Specific factors and methodological decisions influencing brain responses to sexual stimuli in women

Most of the neuroimaging studies on sexual behavior have been conducted with male participants, leading to men-based models of sexual arousal. Here, possible factors and methodological decisions that might influence brain responses to sexual stimuli, specifically for the inclusion of women, will be reviewed. Based on this review, we suggest that future studies consider the following factors: menstrual phase, hormonal contraception use, history of sexual or psychiatric disorders or diseases, and medication use. Moreover, when researching sexual arousal, we suggest future studies assess sexual orientation and preferences, that women should select visual sexual stimuli, and a longer duration than commonly used. This review is thought to represent a useful guideline for future research in sexual arousal, which hopefully will lead to a higher inclusion of women and therefore more accurate neurobiological models of sexual arousal

Alterations in Cerebral Glucose Metabolism Measured by FDG PET in Subjects Performing a Meditation Practice Based on Clitoral Stimulation

Background: The relationship between sexuality, or the libido, and spirituality or religion has long been debated in psychiatry. Recent studies have explored the neurophysiology of both sexual experiences and spiritual practices such as meditation or prayer. In the present study, we report changes in cerebral glucose metabolism in a unique meditation practice augmented by clitoral stimulation called, Orgasmic Meditation, in which a spiritual state is described to be attained by both male and female participants engaged in the practice as a pair. Methods: Male (N=20) and female (N=20) subjects had an intravenous catheter connected to a bag of normal saline inserted prior to the practice. During the practice, men stimulated their partner’s clitoris for exactly 15 minutes (he received no sexual stimulation). Midway through the practice, researchers injected 18F-fluorodeoxyglucose so the scan would reflect cerebral metabolism during the practice. Positron emission tomography (PET) imaging was performed approximately 30 minutes later. Results: In the female participants, the meditation state showed significant decreases in the left inferior frontal, inferior parietal, insula, middle temporal, and orbitofrontal regions as well as in the right angular gyrus, anterior cingulate and parahippocampus compared to a neutral state (p\u3c0.01). Male subjects had significant decreases in the left middle frontal, paracentral, precentral, and postcentral regions as well as the right middle frontal and paracentral regions during meditation (p\u3c0.01). Men also had significantly increased metabolism in the cerebellum and right postcentral and superior temporal regions (p\u3c0.01). Conclusions: These findings represent a distinct pattern of brain activity, for both men and women, that is a hybrid between that of other meditation practices and sexual stimulation. Such findings have potential psychotherapeutic implications and may deepen our understanding of the relationship between spiritual and sexual experience

Alterations in Functional Connectivity Measured by Functional Magnetic Resonance Imaging and the Relationship With Heart Rate Variability in Subjects After Performing Orgasmic Meditation: An Exploratory Study

Background: We measured changes in resting brain functional connectivity, with blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI), associated with a creative meditation practice that is augmented by clitoral stimulation and is designed to not only achieve a spiritual experience but to help individuals manage their most intimate personal relationships. Briefly, the meditative state is attained by both the male and female participants while the male stimulates the woman\u27s clitoris. The goal of this practice, called orgasmic meditation (OM), according to the practitioners is not sexual, but to use the focus on clitoral stimulation to facilitate a meditative state of connectedness and calm alertness between the two participants. Methods: fMRI was acquired on 20 pairs of subjects shortly following one of two states that were randomized in their order - during the OM practice or during a neutral condition. The practice is performed while the female is lying down on pillows with the clitoris exposed. During the practice, the male performs digital stimulation of the clitoris for 15 min. Resting BOLD image acquisition was performed at completion of the practice to assess changes in functional connectivity associated with the performance of the practice. Results: The results demonstrated significant changes (p \u3c 0.05) in functional connectivity associated with the OM compared to the neutral condition. For the entire group there was altered connectivity following the OM practice involving the left superior temporal lobe, the frontal lobe, anterior cingulate, and insula. In female subjects, there was altered connectivity involving the cerebellum, thalamus, inferior frontal lobe posterior parietal lobe, angular gyrus, amygdala and middle temporal gyrus, and prefrontal cortex. In males, functional connectivity changes involved the supramarginal gyrus, cerebellum, and orbitofrontal gyrus, cerebellum, parahippocampus, inferior temporal gyrus, and anterior cingulate. Conclusion: Overall, these findings suggest a complex pattern of functional connectivity changes occurring in both members of the couple pair that result from this unique meditation practice. The changes represent a hybrid of functional connectivity findings with some similarities to meditation based practices and some with sexual stimulation and orgasm. This study has broader implications for understanding the dynamic relationship between sexuality and spirituality

Does erotic stimulus presentation design affect brain activation patterns? Event-related vs. blocked fMRI designs

Background Existing brain imaging studies, investigating sexual arousal via the presentation of erotic pictures or film excerpts, have mainly used blocked designs with long stimulus presentation times. Methods To clarify how experimental functional magnetic resonance imaging (fMRI) design affects stimulus-induced brain activity, we compared brief event-related presentation of erotic vs. neutral stimuli with blocked presentation in 10 male volunteers. Results Brain activation differed depending on design type in only 10% of the voxels showing task related brain activity. Differences between blocked and event-related stimulus presentation were found in occipitotemporal and temporal regions (Brodmann Area (BA) 19, 37, 48), parietal areas (BA 7, 40) and areas in the frontal lobe (BA 6, 44). Conclusion Our results suggest that event-related designs might be a potential alternative when the core interest is the detection of networks associated with immediate processing of erotic stimuli. Additionally, blocked, compared to event-related, stimulus presentation allows the emergence and detection of non-specific secondary processes, such as sustained attention, motor imagery and inhibition of sexual arousal

Novel Research in Sexuality and Mental Health

Sexuality is considered as a great human value related to happiness and satisfaction, but unfortunately, when affecting mental disorders, they tend to be associated with second level human functions. Nevertheless, sexual dysfunction often accompanies psychiatric disorder, intensely influencing compliance, quality of life and human relationships. Sexuality could be influenced either by a mental disorder itself, difficulties to get and maintain couple relationships or by the use of psychotropic treatments. Treatment-related adverse events are unfortunately under-recognized by clinicians, scarcely spontaneously communicated by patients, and rarely investigated in clinical trials. The most frequent psychotropic compounds that could deteriorate sexuality and quality of life include antidepressants, antipsychotics and mood regulators. There are important differences between them related to some variations in mechanisms of action including serotonin, dopamine and prolactin levels. Little is known about the relevance of sexuality and its dysfunctions in chronic and frequent mental and neurological disorders, such as psychosis, mood disorders, anxiety, phobias, eating disorders, alcohol or drug dependencies, epilepsy and childhood pathology. Poor sexual life, low satisfaction and more frequent risky sex behavior than in the general population are associated with severe mental diseases. There is a need for increasing research in this field, including epidemiological, psychological, neurophysiological, neuroanatomical and genetic variables related to sexual life to get a better understanding of the implicated mechanisms. To increase the sensibility of clinicians, the identification and management of sexual disturbances after the onset of any mental disorder should be highlighted. This would avoid unnecessary suffering and deterioration of quality of life

The Rewarding Nature of Anger Rumination in Borderline Personality Disorder: An fMRI Investigation

Anger rumination, or persistently dwelling on feelings of anger, is associated with borderline personality disorder (BPD) and related features, such as aggressive behavior and cognitive distortions. To develop more effective treatments, it is crucial to understand why individuals with BPD engage in anger rumination despite its negative outcomes. The activation of energy associated with anger, as well as feelings of justification and validation, may be experienced in the short-term as rewarding. This may prevent individuals with BPD from attempting to reduce their rumination. Functional magnetic resonance imaging (fMRI) and behavioral methods were utilized to examine this theory in a sample of women diagnosed with BPD (n=13) and healthy controls (n=15). In an initial session, all participants were an administered a diagnostic interview for BPD, as well a series of self-report measures. In a second session, all participants completed an essay-writing task prior to the fMRI scan. All participants were provided with identical, highly critical feedback about their essays from a supposed essay evaluator. In response to this interpersonal provocation, participants with BPD demonstrated higher activation in brain regions associated with self-conscious reactivity to errors (insula, ventrolateral prefrontal cortex). Subsequent directed provocation-focused thought, compared to neutral-focused thought, produced greater activation in regions previously associated with anger rumination (dorsomedial prefrontal cortex, lateral orbitofrontal cortex) across groups. As hypothesized, anger rumination, relative to neutral-focused thought, produced greater activation in brain regions associated with reward and pleasure (nucleus accumbens) for the BPD group only. No significant differences were observed for self-focused thought. Following the directed rumination task, participants completed a competitive reaction time task that provides an opportunity for participants to act aggressively, supposedly against their essay evaluator. The BPD group demonstrated significantly higher levels of aggressive behavior; however, no significant group differences emerged in neural functioning during the task. These findings suggest that anger rumination may be positively reinforcing for individuals with BPD, which has implications for treatment approaches

The effects of c-tactile afferent stimulation on male orgasm and ejaculation

Orgasms and ejaculation are important for relationships and contribute significantly to life satisfaction. There is, however, a lack of research in the current literature regarding orgasm perception. This study tested the effects of endogenous oxytocin on subjective orgasm intensity, ejaculation latency, and ejaculate volume in men. At two separate test sessions, the participants were either stroked on the forearm (to release endogenous oxytocin) or tapped on the hand (to act as a control) with a cosmetic brush. The forearm contains C-tactile afferents that are believed to release oxytocin centrally and peripherally in response to slow, soft stroking stimulation. Then a clinical male vibrator was utilized to induce ejaculation in the absence of any ‘cerebral stimulation’ and without the need for audiovisual stimuli. Given the role of oxytocin in hedonic and sexual responses, C-tactile induced increase in endogenous oxytocin was expected to significantly increase subjective orgasm intensity, ejaculate weight and erection hardness and decrease ejaculation latency. The results were inconclusive: There was no significant difference of subjective orgasm intensity, ejaculate volume, erection hardness, and ejaculation latency between the brushing and tapping condition, however this may be due to the low sample size (n=7). Overall, the data showed a change in favor of a greater sexual response following C-tactile afferent specific stimulation. This novel experimental paradigm is suitable for other male sexual response studies because it was well tolerated and simple enough for participants to follow. Future research should focus on improving recruitment strategies and eliminating the need for a partner

Neural Mechanisms of High-Risk, Appetitive Decisions in Alcohol Dependent Women

Thesis (Ph.D.) - Indiana University, Psychological & Brain Sciences, 2014A defining feature of alcohol dependence (AD) is continuing to drink despite the risk of severe negative consequences. Currently, it is not known if the pattern of disordered activation in AD is more compatible with an over-sensitive reward system, a deficit in control systems or a combination of both to produce the high risk-taking behavior observed in alcohol dependents. Here, fMRI was used to examine neural mechanisms that drive high-risk behavior in alcohol dependent women (ADs). A novel ecological task was developed to assess high- and low-risk decisions to drink alcohol, have sex, eat food, and buy items in ADs and control women. In this dissertation, neural correlates of high-risk decisions to drink (Study 1), neural correlates of high-risk decisions to have sex (Study 2), and functional connectivity (fC) during high-risk decisions to drink using psychophysiological interactions (Study 3) are examined. Across these studies, the focus was on 1.) determining if a specific pattern of activation or fC drives high-risk behavior in ADs, and 2.) determining if neural patterns of activation or fC are specific to high-risk decisions to drink or if they generalize to other appetitive decisions in ADs. The results showed that for high-risk decisions to drink, ADs were significantly more likely to drink high-risk beverages compared to controls, and a specific pattern of activation was associated with high-risk decisions to drink compared to other appetitive decisions, in ADs compared to controls. ADs also had significantly reduced fC compared to controls during high-risk decisions to drink. However, for sexual decisions, there were no behavioral differences between ADs and controls, yet a significant difference in neural activation was observed. Overall, the results suggest that disordered activation and fC in ADs observed during this task may be due to a problem with switching between different neural networks

The von Economo neurons in the frontoinsular and anterior cingulate cortex

The von Economo neurons (VENs) are large bipolar neurons located in the frontoinsular cortex (FI) and limbic anterior (LA) area in great apes and humans but not in other primates. Our stereological counts of VENs in FI and LA show them to be more numerous in humans than in apes. In humans, small numbers of VENs appear the 36th week postconception, with numbers increasing during the first 8 months after birth. There are significantly more VENs in the right hemisphere in postnatal brains; this may be related to asymmetries in the autonomic nervous system. VENs are also present in elephants and whales and may be a specialization related to very large brain size. The large size and simple dendritic structure of these projection neurons suggest that they rapidly send basic information from FI and LA to other parts of the brain, while slower neighboring pyramids send more detailed information. Selective destruction of VENs in early stages of frontotemporal dementia (FTD) implies that they are involved in empathy, social awareness, and self‐control, consistent with evidence from functional imaging

The von Economo neurons in the frontoinsular and anterior cingulate cortex

The von Economo neurons (VENs) are large bipolar neurons located in the frontoinsular cortex (FI) and limbic anterior (LA) area in great apes and humans but not in other primates. Our stereological counts of VENs in FI and LA show them to be more numerous in humans than in apes. In humans, small numbers of VENs appear the 36th week postconception, with numbers increasing during the first 8 months after birth. There are significantly more VENs in the right hemisphere in postnatal brains; this may be related to asymmetries in the autonomic nervous system. VENs are also present in elephants and whales and may be a specialization related to very large brain size. The large size and simple dendritic structure of these projection neurons suggest that they rapidly send basic information from FI and LA to other parts of the brain, while slower neighboring pyramids send more detailed information. Selective destruction of VENs in early stages of frontotemporal dementia (FTD) implies that they are involved in empathy, social awareness, and self‐control, consistent with evidence from functional imaging