Bridging skin, brain, and behavior to understand pleasurable social touch

Mapping the landscape of social behavior

Social interaction is integral to animal behavior. However, lacking tools to describe it in quantitative and rigorous ways has limited our understanding of its structure, underlying principles, and the neuropsychiatric disorders, like autism, that perturb it. Here, we present a technique for high-resolution 3D tracking of postural dynamics and social touch in freely interacting animals, solving the challenging subject occlusion and part-assignment problems using 3D geometric reasoning, graph neural networks, and semi-supervised learning. We collected over 110 million 3D pose samples in interacting rats and mice, including seven monogenic autism rat lines. Using a multi-scale embedding approach, we identified a rich landscape of stereotyped actions, interactions, synchrony, and body contacts. This high-resolution phenotyping revealed a spectrum of changes in autism models and in response to amphetamine not resolved by conventional measurements. Our framework and large library of interactions will facilitate studies of social behaviors and their neurobiological underpinnings.

The evolving neurobiology of early-life stress

Because early-life stress is common and constitutes a strong risk factor for cognitive and mental health disorders, it has been the focus of a multitude of studies in humans and experimental models. Yet, we have an incomplete understanding of what is perceived as stressful by the developing brain, what aspects of stress influence brain maturation, what developmental ages are particularly vulnerable to stress, which molecules mediate the effects of stress on brain operations, and how transient stressful experiences can lead to enduring emotional and cognitive dysfunctions. Here, we discuss these themes, highlight the challenges and progress in resolving them, and propose new concepts and avenues for future research.

The effect of modulation Piezo2 by IGF-1 on tactile hypersensitivity in BTBR model mice

AIMS

Autism spectrum disorder (ASD) is classified as a neurodevelopmental disorder. Individuals with ASD exhibit a higher incidence of tactile hypersensitivity. However, the underlying mechanisms remain unclear. The dorsal root ganglion (DRG) plays a crucial role in influencing tactile processing. This study aims to integrate RNA sequencing (RNA-seq) and molecular biology experiments to identify key molecules involved in tactile hypersensitivity in ASD, further investigate related mechanisms, and develop effective intervention strategy.

MAIN METHODS

Using BTBR as the ASD model mouse and wild-type C57BL/6J as the control mouse, the differences in tactile sensitivity between them was compared. DRG were collected for RNA-seq analysis. Immunofluorescence and Enzyme-linked immunosorbent assay (ELISA) techniques were employed to validate the identified key molecules. And combined western blot to investigate the associated regulatory pathways.

KEY FINDINGS

BTBR mice exhibit tactile hypersensitivity, which are associated with the upregulation of IGF-1 in the DRG. IGF-1 regulates the expression of Piezo2 ion channels. Inhibition of the IGF-1/Piezo2 pathway can significantly alleviate tactile hypersensitivity and social deficits in BTBR mice. Additionally, gentle touch intervention has been shown to reduce the overexpression of IGF-1/Piezo2 in the DRG, thereby ameliorating ASD symptoms.

SIGNIFICANCE

The upregulation of the IGF-1/Piezo2 pathway in DRG may serve as a potential mechanism for tactile hypersensitivity observed in BTBR mice. Restoring the normalization of the IGF-1/Piezo2 is crucial for alleviating tactile hypersensitivity and synergistically rescues social deficits. Gentle touch intervention has the potential to ameliorate these behaviors through regulating IGF-1/Piezo2, positioning it as a promising strategy for ASD.

Electrophysiological activity underlying motor inhibition facilitated by touch

Tactile sensory information obtained from oneself or others may provide a calming effect and has been shown to enhance participants' motor control. The extent to which these touch activities may support motor inhibition and the related electrophysiological mechanisms remain unknown. Here, we investigated these effects in twenty healthy volunteers via electroencephalography under 3 touching conditions (self-touch, other-touch, and no-touch) during a stop-signal task. We found that both the self-touch and other-touch conditions resulted in better stopping accuracy and lower stop-signal reaction times than the no-touch condition. Additionally, these 2 touch conditions elicited larger N2 and P3 responses during successful inhibition of planned finger movements. Time-varying network analysis based on electroencephalography was further used to explore the differences in brain networks during conflict monitoring substages under different touch conditions. A top-down projection from the frontal cortex (Fz) to the parietal and occipital cortices was observed along with increased functional connectivity efficiency under touch conditions. These results indicate that tactile information may enhance neural processing efficiency in the human brain by eliciting larger event-related potential components and promoting information processing in the brain network during conflict monitoring processes, thereby contributing to the reactive inhibitory component of motor inhibition.

Neural Correlates of Social Touch Processing: An fMRI Study on Brain Functional Connectivity

BACKGROUND

The significance of tactile stimulation in human social development and personal interaction is well documented; however, the underlying cerebral processes remain under-researched. This study employed functional magnetic resonance imaging (fMRI) to investigate the neural correlates of social touch processing, with a particular focus on the functional connectivity associated with the aftereffects of touch.

METHODS

A total of 27 experimental subjects were recruited for the study, all of whom underwent a 5-minute calf and foot massage prior to undergoing resting-state fMRI. Additionally, 11 healthy controls participated solely in the resting-state fMRI recording. A functional connectivity network analysis was conducted to examine the alterations in connections between different brain regions following massage.

RESULTS

The findings indicated the involvement of discrete neural networks in the processing of social touch, with notable discrepancies in functional connectivity observed between the experimental and control groups. The study revealed that the control group exhibited a higher degree of connectivity within a subnetwork comprising 25 connections and 23 nodes than the experimental group following the massage intervention. The experimental group showed hypoactivation in this subnetwork following the massage. The left anterior pulvinar thalamus and the right pregenual anterior cingulate cortex, which serve as the key hubs within this subnetwork, exhibited higher clustering and increased node strength in the control group. Relatively small and unequal sample sizes are the limitations of the study that may affect the generalizability of the results.

CONCLUSIONS

These findings elucidate the neural underpinnings of tactile experiences and their potential impact on behavior and emotional state. Gaining insight into these mechanisms could inform therapeutic approaches that utilize touch to mitigate stress and enhance mental health. From a practical standpoint, our results have significant implications for the development of sensory stimulation strategies for patients with prolonged disorders of consciousness, sensory loss, autism spectrum disorders, or limited access to tactile interaction in their upper extremities.

The Impact of Relaxation Massage Prior to Bedtime on Sleep Quality and Quantity in People with Symptoms of Chronic Insomnia: A Home-Based Sleep Study

Background/Objectives: Manual massage is an effective treatment approach for reducing general stress and promoting an overall sense of well-being. Relaxation massage aims to alleviate psychophysiological tension, enhance both blood and lymphatic circulation, and promote mental and physical relaxation. It is particularly beneficial for those with anxiety-related symptoms (such as generalized anxiety disorder and social anxiety) and sleep disorders, aiming to improve calmness and promote sleepiness. Aims: The purpose of the present study was to assess the effectiveness of a single session of relaxation massage prior to bedtime on sleep quality and quantity indices in individuals with symptoms of chronic insomnia. Methods: In total, 20 (N = 20) healthy individuals (aged 25.5 ± 12.0 years; 6F/14M) with a score on the Athens Insomnia Scale of ≥16 participated under three different conditions over one week apart: (1) a 45 min relaxation massage condition (REL), (2) a 45 min sham massage condition (PLA), and (3) a control condition with no massage. Sleep activity was monitored using a portable polysomnographic system. Results: A statistically significant effect was observed between sleep efficiency across the three sessions (p = 0.034), with a notable effect in the relaxation massage (REL) session (p = 0.045). Additionally, sustained sleep efficiency showed a statistically significant difference among the sessions (p = 0.005). Conclusions: Relaxation massage prior to bedtime could be used as an effective and safe non-pharmacological approach for improving sleep efficiency and potentially restoring the fragmented sleep of individuals with symptoms of insomnia. Trial registration number: The trial was registered at clinicaltrials.gov as NCT06781866.

Handholding reduces the recovery of threat memories and magnifies prefrontal hemodynamic responses

Human touch is a powerful means of social and affective regulation, promoting safety behaviors. Yet, despite its importance across human contexts, it remains unknown how touch can promote the learning of new safety memories and what neural processes underlie such effects. The current study used measures of peripheral physiology and brain activity to examine the effects of interpersonal touch during safety learning (extinction) on the recovery of previously learned threat. We observed that handholding during extinction significantly reduced threat recovery, which was reflected in enhanced prefrontal hemodynamic responses. This effect was absent when learners were instructed to hold a rubber ball, independent of the presence of their partners. Our findings indicate that social touch contributes to safety learning, potentially influencing threat memories via prefrontal circuitry.

Psychometric evaluation of the Social Touch Questionnaire in Chinese adolescents

Social touch promotes psychological well-being through inducing positive effects on social affiliation and stress alleviation, especially in adolescence. However, there is a scarcity of instruments available for evaluating adolescents' attitude toward social touch in China. The present study aimed to investigate the validity and reliability of the Social Touch Questionnaire (STQ) in Chinese adolescents. A total of 2839 high school students were enrolled, ranging in age from 11 to 19 years. The dimensions of the scale were conducted by exploratory factor analysis, and validated by confirmatory factor analysis. A three-factor model showed the best fit and consisted of the following subgroups: liking of informal social touch, liking of general social touch, and dislike of social touch. Furthermore, positive associations were found between social touch and interaction anxiety, fear of negative evaluation, depressive and anxiety symptoms, and sleep quality. Short-term prediction of dislike of social touch in anxiety symptoms was determined, while no significant predictor of depressive symptoms was found. The STQ demonstrates reliability and validity as a self-report questionnaire designed to assess behaviors and attitudes toward social touch. It effectively adapts to the nuances of the Chinese context among adolescents.

A narrative review of research linking non-sexual social touch to sleep quality

This narrative review describes the current state of the literature that has examined associations between non-sexual social touch (i.e., affectionate touch, touch therapies, touch with animals and inanimate objects that mimic social touch) and sleep quality. It also highlights areas for future research to clarify the links and to identify underlying mechanisms. Most existing studies have focussed on and shown positive effects of touch therapies (e.g., massage, therapeutic touch) on sleep quality in clinical populations. Although there are fewer studies examining how other forms of social touch are linked with sleep quality, the existing research provides preliminary evidence supporting affectionate touch (e.g., hugging, skin-to-skin contact) and tactile contact with animals (e.g., dogs) and objects that mimic social touch (e.g., robots, weighted blankets) as predictors of better sleep quality, while touch deprivation and touch aversion are associated with worse sleep quality. Informed by the existing literature, we additionally reviewed potential relational-cognitive (e.g., felt-security) and neurobiological (e.g., oxytocin) mechanisms likely to underlie associations between social touch and sleep quality. Overall, current research supports associations between non-sexual social touch and sleep quality. However, future research is needed to establish these links for specific forms of social touch (and in various populations), to test explanatory mechanisms, and to identify boundary conditions. Understanding associations between non-sexual social touch and sleep quality can inform the development of touch-based interventions to improve sleep quality and health.

Mapping the landscape of social behavior

Social interaction is integral to animal behavior. However, we lack tools to describe it with quantitative rigor, limiting our understanding of its principles and neuropsychiatric disorders, like autism, that perturb it. Here, we present a technique for high-resolution 3D tracking of postural dynamics and social touch in freely interacting animals, solving the challenging subject occlusion and part assignment problems using 3D geometric reasoning, graph neural networks, and semi-supervised learning. We collected over 140 million 3D postures in interacting rodents, featuring new monogenic autism rat lines lacking reports of social behavioral phenotypes. Using a novel multi-scale embedding approach, we identified a rich landscape of stereotyped actions, interactions, synchrony, and body contact. This enhanced phenotyping revealed a spectrum of changes in autism models and in response to amphetamine that were inaccessible to conventional measurements. Our framework and large library of interactions will greatly facilitate studies of social behaviors and their neurobiological underpinnings.

Comfort evaluation and physiological effects/autonomic nervous system response of inflatable deep pressure vest in reducing anxiety

Background

Deep pressure therapy treats anxiety by triggering physiological responses and promoting calmness. Moreover, measuring user comfort can improve product quality.

Objective

To investigate the physiological effects and subjective comfort level of inflatable deep pressure vests to enhance their calming effect.

Methods

Experimental research was conducted with a one-group pretest-posttest design for physiological effects using pulse oximetry for peripheral pulse rate and a one-shot case study for three subscale parameters that help evaluate comfort (pressure, touch, and mobility) using the Numerical Rating Scale (NRS). Deep pressure intervention using the Inflatable Vest was performed for three sessions, each lasting 5 min.

Results

This study was conducted with 46 participants (24 males, 22 females) aged 17-20 (19.52 ± 0.78). Although pulse rate consistently decreased in all sessions, session 1 showed a significant decrease (p = 0.014*, d = 0.379), whereas sessions 2 (p = 0.274, d = 0.163) and 3 (p = 0.597, d = 0.078) demonstrated non-significant decreases with small effect sizes. The pressure comfort subscale showed that 87.0 %, 4.3 %, and 8.7 % of the participants, and the touch comfort subscale test revealed that 82.6 %, 8.7 %, and 73.9 % of the participants rated it as comfortable, very comfortable, and less comfortable, respectively. The mobility subscale test showed that 73.9 % of the participants rated no limitation, 17.4 % rated somewhat limited, and only 8.7 % rated limitation. Decreased pulse rate and pressure comfort were significantly positively correlated (r = 0.282**, p < 0.01), whereas touch pressure and mobility were not (r = 0.160, p > 0.05; and r = 0.121, p > 0.05, respectively). Decreased pulse rate was also positively correlated with the overall score for the three aspects (r = 0.201*, p < 0.05).

Conclusions

A comfortable inflatable deep pressure vest provides a physiologically calming effect for therapeutic modalities.

Social-touch and self-touch differ in hemodynamic response in the prefrontal cortex - a fNIRS study conducted during the coronavirus pandemic

Being touched by others (social-touch) and touching oneself (self-touch) are common nonverbal behaviors in everyday interaction. The commonalities and differences between these two types of touching behavior are of particular interest for conditions when social-touch is substantially restricted such as during the corona pandemic. Neuropsychologically, pleasant social-touch is associated with increased activation in frontal brain regions such as frontopolar, dorsolateral prefrontal (dlPFC), and orbitofrontal cortices (OFC). However, for these regions a deactivation has also been reported. Likewise, for self-touch the findings are controversial. Therefore, the aim of this study is to shed light on the controversial findings and to elucidate the relation between self-touch and social-touch. From 2021 to 2022, in a quasi-naturalistic setting, in forty-six participants brain oxygenation and deoxygenation was examined during social-touch and self-touch in frontal cortices applying functional NearInfraRed Spectroscopy (fNIRS). Social-touch compared to self-touch led to a significantly higher brain deoxygenation in the frontopolar areas and in parts of the dlPFC and OFC. In contrast, brain oxygenation in the PFC was significantly increased during self-touch compared to social-touch. The cerebral activation and deactivation pattern in a quasi-naturalistic setting indicates that self-touch cannot achieve the hedonic effects of social-touch, but it can influence internally self-regulating processes.

A failure to discriminate social from non-social touch at the circuit level may underlie social avoidance in autism

Social touch is critical for communication and to impart emotions and intentions. However, certain autistic individuals experience aversion to social touch, especially when it is unwanted. We used a novel social touch assay and Neuropixels probes to compare neural responses to social vs. non-social interactions in three relevant brain regions: vibrissal somatosensory cortex, tail of striatum, and basolateral amygdala. We find that wild type (WT) mice showed aversion to repeated presentations of an inanimate object but not of another mouse. Cortical neurons cared most about touch context (social vs. object) and showed a preference for social interactions, while striatal neurons changed their preference depending on whether mice could choose or not to interact. Amygdalar and striatal neurons were preferentially modulated by forced object touch, which was the most aversive. In contrast, the Fmr1 knockout (KO) model of autism found social and non-social interactions equally aversive and displayed more aversive facial expressions to social touch when it invaded their personal space. Importantly, when Fmr1 KO mice could choose to interact, neurons in all three regions did not discriminate social valence. Thus, a failure to differentially encode social from non-social stimuli at the circuit level may underlie social avoidance in autism.

Virtual social grooming in macaques and its psychophysiological effects

Allogrooming is a widespread, pervasive activity among non-human primates. Besides its hygienic function, it is thought to be instrumental in maintaining social bonds and establishing hierarchical structures within groups. However, the question arises as to whether the physiological and social benefits derived from social touch stem directly from body stimulation, or whether other mechanisms come into play. We address this question by analyzing an elaborate social behavior that we observed in two adult male macaques. This behavior demonstrates the existence of a persistent motivation to interact through a form of simulated grooming, as the animals were housed in adjacent enclosures separated by a glass panel preventing direct tactile contact. We find that such virtual grooming produces similar physiological sensations and social effects as allogrooming. We suggest that this behavior engages affective and reward brain circuits to the same extent as real social touch, and that this is probably achieved through high level processes similar to those involved in bodily illusions or synaesthetic phenomena previously described in humans. This observation reveals the unsuspected capacity of non-human primates to invent alternative, quasi-symbolic strategies to obtain effects similar to those provided by direct bodily interaction, which are so important for maintaining social bonds.

Out of touch? How trauma shapes the experience of social touch - Neural and endocrine pathways

Trauma can shape the way an individual experiences the world and interacts with other people. Touch is a key component of social interactions, but surprisingly little is known about how trauma exposure influences the processing of social touch. In this review, we examine possible neurobiological pathways through which trauma can influence touch processing and lead to touch aversion and avoidance in trauma-exposed individuals. Emerging evidence indicates that trauma may affect sensory touch thresholds by modulating activity in the primary sensory cortex and posterior insula. Disturbances in multisensory integration and oxytocin reactivity combined with diminished reward-related and anxiolytic responses may induce a bias towards negative appraisal of touch contexts. Furthermore, hippocampus deactivation during social touch may reflect a dissociative state. These changes depend not only on the type and severity of the trauma but also on the features of the touch. We hypothesise that disrupted touch processing may impair social interactions and confer elevated risk for future stress-related disorders.

Spatial factors influencing the pain-ameliorating effect of CT-optimal touch: a comparative study for modulating temporal summation of second pain

Recent studies show that CT-optimal touch, gentle slow stroking of the skin, can reduce pain. However, much is unknown regarding the factors influencing its pain-ameliorating effect, such as tactile attention and touch application site. The current study investigates in 36 healthy individuals, whether CT-optimal touch can reduce temporal summation of second pain (TSSP) compared to CT non-optimal touch and tapping the skin. TSSP refers to activation of the C-nociceptors; by stimulating these fibers a burning and/or tingling sensation can be elicited. All participants underwent three conditions on both the contralateral and ipsilateral side of pain induction. The results show that tapping the skin did not reduce TSSP, meaning that pain reduction through touch cannot be explained by tactile attention effects. CT non-optimal touch only reduced TSSP when applied on the ipsilateral side. Importantly, CT-optimal touch effectively reduced TSSP when applied on the contralateral or ipsilateral side. Furthermore, CT-optimal touch was more effective in reducing TSSP compared to CT non-optimal touch and Tapping. This study shows that that CT-optimal touch can reduce TSSP and this effect appears to be independent of touch application site, which is highly relevant for implementing CT-optimal touch as a treatment.

Human sweat contains oxytocin

BACKGROUND

Oxytocin (OT) has been detected in various body fluids, including blood, urine, saliva, breastmilk, and spinal fluid. Consistent with models that regard skin as a social organ and in line with studies demonstrating that skin cells express both OT and its receptor, our study sought to examine the presence of OT in human sweat.

METHODS

Overall, 553 individuals participated in a pilot study and three experiments. Firstly, 50 participants provided sweat after engaging in various sports for different durations. Secondly, 26 participants provided sweat from forehead, upper-chest, forearm, and underarm, including 11 in natural setting and 15 following OT administration and a 30-minute exercise. Thirdly, of 435 volunteers, 97 provided sufficient axillary sweat for assaying. Of these, 84 participated in a naturalistic experiment that involved saliva and sweat collection in response to physical activity in either solitary or social settings. OT and testosterone (TS) were assayed in sweat and saliva.

RESULTS

Intense activity for at least 25 min was required to produce sufficient sweat for OT analysis. Highest OT levels were found in axillary sweat compared to sweat from the forehead, upper-chest, and forearm. Salivary OT and TS increased after both solitary and social physical activity; however, higher sweat OT was found after solitary sports. Post-hoc preliminary findings indicate that highly extroverted individuals exercising in solitary environments showed the highest sweat OT levels.

CONCLUSIONS

Findings demonstrate, for the first time, the presence of OT in human sweat and show the feasibility of its measurement. Much further research is required to illuminate how sweat OT is impacted by personality and social context and to uncover the role of the skin in OT production.

Early tactile stimulation influences the development of Alzheimer's disease in gestationally stressed APP NL-G-F adult offspring NL-G-F/NL-G-F mice

Alzheimer's disease (AD) is associated with cerebral plaques and tangles, reduced synapse number, and shrinkage in several brain areas and these morphological effects are associated with the onset of compromised cognitive, motor, and anxiety-like behaviours. The appearance of both anatomical and behavioural symptoms is worsened by stress. The focus of this study was to examine the effect of neonatal tactile stimulation on AD-like behavioural and neurological symptoms on APP NL-G-F/NL-G-F mice, a mouse model of AD, who have been gestationally stressed. Our findings indicate that neonatal tactile stimulation improves cognition, motor skills, and anxiety-like symptoms in both gestationally stressed and non-stressed adult APP mice and that these alterations are associated with reduced Aβ plaque formation. Thus, tactile stimulation appears to be a promising non-invasive preventative strategy for slowing the onset of dementia in aging animals.

Distinct acute stressors exert an antagonistic effect on complex grooming during novelty habituation in rats

Grooming is a common readout in multiple rat models of neuropsychiatric diseases. It is usually associated with distress and negative emotionality, but also with emotional de-arousal after stress. These seemingly conflicting interpretations may result from specific grooming sequences appearing at different arousal levels and during distinct phases of the stress response. To further explore this hypothesis, we analyzed how distinct stressors affect grooming syntaxis and kinetics. To that end, we explored the independent and interacting effects of foot shocks, corticosterone (CORT), and novelty on exploratory activity, grooming, and ultrasonic vocalizations (USVs) in an open-field test (OF). Wistar rats were intraperitoneally injected either with vehicle or CORT, placed in a chamber where half of them were foot-shocked and then assessed in the OF. The next day, animals were re-exposed to the shock chamber and then tested in the OF without receiving any treatment. On day 1, foot shocks and -to a less extent CORT- increased freezing and inhibited rearing in the chamber, but only foot shocks increased distress USVs. In the OF, both treatments suppressed complex grooming, with foot-shocks also inhibiting exploration and CORT marginally reducing rearing. On day 2, foot-shocked rats showed conditioned fear when re-exposed to the chamber. When tested in the OF, foot-shocked and CORT-treated animals still showed low levels of complex grooming, with the former group also showing increased distress USVs. In this study, all different stressors inhibited complex grooming, suggesting an inverse association between these grooming subtypes and negative emotionality.

Neural mechanisms of comforting: Prosocial touch and stress buffering

Comforting is a crucial form of prosocial behavior that is important for maintaining social unity and improving the physical and emotional well-being of social species. It is often expressed through affiliative social touch toward someone in distress, providing relief for their distressed state. In the face of increasing global distress, these actions are paramount to the continued improvement of individual welfare and the collective good. Understanding the neural mechanisms responsible for promoting actions focused on benefitting others is particularly important and timely. Here, we review prosocial comforting behavior, emphasizing synthesizing recent studies carried out using rodent models. We discuss its underlying behavioral expression and motivations, and then explore both the neurobiology of prosocial comforting in a helper animal and the neurobiology of stress relief following social touch in a recipient as part of a feedback loop interaction.

Socio-sexual touch: On the hunt for a pleasure signal in the mouse brain

Skin-to-skin contact is widespread during social interactions and essential for establishing intimate relationships. To understand the skin-to-brain circuits underlying pleasurable touch, a new study has used mouse genetic tools to specifically target and study sensory neurons that transmit social touch and their role during sexual behavior in mice.

Touch neurons underlying dopaminergic pleasurable touch and sexual receptivity

Pleasurable touch is paramount during social behavior, including sexual encounters. However, the identity and precise role of sensory neurons that transduce sexual touch remain unknown. A population of sensory neurons labeled by developmental expression of the G protein-coupled receptor Mrgprb4 detects mechanical stimulation in mice. Here, we study the social relevance of Mrgprb4-lineage neurons and reveal that these neurons are required for sexual receptivity and sufficient to induce dopamine release in the brain. Even in social isolation, optogenetic stimulation of Mrgprb4-lineage neurons through the back skin is sufficient to induce a conditioned place preference and a striking dorsiflexion resembling the lordotic copulatory posture. In the absence of Mrgprb4-lineage neurons, female mice no longer find male mounts rewarding: sexual receptivity is supplanted by aggression and a coincident decline in dopamine release in the nucleus accumbens. Together, these findings establish that Mrgprb4-lineage neurons initiate a skin-to-brain circuit encoding the rewarding quality of social touch.

Social behavior: Closing the gap for close encounters

Social touch can launch a cascade of emotions with enormous impact on the development and maintenance of emotional, cognitive and social functioning. A recent study identifies a novel pathway that facilitates physical contact via its direct impact on brain circuits controlling social behavior.

Hearing, touching, and multisensory integration during mate choice

Mate choice is a potent generator of diversity and a fundamental pillar for sexual selection and evolution. Mate choice is a multistage affair, where complex sensory information and elaborate actions are used to identify, scrutinize, and evaluate potential mating partners. While widely accepted that communication during mate assessment relies on multimodal cues, most studies investigating the mechanisms controlling this fundamental behavior have restricted their focus to the dominant sensory modality used by the species under examination, such as vision in humans and smell in rodents. However, despite their undeniable importance for the initial recognition, attraction, and approach towards a potential mate, other modalities gain relevance as the interaction progresses, amongst which are touch and audition. In this review, we will: (1) focus on recent findings of how touch and audition can contribute to the evaluation and choice of mating partners, and (2) outline our current knowledge regarding the neuronal circuits processing touch and audition (amongst others) in the context of mate choice and ask (3) how these neural circuits are connected to areas that have been studied in the light of multisensory integration.

The effects of coloring therapy on patients with generalized anxiety disorder

Generalized anxiety disorder (GAD) has harmful effects on physical and mental health and quality of life. Coloring therapy has been reported to have a positive effect on improving patient anxiety and depression. But there are no reported clinical trials examining their effectiveness as a treatment for GAD. This study was planned to evaluate the effectiveness of coloring therapy combined with conventional therapy in improving anxiety, depression, and positive and negative emotions with GAD. This randomized controlled study comprising 88 GAD patients was selected for intervention in different wards. The control group (n = 45) was given conventional antianxiety medication and physical therapy, and the experimental group (n = 43) received coloring therapy combined with conventional therapy. The Self-Rating Depression Scale, Self-Rating Anxiety Scale (SAS), Hamilton Depression Scale, Hamilton Anxiety Scale (HAMA), and Positive and Negative Affect Scale were assessed in both groups before and 3 weeks after the intervention. After the intervention, there were statistical differences in intra- and inter-group comparisons of anxiety, depression, and positive and negative mood scales in the experimental and control groups (p < .05). The minus in anxiety/positive emotions pre- and postintervention in the experimental group was statistically significant compared to that in anxiety/positive emotions pre- and postintervention in the control group (HAMA: d = 1.45, 95% confidence interval [CI] (0.34, 2.57), p = .011; SAS: d = 3.87, 95% CI (1.73,6.00), p = .001; positive: d = 1.76, 95% CI (0.17, 3.34), p = .030). The minus in depressive/negative emotions pre- and postintervention in the experimental group was not statistically significant compared with that in depressive/negative emotions pre- and postintervention in the control group (p > .05). For GAD patients, adding coloring therapy based on conventional drug therapy and physical therapy can not only reduce depression and negative emotions but also have better effects on reducing anxiety and improving positive emotions than conventional therapy.