychiatric samples.

Neural Correlates of Sexual Orientation in Heterosexual, Bisexual, and Homosexual Women

We used fMRI to investigate neural correlates of responses to erotic pictures and videos in heterosexual (N = 26), bisexual (N = 26), and homosexual (N = 24) women, ages 25–50. We focused on the ventral striatum, an area of the brain associated with desire, extending previous findings from the sexual psychophysiology literature in which homosexual women had greater category specificity (relative to heterosexual and bisexual women) in their responses to male and female erotic stimuli. We found that homosexual women’s subjective and neural responses reflected greater bias towards female stimuli, compared with bisexual and heterosexual women, whose responses did not significantly differ. These patterns were also suggested by whole brain analyses, with homosexual women showing category-specific activations of greater extents in visual and auditory processing areas. Bisexual women tended to show more mixed patterns, with activations more responsive to female stimuli in sensory processing areas, and activations more responsive to male stimuli in areas associated with social cognition.

How Hot Are They? Neural Correlates of Genital Arousal: An Infrared Thermographic and Functional Magnetic Resonance Imaging Study of Sexual Arousal in Men and Women

BACKGROUND

The few studies that have examined the neural correlates of genital arousal have focused on men and are methodologically hard to compare.

AIM

To investigate the neural correlates of peripheral physiologic sexual arousal using identical methodology for men and women.

METHODS

2 groups (20 men, 20 women) viewed movie clips (erotic, humor) while genital temperature was continuously measured using infrared thermal imaging. Participants also continuously evaluated changes in their subjective arousal and answered discrete questions about liking the movies and wanting sexual stimulation. Brain activity, indicated by blood oxygen level-dependent (BOLD) response, was measured using functional magnetic resonance imaging.

OUTCOMES

BOLD responses, genital temperature, and subjective sexual arousal.

RESULTS

BOLD activity in a number of brain regions was correlated with changes in genital temperature in men and women; however, activation in women appeared to be more extensive than in men, including the anterior and posterior cingulate cortex, right cerebellum, insula, frontal operculum, and paracingulate gyrus. Examination of the strength of the correlation between BOLD response and genital temperature showed that women had a stronger brain-genital relation compared with men in a number of regions. There were no brain regions in men with stronger brain-genital correlations than in women.

CLINICAL TRANSLATION

Our findings shed light on the neurophysiologic processes involved in genital arousal for men and women. Further research examining the specific brain regions that mediate our findings is necessary to pave the way for clinical application.

STRENGTHS AND LIMITATIONS

A strength of the study is the use of thermography, which allows for a direct comparison of the neural correlates of genital arousal in men and women. This study has the common limitations of most laboratory-based sexual arousal research, including sampling bias, lack of ecologic validity, and equipment limitations, and those common to neuroimaging research, including BOLD signal interpretation and neuroimaging analysis issues.

CONCLUSIONS

Our findings provide direct sex comparisons of the neural correlates of genital arousal in men and women and suggest that brain-genital correlations could be stronger in women. Parada M, Gérard M, Larcher K, et al. How Hot Are They? Neural Correlates of Genital Arousal: An Infrared Thermographic and Functional Magnetic Resonance Imaging Study of Sexual Arousal in Men and Women. J Sex Med 2018;15:217-229.

Introduction: Art and the brain: From pleasure to well-being

Empirical aesthetics in general, and neuroaesthetics in particular, have been very much influenced by Berlyne's psychobiological program. For him, aesthetic appreciation involved the brain's reward and aversion systems. From this point of view, art constitutes a set of potentially rewarding stimuli. Research has certainly made great advances in understanding how the process of artistic valuation takes places, and which brain circuits are involved in generating the pleasure we obtain from artistic practices, performances, and works. But it also suggests that pleasure is not the only effect of the arts. The evidence rather suggests that the arts have other cognitive and emotional effects which are closely related to human psychobiological health and well-being. These are: (1) attentional focus and flow, (2) affective experience, (3) emotion through imagery, (4) interpersonal communication, (5) self-intimation, and (6) social bonding. These effects are beneficial and contribute to the individual's biopsychological health and well-being. The fact that artistic practice has these effects helps explain why the arts are so important to human life, and why they developed in the first place, i.e., as ways to foster these effects. Therefore, a biopsychological science of the arts is emerging, according to which the arts can be conceptualized as an important system of external self-regulation, as a set of activities that contribute to our homeostasis and well-being.

Sexual Responses Are Facilitated by High-Order Contextual Cues in Females but Not in Males

Sexual responses are thought to be controlled by a brain module called the sexual module. Sexual strategies of males and females vary to a great extent, and sexual responses of males and females may be affected by their sexual strategies. However, the current view of the sexual module is that of a unisex module. This might be questionable since brain modules are defined as evolved cognitive mechanisms to solve adaptive problems which are different for males and females. We hypothesize that the sexual module responds differently in the presence of complex (high-order) contextual cues that are related to gender-dimorphic sexual strategies in males and females. We conducted a priming experiment in which stimuli related to sexual strategies were disentangled from their sexual meaning. Nonsexual priming pictures related to either economic resources or social interactions preceded a sexual-target picture in order to test whether the primes were able to modulate the subjective sexual response to the sexual target. In a control condition, priming pictures without relation to mating preferences but with similar emotional impact were presented. In males, sexual responses were similar in the experimental and control conditions. In females, however, primes related to economic resources or social interactions modulated sexual arousal significantly more than the control primes. Our findings suggest that brain modules dedicated to process the experimental primes were functionally connected with the sexual module in females more than in males, making females' sexual responses more prone to the impact of high-order cultural cues than males' sexual responses. A gender-dimorphic connectivity of the sexual module may be the way in which gender-dimorphic sexual strategies are implemented in the human mind.

Ventral Striatal Reactivity in Compulsive Sexual Behaviors

Compulsive Sexual Behaviors (CSB) are a reason to seek treatment. Given this reality, the number of studies on CSB has increased substantially in the last decade and the World Health Organization (WHO) included CSB in its proposal for the upcoming ICD-11. Sixty percent of the neuroimaging studies on CSB published since 2014 aimed to examine similarities and differences between brain mechanisms underlying CSB, gambling disorder, and substance use disorders. One of the crucial brain circuits involved in addiction is the reward system involving the ventral striatum (including nucleus accumbens). There are two distinct theories describing ventral striatal activity in addictions: Incentive Salience Theory (IST) and Reward Deficiency Syndrome (RDS). IST describes increased ventral striatal activations during the anticipation of addiction-related reward, while RDS describes decreased ventral striatal reactivity both during the anticipation of the reward and during the reward processing. Here, we aim to investigate how the findings on ventral striatal reactivity in CSB support each of these two addiction frameworks. For this purpose, we conducted a systematic review of neuroimaging studies on CSB available in Pubmed, EBSCO, and Google Scholar between 2005 and 2018. We found nine relevant research papers. Only four of these studies directly investigated processing of erotic cues and/or rewards and reported findings related to ventral striatum activations. Three of these studies indicate increased ventral striatal reactivity for erotic stimuli, which is consistent with IST and does not support predictions based on RDS. Therefore, the current state of this data suggest that CSB is related to increased ventral striatal reactivity during the anticipation of erotic stimuli.

Sim1 Neurons Are Sufficient for MC4R-Mediated Sexual Function in Male Mice

Sexual dysfunction is a poorly understood condition that affects up to one-third of men around the world. Existing treatments that target the periphery do not work for all men. Previous studies have shown that central melanocortins, which are released by pro-opiomelanocortin neurons in the arcuate nucleus of the hypothalamus, can lead to male erection and increased libido. Several studies specifically implicate the melanocortin 4 receptor (MC4R) in the central control of sexual function, but the specific neural circuitry involved is unknown. We hypothesized that single-minded homolog 1 (Sim1) neurons play an important role in the melanocortin-mediated regulation of male sexual behavior. To test this hypothesis, we examined the sexual behavior of mice expressing MC4R only on Sim1-positive neurons (tbMC4Rsim1 mice) in comparison with tbMC4R null mice and wild-type controls. In tbMC4Rsim1 mice, MC4R reexpression was found in the medial amygdala and paraventricular nucleus of the hypothalamus. These mice were paired with sexually experienced females, and their sexual function and behavior was scored based on mounting, intromission, and ejaculation. tbMC4R null mice showed a longer latency to mount, a reduced intromission efficiency, and an inability to reach ejaculation. Expression of MC4R only on Sim1 neurons reversed the sexual deficits seen in tbMC4R null mice. This study implicates melanocortin signaling via the MC4R on Sim1 neurons in the central control of male sexual behavior.