The cortical sensory representation of genitalia in women and men: a systematic review

App-Mohedo®: A mobile app for the management of chronic pelvic pain. A design and development study

BACKGROUND

Chronic Pelvic Pain (CPP) has been described as a public health priority worldwide, and it is among the most prevalent and costly healthcare problems. Graded motor imagery (GMI) is a therapeutic tool that has been successfully used to improve pain in several chronic conditions. GMI therapy is divided into three stages: laterality training (LRJT, Left Right Judgement Task), imagined movements, and mirror therapy. No tool that allows working with LRJT in pelvic floor has been developed to date.

OBJECTIVE

This research aims to describe the process followed for the development of a highly usable, multi-language and multi-platform mobile application using GMI with LRJT to improve the treatment of patients with CPP. In addition, this will require achieving two other goals: firstly, to generate 550 pelvic floor images and, subsequently, to carry out an empirical study to objectively classify them into different difficulty levels of. This will allow the app to properly organize and plan the different therapy sessions to be followed by each patient.

METHODOLOGY

For the design, evaluation and development of the app, an open methodology of user-centered design (MPIu + a) was applied. Furthermore, to classify and establish the pelvic floor images of the app in different difficulty levels, an observational, cross-sectional study was conducted with 132 volunteers through non-probabilistic sampling.

RESULTS

On one hand, applying MPIu+a, a total of 5 phases were required to generate an easy-to-use mobile application. On the other hand, the 550 pelvic floor images were classified into 3 difficulty levels (based on the percentage of correct answers and response time used by the participants in the classification process of each image): Level 1 (191 images with Accuracy = 100 % and RT = [0-2.5] seconds); Level 2 (208 images with Accuracy = 75-100 % and RT = [2.5-5] seconds); and Level 3 (151 images with Accuracy = 50-75 % and RT > 5 s).

CONCLUSION

App-Mohedo® is the first multi-platform, multi-language and easy-to-use mobile application that, through GMI with LRJT, and with an adequate bank of images classified into three levels of difficulty, can be used as a complementary therapeutic tool in the treatment of patients with CPP. This work can also serve as an example, model or guide when applying a user-centered methodology, as MPIu + a, to the development of other apps, especially in the field of health.

Implicit Motor Imagery for Chronic Pelvic Pain: A Cross-Sectional Case-Control Study

Implicit motor imagery (IMI), with an image laterality discrimination (LD) task, has been proposed as a useful therapeutic tool to restore body schema in patients with chronic pelvic pain (CPP). The aim of this study was to analyse the existence of differences between patients with CPP and healthy individuals in order to justify the use of IMI. An observational, cross-sectional study with non-probabilistic sampling was designed as a one-to-one matched case-control study. Through a web link designed for this purpose, a total of 40 abdominoperineal images were shown to 130 participants during the laterality task. Outcome measures were pain intensity (visual analogue scale, VAS), accuracy, response time (RT), and CPPQ-Mohedo score (Chronic Pelvic Pain Questionnaire-Mohedo). This was an observational, cross-sectional study with a total of 64 CPP patients and 66 healthy individuals. The comparative analysis between groups revealed significant differences in accuracy, CPPQ-Mohedo and VAS (p < 0.001), but not in RT; in patients with CPP, accuracy was correlated with a lower CPPQ-Mohedo score and RT and, the greater the pain intensity, the higher the CPPQ-Mohedo score and RT, and the lower the accuracy. In the LD task, the patients with CPP made more mistakes than the healthy individuals. IMI could be a useful and complementary tool in the therapeutic approach for patients with CPP.

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

Many reviews on sexual arousal in humans focus on different brain imaging methods and behavioral observations. Although neurotransmission in the brain is mainly performed through electrochemical signals, there are no systematic reviews of the electrophysiological correlates of sexual arousal. We performed a systematic search on this subject and reviewed 255 studies including various electrophysiological methods. Our results show how neuroelectric signals have been used to investigate genital somatotopy as well as basic genital physiology during sexual arousal and how cortical electric signals have been recorded during orgasm. Moreover, experiments on the interactions of cognition and sexual arousal in healthy subjects and in individuals with abnormal sexual preferences were analyzed as well as case studies on sexual disturbances associated with diseases of the nervous system. In addition, 25 studies focusing on brain potentials during the interaction of cognition and sexual arousal were eligible for meta-analysis. The results showed significant effect sizes for specific brain potentials during sexual stimulation (P3: Cohen's d = 1.82, N = 300, LPP: Cohen's d = 2.30, N = 510) with high heterogeneity between the combined studies. Taken together, our review shows how neuroelectric methods can consistently differentiate sexual arousal from other emotional states.

A psychophysical and neuroimaging analysis of genital hedonic sensation in men

Current understanding of human genital-brain interactions relates primarily to neuroendocrine and autonomic control, whereas interactions during sexual stimulation remain largely unexplored. Here we present a systematic approach towards identifying how the human brain encodes sensory genital information. Using a validated affective touch paradigm and functional magnetic resonance imaging, we found that hedonic responses to discriminatory versus affective tactile stimulation were distinctly different for both penile shaft and forearm. This suggests that, as with other body sites, genital skin contains small diameter mechanoreceptive nerve fibres that signal pleasant touch. In the brain, secondary somatosensory cortex (S2) distinguished between affective and discriminative touch for the penile shaft, but not for the forearm. Frenulum stimulation induced the greatest reports of subjective pleasure and led to the greatest deactivation of the default-mode network. This study represents a first pass at investigating, in humans, the relationship between innervation of genital surfaces, hedonic feelings, and brain mechanisms, in a systematic way.

Association of Bicycle-Related Genital Numbness and Female Sexual Dysfunction: Results From a Large, Multinational, Cross-Sectional Study

Introduction

Cycling can lead to microtrauma due to increased perineal pressure, possibly contributing to genital numbness and sexual dysfunction in female cyclists.

Aim

We aim to explore the associations between cycling characteristics, female genital numbness, and female sexual dysfunction.

Methods

We conducted a cross-sectional study on female cyclists and sexual wellness. Participants were recruited through Facebook® advertisements and online outreach at athletic clubs. Participants were asked about their cycling characteristics, genital numbness, and female sexual function using the Female Sexual Function Index (FSFI). Univariate and multivariable linear and logistic regression were used to assess risk factors for genital numbness and the association between genital numbness and the FSFI.

Outcome Measures

The outcome measures were cycling characteristics, questions regarding numbness (intensity, duration, location), and the FSFI score.

Results

Eight-hundred and seventy-five women were included in the study. Total lifetime miles cycled, biking duration, frequency, distance, speed, and biking surface were not significantly associated with genital numbness. Higher handlebar height was associated with less numbness. The prevalence of sexual dysfunction in the cohort was 52%. Genital numbness was significantly associated with sexual dysfunction (OR: 1.43, 95% CI: 1.05 – 1.95). Sub-group analysis for location of numbness demonstrated significant increase in risk for sexual dysfunction in cyclists who described numbness aro`und the perineum (OR: 2.72, 95% CI: 1.05 – 7.02) and the vulva (OR: 1.55, 95% CI: 1.13 – 2.13). There was also a significant increase in the risk of sexual dysfunction in cyclists who reported a longer duration of numbness (OR: 6.58, 95% CI: 2.27 – 19.07).

Conclusions

Genital numbness is common in women who cycle and is associated with increased risk of FSD and lower average sexual response scores on FSFI. Lui H, Mmonu N, Awad MA, et al. Association of Bicycle-Related Genital Numbness and Female Sexual Dysfunction: Results From a Large, Multinational, Cross-Sectional Study. Sex Med 2021;9:100365.

Scalp Topography of Lower Urinary Tract Sensory Evoked Potentials

Impaired lower urinary tract (LUT) afferents often cause LUT symptoms. Assessment of LUT afferent pathways is possible using bipolar cortical sensory evoked potential (SEP) recordings with the active electrode at the vertex during electrical stimulation in the LUT. This study aimed to investigate the topographical distribution and microstates of lower urinary tract sensory evoked potentials (LUTSEPs) using different stimulation frequencies. Ninety healthy subjects (18-36 years old, 40 women) were randomly assigned to one of five stimulation locations [bladder dome; trigone; proximal, membranous (men only) or distal urethra]. Cycles of 0.5 Hz/1.1 Hz/1.6 Hz electrical stimulation were applied using a custom-made catheter. Cortical activity was recorded from 64 surface electrodes. Marker setting was performed manually on an individual subject-level for the P1, N1, and P2 components of vertex recordings. N1 and P2 topographies presented with central negativities and positivities around the vertex. Regarding topographical distribution, Randomization Graphical User interface (RAGU) analyses revealed consistent frequency effects and microstates for N1/P2. Higher stimulation frequencies resulted in decreasing map strength for P1, N1, and P2. LUTSEP topographies suggest central generators in the somatosensory cortex, which are not detectable in a bipolar set-up. The observed frequency effect indicates fiber refractoriness at higher frequencies. The multichannel approach allows more comprehensive assessment of LUTSEPs and might therefore be sensitive to pathological changes. Examinations in patients with LUT symptoms are needed to further investigate this biomarker.

Male Urogenital System Mapped Onto the Sensory Cortex: Functional Magnetic Resonance Imaging Evidence

INTRODUCTION

The projection of the human male urogenital system onto the paracentral lobule has not previously been mapped comprehensively.

AIM

To map specific urogenital structures onto the primary somatosensory cortex toward a better understanding of sexual response in men.

METHODS

Using functional magnetic resonance imaging, we mapped primary somatosensory cortical responses to self-stimulation of the penis shaft, glans, testicles, scrotum, rectum, urethra, prostate, perineum, and nipple. We further compared neural response with erotic and prosaic touch of the penile shaft.

MAIN OUTCOME MEASURE

We identified the primary mapping site of urogenital structures on the paracentral lobule and identified networks involved in perceiving touch as erotic.

RESULTS

We mapped sites on the primary somatosensory cortex to which components of the urogenital structures project in men. Evidence is provided that penile cutaneous projection is different from deep penile projection. Similar to a prior report in women, we show that the nipple projects to the same somatosensory cortical region as the genitals. Evidence of differential representation of erotic and nonerotic genital self-stimulation is also provided, the former activating sensory networks other than the primary sensory cortex, indicating a role of "top-down" activity in erotic response.

CLINICAL IMPLICATIONS

We map primary sites of projection of urogenital structures to the primary somatosensory cortex and differentiate cortical sites of erotic from nonerotic genital self-stimulation.

STRENGTH & LIMITATIONS

To our knowledge, this is the first comprehensive mapping onto the primary somatosensory cortex of the projection of the components of the urogenital system in men and the difference in cortical activation in response to erotic vs nonerotic self-stimulation. The nipple was found to project to the same cortical region as the genitals. Evidence is provided that superficial and deep penile stimulation project differentially to the cortex, suggesting that sensory innervation of the penis is provided by more than the (pudendal) dorsal nerve.

CONCLUSION

This study reconciles prior apparently conflicting findings and offers a comprehensive mapping of male genital components to the paracentral lobule. We provide evidence of differential projection of light touch vs pressure applied to the penile shaft, suggesting differential innervation of its superficial, vs deep structure. Similar to the response in women, we found nipple projection to genital areas of the paracentral lobule. We also provide evidence of differential representation of erotic and nonerotic genital self-stimulation, the former activating sensory networks other than the primary sensory cortex, indicating a role of top-down activity in erotic response. Allen K, Wise N, Frangos E, et al. Male Urogenital System Mapped Onto the Sensory Cortex: Functional Magnetic Resonance Imaging Evidence. J Sex Med 2020;17:603-613.

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.

Mediating Effects of Patients' Stigma and Self-Efficacy on Relationships Between Doctors' Empathy Abilities and Patients' Cellular Immunity in Male Breast Cancer Patients

BACKGROUND Doctors' empathy is closely related to patients' health. This study aimed to examine whether patients' stigma and self-efficacy play a mediating role in the relationship between doctors' empathy abilities and patients' cellular immunity in male patients with breast cancer. MATERIAL AND METHODS Doctors' empathy scores and patients' demographic data, disease condition, stigma, and self-efficacy were measured. Patient T cell subset was tested at admission and 3 months after the operation and was compared by paired t test. The multivariate linear regression model was applied to analyze the factors influencing the immune index. Pearson correlation analysis and structural equation modeling were applied to explore the relationships among patients' stigma, self-efficacy, and cellular immunity and doctors' empathy abilities. RESULTS At the 2 time points, only the change in NK subset was statistically significant, while the changes in percentage of CD3+, CD4+, CD8+, and B cells were not statistically significant. The doctors' empathy abilities were negatively correlated with patients' stigma and were positively related to patients' self-efficacy. Patients' stigma was negatively related to NK subset, while self-efficacy was positively associated with NK subset. Patients' stigma and self-efficacy played a mediating role in the relationship between doctors' empathy abilities and patients' NK subset, and stigma had a stronger effect than self-efficacy. CONCLUSIONS Doctors' empathy abilities affected breast cancer patients' NK subset through their stigma and self-efficacy. The mental health of male breast cancer patients need more attention and empathy education needs to be improved.

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.

Somatosensory maps

Somatosensory areas containing topographic maps of the body surface are a major feature of parietal cortex. In primates, parietal cortex contains four somatosensory areas, each with its own map, with the primary cutaneous map in area 3b. Rodents have at least three parietal somatosensory areas. Maps are not isomorphic to the body surface, but magnify behaviorally important skin regions, which include the hands and face in primates, and the whiskers in rodents. Within each map, intracortical circuits process tactile information, mediate spatial integration, and support active sensation. Maps may also contain fine-scale representations of touch submodalities, or direction of tactile motion. Functional representations are more overlapping than suggested by textbook depictions of map topography. The whisker map in rodent somatosensory cortex is a canonic system for studying cortical microcircuits, sensory coding, and map plasticity. Somatosensory maps are plastic throughout life in response to altered use or injury. This chapter reviews basic principles and recent findings in primate, human, and rodent somatosensory maps.

S100A10 identified in a genome-wide gene × cannabis dependence interaction analysis of risky sexual behaviours

BACKGROUND

We conducted a genome-wide gene × environment interaction analysis to identify genetic variants that interact with cannabis dependence (CaD) in influencing risky sexual behaviours (RSB).

METHODS

Our sample included cannabis-exposed and sexually experienced African-American and European-American participants. A DSM-IV CaD diagnosis and RSB were evaluated using the Semi-Structured Assessment for Drug Dependence and Alcoholism. We analyzed RSBs as a score that takes into account experiences of unprotected sex and multiple sexual partners.

RESULTS

A total of 3350 people participated in our study; 43% had a CaD diagnosis, 56% were African-American and 33% were women. We identified a genome-wide significant locus in African-American participants (S100A10 rs72993629, p = 2.73 × 10^-8) and a potential transpopulation signal in women (CLTC rs12944716, p = 5.27 × 10^-8). A resting-state fMRI follow-up analysis of S100A10 rs72993629 conducted in an independent cohort showed 2 significant associations: reduced power of the left paracentral lobule in amplitude of low frequency fluctuations (ALFF) analysis (p = 7.8 × 10^-3) and reduced power of the right pallidum in fractional ALFF analysis (p = 4.6 × 10^-3). The activity of these brain regions is known to be involved in sexual functions and behaviours. The S100A10 result functionally recapitulated our S100B finding observed in our previous genome-wide association study of CaD. The probability of identifying 2 S100 genes in 2 independent genome-wide investigations by chance is approximately 1 in 1.1 million.

LIMITATIONS

We were not able to identify any African-American cohort with appropriate sample size, and phenotypic assessment is available to replicate our findings.

CONCLUSION

The S100A10 and S100B genes, which are located on different chromosomes, encode specialized calcium-binding proteins. These data support a role for calcium homeostasis in individuals with CaD and its induced behaviours.

fMRI after Phalloplasty with Nerve Anastomosis in a Trans-Man Patient

We report on a case of a trans-man patient, who underwent penile reconstruction with the use of a radial forearm flap, urethroplasty, vaginectomy and scrotoplasty, insertion of testicle implants, and penile erection implants, similar to previously described methods. One of the requirements for an ideal phalloplasty is the preservation of erogenous sensitivity, which is often demanded by the patients for fulfilling their sexual well-being. For the first time known to us, we use a functional magnetic resonance imaging following radial forearm flap phalloplasty with nerve anastomosis to assess the cortical activation after clitoral stimulation. The patient was poked with a plastic pen on the neophallus and the groin. Regular block design with T1 and BOLD-T2* images were used. The results contradict the classic Penfield and Rasmussen homunculus, that is, the activations in the primary somatosensory cortex (S1) were bilateral with a left-sided dominance in the lateral parts of the medial postcentral gyrus (same region as the groin), and no activations were observed in the mesial parts of the postcentral gyrus. We also reported bilateral activations with a left-sided dominance in the secondary somatosensory cortex (S2) and near Broca's area at the sylvian fissure just posterior to ramus ascendens. Our findings are similar to previous studies reporting on imaging related to genital sensitivity.

Innervation of the Male Breast: Psychological and Physiological Consequences

Breasts, including the nipple and areola, have two functions: lactation and as an erogenous area. Male breasts are much less studied that those of women. In men, breasts have only an erotic function. Because there is dense and very well organized innervation of the nipple-areola complex in men, nipple erection occurs frequently and via different mechanisms from penile erection. Although it seems to be less important for men than for women and it is poorly studied, the erotic value of breast stimulation is notable. Consequently, there is a need to include this aspect in sexological and andrological studies and to preserve breasts and their innervation or to reconstruct them in cases of surgical intervention.

Activation of sensory cortex by imagined genital stimulation: an fMRI analysis

Background

During the course of a previous study, our laboratory made a serendipitous finding that just thinking about genital stimulation resulted in brain activations that overlapped with, and differed from, those generated by physical genital stimulation.

Objective

This study extends our previous findings by further characterizing how the brain differentially processes physical ‘touch’ stimulation and ‘imagined’ stimulation.

Design

Eleven healthy women (age range 29–74) participated in an fMRI study of the brain response to imagined or actual tactile stimulation of the nipple and clitoris. Two additional conditions – imagined dildo self-stimulation and imagined speculum stimulation – were included to characterize the effects of erotic versus non-erotic imagery.

Results

Imagined and tactile self-stimulation of the nipple and clitoris each activated the paracentral lobule (the genital region of the primary sensory cortex) and the secondary somatosensory cortex. Imagined self-stimulation of the clitoris and nipple resulted in greater activation of the frontal pole and orbital frontal cortex compared to tactile self-stimulation of these two bodily regions. Tactile self-stimulation of the clitoris and nipple activated the cerebellum, primary somatosensory cortex (hand region), and premotor cortex more than the imagined stimulation of these body regions. Imagining dildo stimulation generated extensive brain activation in the genital sensory cortex, secondary somatosensory cortex, hippocampus, amygdala, insula, nucleus accumbens, and medial prefrontal cortex, whereas imagining speculum stimulation generated only minimal activation.

Conclusion

The present findings provide evidence of the potency of imagined stimulation of the genitals and that the following brain regions may participate in erogenous experience: primary and secondary sensory cortices, sensory-motor integration areas, limbic structures, and components of the ‘reward system’. In addition, these results suggest a mechanism by which some individuals may be able to generate orgasm by imagery in the absence of physical stimulation.