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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 policy Our 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., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article.

Background: Face individual identity recognition skill is heritable and independent of intellectual ability. Difficulties in face individual identity recognition are present in autistic individuals and their family members and are possibly linked to oxytocin polymorphisms in families with an autistic child. While it is reported that developmental prosopagnosia (i.e., impaired face identity recognition) occurs in 2-3% of the general population, no prosopagnosia prevalence estimate is available for autism. Furthermore, an autism within-group approach has not been reported towards characterizing impaired face memory and to investigate its possible links to social and communication difficulties., Methods: The present study estimated the prevalence of prosopagnosia in 80 autistic adults with no intellectual disability, investigated its cognitive characteristics and links to autism symptoms' severity, personality traits, and mental state understanding from the eye region by using standardized tests and questionnaires., Results: More than one third of autistic participants showed prosopagnosia. Their face memory skill was not associated with their symptom's severity, empathy, alexithymia, or general intelligence. Face identity recognition was instead linked to mental state recognition from the eye region only in autistic individuals who had prosopagnosia, and this relationship did not depend on participants' basic face perception skills. Importantly, we found that autistic participants were not aware of their face memory skills., Limitations: We did not test an epidemiological sample, and additional work is necessary to establish whether these results generalize to the entire autism spectrum., Conclusions: Impaired face individual identity recognition meets the criteria to be a potential endophenotype in autism. In the future, testing for face memory could be used to stratify autistic individuals into genetically meaningful subgroups and be translatable to autism animal models.

Facial mimicry, the automatic imitation of another person's emotion, is a mechanism underlying emotion recognition and emotional contagion, a phylogenetically conserved form of empathy that precedes later developing empathic skills. We tested the possibility to increase facial mimicry by blurring self-other distinction via the enfacement illusion. To do so we delivered synchronous, versus asynchronous, visuo-tactile interpersonal multisensory stimulation on the observer and expresser's faces and then recorded surface facial EMG while participants observed videos of happy and sad facial expressions displayed by the expresser. Our results show that synchronous visuo-tactile stimulation can indeed enhance facial mimicry and that this depends on participants' baseline tendency to mimic.. Our findings could set the basis for developing novel interventions for conditions characterized by reduced empathic and emotion recognition skills, including autism and schizophrenia., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Understanding how self-representation is built, maintained and updated across the lifespan is a fundamental challenge for cognitive psychology and neuroscience. Studies demonstrate that the detection of body-related multisensory congruency builds bodily and facial self-representations that are crucial to developing self-recognition. Studies showing that the bodily self is more malleable than previously believed were mainly concerned with full-bodies and non-facial body parts. Crucially, however, intriguing recent evidence indicates that simple experimental manipulations could even affect self-face representation that has long been considered a stable construct impervious to change. In this review, we discuss how Interpersonal Multisensory Stimulation (IMS) paradigms can be used to temporarily induce Enfacement, i.e., the subjective illusion of looking at oneself in the mirror when in fact looking at another person's face. We show that Enfacement is a subtle but robust phenomenon occurring in a variety of experimental conditions and assessed by multiple explicit and implicit measures. We critically discuss recent findings on i) the role of sensory extero/proprio-ceptive (visual, tactile, and motor) and interoceptive (cardiac) signals in self-face plasticity, ii) the importance of multisensory integration mechanisms for the bodily self, and iii) the neural network related to IMS-driven changes in self-other face processing, within the predictive coding theoretical framework., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background: Despite the fact that deficits in social communication and interaction are at the core of Autism Spectrum Conditions (ASC), no study has yet tested individuals on a continuum from neurotypical development to autism in an on-line, cooperative, joint action task. In our study, we aimed to assess whether the degree of autistic traits affects participants' ability to modulate their motor behavior while interacting in a Joint Grasping task and according to their given role., Methods: Sixteen pairs of adult participants played a cooperative social interactive game in which they had to synchronize their reach-to-grasp movements. Pairs were comprised of one ASC and one neurotypical with no cognitive disability. In alternate experimental blocks, one participant knew what action to perform (instructed role) while the other had to infer it from his/her partner's action (adaptive role). When in the adaptive condition, participants were told to respond with an action that was either opposite or similar to their partner. Participants also played a non-social control game in which they had to synchronize with a non-biological stimulus., Results: In the social interactive task, higher degree of autistic traits predicted less ability to modulate joint action according to one's interactive role. In the non-social task, autistic traits did not predict differences in movement preparation and planning, thus ruling out the possibility that social interactive task results were due to basic motor or executive function difficulties. Furthermore, when participants played the non-social game, the higher their autistic traits, the more they were interfered by the non-biological stimulus., Conclusions: Our study shows for the first time that high autistic traits predict a stereotypical interaction style when individuals are required to modulate their movements in order to coordinate with their partner according to their role in a joint action task. Specifically, the infrequent emergence of role-based motor behavior modulation during on-line motor cooperation in participants with high autistic traits sheds light on the numerous difficulties ASC have in nonverbal social interactions.

Gaze-following is a pivotal social behaviour that, although largely automatic, is permeable to high-order variables like political affiliation. A few years ago we reported that the gaze of Italian right-wing voters was selectively captured by the gaze of their leader Silvio Berlusconi. This effect was particularly evident in voters who saw themselves as similar to Berlusconi. Two years later, we were able to run the present follow-up study because Berlusconi's popularity had drastically dropped due to sex and political scandals, and he resigned from office. In a representative subsample of our original group, we investigated whether perceived similarity and gaze-following reflected Berlusconi's loss in popularity. We were also able to test the same hypothesis in an independent group of right-wing voters when their leader, Renata Polverini, resigned as Governor of 'Regione Lazio' due to political scandals. Our results show that the leaders' fall in popularity paralleled the reduction of their gaze's attracting power, as well as the decrease in similarity perceived by their voters. The less similar right-wing voters felt to their leader, the less they followed his/her gaze. Thus, the present experimental findings suggest that gaze-following can be modulated by complex situational and dispositional factors such as leader's popularity and voter-leader perceived similarity.

The illusory subjective experience of looking at one's own face while in fact looking at another person's face can surprisingly be induced by simple synchronized visuotactile stimulation of the two faces. A recent study (Apps MA, Tajadura-Jiménez A, Sereno M, Blanke O, Tsakiris M. Cereb Cortex. First published August 20, 2013; doi:10.1093/cercor/bht199) investigated for the first time the role of visual unimodal and temporoparietal multimodal brain areas in the enfacement illusion and suggested a model in which multisensory mechanisms are crucial to construct and update self-face representation., (Copyright © 2015 the American Physiological Society.)

Vestibular processing is fundamental to our sense of orientation in space which is a core aspect of the representation of the self. Vestibular information is processed in a large subcortical-cortical neural network. Tasks requiring mental rotations of human bodies in space are known to activate neural regions within this network suggesting that vestibular processing is involved in the control of mental rotation. We studied whether mental rotation is impaired in patients suffering from two different forms of unilateral vestibular disorders (vestibular neuritis - VN - and Benign Paroxysmal positional Vertigo - BPPV) with respect to healthy matched controls (C). We used two mental rotation tasks in which participants were required to: (i) mentally rotate their own body in space (egocentric rotation) thus using vestibular processing to a large extent and (ii) mentally rotate human figures (allocentric rotation) thus using own body representations to a smaller degree. Reaction times and accuracy of responses showed that VN and BPPV patients were impaired in both tasks with respect to C. Significantly, the pattern of results was similar in the three groups suggesting that patients were actually performing the mental rotation without using a different strategy from the control individuals. These results show that dysfunctional vestibular inflow impairs mental rotation of both own body and human figures suggesting that unilateral acute disorders of the peripheral vestibular input massively affect the cerebral processes underlying mental rotations.

Perceiving pain in others may induce the covert simulation of both sensory and emotional components of others' pain experience. Previous transcranial magnetic stimulation (TMS) studies have investigated the motor counterpart of this resonant mapping by showing suppression of motor-evoked potentials (MEPs) during the observation of a needle entering body parts of another person. Here we explored whether MEPs recorded from an onlooker's hand (e.g., the right hand, TMS to the left motor cortex) are differentially influenced by the observation of painfully stimuli delivered to the same (right) or the opposite (left) hand in a model. Congruency between observed (model) and recorded (onlooker) hand brought about a reduction of MEPs amplitude. This resonant inhibitory response in the onlooker was specific for the muscle penetrated in the model. In contrast, observing pain on the model's hand opposite to that from which MEPs were recorded brought about a generalized increase of hand corticospinal excitability. Corticospinal inhibition and facilitation effects were comparable in the two hemispheres and specific for the corresponding and opposite hand. Results suggest that observing pain in another person's hand automatically induces the covert simulation of potentially adaptive freezing and avoidance responses in the onlooker's corticospinal system.

Background: Asperger syndrome (AS) is a neurodevelopmental condition within the autism spectrum conditions (ASC) characterized by specific difficulties in communication, social interaction, and empathy that is essential for sharing and understanding others' feelings and emotions. Although reduced empathy is considered a core feature of ASC, neurophysiological evidence of empathic deficits before and below mentalizing and perspective taking is lacking. We explored whether people with AS differ from neurotypical control participants in their empathic corticospinal response to the observation of others' pain and the modulatory role played by phenomenal experience of observed pain and personality traits., Methods: Sixteen right-handed men with AS (aged 28.0+/-7.2 years) and 20 neurotypical controls (aged 25.3+/-6.7 years) age, sex, and IQ matched, underwent single-pulse transcranial magnetic stimulation during observation of painful and nonpainful stimuli affecting another individual., Results: When observing other's pain, participants with AS, in contrast to neurotypical control participants, did not show any amplitude reduction of motor-evoked potentials recorded from the muscle vicariously affected by pain, nor did their neurophysiological response correlate with imagined pain sensory qualities. Participants with AS represented others' pain in relation to the self-oriented arousal experienced while watching pain videos., Conclusions: Finding no embodiment of others' pain provides neurophysiological evidence for reduced empathic resonance in people with AS and indicates that their empathic difficulties involve not only cognitive dimensions but also sensorimotor resonance with others. We suggest that absence of embodied empathy may be linked to changes at very basic levels of neural processing.

The study of inter-individual differences at behavioural and neural levels represents a new avenue for neuroscience. The response to socio-emotional stimuli varies greatly across individuals. For example, identification with the feelings of a movie character may be total for some people or virtually absent for others. Inter-individual differences may reflect both the on-line effect (state) of the observed stimuli and more stable personal characteristics (trait). Here we show that somatomotor mirror responses when viewing others' pain are modulated by both state- and trait-differences in empathy. We recorded motor-evoked potentials (MEPs) induced by Transcranial Magnetic Stimulation (TMS) in healthy individuals observing needles penetrating a model's hand. We found a reduction of corticospinal excitability that was specific for the muscle that subjects observed being penetrated. This inhibition correlated with sensory qualities of the pain ascribed to the model. Moreover, it was greater in subjects with high trait-cognitive empathy and lower in subjects with high trait-personal distress and in those with high aversion for the observed movies. Results indicate that somatomotor responses to others' pain are influenced by specific onlookers' personality traits and self-oriented emotional reactions. Our findings suggest that multiple distinct mechanisms shape mirror mapping of others' pain.

Empathy may allow interindividual sharing not only of emotions (e.g., joy, sadness, disgust) but also of sensations (e.g., touch, itching, pain). Although empathy for pain may rely upon both sensory and affective components of the pain experience, neuroimaging studies indicate that only the affective component of the pain matrix is involved in empathy for pain. By using transcranial magnetic stimulation (TMS), we highlighted the sensorimotor side of empathy for pain by showing a clear motor inhibition during the mere observation of needles penetrating body parts of a human model. Here, we explored stimulus-specific and instruction-specific influences on this inhibition by manipulating task instructions (request to adopt first- or third-person perspective vs. passive observation) and painfulness of the experimental stimuli (presentation of videos of needles deeply penetrating or simply pinpricking a hand). We found a significant reduction in amplitudes of motor-evoked potentials (MEPs) specific to the muscle the subjects observed being penetrated that correlated with the intensity of the pain attributed to the model. Crucially, this motor inhibition was present during observation of penetrating but not of pinpricking needles. Moreover, no MEPs modulation contingent upon different task instructions was found. Results suggest that the motor inhibition elicited by the observation of "flesh and bone" pain stimuli is more stimulus-driven than instruction-driven.

Seeing or imagining others in pain may activate both the sensory and affective components of the neural network (pain matrix) that is activated during the personal experience of pain. Transcranial magnetic stimulation (TMS), proved adept at highlighting the sensorimotor side of empathy for pain in studies where mere observation of needles penetrating body parts of a human model brought about a clear corticospinal motor inhibition. By using TMS, we investigated whether inferring the sensory properties of the pain of a model influenced the somatomotor system of an onlooker. Moreover, we tested the possible lateralization of the motor substrates underlying this reading process. We recorded motor-evoked potentials (MEPs) to left and right motor cortex stimulation during the observation of "flesh and bone" painful stimulations of right and left hands respectively. We found a significant reduction of onlookers' MEPs amplitudes specific to the muscle penetrated in the model. Subjective inferences about localization and intensity of the observed pain were associated with specific patterns of motor modulation with larger inhibitory effects following stimulation of the left motor cortex. Thus, results indicate that the mental simulation of the sensory qualities of others' pain may be lateralized to the left hemisphere.