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The interplay between the different components of emotional contagion (i.e. emotional state and facial motor resonance), both during implicit and explicit appraisal of emotion, remains controversial. The aims of this study were (i) to distinguish between these components thanks to vocal smile processing and (ii) to assess how they reflect implicit processes and/or an explicit appraisal loop. Emotional contagion to subtle vocal emotions was studied in 25 adults through motor resonance and Autonomic Nervous System (ANS) reactivity. Facial expressions (fEMG: facial electromyography) and pupil dilation were assessed during the processing and judgement of artificially emotionally modified sentences. fEMG revealed that Zygomaticus major was reactive to the perceived valence of sounds, whereas the activity of Corrugator supercilii reflected explicit judgement. Timing analysis of pupil dilation provided further insight into both the emotional state and the implicit and explicit processing of vocal emotion, showing earlier activity for emotional stimuli than for neutral stimuli, followed by valence-dependent variations and a late judgement-dependent increase in pupil diameter. This innovative combination of different electrophysiological measures shed new light on the debate between central and peripherical views within the framework of emotional contagion., (© 2024. The Author(s).)

Human facial features (eyes, nose, and mouth) allow us to communicate with others. Observing faces triggers physiological responses, including pupil dilation. Still, the relative influence of social and motion content of a visual stimulus on pupillary reactivity has never been elucidated. A total of 30 adults aged 18-33 years old were recorded with an eye tracker. We analysed the event-related pupil dilation in response to stimuli distributed along a gradient of social salience (non-social to social, going from objects to avatars to real faces) and dynamism (static to micro- to macro-motion). Pupil dilation was larger in response to social (faces and avatars) compared to non-social stimuli (objects), with surprisingly a larger response for avatars. Pupil dilation was also larger in response to macro-motion compared to static. After quantifying each stimulus' real quantity of motion, we found that the higher the quantity of motion, the larger the pupil dilated. However, the slope of this relationship was not higher for social stimuli. Overall, pupil dilation was more sensitive to the real quantity of motion than to the social component of motion, highlighting the relevance of ecological stimulations. Physiological response to faces results from specific contributions of both motion and social processing., (© The Author(s) 2024. Published by Oxford University Press.)

This study aimed at evaluating the autonomic response to pleasant affective touch in children with Autism Spectrum Disorders (ASD) and age-matched typically developing (TD) peers, thanks to multiple autonomic nervous system (ANS) parameters and by contrasting CT (C-tactile fibers) high- vs. low-density territory stimulations. We measured pupil diameter, skin conductance, and heart rate during gentle stroking of two skin territories (CT high- and low-density, respectively, forearm and palm of the hand) in thirty 6-12-year-old TD children and twenty ASD children. TD children showed an increase in pupil diameter and skin conductance associated with a heart rate deceleration in response to tactile stimulations at the two locations. Only the pupil was influenced by the stimulated location, with a later dilation peak following CT low-density territory stimulation. Globally, ASD children exhibited reduced autonomic responses, as well as different ANS baseline values compared to TD children. These atypical ANS responses to pleasant touch in ASD children were not specific to CT-fiber stimulation. Overall, these results point towards both basal autonomic dysregulation and lower tactile autonomic evoked responses in ASD, possibly reflecting lower arousal and related to social disengagement.

Introduction: The COVID-19 pandemic has imposed to wear a face mask that may have negative consequences for social interactions despite its health benefits. A lot of recent studies focused on emotion recognition of masked faces, as the mouth is, with the eyes, essential to convey emotional content. However, none have studied neurobehavioral and neurophysiological markers of masked faces perception, such as ocular exploration and pupil reactivity. The purpose of this eye tracking study was to quantify how wearing a facial accessory, and in particular a face mask, affected the ocular and pupillary response to a face, emotional or not., Methods: We used videos of actors wearing a facial accessory to characterize the visual exploration and pupillary response in several occlusion (no accessory, sunglasses, scarf, and mask) and emotional conditions (neutral, happy, and sad) in a population of 44 adults., Results: We showed that ocular exploration differed for face covered with an accessory, and in particular a mask, compared to the classical visual scanning pattern of a non-covered face. The covered areas of the face were less explored. Pupil reactivity seemed only slightly affected by the mask, while its sensitivity to emotions was observed even in the presence of a facial accessory., Discussion: These results suggest a mixed impact of the mask on attentional capture and physiological adjustment, which does not seem to be reconcilable with its strong effect on behavioral emotional recognition previously described., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Rabadan, Ricou, Latinus, Aguillon-Hernandez and Wardak.)

Considering the suspected involvement of the autonomic nervous system (ANS) in several neurodevelopmental disorders, a description of its tonus in typical populations and of its maturation between childhood and adulthood is necessary. We aimed to arrive at a better understanding of the maturation of the sympathetic (SNS) and parasympathetic (PNS) tonus by comparing children and adults at rest, via recordings of multiple ANS indices. We recorded simultaneously pupil diameter, electrodermal activity (EDA) and cardiac activity (RR interval and HRV: heart rate variability) in 29 children (6-12 years old) and 30 adults (20-42 years old) during a 5-min rest period. Children exhibited lower RR intervals, higher LF peak frequencies, and lower LF/HF (low frequency/high frequency) ratios compared to adults. Children also produced more spontaneous EDA peaks, reflected in a larger EDA AUC (area under the curve), in comparison with adults. Finally, children displayed a larger median pupil diameter and a higher pupillary hippus frequency than adults. Our results converged towards higher SNS and PNS tones in children compared to adults. Childhood would thus be characterized by a high autonomic tone, possibly reflecting a physiological state compatible with developmental acquisitions., (Copyright © 2022 Elsevier B.V. All rights reserved.)

With the COVID-19 pandemic, we have become used to wearing masks and have experienced how masks seem to impair emotion and speech recognition. While several studies have focused on facial emotion recognition by adding images of masks on photographs of emotional faces, we have created a video database with actors really wearing masks to test its effect in more ecological conditions. After validating the emotions displayed by the actors, we found that surgical mask impaired happiness and sadness recognition but not neutrality. Moreover, for happiness, this effect was specific to the mask and not to covering the lower part of the face, possibly due to a cognitive bias associated with the surgical mask. We also created videos with speech and tested the effect of mask on emotion and speech recognition when displayed in auditory, visual, or audiovisual modalities. In visual and audiovisual modalities, mask impaired happiness and sadness but improved neutrality recognition. Mask impaired the recognition of bilabial syllables regardless of modality. In addition, it altered speech recognition only in the audiovisual modality for participants above 70 years old. Overall, COVID-19 masks mainly impair emotion recognition, except for older participants for whom it also impacts speech recognition, probably because they rely more on visual information to compensate age-related hearing loss., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Aguillon-Hernandez, Jusiak, Latinus and Wardak.)

Background: For hearing-impaired individuals, hearing aids are clinically fit according to subjective measures of threshold and loudness. The goal of this study was to evaluate objective measures of loudness perception that might benefit hearing aid fitting. Method: Seventeen adult hearing aid users and 17 normal-hearing adults participated in the study. Outcome measures including categorical loudness scaling, cortical auditory evoked potentials (CAEPs), and pupillometry. Stimuli were 1-kHz tone bursts presented at 40, 60, and 80 dBA. Results: Categorical loudness scaling showed that loudness significantly increased with intensity for all participants (p < 0.05). For CAEPs, high intensity was associated with greater P1, N1, and P2 peak amplitude for all listeners (p < 0.05); a significant but small effect of hearing aid amplification was observed. For all participants, pupillometry showed significant effects of high intensity on pupil dilation (p < 0.05); there was no significant effect of hearing aid amplification. A Focused Principal Component analysis revealed significant correlations between subjective loudness and some of the objective measures. Conclusion: The present data suggest that intensity had a significant impact on loudness perception, CAEPs, and pupil response. The correlations suggest that pupillometry and/or CAEPs may be useful in determining comfortable amplification for hearing aids.

Background: Faces are crucial social stimuli, eliciting automatic processing associated with increased physiological arousal in observers. The level of arousal can be indexed by pupil diameter (the 'Event-Related Pupil Dilation', ERPD). However, many parameters could influence the arousal evoked by a face and its social saliency (e.g. virtual vs. real, neutral vs. emotional, static vs. dynamic). A few studies have shown an atypical ERPD in autism spectrum disorder (ASD) patients using several kinds of faces but no study has focused on identifying which parameter of the stimulus is the most interfering with face processing in ASD., Methods: In order to disentangle the influence of these parameters, we propose an original paradigm including stimuli along an ecological social saliency gradient: from static objects to virtual faces to dynamic emotional faces. This strategy was applied to 186 children (78 ASD and 108 typically developing (TD) children) in two pupillometric studies (22 ASD and 47 TD children in the study 1 and 56 ASD and 61 TD children in the study 2)., Results: Strikingly, the ERPD in ASD children is insensitive to any of the parameters tested: the ERPD was similar for objects, static faces or dynamic faces. On the opposite, the ERPD in TD children is sensitive to all the parameters tested: the humanoid, biological, dynamic and emotional quality of the stimuli. Moreover, ERPD had a good discriminative power between ASD and TD children: ASD had a larger ERPD than TD in response to virtual faces, while TD had a larger ERPD than ASD for dynamic faces., Conclusions: This novel approach evidences an abnormal physiological adjustment to socially relevant stimuli in ASD., (© 2019 Association for Child and Adolescent Mental Health.)

Since the online publication of the above article, the authors have noted errors with the author list. The author names were listed as '(last name)(first name)' instead of '(first name)(last name)'.

Phelan-McDermid syndrome is related to terminal 22q13 deletions of various sizes affecting the SHANK3 gene. In this neurodevelopmental disorder, behavioural symptoms of autism spectrum disorder (ASD) are reported in half of cases. Extensive clinical and neurophysiological characterization is lacking to understand the genotype-phenotype correlation. Eighteen patients (8 males, mean age 12.7 years, SD = 9.2) with known 22q13 deletions were fully explored with determination of deletion size, along with behavioural, language and cognitive standardized assessments. Neurophysiological indices previously reported to be altered in autism (i.e., eye tracking in a social/non-social task and auditory evoked potential mismatch) were also recorded. Thirty-nine percent met ASD clinical criteria, exceeding cut-off scores on both ADI-R (Autism Diagnosis Interview based on the period spanning 4-5 years of age) and ADOS-2 (Autism Diagnosis Observation Schedule for the current period). All patients had intellectual disability and language disability. Deletion size was significantly correlated with expressive and receptive language disability but not with ASD standardized assessment scores. Developmental Quotient tended to be lower in patients with the largest deletions. Using Eye Tracking, smaller pupil size, which is typically described in ASD, was not observed in these patients. Furthermore, atypical shortened latency of mismatch negativity response previously reported in ASD was not observed, whereas the N250 pattern, related to language, was affected. Language disability combined with cognitive deficits may lead to autistic behavioural symptoms, but with different neurophysiological networks compared to typical autism. These results highlight the indication for early speech therapy rather than intensive autism programme to treat these patients.

Autism and Autism Spectrum Disorder (ASD) cover a large variety of clinical profiles which share two main dimensions: social and communication impairment and repetitive behaviors or restricted interests, which are present during childhood. There is now no doubt that genetic factors are a major component in the etiology of autism but precise physiopathological pathways are still being investigated. Furthermore, developmental trajectories combined with compensatory mechanisms will lead to various clinical and neurophysiological profiles which together constitute this Autism Spectrum Disorder. To better understand the pathophysiology of autism, comprehension of key neurophysiological mechanisms and brain circuits underlying the different bioclinical profiles is thus crucial. To achieve this goal we propose a strategy which investigates different levels of information processing from sensory perception to complex cognitive processing, taking into account the complexity of the stimulus and whether it is social or non-social in nature. In order to identify different developmental trajectories and to take into account compensatory mechanisms, we further propose that such protocols should be carried out in individuals from childhood to adulthood representing a wide variety of clinical forms., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Objective: The aim of this study was to characterize ocular exploration of neutral and emotional faces in the typical development of a child., Subjects and Method: In this eye-tracking study, visual exploration of faces (with neutral or emotional expressions: happiness or sadness) was characterized in a population of 52 children (24 girls and 28 boys from 4 to 15 years of age) and 44 adults (22 women and 22 men from 18 to 35 years of age). The time spent on the eyes, nose and mouth of the faces was measured., Results: All participants spent more time on the eyes (13%) rather than the nose and mouth (6%). The youngest participants spent less time exploring the eyes than the older participants, suggesting the progressive establishment of interest in these informative regions of the face during maturation. This process seemed to occur later in females (7-9 years) than males (4-6 years)., Conclusion: These results confirm the importance of the eye area and the capacity of this region to capture attention. In addition, this study shows that the exploration of this region increases with age and is lower among girls aged 4-6 years compared with boys of the same age., (© 2016 S. Karger AG, Basel.)

Olfactory disorders constitute a potential marker of many diseases and are considered valuable clues to the diagnosis and evaluation of progression for many disorders. The most commonly used test for the evaluation of impairments of olfactory identification requires the active participation of the subject, who must select the correct name of the perceived odor from a list. An alternative method is required because speech may be impaired or not yet learned in many patients. As odor identification is known to be facilitated by searching for visual clues, we aimed to develop an objective, vision-based approach for the evaluation of odor identification. We used an eye tracking method to quantify pupillary and ocular responses during the simultaneous presentation of olfactory and visual stimuli, in 39 healthy participants aged from 19 to 77years. Odor presentation triggered an increase in pupil dilation and gaze focus on the picture corresponding to the odor presented. These results suggest that odorant stimuli increase recruitment of the sympathetic system (as demonstrated by the reactivity of the pupil) and draw attention to the visual clue. These results validate the objectivity of this method., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The euthymic phase of bipolar disorders may be associated with residual emotional and/or subsyndromal symptoms. The aim of this study was to compare subjective and physiologic emotional response to negative, neutral and positive emotion eliciting pictures between euthymic bipolar patients (n=26) and healthy controls (n=30). We evaluated emotional response using an emotional induction method with emotional pictures from the International Affective Picture System. We measured subjective emotional response with the Self-Assessment Manikin and physiological emotional response by measuring pupil size. No difference was found between euthymic bipolar patients and controls regarding subjective emotional response. However, upon viewing positive pictures, pupil dilation was significantly lower in euthymic bipolar patients compared to controls. This finding suggests that euthymic bipolar phase may be associated with reduced physiologic emotional response to positive valence, which is consistent with a more general negative emotional bias or can be understood as a residual emotional subsyndromal symptom., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)