Update on cannabis in human sexuality.

RATIONALE: Sexuality is a central aspect of being human that encompasses many facets. Cannabis, a widely used psychoactive substance, has been associated with various effects on sexuality. The relationship between cannabis and sexuality is complex and multifaceted, involving physiological, psychological, and social factors. OBJECTIVES: This review aims to provide an overview of the current literature on the effects of cannabis on several sexual functions, including sexual desire, arousal, orgasm, and sexual satisfaction. It also discusses the potential mechanisms underlying these effects, as well as the impact of dose and frequency of use. RESULTS: This review has revealed a complex relationship between cannabis dosage and its influence on sexuality. It appears that the frequency of cannabis use in humans has been associated with the frequency of sexual activities. Individuals who use cannabis more frequently tend to report higher levels of sexual activity. Moreover, there is a notable gender difference in how cannabis affects sexuality. In addition, we found lower doses of cannabis to be linked to heightened sexual desire and enjoyment, whereas higher doses may lead to a decrease in sexual desire and performance. CONCLUSIONS: Overall, the association between cannabis and sexuality is complex and warrants further research to better understand the psychological and neurological mechanisms that underlie the effect of cannabis on these sexuality functions and its implications for sexual health. To advance in this endeavor, a crucial step is establishing a precise measurement of dosage in human studies.

Graph analysis uncovers an opposing impact of methylphenidate on connectivity patterns within default mode network sub-divisions.

BACKGROUND: The Default Mode Network (DMN) is a central neural network, with recent evidence indicating that it is composed of functionally distinct sub-networks. Methylphenidate (MPH) administration has been shown before to modulate impulsive behavior, though it is not yet clear whether these effects relate to MPH-induced changes in DMN connectivity. To address this gap, we assessed the impact of MPH administration on functional connectivity patterns within and between distinct DMN sub-networks and tested putative relations to variability in sub-scales of impulsivity. METHODS: Fifty-five right-handed healthy adults underwent two resting-state functional MRI (rs-fMRI) scans, following acute administration of either MPH (20 mg) or placebo, via a randomized double-blind placebo-controlled design. Graph modularity analysis was implemented to fractionate the DMN into distinct sub-networks based on the impact of MPH (vs. placebo) on DMN connectivity patterns with other neural networks. RESULTS: MPH administration led to an overall decreased DMN connectivity, particularly with the auditory, cinguloopercular, and somatomotor networks, and increased connectivity with the parietomedial network. Graph analysis revealed that the DMN could be fractionated into two distinct sub-networks, with one exhibiting MPH-induced increased connectivity and the other decreased connectivity. Decreased connectivity of the DMN sub-network with the cinguloopercular network following MPH administration was associated with elevated impulsivity and non-planning impulsiveness. CONCLUSION: Current findings highlight the intricate effects of MPH administration on DMN rs-fMRI connectivity, uncovering its opposing impact on distinct DMN sub-divisions. MPH-induced dynamics in DMN connectivity patterns with other neural networks may account for some of the effects of MPH administration on impulsive behavior.

Fronto-striatal connectivity patterns account for the impact of methylphenidate on choice impulsivity among healthy adults.

Choice impulsivity depicts a preference towards smaller-sooner rewards over larger-delayed rewards, and is often assessed using a delay discounting (DD) task. Previous research uncovered the prominent role of dopaminergic signaling within fronto-striatal circuits in mediating choice impulsivity. Administration of methylphenidate (MPH), an indirect dopaminergic agonist, was shown to reduce choice impulsivity in animals and pathological populations, although significant inter-individual variability in these effects was reported. Whether MPH impacts choice impulsivity among healthy individuals, and whether variability in the impact of MPH is related to fronto-striatal activation and connectivity patterns, has yet to be assessed. Here, fifty-seven healthy young adults completed the DD task twice during fMRI scans, after acute administration of either MPH (20 mg) or placebo, in a randomized double-blind placebo-controlled design. Acute MPH administration was found to reduce choice impulsivity at the group level, yet substantial variability in this behavioral response was observed. MPH was also found to increase activation in the bilateral putamen and the right caudate, and to enhance functional connectivity between the left putamen and medial prefrontal cortex (mPFC), particularly during non-impulsive choices. Notably, the more putamen-mPFC functional connectivity increased during non-impulsive choices following MPH administration, the less an individual was likely to make impulsive choices. These findings reveal, for the first time in healthy adults, that acute MPH administration is associated with reduced choice impulsivity and increased striatal activation and fronto-striatal connectivity; and furthermore, that the magnitude of MPH-induced change in fronto-striatal connectivity may account for individual differences in the impact of MPH on impulsive behavior.

Touched by loneliness-how loneliness impacts the response to observed human touch: a tDCS study.

Lonely people often crave connectedness. However, they may also experience their environment as threatening, entering a self-preserving state that perpetuates loneliness. Research shows conflicting evidence about their response to positive social cues, and little is known about their experience of observed human touch. The right inferior frontal gyrus (rIFG) is part of an observation-execution network implicated in observed touch perception. Correlative studies also point to rIFG's involvement in loneliness. We examined the causal effect of rIFG anodal transcranial direct current stimulation on high- and low-loneliness individuals observing human touch. In a cross-over design study, 40 participants watched pictures of humans or objects touching or not touching during anodal and sham stimulations. Participants indicated whether pictures contained humans or objects, and their reaction time was measured. Results show that the reaction time of low-loneliness individuals to observed human touch was significantly slower during anodal stimulation compared to high-loneliness individuals, possibly due to them being more emotionally distracted by it. Lonely individuals also reported less liking of touch. Our findings support the notion that lonely individuals are not drawn to positive social cues. This may help explain the perpetuation of loneliness, despite social opportunities that could be available to lonely people.

Methylphenidate reduces orienting bias in healthy individuals.

BACKGROUND: Healthy individuals show subtle orienting bias, a phenomenon known as pseudoneglect, reflected in a tendency to direct greater attention toward one hemispace. Accumulating evidence indicates that this bias is an individual trait, and attention is preferentially directed contralaterally to the hemisphere with higher dopamine signaling. Administration of methylphenidate (MPH), a dopamine transporter inhibitor, was shown to normalize aberrant spatial attention bias in psychiatric and neurological patients, suggesting that the reduced orienting bias following administration of MPH reflects an asymmetric effect of the drug, increasing extracellular dopamine in the hemisphere with lower dopamine signaling. AIM: We predicted that, similarly to its effect on patients with brain pathology, MPH will reduce the orienting bias in healthy subjects. METHODS: To test this hypothesis, we examined the behavioral effects of a single dose (20 mg) of MPH on orienting bias in 36 healthy subjects (18 females) in a randomized, double-blind placebo-controlled, within-subject design, using the greyscales task, which has been shown to detect subtle attentional biases in both patients and healthy individuals. RESULTS/OUTCOMES: Results demonstrate that healthy individuals vary in both direction and magnitude of spatial orienting bias and show reduced magnitude of orienting bias following MPH administration, regardless of the initial direction of asymmetry. CONCLUSIONS/INTERPRETATIONS: Our findings reveal, for the first time in healthy subjects, that MPH decreases spatial orienting bias in an asymmetric manner. Given the well-documented association between orienting bias and asymmetric dopamine signaling, these findings also suggest that MPH might exert a possible asymmetric neural effect in the healthy brain.

Exogenous effects of oxytocin in five psychiatric disorders: a systematic review, meta-analyses and a personalized approach through the lens of the social salience hypothesis.

Oxytocin (OT) has been implicated in various aspects of social behaviors. During the past decades there has been a surge of interest in the therapeutic potential of OT in psychiatric disorders, especially those characterized by social deficits, which the available therapeutic agents, cannot fully target. This systematic review and meta-analysis examines available evidence for the therapeutic role of OT in five psychiatric disorders characterized with difficulties in social abilities: autism spectrum disorder, schizophrenia, post-traumatic stress disorder, mood disorders and borderline personality disorder. For each disorder, we review the sample size, gender distribution and single versus long-term effects of OT. Moreover, we examine effects of OT through the lens of the social salience hypothesis, in order to identify individual characteristics and contexts that may affect the response to OT, across the disorders. We show that OT has diverse effects depending on symptoms and context. The meta-analyses revealed a small effect size of OT efficacy in schizophrenia and repetitive behaviors in ASD. Finally, we discuss shortcomings and provide recommendations for future research.

A scent of romance: human putative pheromone affects men's sexual cognition.

Previous studies suggest that the putative human pheromone estratetraenol affects several systems underlying human functioning and appears to activate neural systems that are known to affect sexual behavior. In this study, we investigated whether exposure to estratetraenol affects men's social cognition abilities. In the first experiment, men performed the Interpersonal Perception task while being exposed to estratetraenol and to a control solution. Men performed the task with better accuracy while being exposed to estratetraenol. This improvement was evident especially in the Intimacy category where participants evaluated romantic relationships. In a second experiment, we exposed a different sample of men to estratetraenol and to a control solution while performing a task that implicitly measured their emotional reaction to photos depicting two humans either romantically touching or not, with a control condition of two inanimate objects either touching or not. We found that the participants' emotional reaction to touch was stronger under exposure to estratetraenol. Together, these results suggest that exposure to estratetraenol may trigger a change in men's social cognition, especially in sexually related situations.

The role of the inferior frontal gyrus in vicarious social touch: A transcranial direct current stimulation (tDCS) study.

The neural mechanisms facilitating the experience of vicarious social touch are largely unknown. The right inferior frontal gyrus (rIFG) has been suggested as part of a simulation observation-execution neural network that plays a key role in the perception of tactile stimuli. Considering that vicarious social touch involves vicarious sharing of emotions, we hypothesized that emotional empathy, i.e., the ability to feel what another individual is feeling, modulates the neural responses to vicarious touch. To examine the role of the rIFG in vicarious touch and its modulation by levels of emotional empathy, we used anodal transcranial direct current stimulation (tDCS) on forty participants who observed photos depicting social touch, nonsocial touch or no touch during tDCS or sham stimulation. The results show that while participants with high levels of emotional empathy exhibited no change in ratings of vicarious social touch, participants with low levels of emotional empathy rate human touch as more emotional following anodal stimulation of the rIFG than following sham stimulation. These findings indicate that emotional responses to vicarious social touch are associated with rIFG activity and are modulated by levels of emotional empathy. This result has major therapeutic potential for individuals with low empathic abilities, such as those with ASD.

Don't touch me! autistic traits modulate early and late ERP components during visual perception of social touch.

Although individuals with autism spectrum disorder (ASD) have impaired responses to interpersonal touch, the underlying neural correlates remain largely unknown. Here, we examined the neural correlates that underlie interpersonal touch perception in individuals with either high or low autistic traits. Fifty-three participants were classified as having either high or low autistic traits based on their performance on the autism quotient (AQ) questionnaire. We hypothesized that individuals with high AQ scores would have relatively high touch hypervigilance, reflected as earlier P1 and stronger late positive potential (LPP) responses, two components of event-related potentials that serve as electrophysiological markers of anxiety bias. We recorded each participant's electroencephalography activity during presentation of images depicting human touch, object touch, and non-touch control images. Consistent with our hypothesis, AQ scores were positively correlated with social touch aversion. Moreover, participants with high AQ scores had earlier P1 and stronger LPP responses when presented with human touch compared to the control images. Importantly, a regression model revealed that earlier P1 and larger LPP amplitude measured during social touch observation can accurately predict higher autistic trait levels. Taken together, these findings indicate that individuals with high levels of autistic traits may have a hypervigilant response to observed social touch. Autism Res 2017, 0: 000-000. © 2017 International Society for Autism Research, Wiley Periodicals, Inc. Autism Res 2017, 10: 1141-1154. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.

The role of empathy in the neural responses to observed human social touch.

One of the ways in which individuals convey feelings and thoughts to one another is through touch. Although the neural responses to felt and observed tactile stimuli between an inanimate object and a part of the human body have been vastly explored, the neural responses to observed human interaction involving touch are not well understood. Considering that the observation of social touch involves vicarious sharing of emotions, we hypothesized that levels of empathic traits modulate the neural responses to observed touch and focused on the attenuation in the mu\alpha rhythm (8-13Hz), a neural marker that has been related to sensorimotor resonance. Fifty-four participants observed photos depicting social touch, nonsocial touch, or no touch while their electroencephalography (EEG) activity was recorded. Results showed that interindividual differences in levels of empathic traits modulated both behavioral and electrophysiological responses to human social touch, such that highly empathic participants evaluated human social touch as inducing more pleasant emotions and exhibited greater mu suppression upon observation of human social touch compared to less empathic participants. Specifically, both the behavioral and the electrophysiological responses to observed social touch were predicted by levels of personal distress, a measure of emotional contagion. These findings indicate that the behavioral and electrophysiological responses to observed social touch are modulated by levels of empathy.

The effect of oxytocin on the anthropomorphism of touch.

One of the leading hypotheses regarding the mechanism underlying the social effects of oxytocin (OT) is the "social salience hypothesis", which proposes that OT alters the attentional salience of social cues in a context-dependent manner. Recently, OT was implicated in the process of anthropomorphism; specifically, OT was found to increase the tendency to ascribe social meaning to inanimate stimuli. However, the precise component of social interaction that contributes to this effect remains unclear. Because OT plays a role in the response to touch, whether or not objects are touching in a social context may represent the prominent trigger. Given that OT plays a major role in both anthropomorphism and touch, it is reasonable to assume that OT enhances anthropomorphism specifically for non-human touch, further clarifying its role in altering the perceptual salience of social cues. Here, we examined whether intranasal delivery of OT influences anthropomorphism for touch in inanimate objects. To that end, we implicitly measured the emotional reactions of participants (N=51) to photos that depicted two humans or two inanimate objects either touching or not touching. We asked them to rate whether they will include each photo in an emotional album and found that OT treatment increased the likelihood of inclusion in an emotional album to photos that contain touch, particularly between inanimate objects. In a follow-up experiment we found that the more human the inanimate objects were perceived, the more included they were in the emotional album. Our findings demonstrate that OT can enhance the social meaning of touch between two inanimate objects and advance our understanding of the mechanisms underlying the ability of OT to anthropomorphize environmental cues.