[Anatomy of the frontal region]. / Anatomie de la région frontale.

The forehead is an anatomic region located between the frontal hairline cranially, the eyebrow and the glabella caudally, and the anterior border of the temporal fossa laterally on both sides. Its vertical situation, due to the telencephalon growth, is specific of the human species. From surface to deep planes, the skin and sub-cutaneous fat pads are described first. The muscular plane is constituted of the frontal muscles elevators of the forehead and the eyebrow, and the depressors which are the procerus and orbicularis oculi muscles superficially, the depressor supercilii muscle, and the corrugator supercilii in a deep plane. The galea aponeurotica, located deep to the frontal muscles, is a fibrous lamina on which the muscles of the skull insert. There is a sexual dimorphism of the frontal bone. The male forehead has extensive supraorbital bossing, and above this there is often a flat area, in teh femalethe supraorbital bossing is often nonexistent and above, there is a continous mild curvature. Blood supply to the forehead is given by an anterior pedicle constituted by the supraorbital and supratrochlear vessels and a lateral pedicle made of the anterior branches from the superficial temporal vessels. The sensory innervation of the forehead is given by the ophtalmic nerve which divides in frontal, nasociliar and lacrymal nerves. The motor innervation is given by the temporal ramus of the facial nerve which passes laterally to the zygomatic arch, and gives the innervation of the frontal, corrugator supercilii and procerus muscles.

Emotion regulation flexibility: EEG/EMG predictors and consequences of switching between reappraisal and distraction strategies.

Flexible use of emotion regulation (ER) strategies is central to mental health. To advance our understanding of what drives adaptive strategy-switching decisions, in this preregistered study, we used event-related potentials (late positive potential, LPP and stimulus preceding negativity, SPN) and facial electromyography (EMG corrugator activity) to test the antecedents and consequences of switching to an alternative ER strategy. Participants (N = 63, Mage = 24.8 years, all female) passively watched and then implemented an instructed ER strategy (reappraisal or distraction) in response to high-intensity negative pictures that were either easy or difficult to reinterpret (high or low reappraisal affordance, respectively). Next, they decided to "switch from" or "maintain" the instructed strategy and subsequently implemented the chosen strategy. Reappraisal affordance manipulations successfully induced switching. Regarding antecedents, switching was predicted by the reduced ER efficacy of the current strategy (corrugator, but not LPP). Switching to distraction was additionally predicted by increased responses to the stimulus during passive viewing (corrugator and LPP) and increased anticipatory effort in implementing reappraisal (SPN). Concerning consequences, switching to distraction improved, whereas switching to reappraisal impaired post-choice ER effects (LPP). However, starting with reappraisal was overall more effective than starting with distraction, irrespective of the subsequent decision (corrugator). Our results suggest that switching between ER strategies occurs in accordance with situational demands (stimulus affordances) and is predicted by reduced peripheral physiological ER efficacy. However, only switching to distraction leads to improved regulatory effects. These insights provide neurocognitively grounded starting points for developing interventions targeting ER flexibility.

Temporal dynamics of positive emotion regulation: insights from facial electromyography.

Introduction: Emotion regulation (ER) is a complex process that manifests gradually over time. This study investigated the temporal dynamics of ER in modifying positive emotions in terms of both negative affect (NA) and positive affect (PA) dimensions. Methods: After participants had been exposed to pleasant pictures for 8,000 ms, they received instructions to either continue viewing the picture (no regulation) or reappraise it with a neutral meaning (neutralize goal) or negative meaning (transform goal) for another 8,000 ms. We obtained corrugator supercilii and zygomaticus major electromyography (EMG) as objective measures of NA and PA. Results: For the no-regulation condition, upon instruction onset, we observed maintained low levels of corrugator and high levels of zygomaticus EMG reactivity, indicating sustained PA activation. Compared to the no-regulation condition, for the neutralize goal, we observed no change in corrugator reactivity, which remained at a low level, while zygomaticus reduction started at 1,000 ms after instruction onset, indicating decreased PA and generation of a neutral emotional state. For the transform goal, we observed corrugator increase and zygomaticus decrease both starting at 1,500 ms after instruction onset and co-existing throughout the regulation period. These results indicate increased NA and decreased PA, relating to generation of a negative emotional state. The transform goal differed from the neutralize goal in terms of corrugator increase starting at 2,500 ms after instruction onset. Albeit simultaneous onset of changes on corrugator and zygomaticus reactivity under the transform goal, model-fitting analyses indicated that the best-fitting trajectory was one that first emphasized PA reduction until, at 3,000 ms, it turned into primary NA increase. Discussion: These distinct temporal patterns highlight the possibility of effecting one-dimensional PA change with the neutralize goal and sequential two-dimensional change (first decreasing PA, then increasing NA) with the transform goal. This research sheds light on the time course of emotional change brought about by different regulatory goals.

Can neutral episodic memories become emotional? Evidence from facial expressions and subjective feelings.

Maladaptive emotional memories are a transdiagnostic feature of mental health problems. Therefore, understanding whether and how emotional memories can change might help to prevent and treat mental disorders. We tested whether neutral memories of naturalistic events can retroactively acquire positive or negative affect, in a preregistered three-day Modification of Valence in Episodes (MOVIE) paradigm. On Day 1, participants (N = 41) encoded memories of neutral movie scenes, representing lifelike naturalistic experiences. On Day 2, they retrieved each episode before viewing a happy, sad, or neutral scene from the same movie (yielding a within-subjects design with a neutral-negative, neutral-positive, and neutral-neutral condition). On Day 3, participants again retrieved each memory from Day 1. We assessed the affective tone of episodes through facial expressions of positive and negative affect (using facial electromyography, fEMG) and through self-reported feelings. Positive updating of neutral episodes led to increased expressions of positive affect, whereas negative updating led to increased self-reported negative feelings. These results suggest that complex neutral episodic memories can retroactively acquire an affective tone, but the effects were modest and inconsistent across affect readouts. Future research should investigate alternative approaches to updating emotional memories that produce more profound changes in the valence of memories.

Corrugator Muscle Activity Associated with Pressure Pain in Adults with Neck/Shoulder Pain.

Background and Objectives: No studies have reported corrugator muscle activity associated with pain in people with pain. This study aimed to develop an objective pain assessment method using corrugator muscle activity with pressure pain stimulation to the skeletal muscle. Methods: Participants were 20 adults (a mean ± SD age of 22.0 ± 3.1 years) with chronic neck/shoulder pain. Surface electromyography (sEMG) of corrugator muscle activity at rest (baseline) and without and with pressure pain stimulation applied to the most painful tender point in the shoulder was recorded. Participants evaluated the intensity of the neck/shoulder pain and the sensory and affective components of pain with pressure stimulation using a visual analogue scale (VAS). The percentages of integrated sEMG (% corrugator activity) without and with pressure pain stimulation to the baseline integrated sEMG were compared, and the relationships between the % corrugator activity and the sensory and affective components of pain VAS scores were evaluated. Results: Without pressure stimulation, an increase in corrugator muscle activity due to chronic neck/shoulder pain was not observed. The % corrugator activity with pressure pain stimulation was significantly higher than that without stimulation (p < 0.01). A significant positive correlation between corrugator muscle activity and the affective components of pain VAS scores with pressure stimulation was found (ρ = 0.465, p = 0.039) and a tendency of positive correlation was found for the sensory component of pain VAS scores (ρ = 0.423, p = 0.063). Conclusions: The increase in corrugator muscle activity with pressure pain stimulation to the tender point in adults with chronic neck/shoulder pain was observed, although increased corrugator muscle activity resulting from the chronic neck/shoulder pain was not. These findings suggest that corrugator muscle activity with pressure pain stimulation can be a useful objective indication for tender point sensitivity assessment in the skeletal muscle with pain.

A Phase III Clinical Study of the Efficacy and Safety of Botulinum Toxin Type A (MASPORT) with DYSPORT for the Treatment of Glabellar Lines.

BACKGROUND: Botulinum toxin type A is a widely used treatment of facial wrinkles. The objective of this study was to compare the efficacy and safety of a new botulinum toxin type A (Masport [abobotulinum toxin A], MasoonDarou Co) with DYSPORT® for the treatment of glabellar lines. METHODS: 262 subjects with moderate-to-severe glabellar lines received either a fixed dose of 50 units of MASPORT® or DYSPORT® (Ipsen Company, England). Subjects were followed up at 14, 30, 60, 90 and 120 days after injection. Efficacy was assessed by investigator at maximum frown and rest and also by Subject Global Assessment of Change (SGA). The responders were defined as persons with +2 grade improvement from baseline for both investigator and patient assessment. The occurrence and duration of adverse effects were recorded up throughout the study. RESULTS: According to the investigator evaluations, the responder rate at maximum frown were 94.5% for MASPORT and 95.6% for DYSPORT group on day 30 and at rest were 85.45% and 85.68% for MASPORT and DYSPORT group, respectively. According to the subject self-assessment, the proportion of responders in MASPORT group at day 30 was 95.28% versus 97.04% for DYSPORT group. No serious drug related adverse effect was recorded in either study groups, and the rates of adverse effects were similar for both groups. CONCLUSION: Abobotulinum toxin A [MASPORT] is equally safe and effective as commercial product [DYSPORT] for the treatment of glabellar lines with the dose of 50 units, up to 120 days. LEVEL OF EVIDENCE I: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

EEG and peripheral markers of viewer ratings: a study of short films.

Introduction: Cinema is an important part of modern culture, influencing millions of viewers. Research suggested many models for the prediction of film success, one of them being the use of neuroscientific tools. The aim of our study was to find physiological markers of viewer perception and correlate them to short film ratings given by our subjects. Short films are used as a test case for directors and screenwriters and can be created to raise funding for future projects; however, they have not been studied properly with physiological methods. Methods: We recorded electroencephalography (18 sensors), facial electromyography (corrugator supercilii and zygomaticus major), photoplethysmography, and skin conductance in 21 participants while watching and evaluating 8 short films (4 dramas and 4 comedies). Also, we used machine learning (CatBoost, SVR) to predict the exact rating of each film (from 1 to 10), based on all physiological indicators. In addition, we classified each film as low or high rated by our subjects (with Logistic Regression, KNN, decision tree, CatBoost, and SVC). Results: The results showed that ratings did not differ between genres. Corrugator supercilii activity ("frowning" muscle) was larger when watching dramas; whereas zygomaticus major ("smiling" muscle) activity was larger during the watching of comedies. Of all somatic and vegetative markers, only zygomaticus major activity, PNN50, SD1/SD2 (heart rate variability parameters) positively correlated to the film ratings. The EEG engagement indices, beta/(alpha+theta) and beta/alpha correlated positively with the film ratings in the majority of sensors. Arousal (betaF3 + betaF4)/(alphaF3 + alphaF4), and valence (alphaF4/betaF4) - (alphaF3/betaF3) indices also correlated positively to film ratings. When we attempted to predict exact ratings, MAPE was 0.55. As for the binary classification, logistic regression yielded the best values (area under the ROC curve = 0.62) than other methods (0.51-0.60). Discussion: Overall, we revealed EEG and peripheral markers, which reflect viewer ratings and can predict them to a certain extent. In general, high film ratings can reflect a fusion of high arousal and different valence, positive valence being more important. These findings broaden our knowledge about the physiological basis of viewer perception and can be potentially used at the stage of film production.

Self-Relevance Moderates the Relationship between Depressive Symptoms and Corrugator Activity during the Imagination of Personal Episodic Events.

Accumulating evidence suggests depression is associated with blunted reactivity to positive and negative stimuli, known as emotion context insensitivity (ECI). However, ECI is not consistently observed in the literature, suggesting moderators that influence its presence. We propose self-relevance as one such moderator, with ECI most apparent when self-relevance is low. We examined this proposal by measuring self-report and facial electromyography (EMG) from the corrugator muscle while participants (n = 81) imagined hypothetical scenarios with varying self-relevance and recalled autobiographical memories. Increased depressive symptoms on the Center for Epidemiologic Studies Depression Scale were associated with less differentiated arousal and self-relevance ratings between happy, neutral, and sad scenarios. EMG analyses further revealed that individuals with high depressive symptoms exhibited blunted corrugator reactivity (reduced differentiation) for sad, neutral, and happy scenarios with low self-relevance, while corrugator reactivity remained sensitive to valence for highly self-relevant scenarios. By comparison, in individuals with low depressive symptoms, corrugator activity differentiated valence regardless of stimulus self-relevance. Supporting a role for self-relevance in shaping ECI, we observed no depression-related differences in emotional reactivity when participants recalled highly self-relevant happy or sad autobiographical memories. Our findings suggest ECI is primarily associated with blunted reactivity towards material deemed low in self-relevance.

Botulinum Toxin Treatment for Depression: A New Paradigm for Psychiatry.

Multiple randomized double-blind placebo-controlled trials have shown that botulinum toxin A (BoNT/A), when injected into the frown musculature, is an antidepressant. This review outlines the conceptual narrative behind this treatment modality, starting with theory developed by Charles Darwin. We develop the concept of emotional proprioception and discuss how the muscles of facial expression play an important role in relaying valenced information to the brain's emotional neuroanatomical circuit. We review the role of facial frown musculature as the brain's barometer and transmitter of negatively valanced emotional information. The direct connections between the corrugator muscles and the amygdala are reviewed, and these provide a neuroanatomical circuit that is a logical target for treatment with BoNT/A. The centrality of amygdala dysfunction in the pathogenesis of many psychiatric disorders, and the evidence that BoNT/A modulates amygdala activity, provides the mechanistic link between BoNT/A and its antidepressant activity. Animal models of BoNT/A's antidepressant effects confirm the evolutionary conservation of this emotional circuit. The clinical and theoretical implications of this evidence, as it relates to the potential treatment of a broad range of psychiatric disorders by BoNT/A, is discussed. The ease of administration, long duration, and favorable side effect profile of this therapy is reviewed in the context of existing antidepressant treatments.

Crosstalk in Facial EMG and Its Reduction Using ICA.

There is ample evidence that electromyography (EMG) signals from the corrugator supercilii and zygomatic major muscles can provide valuable information for the assessment of subjective emotional experiences. Although previous research suggested that facial EMG data could be affected by crosstalk from adjacent facial muscles, it remains unproven whether such crosstalk occurs and, if so, how it can be reduced. To investigate this, we instructed participants (n = 29) to perform the facial actions of frowning, smiling, chewing, and speaking, in isolation and combination. During these actions, we measured facial EMG signals from the corrugator supercilii, zygomatic major, masseter, and suprahyoid muscles. We performed an independent component analysis (ICA) of the EMG data and removed crosstalk components. Speaking and chewing induced EMG activity in the masseter and suprahyoid muscles, as well as the zygomatic major muscle. The ICA-reconstructed EMG signals reduced the effects of speaking and chewing on zygomatic major activity, compared with the original signals. These data suggest that: (1) mouth actions could induce crosstalk in zygomatic major EMG signals, and (2) ICA can reduce the effects of such crosstalk.

Enhanced Empathic Pain by Facial Feedback.

The facial feedback hypothesis states that feedback from cutaneous and muscular afferents affects our emotion. Based on the facial feedback hypothesis, the purpose of this study was to determine whether enhancing negative emotion by activating a facial muscle (corrugator supercilii) increases the intensity of cognitive and emotional components of empathic pain. We also assessed whether the muscle contraction changed the pupil size, which would indicate a higher level of arousal. Forty-eight individuals completed 40 muscular contraction and relaxation trials while looking at images of five male and five female patients with neutral and painful facial expressions, respectively. Participants were asked to rate (1) how much pain the patient was in, and (2) how unpleasant their own feelings were. We also examined their facial muscle activities and changes in pupil size. No significant differences in pain or unpleasantness ratings were detected for the neutral face between the two conditions; however, the pain and unpleasantness ratings for the painful face were considerably higher in the contraction than relaxation condition. The pupils were considerably larger in the contraction than relaxation condition for both the painful and neutral faces. Our findings indicate that, by strengthening the corrugator supercilii, facial feedback can affect both the cognitive evaluative and affective sharing aspects of empathic pain.

Just let me check: The role of individual differences in self-reported anxiety and obsessive-compulsive features on subjective, behavioural, and physiological indices during a checking task.

Checking behaviour has been described as a form of preventative behaviour used by an individual to establish control over the environment and avoid future misfortune. However, when compulsive, checking behaviours can become disabling and distressing and have been linked to the maintenance of anxiety and obsessive-compulsive disorders. Despite this, there is limited literature across the field that has assessed the impact of dimensional measures of anxiety and obsessive-compulsive features (i.e., negative affect, uncertainty, and perfectionism) in driving checking behaviour. As such, the present study examined the impact of individual differences in self-reported anxiety and obsessive-compulsive features on subjective, behavioural, and physiological indices during a visual discrimination and checking task (n = 87). Higher self-reported anxiety and obsessive-compulsive features were associated with higher subjective ratings of unpleasantness and the urge to check during the task. Moreover, higher self-reported anxiety and obsessive-compulsive features related to general negative affect, uncertainty, and perfectionism were associated with greater checking frequency during the task. Lastly, stronger obsessional beliefs about perfectionism and the need for certainty were found to predict poorer accuracy, slower reaction times, and higher engagement of the corrugator supercilii during the task. In sum, these findings demonstrate how different anxiety and obsessive-compulsive features, in particular perfectionism and the need for certainty, may relate to and maintain checking behaviour in low threat contexts, which likely has implications for models of excessive and persistent checking in anxiety and obsessive-compulsive disorders.

Anatomical Proposal for Botulinum Neurotoxin Injection for Glabellar Frown Lines.

Botulinum neurotoxin injection for treating glabellar frown lines is a commonly used method; however, side effects, such as ptosis and samurai eyebrow, have been reported due to a lack of comprehensive anatomical knowledge. The anatomical factors important for the injection of the botulinum neurotoxin into the corrugator supercilii muscle has been reviewed in this study. Current understanding on the localization of the botulinum neurotoxin injection point from newer anatomy examination was evaluated. We observed that for the glabellar-frown-line-related muscles, the injection point could be more accurately demarcated. We propose the injection method and the best possible injection sites for the corrugator supercilii muscle. We propose the optimal injection sites using external anatomical landmarks for the frequently injected muscles of the face to accelerate effective glabellar frown line removal. Moreover, these instructions would support a more accurate procedure without adverse events.

Evaluation of the safety and efficacy of a biosimilar abobotulinum toxin type A in treating moderate-to-severe glabellar lines: A non-inferiority double blinded randomized controlled trial.

BACKGROUND: Injection of botulinum toxin for cosmetic purposes is a well-established practice. OBJECTIVES: This study was conducted to compare the safety and efficacy of Dyston® (investigational biosimilar abobotulinumtoxinA) with Dysport® (abobotulinumtoxinA, Ipsen) in the treatment of moderate-to-severe glabellar lines. METHODS: Out of 193 screened subjects, 126 volunteers with moderate-to-severe glabellar lines fulfilling eligibility criteria were randomized in a 1:1 ratio to receive either an intramuscular injection of 40-60 units of Dyston® or Dysport® . The primary objective was to test the non-inferiority of Dyston® compared with Dysport® as measured by the percentage of volunteers who achieved no or mild glabellar lines at maximum frown assessed by the physicians based on the Glabellar Line Severity Score (GLSS) at Day 30. Secondary endpoints included the improvement in the glabellar lines at maximum frown and rest states at Days 14, 60, 90, and 120 as well as the side effects of the treatment. RESULTS: Response rates at maximum frown were 75.44% (43/57) in the Dyston® group and 76.67% (46/60) in the Dysport® group on Day 30 (p value: 0.88, 95% CI: -14.24 to 16.70, diff: 1.23) as per-protocol set, and were 75.81% (47/62) and 76.19 (48/63) (p value: 0.96, 95% CI: -14.59 to 15.35, diff: 0.3) in the Dyston® and the Dysport® groups, respectively, based on modified intention to treat population. Adverse events were similar in both groups and mostly mild and well-tolerated. CONCLUSION: Treatment of moderate-to-severe glabellar lines with Dyston® was effective, tolerable, and non-inferior compared with Dysport® .

Prone to food in bad mood-Emotion-potentiated food-cue reactivity in patients with binge-eating disorder.

OBJECTIVE: Theories on emotional eating are central to our understanding of etiology, maintenance, and treatment of binge eating. Yet, findings on eating changes under induced negative emotions in binge-eating disorder (BED) are equivocal. Thus, we studied whether food-cue reactivity is potentiated under negative emotions in BED, which would point toward a causal role of emotional eating in this disorder. METHODS: Patients with BED (n = 24) and a control group without eating disorders (CG; n = 69) completed a food picture reactivity task after induction of negative versus neutral emotions. Food-cue reactivity (self-reported food pleasantness, desire to eat [DTE], and corrugator supercilii muscle response, electromyogram [EMG]) was measured for low- and high-caloric food pictures. RESULTS: Patients with BED showed emotion-potentiated food-cue reactivity compared to controls: Pleasantness and DTE ratings and EMG response were increased in BED during negative emotions. This was independent of caloric content of the images. CONCLUSIONS: Food-cue reactivity in BED was consistent with emotional eating theories and points to a heightened response to all foods regardless of calorie content. The discrepancy of appetitive ratings with the aversive corrugator response points to ambivalent food responses under negative emotions in individuals with BED.

Intolerance of uncertainty and physiological responses during instructed uncertain threat: A multi-lab investigation.

Individuals with high self-reported Intolerance of uncertainty (IU) tend to interpret uncertainty negatively. Recent research has been inconclusive on evidence of an association between IU and physiological responses during instructed uncertain threat. To address this gap, we conducted secondary analyses of IU and physiology data recorded during instructed uncertain threat tasks from two lab sites (Wisconsin-Madison; n = 128; Yale, n = 95). No IU-related effects were observed for orbicularis oculi activity (auditory startle-reflex). Higher IU was associated with: (1) greater corrugator supercilii activity to predictable and unpredictable threat of shock, compared to the safety from shock, and (2) poorer discriminatory skin conductance response between the unpredictable threat of shock, relative to the safety from shock. These findings suggest that IU-related biases may be captured differently depending on the physiological measure during instructed uncertain threat. Implications of these findings for neurobiological models of uncertainty and anticipation in anxiety are discussed.

Expressive suppression versus cognitive reappraisal: Effects on self-report and peripheral psychophysiology.

Effectiveness of various emotion regulation (ER) strategies have received much attention in recent research. Among the most studied ER strategies are cognitive reappraisal and expressive suppression. However, the evidence of their effectiveness is controversial and depends on the measures used. The aim of the present study was to compare the effectiveness of cognitive reappraisal and expressive suppression strategies of ER via different measures such as self-report, facial expressions (zygomaticus major and corrugator supercilii electromyography), and physiological assessment (skin conductance response and heart rate deceleration). Participants were presented with intensely unpleasant or neutral pictures and performed ER tasks. We expected that the implementation of ER strategies would reduce negative emotions, and cognitive reappraisal would produce greater reduction in negative emotions compared to expressive suppression. Self-report data showed that reappraisal had a greater effect on the reduction of negative emotions compared to suppression. There was no difference between reappraisal and suppression assessed with skin conductance response and electromyography. Curiously, heart rate deceleration increased while participants tried to suppress their emotional expressions, which could reflect efforts exerted in the attempt to suppress. The ER strategies reduced negative emotions during the presentation of unpleasant pictures partially in skin conductance response and heart rate deceleration. Overall, reappraisal is more effective in changing subjective experience, whereas the physiological reactions do not differ substantially between the two ER strategies explored. We therefore recommend that the assessment of ER strategies in the laboratory should accommodate more than one type of measures to come to more reliable conclusions.

Embodied power: Specific facial muscles automatically respond to power-related information processing.

Derived from embodiment approaches, we tested the assumption that specific facial muscle contractions are simulated upon the categorization of power-related words. For this, we used an interference task that required participants to categorize trait adjectives according to their underlying power. Response latencies of contractions of either the corrugator supercilii (pulls the eyebrows together) or the depressor anguli oris muscle (pulls the corners of the mouth downwards) were assessed. In two experiments, we expected and found that the speed of facial responses crucially depends on whether a high power or low power adjective was categorized. More precisely, corrugator responses were faster to high power adjectives whereas depressor responses were faster to low power adjectives. These findings support the assumption that the meaning of power is at least partially grounded in motor representations underlying specific facial expressions.

Grumpy face during adult sleep: A clue to negative emotion during sleep?

Negative facial expressions and frowns have been studied (albeit more rarely than smiles) in fetus' and neonate' sleep, but they have not been investigated during adult sleep. Video polysomnography (including corrugator muscle electromyography and face-focussed video) was used to study negative facial expressions in sleeping adults, including healthy subjects and patients with/out parasomnia. Frowns were observed during sleep in 89/91 (97.8%) adults during normal (29 healthy subjects) and abnormal sleep (29 patients without parasomnia, 15 patients with disorders of arousal and 18 patients with rapid eye movement [REM] sleep behaviour disorder [RBD]). In healthy subjects, the following events occurred in decreasing frequency: isometric corrugator activations, brief frowns, and then prolonged frowns and raised eyebrows (both similarly rare). Frowns predominated in REM sleep, and had a lower frequency in non-REM sleep. In healthy subjects, frowns were elementary and not associated with other face movements to the point of composing negative expressions. In contrast, frowns were occasionally associated with overt negative facial expressions in REM sleep in patients with RBD and a young patient with night terrors. They included mostly painful expressions and rarely sadness and anger in connection with apparently negative behaviours (shouts, painful moaning, and speeches). Frowns persist during normal sleep (mostly in REM sleep) in adults, but overt negative facial expressions are restricted to patients with parasomnia. Whether elementary frowns translate a negative dream emotion should be determined, but overt negative facial expressions during RBD could be used as a direct access to dream emotions.