Topography of Human Erogenous Zones

Pleasurable and problematic receptive anal intercourse and diseases of the colon, rectum and anus

The ability to experience pleasurable sexual activity is important for human health. Receptive anal intercourse (RAI) is a common, though frequently stigmatized, pleasurable sexual activity. Little is known about how diseases of the colon, rectum, and anus and their treatments affect RAI. Engaging in RAI with gastrointestinal disease can be difficult due to the unpredictability of symptoms and treatment-related toxic effects. Patients might experience sphincter hypertonicity, gastrointestinal symptom-specific anxiety, altered pelvic blood flow from structural disorders, decreased sensation from cancer-directed therapies or body image issues from stoma creation. These can result in problematic RAI - encompassing anodyspareunia (painful RAI), arousal dysfunction, orgasm dysfunction and decreased sexual desire. Therapeutic strategies for problematic RAI in patients living with gastrointestinal diseases and/or treatment-related dysfunction include pelvic floor muscle strengthening and stretching, psychological interventions, and restorative devices. Providing health-care professionals with a framework to discuss pleasurable RAI and diagnose problematic RAI can help improve patient outcomes. Normalizing RAI, affirming pleasure from RAI and acknowledging that the gastrointestinal system is involved in sexual pleasure, sexual function and sexual health will help transform the scientific paradigm of sexual health to one that is more just and equitable.

Tickle fetishism: pleasure beyond playfulness

Tickling is commonly perceived as juvenile play associated with laughter. However, its potential connection to adult sexual behavior has largely remained unexplored. Our online survey, primarily distributed among individuals interested in tickle fetishism, explored tickling and its association with sexual behavior. Ticklishness types, tools, preferred body parts, and partner preferences, were examined. Results revealed diverse patterns of ticklishness changes over time and distinct body-part preferences for different types of tickling. Childhood experiences and exposure to tickling content in television were found to shape individuals' affinity for tickle fetishism. A quarter of respondents reported experiencing orgasms exclusively from tickling, while around 88% expressed sexual satisfaction through tickling alone, indicating its sufficiency as a sexual stimulus among fetishists. Tickling desire decreased after orgasm, indicating an association between tickling and sexual activity. Moreover, ticklishness degree predicted preferences for being tickled rather than tickling others. Exploratory factor analysis identified three factors underlying tickling and sexual experiences: enjoyment and frequency of tickling during sexual activity; preference for intense sexual experiences; age of becoming sexually active. In conclusion, this study provides unique insights into tickling and its connections to sexual context, enhancing our understanding of diverse human sexual behavior and tickle fetishism as a distinct preference.

Exploring social touch in autistic and non-autistic adults via a self-report body-painting task: The role of sex, social context and body area

LAY ABSTRACT

What is already known about the topic?At least in neurotypical individuals, social touch represents an important channel for emotional communication associated with social bonding and pain/anxiety modulation. Autistic adults report to avoid social touch more and to have different tactile sensitivity than their non-autistic comparisons.What this paper adds?Few studies specifically investigated social touch in autistic individuals, and none of them examined the role of participants' sex, social context in which social touch occurs, and specific body areas being touched. In our study, adult participants reported how pleasant, erogenous and appropriate they would consider touches delivered by another person over their entire body in intimate (date), friendly (dance class) and professional (physiotherapy-massage session) social contexts. Autistic adults reported social touch to be less pleasant, erogenous and appropriate specifically in intimate and friendly social contexts and in body areas typically touched in these situations. Importantly, autistic females seem more at risk to experience unpleasant social touch as, although they considered it more unpleasant than non-autistic females and autistic males, they did consider it similarly appropriate in professional social contexts where touch is normed to be socially appropriate.Implications for practice, research or policyOur results might improve awareness and understanding about autistic adults' different, and often more discomforting, experience of social touch and thus help consider and respect it during everyday social interactions. Our results might also benefit future research investigating, for instance, the neural underpinnings of social touch differences in autism or aiming at developing support for autistic individuals seeking help in the diverse spheres of social touch.

Topography and relationship-specific social touching in individuals displaying body image disturbances

Interpersonal touch is intimately related to the emotional bond between the touch giver and the touch receiver. Which bodily regions we touch in those individuals in our social network is relationship specific. Perception of interpersonal touch is altered in psychiatric disorders characterised by body image disturbances (BIDs). Here, we examined whether the 'imagined' experience of social touch in individuals with BIDs is body topography- and relationship-specific. By using an interactive media mobile App, the Virtual Touch Toolkit, high versus low levels of BIDs participants completed heatmaps of full-body virtual avatars, to indicate the body regions they find soothing/unpleasant to be touched by a loved one versus an acquaintance. Self-reports of interoceptive awareness and dysmorphic concerns were also measured. Overall, imagined touch was rated as the most soothing when received from a loved one, and also when this was delivered to 'social' body regions. The importance of the social relationship for the imagined tactile interactions was particularly evident for the high levels of BIDs group, with greater problems with interoceptive awareness predicting higher soothing touch ratings when this was received by a loved one. Despite the evidence that imagined bodily contacts between meaningful people is the most pleasant for socially acceptable bodily regions, our findings may suggest a greater sensitivity to relation-specific bodily patterns of social touch particularly in the high level of BIDs group. Heightened interoceptive awareness may also play a key role in this experience of bodily affective contacts. Future research for body-oriented therapy for BIDs is encouraged to systematically probe the efficacy of imagined social touch interaction protocols which use more plausible, ecological, scenarios where touch is delivered by loved ones and to socially acceptable bodily regions.

Sexual incentive motivation, sexual behavior, and general arousal: Do rats and humans tell the same story?

Sexual incentive stimuli activate sexual motivation and heighten the level of general arousal. The sexual motive may induce the individual to approach the incentive, and eventually to initiate sexual acts. Both approach and the ensuing copulatory interaction further enhance general arousal. We present data from rodents and humans in support of these assertions. We then suggest that orgasm is experienced when the combined level of excitation surpasses a threshold. In order to analyze the neurobiological bases of sexual motivation, we employ the concept of a central motive state. We then discuss the mechanisms involved in the long- and short-term control of that state as well as those mediating the momentaneous actions of sexual incentive stimuli. This leads to an analysis of the neurobiology behind the interindividual differences in responsivity of the sexual central motive state. Knowledge is still fragmentary, and many contradictory observations have been made. Nevertheless, we conclude that the basic mechanisms of sexual motivation and the role of general arousal are similar in rodents and humans.

μ-opioid receptor availability is associated with sex drive in human males

The endogenous mu-opioid receptor (MOR) system modulates a multitude of social and reward-related functions, and exogenous opiates also influence sex drive in humans and animals. Sex drive shows substantial variation across humans, and it is possible that individual differences in MOR availability underlie interindividual of variation in human sex drive. We measured healthy male subjects’ (n = 52) brain’s MOR availability with positron emission tomography (PET) using an agonist radioligand, [¹¹C]carfentanil, that has high affinity for MORs. Sex drive was measured using self-reports of engaging in sexual behaviour (sex with partner and masturbating). Bayesian hierarchical regression analysis revealed that sex drive was positively associated with MOR availability in cortical and subcortical areas, notably in caudate nucleus, hippocampus, and cingulate cortices. These results were replicated in full-volume GLM analysis. These widespread effects are in line with high spatial autocorrelation in MOR expression in human brain. Complementary voxel-based morphometry analysis (n = 108) of anatomical MR images provided limited evidence for positive association between sex drive and cortical density in the midcingulate cortex. We conclude that endogenous MOR tone is associated with individual differences in sex drive in human males.

Heterosexual, gay, and lesbian people's reactivity to virtual caresses on their embodied avatars' taboo zones

Embodying an artificial agent through immersive virtual reality (IVR) may lead to feeling vicariously somatosensory stimuli on one's body which are in fact never delivered. To explore whether vicarious touch in IVR reflects the basic individual and social features of real-life interpersonal interactions we tested heterosexual men/women and gay men/lesbian women reacting subjectively and physiologically to the observation of a gender-matched virtual body being touched on intimate taboo zones (like genitalia) by male and female avatars. All participants rated as most erogenous caresses on their embodied avatar taboo zones. Crucially, heterosexual men/women and gay men/lesbian women rated as most erogenous taboo touches delivered by their opposite and same gender avatar, respectively. Skin conductance was maximal when taboo touches were delivered by female avatars. Our study shows that IVR may trigger realistic experiences and ultimately allow the direct exploration of sensitive societal and individual issues that can otherwise be explored only through imagination.

The Erogenous Mirror: Intersubjective and Multisensory Maps of Sexual Arousal in Men and Women

Erogenous zones of the body are sexually arousing when touched. Previous investigations of erogenous zones were restricted to the effects of touch on one's own body. However, sexual interactions do not just involve being touched, but also involve touching a partner and mutually looking at each other's bodies. We take a novel interpersonal approach to characterize the self-reported intensity and distribution of erogenous zones in two modalities: touch and vision. A large internet sample of 613 participants (407 women) completed a questionnaire, where they rated intensity of sexual arousal related to different body parts, both on one's own body and on an imagined partner's body in response to being touched but also being looked at. We report the presence of a multimodal erogenous mirror between sexual partners, as we observed clear correspondences in topographic distributions of self-reported arousal between individuals' own bodies and their preferences for a partner's body, as well as between those elicited by imagined touch and vision. The erogenous body is therefore organized and represented in an interpersonal and multisensory way.

Relationship-specific Encoding of Social Touch in Somatosensory and Insular Cortices

Humans use touch to maintain their social relationships, and the emotional qualities of touch depend on who touches whom. However, it is not known how affective and social dimensions of touch are processed in the brain. We measured haemodynamic brain activity with functional magnetic resonance imaging (fMRI) from 19 subjects (10 males), while they were touched on their upper thigh by either their romantic partner, or an unfamiliar female or male confederate or saw the hand of one of these individuals near their upper thigh but were not touched. We used multi-voxel pattern analysis on pre-defined regions of interest to reveal areas that encode social touch in a relationship-specific manner. The accuracy of the machine learning classifier to identify actor for both feeling touch and seeing hand exceeded the chance level in the primary somatosensory cortex, while in the insular cortex accuracy was above chance level only for the touch condition. When classifying the relationship (partner or stranger), while keeping the toucher sex fixed, amygdala (AMYG), orbitofrontal cortex (OFC), and primary and secondary somatosensory cortices were able to discriminate toucher significantly above chance level. These results suggest that information on the social relationship of the toucher is processed consistently across several regions. More complex information about toucher identity is processed in the primary somatosensory and insular cortices, both of which can be considered early sensory areas.

Male genital sensation after spinal cord injury: a review

Genital sensation (GS) is an essential component of male sexual function. Genital sensory disturbance (GSD) caused by spinal cord injury (SCI) has a severe impact on the patients' sexual function but has garnered little research focus. Under normal conditions, GS encompasses the erection, ejaculation, sexual arousal, and orgasm courses associated with physiological and psychological responses in male sexual activity. However, in SCI patients, the deficiency of GS makes the tactile stimulation of the penis unable to cause sexual arousal, disturbs the normal processes of erection and ejaculation, and decreases sexual desire and satisfaction. To provide an overview of the contemporary conception and management of male GS after SCI, we review the innervation and sexual function of male GS in this article, discuss the effects of GSD following SCI, and summarize the current diagnosis and treatment of GSD in male SCI patients.

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.

Imaging Real-Time Tactile Interaction With Two-Person Dual-Coil fMRI

Studies of brain mechanisms supporting social interaction are demanding because real interaction only occurs when persons are in contact. Instead, most brain imaging studies scan subjects individually. Here we present a proof-of-concept demonstration of two-person blood oxygenation dependent (BOLD) imaging of brain activity from two individuals interacting inside the bore of a single MRI scanner. We developed a custom 16-channel (8 + 8 channels) two-helmet coil with two separate receiver-coil pairs providing whole-brain coverage, while bringing participants into a shared physical space and realistic face-to-face contact. Ten subject pairs were scanned with the setup. During the experiment, subjects took turns in tapping each other's lip versus observing and feeling the taps timed by auditory instructions. Networks of sensorimotor brain areas were engaged alternatingly in the subjects during executing motor actions as well as observing and feeling them; these responses were clearly distinguishable from the auditory responses occurring similarly in both participants. Even though the signal-to-noise ratio of our coil system was compromised compared with standard 32-channel head coils, our results show that the two-person fMRI scanning is feasible for studying the brain basis of social interaction.

Genital Cortex: Development of the Genital Homunculus

The cortical representation of male and female genitals, unlike that of the rest of the body, undergoes late expansion during puberty and is modulated by sexual experience. Using chronic imaging, a recent study has shed light on the cellular changes that accompany the sex-hormone- and experience-dependent expansion of the genital cortex.

Neural Control and Physiology of Sexual Function: Effect of Spinal Cord Injury

Objective: To present the current understanding of normal anatomy, physiology, sexual physiology, pathophysiology and the consequential sexual changes and dysfunctions following a spinal cord injury (SCI). Methods: Narrative review of the latest literature. Results: Peripheral innervations of the pelvis involve 3 sets of efferent neurons coordinated though the pelvic plexus (somatic, thoracolumbar sympathetic, and sacral parasympathetic), and these are under cerebral descending excitatory and inhibitory control. SCI, depending on the level of lesion and completeness, can alter this cerebral control, affecting the psychological and reflexogenic potential for genital arousal and also ejaculation and orgasm. During arousal, nitric oxide is the main neurotransmitter for smooth muscle relaxation in both male and female erectile tissue. In men, erection, ejaculation, and orgasm are under separate neurological control and can be individually affected by SCI. Conclusions: Since sexual function is rated amongst the highest priorities by individuals living with SCI, methods employed to affect the neurological changes to maximize sexual neurophysiology prior to initiating medical therapies including paying attention to sexual sensate areas and visceral signals with mindfulness techniques, practicing body mapping, and sexual stimulation of sensate areas to encourage neuroplasticity. Attention should be paid to the biopsychosocial sexual contexts within which persons with SCI live to maximize their sexual and fertility rehabilitation.