The neural correlates of visual self-recognition

Visual self-face and self-body recognition in a left-brain-damaged prosopagnosic patient

The present case study describes the patient N.G., who reported prosopagnosia along with difficulty in recognising herself in the mirror following a left-sided temporo-occipital hemispheric stroke. The neuropsychological and experimental investigation revealed only a mild form of apperceptive prosopagnosia, without visual agnosia, primarily caused by an impaired visual processing of face-parts and body parts but not of full faces. Emotional expressions did not modulate her face processing. On the other hand, N.G. showed a marked impairment of visual self-recognition, as assessed with visual matching-to-sample tasks, both at the level of body-part and face-part processing and at a full-face level, featured by a deficit in the perceptual discrimination of her own face and body, as compared to the others' face and body. N.G.'s lesion mapping showed damage to the left inferior occipito-temporal cortex, affecting the inferior occipital gyrus and compromising long-range connections between the occipital/temporo-occipital areas and the anterior fronto-temporal areas. Overall, the present case report documents that visual processing of the person's own face may be selectively compromised by a left-sided hemispheric lesion disconnecting extra-striate body- and face-selective visual areas to self-representation regions. Moreover, others' (full) face processing may be preserved, as compared with the impaired ability to discriminate others' body and face parts.

Brain Charts for the Rhesus Macaque Lifespan

Recent efforts to chart human brain growth across the lifespan using large-scale MRI data have provided reference standards for human brain development. However, similar models for nonhuman primate (NHP) growth are lacking. The rhesus macaque, a widely used NHP in translational neuroscience due to its similarities in brain anatomy, phylogenetics, cognitive, and social behaviors to humans, serves as an ideal NHP model. This study aimed to create normative growth charts for brain structure across the macaque lifespan, enhancing our understanding of neurodevelopment and aging, and facilitating cross-species translational research. Leveraging data from the PRIMatE Data Exchange (PRIME-DE) and other sources, we aggregated 1,522 MRI scans from 1,024 rhesus macaques. We mapped non-linear developmental trajectories for global and regional brain structural changes in volume, cortical thickness, and surface area over the lifespan. Our findings provided normative charts with centile scores for macaque brain structures and revealed key developmental milestones from prenatal stages to aging, highlighting both species-specific and comparable brain maturation patterns between macaques and humans. The charts offer a valuable resource for future NHP studies, particularly those with small sample sizes. Furthermore, the interactive open resource (https://interspeciesmap.childmind.org) supports cross-species comparisons to advance translational neuroscience research.

Causal Relationship between Aging and Anorexia Nervosa: A White-Matter-Microstructure-Mediated Mendelian Randomization Analysis

This study employed a two-step Mendelian randomization analysis to explore the causal relationship between telomere length, as a marker of aging, and anorexia nervosa and to evaluate the mediating role of changes in the white matter microstructure across different brain regions. We selected genetic variants associated with 675 diffusion magnetic resonance imaging phenotypes representing changes in brain white matter. F-statistics confirmed the validity of the instruments, ensuring robust causal inference. Sensitivity analyses, including heterogeneity tests, horizontal pleiotropy tests, and leave-one-out tests, validated the results. The results show that telomere length is significantly negatively correlated with anorexia nervosa in a unidirectional manner (p = 0.017). Additionally, changes in specific white matter structures, such as the internal capsule, corona radiata, posterior thalamic radiation, left cingulate gyrus, left longitudinal fasciculus, and left forceps minor (p < 0.05), were identified as mediators. These findings enhance our understanding of the neural mechanisms, underlying the exacerbation of anorexia nervosa with aging; emphasize the role of brain functional networks in disease progression; and provide potential biological targets for future therapeutic interventions.

This is me! Neural correlates of self-recognition in 6- to 8-month-old infants

Historically, evidence of self-recognition in development has been associated with the "rouge test"; however, this has been often criticized for providing a reductionist picture of self-conscious behavior. With two event-related potential (ERP) experiments, this study investigated the origin of self-recognition. Six- to eight-month-old infants (42 males and 35 females, predominately White, tested in the UK in 2022-2023) were presented with images of their face, another peer's face, and their mother's face (N = 38, Exp.1), and images of their own face morphed into another peer's face (N = 39, Exp.2). Results showed an enhanced P100 in infants' ERP response to their own face compared to others' faces (Exp.1 only), suggesting the presence of an enhanced attentional mechanism to one own's face as early as 6 months.

Fluid face but not gender: Enfacement illusion through digital face filters does not affect gender identity

It has been shown that observing a face being touched or moving in synchrony with our own face increases self-identification with the former which might alter both cognitive and affective processes. The induction of this phenomenon, termed enfacement illusion, has often relied on laboratory tools that are unavailable to a large audience. However, digital face filters applications are nowadays regularly used and might provide an interesting tool to study similar mechanisms in a wider population. Digital filters are able to render our faces in real time while changing important facial features, for example, rendering them more masculine or feminine according to normative standards. Recent literature using full-body illusions has shown that participants' own gender identity shifts when embodying a different gendered avatar. Here we studied whether participants' filtered faces, observed while moving in synchrony with their own face, may induce an enfacement illusion and if so, modulate their gender identity. We collected data from 35 female and 33 male participants who observed a stereotypically gender mismatched version of themselves either moving synchronously or asynchronously with their own face on a screen. Our findings showed a successful induction of the enfacement illusion in the synchronous condition according to a questionnaire addressing the feelings of ownership, agency and perceived similarity. However, we found no evidence of gender identity being modulated, neither in explicit nor in implicit measures of gender identification. We discuss the distinction between full-body and facial processing and the relevance of studying widely accessible devices that may impact the sense of a bodily self and our cognition, emotion and behaviour.

Me, Myself, and I: Neural Activity for Self versus Other across Development

Although adults and children differ in self-vs.-other perception, a developmental perspective on this discriminative ability at the brain level is missing. This study examined neural activation for self-vs.-other in a sample of 39 participants spanning four different age groups, from 4-year-olds to adults. Self-related stimuli elicited higher neural activity within two brain regions related to self-referential thinking, empathy, and social cognition processes. Second, stimuli related to 'others' (i.e., unknown peer) elicited activation within nine additional brain regions. These regions are associated with multisensory processing, somatosensory skills, language, complex visual stimuli, self-awareness, empathy, theory of mind, and social recognition. Overall, activation maps were gradually increasing with age. However, patterns of activity were non-linear within the medial cingulate cortex for 'self' stimuli and within the left middle temporal gyrus for 'other' stimuli in 7-10-year-old participants. In both cases, there were no self-vs.-other differences. It suggests a critical period where the perception of self and others are similarly processed. Furthermore, 11-19-year-old participants showed no differences between others and self within the left inferior orbital gyrus, suggesting less distinction between self and others in social learning. Understanding the neural bases of self-vs.-other discrimination during development can offer valuable insights into how social contexts can influence learning processes during development, such as when to introduce peer-to-peer teaching or group learning.

The relevance of familiarity in the context of self-related information processing

Humans are inclined to preferentially process self-related content, referred to as the "self-bias." Different paradigms have been used to study this effect. However, not all paradigms included a familiar other condition (but rather an unfamiliar other condition), needed to differentiate self-specific effects from the impact of familiarity. The primary goal of our study was to test the suitability for studying the self-bias of two paradigms that provide robust measures of salience effects-that is, the Repetition Blindness (RB) effect and the Emotional Stroop (ES) interference-while addressing the familiarity confound. We further explored whether self-bias effects were related to autism symptomatology, as a reduced self-bias in autism has been reported in previous research. In an online procedure, 82 adults performed an RB task and an ES task in a counterbalanced order, while being presented with both self- and familiar other-related stimuli. Results of both frequentist and Bayesian analyses did not provide evidence in favour of a specific self-bias on either task: we found no significant modulation of the RB effect, nor of the ES interference, for the own versus a close other's name. Moreover, no link with autism symptomatology was found. Tackling a crucial shortcoming from earlier studies, our investigation raises awareness on the importance of accounting for familiarity when investigating self-related processing.

Neurofeedback and Affect Regulation Circuitry in Depressed and Healthy Adolescents

Neurodevelopmental psychopathology seeks to understand higher-order emotion regulation circuitry to develop new therapies for adolescents with depression. Depressed (N = 34) and healthy youth (N = 19) completed neurofeedback (NF) training and exhibited increased bilateral amygdala and hippocampus activity in the region of interest (ROI) analyses by recalling positive autobiographical memories. We tested factors supportive of the engagement of emotion regulation's neural areas during NF (i.e., parental support, medication, and gender effects upon anterior cingulate cortex (ACC) engagement). Whole-brain analyses yielded effects of NF vs. control condition and effects of diagnosis. Youth showed higher amygdala and hippocampus (AMYHIPPO) activity during the NF vs. control condition, particularly in the left hippocampus. ACC's activity was also higher during NF vs. control. Higher average ACC activity was linked to better parental support, absent depression, female gender, and absent medication. Control youth showed higher average AMYHIPPO and ACC activity throughout the task and a faster decline in activity vs. depressed youths. Whole-brain level analyses showed higher activity in the frontotemporal network during the NF vs. control conditions, suggesting targeting their connectivity in future neurofeedback trials.

Hypoactive Visual Cortex, Prefrontal Cortex and Insula during Self-Face Recognition in Adults with First-Episode Major Depressive Disorder

Self-face recognition is a vital aspect of self-referential processing, which is closely related to affective states. However, neuroimaging research on self-face recognition in adults with major depressive disorder is lacking. This study aims to investigate the alteration of brain activation during self-face recognition in adults with first-episode major depressive disorder (FEMDD) via functional magnetic resonance imaging (fMRI); FEMDD (n = 59) and healthy controls (HC, n = 36) who performed a self-face-recognition task during the fMRI scan. The differences in brain activation signal values between the two groups were analyzed, and Pearson correlation analysis was used to evaluate the relationship between the brain activation of significant group differences and the severity of depressive symptoms and negative self-evaluation; FEMDD showed significantly decreased brain activation in the bilateral occipital cortex, bilateral fusiform gyrus, right inferior frontal gyrus, and right insula during the task compared with HC. No significant correlation was detected between brain activation with significant group differences and the severity of depression and negative self-evaluation in FEMDD or HC. The results suggest the involvement of the malfunctioning visual cortex, prefrontal cortex, and insula in the pathophysiology of self-face recognition in FEMDD, which may provide a novel therapeutic target for adults with FEMDD.

Re-cognizing the new self: The neurocognitive plasticity of self-processing following facial transplantation

The face is a defining feature of our individuality, crucial for our social interactions. But what happens when the face connected to the self is radically altered or replaced? We address the plasticity of self-face recognition in the context of facial transplantation. While the acquisition of a new face following facial transplantation is a medical fact, the experience of a new identity is an unexplored psychological outcome. We traced the changes in self-face recognition before and after facial transplantation to understand if and how the transplanted face gradually comes to be perceived and recognized as the recipient's own new face. Neurobehavioral evidence documents a strong representation of the pre-injury appearance pre-operatively, while following the transplantation, the recipient incorporates the new face into his self-identity. The acquisition of this new facial identity is supported by neural activity in medial frontal regions that are considered to integrate psychological and perceptual aspects of the self.

Look at me now! Enfacement illusion over computer-generated faces

According to embodied cognition research, one’s bodily self-perception can be illusory and temporarily shifted toward an external body. Similarly, the so-called “enfacement illusion” induced with a synchronous multisensory stimulation over the self-face and an external face can result in implicit and explicit changes in the bodily self. The present study aimed to verify (i) the possibility of eliciting an enfacement illusion over computer-generated faces and (ii) which multisensory stimulation condition was more effective. A total of 23 participants were asked to look at a gender-matched avatar in three synchronous experimental conditions and three asynchronous control conditions (one for each stimulation: visuotactile, visuomotor, and simple exposure). After each condition, participants were asked to complete a questionnaire assessing both the embodiment and the enfacement sensations to address different facets of the illusion. Results suggest a stronger effect of synchronous vs. asynchronous stimulation, and the difference was more pronounced for the embodiment items of the questionnaire. We also found a greater effect of visuotactile and visuomotor stimulations as compared to the simple exposure condition. These findings support the enfacement illusion as a new paradigm to investigate the ownership of different face identities and the specific role of visuotactile and visuomotor stimulations with virtual reality stimuli.

The Virtual "Enfacement Illusion" on Pain Perception in Patients Suffering from Chronic Migraine: A Study Protocol for a Randomized Controlled Trial

BACKGROUND

given the limited efficacy, tolerability, and accessibility of pharmacological treatments for chronic migraine (CM), new complementary strategies have gained increasing attention. Body ownership illusions have been proposed as a non-pharmacological strategy for pain relief. Here, we illustrate the protocol for evaluating the efficacy in decreasing pain perception of the enfacement illusion of a happy face observed through an immersive virtual reality (VR) system in CM.

METHOD

the study is a double-blind randomized controlled trial with two arms, involving 100 female CM patients assigned to the experimental group or the control group. The experimental group will be exposed to the enfacement illusion, whereas the control group will be exposed to a pleasant immersive virtual environment. Both arms of the trial will consist in three VR sessions (20 min each). At the baseline and at the end of the intervention, the patients will fill in questionnaires based on behavioral measures related to their emotional and psychological state and their body satisfaction. Before and after each VR session, the level of pain, the body image perception, and the affective state will be assessed.

DISCUSSION

this study will provide knowledge regarding the relationship between internal body representation and pain perception, supporting the effectiveness of the enfacement illusion as a cognitive behavioral intervention in CM.

Self-reference processing of fat-face and sick-face in individuals with different disgust sensitivity: Evidence from behavioral and neuroelectrophysiology

Self-reference effect has been widely discussed. Previous scholars believed that self-related information can be processed faster is due to the positive attribute of self-concept which speeds up self-related information processing. When self-related information is given negative attributes, the self-reference effect will be weakened. In this study, fat and sick, two kinds of stimuli associated with disgust characteristics, were added to self- and other-faces. We found that disease stimuli, which are closely related to survival threats, eliminated the self-reference effect while the obesity stimuli only weakened the self-reference effect to a certain extent. Event-related potential (ERP) analysis demonstrated that sick-faces have a greater amplitude than standard-faces in the EPN and LPP components. We believe that this may be due to the urgency of the disease threat, which leads to the selective attention to the disease threat in the early perception stage and the allocation of more attention resources for rapid response in the later stage. In addition, we found that disgust sensitivity specifically maintains individuals' self-referential effects by dissociating individuals from others in disease contexts. These results further support the behavioral immune function of disgust as a gatekeeper of the self in potentially contaminated environments. In conclusion, our study showed that in the face of survival threat, the self-reference effect is eliminated, and disgust tried to slow down this elimination effect to protect self. This study extends the behavioral immunity theory to some extent and further deepens the understanding of the relationship between disgust and self.

The salience network is activated during self-recognition from both first-person and third-person perspectives

We usually observe ourselves from two perspectives. One is the first-person perspective, which we perceive directly with our own eyes, and the other is the third-person perspective, which we observe ourselves in a mirror or a picture. However, whether the self-recognition associated with these two perspectives has a common or separate neural basis remains unclear. To address this, we used functional magnetic resonance imaging to examine brain activity while participants viewed pretaped video clips of themselves and others engaged in meal preparation taken from first-person and third-person perspectives. We found that the first-person behavioral videos of the participants and others induced greater activation in the premotor-intraparietal region. In contrast, the third-person behavioral videos induced greater activation in the default mode network compared with the first-person videos. Regardless of the perspective, the videos of the participants induced greater activation in the salience network than the videos of others. On the other hand, the videos of others induced greater activation in the precuneus and lingual gyrus than the videos of the participants. These results suggest that the salience network is commonly involved in self-recognition from both perspectives, even though the brain regions involved in action observation for the two perspectives are distinct.

The own-voice benefit for word recognition in early bilinguals

The current study examines the self-voice benefit in an early bilingual population. Female Cantonese-English bilinguals produced words containing Cantonese contrasts. A subset of these minimal pairs was selected as stimuli for a perception task. Speakers' productions were grouped according to how acoustically contrastive their pronunciation of each minimal pair was and these groupings were used to design personalized experiments for each participant, featuring their own voice and the voices of others' similarly-contrastive tokens. The perception task was a two-alternative forced-choice word identification paradigm in which participants heard isolated Cantonese words, which had undergone synthesis to mask the original talker identity. Listeners were more accurate in recognizing minimal pairs produced in their own (disguised) voice than recognizing the realizations of speakers who maintain similar degrees of phonetic contrast for the same minimal pairs. Generally, individuals with larger phonetic contrasts were also more accurate in word identification for self and other voices overall. These results provide evidence for an own-voice benefit for early bilinguals. These results suggest that the phonetic distributions that undergird phonological contrasts are heavily shaped by one's own phonetic realizations.

Investigation of Brain Activation Patterns Related to the Feminization or Masculinization of Body and Face Images across Genders

Previous studies demonstrated sex-related differences in several areas of the human brain, including patterns of brain activation in males and females when observing their own bodies and faces (versus other bodies/faces or morphed versions of themselves), but a complex paradigm touching multiple aspects of embodied self-identity is still lacking. We enrolled 24 healthy individuals (12 M, 12 F) in 3 different fMRI experiments: the vision of prototypical body silhouettes, the vision of static images of the face of the participants morphed with prototypical male and female faces, the vision of short videos showing the dynamic transformation of the morphing. We found differential sexual activations in areas linked to self-identity and to the ability to attribute mental states: In Experiment 1, the male group activated more the bilateral thalamus when looking at sex congruent body images, while the female group activated more the middle and inferior temporal gyrus. In Experiment 2, the male group activated more the supplementary motor area when looking at their faces; the female group activated more the dorsomedial prefrontal cortex (dmPFC). In Experiment 3, the female group activated more the dmPFC when observing either the feminization or the masculinization of their face. The defeminization produced more activations in females in the left superior parietal lobule and middle occipital gyrus. The performance of all classifiers built using single ROIs exceeded chance level, reaching an area under the ROC curves > 0.85 in some cases (notably, for Experiment 2 using the V1 ROI). The results of the fMRI tasks showed good agreement with previously published studies, even if our sample size was small. Therefore, our functional MRI protocol showed significantly different patterns of activation in males and females, but further research is needed both to investigate the gender-related differences in activation when observing a morphing of their face/body, and to validate our paradigm using a larger sample.

A featural account for own-face processing? Looking for support from face inversion, composite face, and part-whole tasks

It is widely accepted that face perception relies on holistic processing. However, this holistic advantage is not always found in the processing of the own face. Our study aimed to explore the role of holistic and featural processing in the identification of the own face, using three standard, but largely independent measures of holistic face processing: the face inversion task, the composite face task, and the part-whole task. Participants were asked to identify their face, a friend’s face, and an unfamiliar face in three different experimental blocks: (a) inverted versus upright; (b) top and bottom halves of the face aligned versus misaligned; and (c) facial features presented in isolation versus whole foil face context. Inverting a face impaired its identification, regardless of the identity. However, alignment effects were only found when identifying a friend or an unfamiliar face. In addition, a stronger feature advantage (i.e., better recognition for isolated features compared to in a whole-face context) was observed for the own face compared to the friend and unfamiliar faces. Altogether, these findings suggest that the own face is processed in a more featural manner but also relies on holistic processing. This work also highlights the importance of taking into consideration that different holistic processing paradigms could tap different forms of holistic processing.

Towards an animal model of consciousness based on the platform theory

The evolution of intellectual capacities has brought forth a continuum of consciousness levels subserved by neuronal networks of varying complexity. Brain pathologies, neurodegenerative, and mental diseases affect conscious cognition and behavior. Although impairments in consciousness are among the most devastating consequences of neurological and mental diseases, valid and reliable animal models of consciousness, that could be used for preclinical research are missing. The platform theory holds that the brain enters a conscious operation mode, whenever mental representations of stimuli, associations, concepts, memories, and experiences are effortfully maintained (in working memory) and actively manipulated. We used the platform theory as a framework and evaluation standard to categorize behavioral paradigms with respect to the level of consciousness involved in task performance. According to the platform theory, a behavioral paradigm involves conscious cognitive operations, when the problem posed is unexpected, novel or requires the maintenance and manipulation of a large amount of information to perform cognitive operations on them. Conscious cognitive operations are associated with a relocation of processing resources and the redirection of attentional focus. A consciousness behavioral test battery is proposed that is composed of tests which are assumed to require higher levels of consciousness as compared to other tasks and paradigms. The consciousness test battery for rodents includes the following tests: Working memory in the radial arm maze, episodic-like memory, prospective memory, detour test, and operant conditioning with concurrent variable-interval variable-ratio schedules. Performance in this test battery can be contrasted with the performance in paradigms and tests that require lower levels of consciousness. Additionally, a second more comprehensive behavioral test battery is proposed to control for behavioral phenotypes not related to consciousness. Our theory could serve as a guidance for the decryption of the neurobiological basis of consciousness.

Impaired attentional bias toward one's own face in autism spectrum disorder: ERP evidence

Converging lines of evidence seem to indicate reduced self-referential processing in individuals with autism spectrum disorder (ASD). However, processing of one's own face has rarely been investigated in the context of ASD. Thus, the aim of the present study was to elucidate the role of attentional biases in the processing of self- and other faces in ASD. To achieve this goal we presented participants with images of their own face, the face of a close-other, and famous and unknown faces in a Stroop-like paradigm. Participants (22 with ASD, 22 typically developing [TD]) were instructed to indicate the color of presented faces while EEG was recorded. Our event-related potential results clearly showed that self-face was associated with larger P3 amplitudes than all other faces in the TD group, thus indicating a strong attentional bias toward one's own face. In the ASD group, P3 to the self-face and the close-other's face did not differ, suggesting similar attentional biases in both cases. In line with these P3 findings, nonparametric cluster-based permutation tests showed an analogous pattern of results: significant clusters for the self-face compared with all other faces in the TD group, and no significant cluster in the ASD group. Overall, our findings revealed impaired attentional bias to one's own face and diminished self versus other differentiation in individuals with ASD. The similar neural underpinnings of the self-face and other faces supports previous findings indicating reduced self-prioritization among individuals with ASD.

The upside-down self: One's own face recognition is affected by inversion

One's own face is recognized more efficiently than any other face, although the neural mechanisms underlying this phenomenon remain poorly understood. Considering the extensive visual experience that we have with our own face, some authors have proposed that self-face recognition involves a more analytical perceptual strategy (i.e., based on face features) than other familiar faces, which are commonly processed holistically (i.e., as a whole). However, this hypothesis has not yet been tested with brain activity data. In the present study, we employed an inversion paradigm combined with event-related potential (ERP) recordings to investigate whether the self-face is processed more analytically. Sixteen healthy participants were asked to identify their own face and a familiar face regardless of its orientation, which could either be upright or inverted. ERP analysis revealed an enhanced amplitude and a delayed latency for the N170 component when faces were presented in an inverted orientation. Critically, both the self and a familiar face were equally vulnerable to the inversion effect, suggesting that the self-face is not processed more analytically than a familiar face. In addition, we replicated the recent finding that the attention-related P200 component is a specific neural index of self-face recognition. Overall, our results suggest that the advantage for self-face processing might be better explained by the engagement of self-related attentional mechanisms than by the use of a more analytical visuoperceptual strategy.

Development and validation of the mirror image comfort and avoidance scale (MICAS)

PURPOSE

The purpose of this study was to develop an instrument to measure the experience of viewing one's reflection in the mirror for use in rehabilitation, nursing, psychology, and in research studies designed to improve the mirror-viewing experience for those who have suffered psychological or bodily trauma. A secondary purpose was to explore demographic differences in each subscale of the instrument.

METHODS

The developed items went through content expert validation, exploratory and confirmatory factor analyses, and internal consistency reliability testing.

RESULTS

Using an exploratory factor analysis (n = 137) and a confirmatory factor analysis (n = 142), we validated a 17-item instrument for two distinct populations: veterans (n = 108) and individuals with upper and lower limb loss (n = 210). The mirror viewing comfort subscale (9 items; α = 0.90) and the mirror avoidance subscale (8 items, α = 0.94) were deemed reliable. Strong, significant correlations between pre-and post-comfort scores (r = 0.81, p < 0.001), as well as pre-and post-avoidance scores (r = 0.94, p < 0.001) provide evidence of test-retest reliability. Demographic differences were noted in the subscales.

CONCLUSIONS

This instrument contributes to a greater understanding of the experience of mirror-viewing in clinical practice. In interventional research studies to improve the mirror-viewing experience, this instrument can act as a manipulation check or outcome measure.Implications for rehabilitationIndividuals who suffer actual or perceived body disfigurement due to surgery or trauma may suffer mirror discomfort or mirror trauma when viewing their bodies in a mirror. This reaction is due to a pre-frontal cortex neurological disruption and autonomic nervous system fright/flight or faint. Psychological disorders (e.g., devastation, shame, self-revulsion, decreased body image) may ensue.Falls have occurred due to mirror trauma due to an autonomic nervous system disturbance (faint) and may result in ongoing mirror avoidance. When mirrors are needed for incision visualization, mirror avoidance has led to severe surgical site infections.Although there were many scales available in the literature to measure several aspects of the effects of actual or perceived body disfigurement, there were no scales that measured the mirror-viewing experience.Clinicians and researchers can use the Mirror Comfort and Avoidance Scale (MICAS) to assess mirror comfort and avoidance.

Neural Circuits, Microtubule Processing, Brain's Electromagnetic Field-Components of Self-Awareness

The known theories discussing the essence of consciousness have been recently updated. This prompts an attempt to integrate these explanations concerning several distinct components of the consciousness phenomenon such as the ego, and qualia perceptions. Therefore, it is useful to consider the latest publications on the 'Orch OR' and 'cemi' theories, which assume that quantum processing occurs in microtubules and that the brain's endogenous electromagnetic field is important. The authors combine these explanations with their own theory describing the neural circuits realizing imagery. They try to present such an interdisciplinary, integrated theoretical model in a manner intuitively understandable to people with a typical medical education. In order to do this, they even refer to intuitively understandable metaphors. The authors maintain that an effective comprehension of consciousness is important for health care professionals because its disorders are frequent medical symptoms in emergencies, during general anesthesia and in the course of cognitive disorders in elderly people. The authors emphasize the current possibilities to verify these theses regarding the essence of consciousness thanks to the development of functional brain imaging methods-magnetoencephalography, transcranial magnetic stimulation-as well as clinical studies on the modification of perceptions and feelings by such techniques as mindfulness and the use of certain psychoactive substances, especially among people with self-awareness and identity disorders.

Self-face and emotional faces-are they alike?

The image of one’s own face is a particularly distinctive feature of the self. The self-face differs from other faces not only in respect of its familiarity but also in respect of its subjective emotional significance and saliency. The current study aimed at elucidating similarities/dissimilarities between processing of one’s own face and emotional faces: happy faces (based on the self-positive bias) and fearful faces (because of their high perceptual saliency, a feature shared with self-face). Electroencephalogram data were collected in the group of 30 participants who performed a simple detection task. Event-related potential analyses indicated significantly increased P3 and late positive potential amplitudes to the self-face in comparison to all other faces: fearful, happy and neutral. Permutation tests confirmed the differences between the self-face and all three types of other faces for numerous electrode sites and in broad time windows. Representational similarity analysis, in turn, revealed distinct processing of the self-face and did not provide any evidence in favour of similarities between the self-face and emotional (either negative or positive) faces. These findings strongly suggest that the self-face processing do not resemble those of emotional faces, thus implying that prioritized self-referential processing is driven by the subjective relevance of one’s own face.

The integration of sensations and mental experiences into a unified experience: A neuropsychological model for the "sense of self"

A continued weakness in the cognitive neurosciences is the lack of a model to explain the phenomenological experience of the "self." This article proposes a model that suggests that the right hemisphere association area integrates physical sensations and mental experiences into a unified experience (i.e., a "sense of self") that is best conceptualized and understood as the subjective experience of "mineness." This model presents a unifying framework for neurologic and psychiatric disorders of the self (i.e., dis-integrated sense of "mineness"), as well as a neuropsychological framework to explain several human characteristics and experiences. Research is reviewed that indicates the sense of self can be activated to serve as the neuropsychological foundation of "self-integrated" character traits such as empathy (i.e., experiencing other's thoughts/emotions as "mine"), and conversely, the inhibition of this integrative process which can serve as the foundation of "selfless" experiences such as transcendence and forgiveness. Future research and clinical applications are discussed.

My own face looks larger than yours: A self-induced illusory size perception

Size perception of visual objects is highly context dependent. Here we report a novel perceptual size illusion that the self-face, being a unique and distinctive self-referential stimulus, can enlarge its perceived size. By using a size discrimination paradigm, we found that the self-face was perceived as significantly larger than the other-face of the same size. This size overestimation effect was not due to the familiarity of the self-face, since it could be still observed when the self-face was directly compared with a famous face. More crucially, such illusion effect could be extended to a new cartoon face that was transiently associated with one's own face and could also exert further contextual influences on visual size perception of other objects. These findings together highlight the role of self-awareness in visual size perception and point to a special mechanism of size perception tuned to self-referential information.

Gray-Matter Expansion of Social Brain Networks in Individuals High in Public Self-Consciousness

Self-consciousness is a personality trait associated with an individual’s concern regarding observable (public) and unobservable (private) aspects of self. Prompted by previous functional magnetic resonance imaging (MRI) studies, we examined possible gray-matter expansions in emotion-related and default mode networks in individuals with higher public or private self-consciousness. One hundred healthy young adults answered the Japanese version of the Self-Consciousness Scale (SCS) questionnaire and underwent structural MRI. A voxel-based morphometry analysis revealed that individuals scoring higher on the public SCS showed expansions of gray matter in the emotion-related regions of the cingulate and insular cortices and in the default mode network of the precuneus and medial prefrontal cortex. In addition, these gray-matter expansions were particularly related to the trait of “concern about being evaluated by others”, which was one of the subfactors constituting public self-consciousness. Conversely, no relationship was observed between gray-matter volume in any brain regions and the private SCS scores. This is the first study showing that the personal trait of concern regarding public aspects of the self may cause long-term substantial structural changes in social brain networks.

A century of prosopometamorphopsia studies

Prosopometamorphopsia is an extremely rare disorder of visual perception characterised by facial distortions. We here review 81 cases (eight new ones and 73 cases published over the past century) to shed light on the perception of face gestalts. Our analysis indicates that the brain systems underlying the perception of face gestalts have genuine network properties, in the sense that they are widely disseminated and built such that spatially normal perception of faces can be maintained even when large parts of the network are compromised. We found that bilateral facial distortions were primarily associated with right-sided and bilateral occipital lesions, and unilateral facial distortions with lesions ipsilateral to the distorted hemifield and with the splenium of the corpus callosum. We also found tentative evidence for the involvement of the left frontal regions in the fusing of vertical hemi-images of faces, and of right parietal regions in the fusing of horizontal hemi-images. Evidence supporting the remarkable adaptability of the network comes from the relatively high recovery rates that we found, from the ipsilateral hemifield predominance of hemi-prosopometamorphopsia, and from a phenomenon called cerebral asthenopia (heightened visual fatigability) which points to the dynamic nature of compensatory mechanisms maintaining normal face perception, even in chronic cases of prosopometamorphopsia. Finally, our analysis suggests that specialised networks for the representation of face gestalts in familiar-versus-unfamiliar faces and for own-versus-other face may be present, although this is in need of further study.

Effects of right or left face stimulation on self and other perception in enfacement illusion

Enfacement illusion is a visuo-tactile illusion elicited by being touched on one's own face while observing another face being touched at the same time, resulting in a change in self-face recognition. Left-face stimulation is usually preferred in enfacement studies. We investigated whether left or right face stimulation has any effect on the vividness of the illusion and if any relationship exists between emphatic abilities, personality traits and vividness of the illusion. The enfacement procedure included two stimuli: a cotton swab touching to face and a syringe approaching to face. We assessed subjective feeling of the illusion using a questionnaire and morphed face evaluations between self and other. Additionally, galvanic skin response (GSR) was measured. The results indicated that the syringe elicited higher GSR than that of touching and left face stimulation was much more sensitive in discriminating synchronous and asynchronous conditions. We found a significant relationship between self-to-other morph evaluations and GSR when the left side of the face was stimulated synchronously. However, a significant relationship was found between other-to-self evaluations and GSR when the right side of the face was stimulated asynchronously. We also noted significant correlations between vividness of the illusion and emphatic concern, extraversion and psychoticism traits.

Neural Evidence of Mirror Self-Recognition in the Secondary Somatosensory Cortex of Macaque: Observations from a Single-Cell Recording Experiment and Implications for Consciousness

Despite mirror self-recognition being regarded as a classical indication of self-awareness, little is known about its neural underpinnings. An increasing body of evidence pointing to a role of multimodal somatosensory neurons in self-recognition guided our investigation toward the secondary somatosensory cortex (SII), as we observed single-neuron activity from a macaque monkey sitting in front of a mirror. The monkey was previously habituated to the mirror, successfully acquiring the ability of mirror self-recognition. While the monkey underwent visual and somatosensory stimulation, multimodal visual and somatosensory activity was detected in the SII, with neurons found to respond to stimuli seen through the mirror. Responses were also modulated by self-related or non-self-related stimuli. These observations corroborate that vision is an important aspect of SII activity, with electrophysiological evidence of mirror self-recognition at the neuronal level, even when such an ability is not innate. We also show that the SII may be involved in distinguishing self and non-self. Together, these results point to the involvement of the SII in the establishment of bodily self-consciousness.

The self-face captures attention without consciousness: Evidence from the N2pc ERP component analysis

It is well established that stimuli representing or associated with ourselves, like our own name or an image of our own face, benefit from preferential processing. However, two key questions concerning the self-prioritization mechanism remain to be addressed. First, does it operate in an automatic manner during the early processing, or rather in a more controlled fashion at later processing stages? Second, is it specific to the self-related stimuli, or can it be activated also by other stimuli that are familiar or salient? We conducted a dot-probe experiment to investigate the mechanism behind the attentional prioritization of the self-face image and to tackle both questions. The former, by employing a backwards masking procedure to isolate the early and preconscious processing stages. The latter, by investigating whether a face that becomes visually familiar due to repeated presentations is able to capture attention in a similar manner as the self-face. Analysis of the N2pc ERP component revealed that the self-face image automatically captures attention, both when processed consciously and unconsciously. In contrast, the visually familiar face did not attract attention, neither in the conscious, nor in the unconscious condition. We conclude that the self-prioritization mechanism is early and automatic, and is not triggered by mere visual familiarity. More generally, our results provide further evidence for efficient unconscious processing of faces, and for dissociation between attention and consciousness.

Getting to Know Someone: Familiarity, Person Recognition, and Identification in the Human Brain

In our everyday life, we continuously get to know people, dominantly through their faces. Several neuroscientific experiments showed that familiarization changes the behavioral processing and underlying neural representation of faces of others. Here, we propose a model of the process of how we actually get to know someone. First, the purely visual familiarization of unfamiliar faces occurs. Second, the accumulation of associated, nonsensory information refines person representation, and finally, one reaches a stage where the effortless identification of very well-known persons occurs. We offer here an overview of neuroimaging studies, first evaluating how and in what ways the processing of unfamiliar and familiar faces differs and, second, by analyzing the fMRI adaptation and multivariate pattern analysis results we estimate where identity-specific representation is found in the brain. The available neuroimaging data suggest that different aspects of the information emerge gradually as one gets more and more familiar with a person within the same network. We propose a novel model of familiarity and identity processing, where the differential activation of long-term memory and emotion processing areas is essential for correct identification.

Involvement of the primary motor cortex in the early processing stage of the affective stimulus-response compatibility effect in a manikin task

Compatible (positive approaching and negative avoiding) and incompatible (positive avoiding and negative approaching) behavior are of great significance for biological adaptation and survival. Previous research has found that reaction times of compatible behavior are shorter than the incompatible behavior, which is termed the stimulus-response compatibility (SRC) effect. However, the underlying neurophysiological mechanisms of the SRC effect applied to affective stimuli is still unclear. Here, we investigated preparatory activities in both the left and right primary motor cortex (M1) before the execution of an approaching-avoiding behavior using the right index finger in a manikin task based on self-identity. The results showed significantly shorter reaction times for compatible than incompatible behavior. Most importantly, motor-evoked potential (MEP) amplitudes from left M1 stimulation were significantly higher during compatible behavior than incompatible behavior at 150 and 200 ms after stimulus presentation, whereas the reversed was observed for right M1 stimulation with lower MEP amplitude in compatible compared to incompatible behavior at 150 ms. The current findings revealed the compatibility effect at both behavioral and neurophysiological levels, indicating that the affective SRC effect occurs early in the motor cortices during stimulus processing, and MEP modulation at this early processing stage could be a physiological marker of the affective SRC effect.

Demystifying the mirror taboo: A neurocognitive model of viewing self in the mirror

Research has consistently demonstrated that viewing one's body in a mirror after an amputation or other perceived or visible body disfigurements can be a traumatic experience. Mirror viewing or mirroring is a taboo subject, which may be the reason this trauma has not been previously detected or acknowledged. Traumatic mirror viewing may lead to mirror discomfort, mirror avoidance, and a host of psychosocial concerns, including post-traumatic stress. As mirroring is complex, four qualitative mirror viewing studies, embodiment concepts, polyvagal theory, and memory theories were used to develop a model. In this article, foundational knowledge that led to the development of the model is shared. A neurocognitive model of mirror viewing is offered together with implications for nursing research, practice, and education.

Temporo-parietal contribution to the mental representations of self/other face

Face recognition requires comparing the current visual input with stored mental representations of faces. Based on its role in visual recognition of faces and mental representation of the body, we hypothesized that the right temporo-parietal junction (rTPJ) could be implicated also in processing mental representation of faces. To test this hypothesis, we asked 30 neurotypical participants to perform mental rotation (laterality judgment of rotated pictures) of self- and other-face images, before and after the inhibition of rTPJ through repetitive transcranial magnetic stimulation. After inhibition of rTPJ the mental rotation of self-face was slower than other-face. In the control condition the mental rotation of self/other faces was not significantly different. This supports that the role of rTPJ extends to mental representation of faces, specifically for the self. Since the experimental task did not require to explicitly recognize identity, we propose that unconscious identity attribution affects also the mental representation of faces. The present study offers insights on the involvement rTPJ in mental representation of faces and proposes that the neural substrate dedicated to mental representation of faces goes beyond the traditional visual and memory areas.

The 'Narcissus Effect': Top-down alpha-beta band modulation of face-related brain areas during self-face processing

Self-related information, such as one's own face, is prioritized by our cognitive system. Whilst recent theoretical developments suggest that this is achieved by an interplay between bottom-up and top-down attentional mechanisms, their underlying neural dynamics are still poorly understood. Furthermore, it is still matter of discussion as to whether these attentional mechanisms are truly self-specific or instead driven by face familiarity. To address these questions, we used EEG to record the brain activity of twenty-five healthy participants whilst identifying their own face, a friend's face and a stranger's face. Time-frequency analysis revealed a greater sustained power decrease in the alpha and beta frequency bands for the self-face, which emerged at late latencies and was maintained even when the face was no longer present. Critically, source analysis showed that this activity was generated in key brain regions for self-face recognition, such as the fusiform gyrus. As in the Myth of Narcissus, our results indicate that one's own face might have the potential to hijack attention. We suggest that this effect is specific to the self and driven by a top-down attentional control mechanism, which might facilitate further processing of personally relevant events.

Approach and avoidance bias for thin-ideal and normal-weight body shapes in anorexia nervosa

OBJECTIVE

The two studies aimed to examine implicit affective evaluations of thin-ideal and normal-weight body shapes in women with anorexia nervosa (AN), taking identification with body shapes into account.

METHOD

In study 1, approach-avoidance bias for thin-ideal and normal-weight bodies was assessed in 40 women with AN and 40 healthy women by using an Approach-Avoidance Task and female avatar bodies with a standard face as stimuli. In study 2, 39 women with AN and 38 healthy women underwent a similar task but identification with bodies was manipulated by presenting bodies once with the participant's own face and once with another woman's face.

RESULTS

In study 1, patients with AN did not differ from healthy participants in their automatic approach-avoidance tendencies towards thin-ideal and normal-weight bodies. In study 2, no definite approach bias for a thin self and no avoidance bias for thin other women or for a normal-weight self were found. However, as compared to healthy women, those with AN showed a less positive implicit evaluation of thin other women, and an implicit preference for thin bodies depicted as themselves over thin bodies depicted as another woman.

CONCLUSIONS

The findings suggest that intra-sexual competition for being slim is increased in AN.

Voice gender categorization in the connected and disconnected hemispheres

The role of the left and right hemispheres in processing the gender of voices is controversial, some evidence suggesting a bilateral involvement, some others suggesting a right-hemispheric superiority. We investigated this issue in a gender categorization task involving healthy participants and a male split-brain patient: female or male natural voices were presented in one ear during the simultaneous presentation of white noise in the other ear (dichotic listening paradigm). Results revealed faster responses by the healthy participants for stimuli presented in the left than in the right ear, although no asymmetries emerged between the two ears in the accuracy of both the patient and the control group. Healthy participants were also more accurate at categorizing female than male voices, and an opposite-gender bias emerged - at least in females - showing faster responses in categorizing voices of the opposite gender. The results support a bilateral hemispheric involvement in voice gender categorization, without asymmetries in the patient, but with a faster categorization when voices are directly presented to the right hemisphere in the healthy sample. Moreover, when the two hemispheres directly interact with one another, a faster categorization of voices of the opposite gender emerges, and it can be an evolutionary grounded bias.

The Molecular Organization of Self-awareness: Paralimbic Dopamine-GABA Interaction

The electrophysiology of the paralimbic network ("default mode") for self-awareness has drawn much attention in the past couple of decades. In contrast, knowledge of the molecular organization of conscious experience has only lately come into focus. We here review newer data on dopaminergic control of awareness in humans, particularly in self-awareness. These results implicate mainly dopaminergic neurotransmission and the control of GABAergic function directly in the paralimbic network. The findings are important for understanding addiction, developmental disorders, and dysfunctional consciousness.

Multisensory stimulation modulates perceptual and post perceptual face representations: Evidence from event-related potentials

Seeing a face being touched in spatial and temporal synchrony with the own face produces a bias in self-recognition, whereby the other face becomes more likely to be perceived as the self. The present study employed event-related potentials to explore whether this enfacement effect reflects initial face encoding, enhanced distinctiveness of the enfaced face, modified self-identity representations, or even later processing stages that are associated with the emotional processing of faces. Participants were stroked in synchrony or asynchrony with an unfamiliar face they observed on a monitor in front of them, in a situation approximating a mirror image. Subsequently, event-related potentials were recorded during the presentation of (a) a previously synchronously stimulated face, (b) an asynchronously stimulated face, (c) observers' own face, (d) filler faces, and (e) a to-be-detected target face, which required a response. Observers reported a consistent enfacement illusion after synchronous stimulation. Importantly, the synchronously stimulated face elicited more prominent N170 and P200 responses than the asynchronously stimulated face. By contrast, similar N250 and P300 responses were observed in these conditions. These results suggest that enfacement modulates early neural correlates of face encoding and facial prototypicality, rather than identity self-representations and associated emotional processes.

Double standards in body evaluation? The influence of identification with body stimuli on ratings of attractiveness, body fat, and muscle mass

Although it is well documented that women evaluate their own body differently from other bodies, it remains unclear whether this discrepancy is based on double standards because of identity or on objective differences between these bodies. The aim of this study was therefore to test whether women apply double standards depending on a body's identity when evaluating the same bodies presented with different faces. Average-weight women (N = 104) rated body attractiveness, body fat, and muscle mass of thin, average-weight, overweight, athletic, and hypermuscular bodies with either another female's face or their own face. With their own face, subjects rated overweight bodies as more unattractive, higher in body fat and lower in muscle mass than with another female's face. However, for non-overweight bodies, body ratings did not differ depending on body identity. Based on the self-deprecating double standards for overweight bodies, a body-related identity bias might be considered in theoretical models of body image.Level of evidence Level V, descriptive study.

Altered thalamo–cortical and occipital–parietal– temporal–frontal white matter connections in patients with anorexia and bulimia nervosa: a systematic review of diffusion tensor imaging studies

BACKGROUND

Anorexia nervosa and bulimia nervosa are complex mental disorders, and their etiology is still not fully understood. This paper reviews the literature on diffusion tensor imaging studies in patients with anorexia nervosa and bulimia nervosa to explore the usefulness of white matter microstructural analysis in understanding the pathophysiology of eating disorders.

METHODS

We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to identify diffusion tensor imaging studies that compared patients with an eating disorder to control groups. We searched relevant databases for studies published from database inception to August 2018, using combinations of select keywords. We categorized white matter tracts according to their 3 main classes: projection (i.e., thalamo–cortical), association (i.e., occipital–parietal–temporal–frontal) and commissural (e.g., corpus callosum).

RESULTS

We included 19 papers that investigated a total of 427 participants with current or previous eating disorders and 444 controls. Overall, the studies used different diffusion tensor imaging approaches and showed widespread white matter abnormalities in patients with eating disorders. Despite differences among the studies, patients with anorexia nervosa showed mainly white matter microstructural abnormalities of thalamo–cortical tracts (i.e., corona radiata, thalamic radiations) and occipital–parietal–temporal–frontal tracts (i.e., left superior longitudinal and inferior fronto-occipital fasciculi). It was less clear whether white matter alterations persist after recovery from anorexia nervosa. Available data on bulimia nervosa were partially similar to those for anorexia nervosa.

LIMITATIONS

Study sample composition and diffusion tensor imaging analysis techniques were heterogeneous. The number of studies on bulimia nervosa was too limited to be conclusive.

CONCLUSION

White matter microstructure appears to be affected in anorexia nervosa, and these alterations may play a role in the pathophysiology of this eating disorder. Although we found white matter alterations in bulimia nervosa that were similar to those in anorexia nervosa, white matter changes in bulimia nervosa remain poorly investigated, and these findings were less conclusive. Further studies with longitudinal designs and multi-approach analyses are needed to better understand the role of white matter changes in eating disorders.

The Organization of the Primate Insular Cortex

Long perceived as a primitive and poorly differentiated brain structure, the primate insular cortex recently emerged as a highly evolved, organized and richly connected cortical hub interfacing bodily states with sensorimotor, environmental, and limbic activities. This insular interface likely substantiates emotional embodiment and has the potential to have a key role in the interoceptive shaping of cognitive processes, including perceptual awareness. In this review, we present a novel working model of the insular cortex, based on an accumulation of neuroanatomical and functional evidence obtained essentially in the macaque monkey. This model proposes that interoceptive afferents that represent the ongoing physiological status of all the organs of the body are first being received in the granular dorsal fundus of the insula or “primary interoceptive cortex,” then processed through a series of dysgranular poly-modal “insular stripes,” and finally integrated in anterior agranular areas that serve as an additional sensory platform for visceral functions and as an output stage for efferent autonomic regulation. One of the agranular areas hosts the specialized von Economo and Fork neurons, which could provide a decisive evolutionary advantage for the role of the anterior insula in the autonomic and emotional binding inherent to subjective awareness.

Self-Resemblance Modulates Processing of Socio-Emotional Pictures in a Context-Sensitive Manner

Abstract. Relevance of emotional information varies with self-involvement. The current study was undertaken to test whether subtle facial self-resemblance is sufficient to affect attentional and affective processing of complex socio-emotional pictures. Faces digitally manipulated to resemble the participants’ (final sample: N = 21) own versus unfamiliar control faces (form and color morphs) were presented in pictures of emotionally evocative social interactions, that is, threat versus sex scenes. At stimulus onset asynchronies (SOAs) of either 300 ms or 3,000 ms after picture onset, startle responses were elicited by acoustic white noise bursts (50 ms, 105 dB), and recorded at the orbicularis oculi via electromyography (EMG). The majority of participants remained unaware of the morphing manipulation, and awareness did not affect the principal results. As indexed by inhibition of startle at short lead intervals and by picture-evoked heart rate deceleration, facial self-resemblance modulates effects of motivational salience in a context-sensitive way, increasing prepulse inhibition with threat-related, but not erotic cues. Overall, the present study suggests that visual cues of general motivational significance and of self-relevance are integrated in a fast, presumably automatic manner.

The effects of childhood maltreatment on brain structure in adults with eating disorders

Objectives: Childhood maltreatment is a non-specific risk factor for eating disorders (EDs). However, so far, no study has assessed the impact of childhood maltreatment on brain structure of adults with EDs. Therefore, we investigated brain area volumes and fibre tract integrity of childhood maltreated (Mal) and non-maltreated (noMal) patients with EDs. Methods: Thirty-six ED women and 16 healthy women underwent an MRI scan, including acquisition of a diffusion tensor imaging (DTI) sequence and a high-resolution T1-weighted scan. ED participants were classified as Mal (18 patients) or noMal (18 patients) according to their childhood exposure to traumatic events assessed by the Childhood Trauma Questionnaire (CTQ). Results: Significantly reduced grey matter volume was detected in the right paracentral lobule and in the left inferior temporal gyrus of Mal patients. DTI analyses revealed reduced white matter integrity in the corpus callosum, internal capsule, posterior thalamic radiation, longitudinal fasciculus and corona radiata of Mal patients. Negative correlations emerged between white/grey matter changes and CTQ emotional and physical neglect scores. Conclusions: These results show that childhood trauma affects the integrity of brain structures modulating brain processes, such as reward, taste and body image perception, which play a fundamental role in the psychopathology of EDs.

Malleability of the self: electrophysiological correlates of the enfacement illusion

Self-face representation is fundamentally important for self-identity and self-consciousness. Given its role in preserving identity over time, self-face processing is considered as a robust and stable process. Yet, recent studies indicate that simple psychophysics manipulations may change how we process our own face. Specifically, experiencing tactile facial stimulation while seeing similar synchronous stimuli delivered to the face of another individual seen as in a mirror, induces 'enfacement' illusion, i.e. the subjective experience of ownership of the other's face and a bias in attributing to the self, facial features of the other person. Here we recorded visual Event-Related Potentials elicited by the presentation of self, other and morphed faces during a self-other discrimination task performed immediately after participants received synchronous and control asynchronous Interpersonal Multisensory Stimulation (IMS). We found that self-face presentation after synchronous as compared to asynchronous stimulation significantly reduced the late positive potential (LPP; 450-750 ms), a reliable electrophysiological marker of self-identification processes. Additionally, enfacement cancelled out the differences in LPP amplitudes produced by self- and other-face during the control condition. These findings represent the first direct neurophysiological evidence that enfacement may affect self-face processing and pave the way to novel paradigms for exploring defective self-representation and self-other interactions.

A mechanistic account of bodily resonance and implicit bias

Implicit social biases play a critical role in shaping our attitudes towards other people. Such biases are thought to arise, in part, from a comparison between features of one's own self-image and those of another agent, a process known as 'bodily resonance'. Recent data have demonstrated that implicit bias can be remarkably plastic, being modulated by brief immersive virtual reality experiences that place participants in a virtual body with features of an out-group member. Here, we provide a mechanistic account of bodily resonance and implicit bias in terms of a putative self-image network that encodes associations between different features of an agent. When subsequently perceiving another agent, the output of this self-image network is proportional to the overlap between their respective features, providing an index of bodily resonance. By combining the self-image network with a drift diffusion model of decision making, we simulate performance on the implicit association test (IAT) and show that the model captures the ubiquitous implicit bias towards in-group members. We subsequently demonstrate that this implicit bias can be modulated by a simulated illusory body ownership experience, consistent with empirical data; and that the magnitude and plasticity of implicit bias correlates with self-esteem. Hence, we provide a simple mechanistic account of bodily resonance and implicit bias which could contribute to the development of interventions for reducing the negative evaluation of social out-groups.

The Own-Race Bias and the cerebral hemispheres

The Own-Race Bias (ORB) is the ability to better recognize and categorize a face when the depicted person belongs to the observer's ethnicity group. The relationship between the ORB and hemispheric asymmetries has been poorly explored, and the present study was aimed at investigating this relationship, as well as that between the ORB and the bias to better recognize own gender faces. Female and male Caucasian participants categorized the ethnicity of Caucasian and Asian female and male facial stimuli in a divided visual field paradigm. In a control experiment the same stimuli were presented centrally, confirming the ORB. Importantly, the lateralized presentation reversed the bias with higher accuracy and shorter response times in the categorization of Asian than Caucasian faces. This reversed bias was significant for female and male faces, and it was observed when stimuli were presented in the left but not in the right visual field, revealing the crucial role of the right hemisphere in face processing. These results shed new light on the hemispheric abilities in the categorization of facial features, and they are compared to previous evidence of cerebral asymmetries for facial age, gender and identity, both in healthy participants and in neurological patients.