Both of us disgusted in My insula: the common neural basis of seeing and feeling disgust

What neural mechanism underlies the capacity to understand the emotions of others? Does this mechanism involve brain areas normally involved in experiencing the same emotion? We performed an fMRI study in which participants inhaled odorants producing a strong feeling of disgust. The same participants observed video clips showing the emotional facial expression of disgust. Observing such faces and feeling disgust activated the same sites in the anterior insula and to a lesser extent in the anterior cingulate cortex. Thus, as observing hand actions activates the observer's motor representation of that action, observing an emotion activates the neural representation of that emotion. This finding provides a unifying mechanism for understanding the behaviors of others.     

Disgust: the disease-avoidance emotion and its dysfunctions

This review analyses the accumulating evidence from psychological, psychophysiological, neurobiological and cognitive studies suggesting that the disease-avoidance emotion of disgust is a predominant emotion experienced in a number of psychopathologies. Current evidence suggests that disgust is significantly related to small animal phobias (particularly spider phobia), blood-injection-injury phobia and obsessive-compulsive disorder contamination fears, and these are all disorders that have primary disgust elicitors as a significant component of their psychopathology. Disgust propensity and sensitivity are also significantly associated with measures of a number of other psychopathologies, including eating disorders, sexual dysfunctions, hypochondriasis, height phobia, claustrophobia, separation anxiety, agoraphobia and symptoms of schizophrenia--even though many of these psychopathologies do not share the disease-avoidance functionality that characterizes disgust. There is accumulating evidence that disgust does represent an important vulnerability factor for many of these psychopathologies, but when disgust-relevant psychopathologies do meet the criteria required for clinical diagnosis, they are characterized by significant levels of both disgust and fear/anxiety. Finally, it has been argued that disgust may also facilitate anxiety and distress across a broad range of psychopathologies through its involvement in more complex human emotions such as shame and guilt, and through its effect as a negative affect emotion generating threat-interpretation biases.     

Dissociation between Emotional Remapping of Fear and Disgust in Alexithymia

There is growing evidence that individuals are able to understand others’ emotions because they “embody” them, i.e., re-experience them by activating a representation of the observed emotion within their own body. One way to study emotion embodiment is provided by a multisensory stimulation paradigm called emotional visual remapping of touch (eVRT), in which the degree of embodiment/remapping of emotions is measured as enhanced detection of near-threshold tactile stimuli on one’s own face while viewing different emotional facial expressions. Here, we measured remapping of fear and disgust in participants with low (LA) and high (HA) levels of alexithymia, a personality trait characterized by a difficulty in recognizing emotions. The results showed that fear is remapped in LA but not in HA participants, while disgust is remapped in HA but not in LA participants. To investigate the hypothesis that HA might exhibit increased responses to emotional stimuli producing a heightened physical and visceral sensations, i.e., disgust, in a second experiment we investigated participants’ interoceptive abilities and the link between interoception and emotional modulations of VRT. The results showed that participants’ disgust modulations of VRT correlated with their ability to perceive bodily signals. We suggest that the emotional profile of HA individuals on the eVRT task could be related to their abnormal tendency to be focalized on their internal bodily signals, and to experience emotions in a “physical” way. Finally, we speculated that these results in HA could be due to a enhancement of insular activity during the perception of disgusted faces.     

“I Feel Contaminated in My Fake Hand”: Obsessive-Compulsive-Disorder like Disgust Sensations Arise from Dummy during Rubber Hand Illusion

Despite its theoretical and clinical interest, there are no experimental studies exploring obsessive-compulsive disorder (OCD)-like disgust sensations through using somatosensory illusions. Such illusions provide important clues to the nature and limits of multisensory integration and how the brain constructs body image; and may potentially inform novel therapies. One such effect is the rubber hand illusion (RHI) in which tactile sensations are referred to a rubber hand; if the experimenter simultaneously strokes a subject’s occluded hand together with a visible fake hand, the subject starts experiencing the touch sensations as arising from the dummy. In this study, we explore whether OCD-like disgust may result from contamination of a dummy hand during the RHI; suggesting a possible integration of somatosensory and limbic inputs in the construction of body image. We predicted that participants would experience sensations of disgust, when placing a disgust stimulus (fake feces, vomit or blood) on the dummy hand after establishing the RHI. We found that 9 out of 11 participants experienced greater disgust during the synchronous condition (real hidden hand and fake hand are stroked in synchrony) compared to the asynchronous control condition (real hidden hand and fake hand are stroked in asynchrony); and on average such disgust was significantly greater during the synchronous condition compared to the asynchronous control condition, Z = 2.7, p = .008. These results argue against a strictly hierarchical modular approach to brain function and suggest that a four-way multisensory interaction occurs between vision, touch, proprioception on the one hand and primal emotions like disgust on the other. These findings may inform novel clinical approaches for OCD; that is, contaminating a dummy during the RHI could possibly be used as part of an in-vivo exposure-intervention for OCD.     

Disgust implicated in obsessive-compulsive disorder.

Psychiatric classificatory systems consider obsessions and compulsions as forms of anxiety disorder. However, the neurology of diseases associated with obsessive-compulsive symptoms suggests the involvement of fronto-striatal regions likely to be involved in the mediation of the emotion of disgust, suggesting that dysfunctions of disgust should be considered alongside anxiety in the pathogenesis of obsessive-compulsive behaviours. We therefore tested recognition of facial expressions of basic emotions (including disgust) by groups of participants with obsessive-compulsive disorder (OCD) and with Gilles de la Tourette''s syndrome (GTS) with an without co-present obsessive-compulsive behaviours (GTS with OCB; GTS without OCB). A group of people suffering from panic disorder and generalized anxiety were also included in the study. Both groups with obsessive-compulsive symptoms (OCD; GTS with OCB) showed impaired recognition of facial expressions of disgust. Such problems were not evident in participants with panic disorder and generalized anxiety, or for participants with GTS without obsessions or compulsions, indicating that the deficit is closely related to the presence of obsessive-compulsive symptoms. Participants with OCD were able to assign words to emotion categories without difficulty, showing that their problem with disgust is linked to a failure to recognize this emotion in others and not a comprehension or response criterion effect. Impaired recognition of disgust is consistent with the neurology of OCD and with the idea that abnormal experience of disgust may be involved in the genesis of obsessions and compulsions.     

When Action Meets Emotions: How Facial Displays of Emotion Influence Goal-Related Behavior

Many authors have proposed that facial expressions, by conveying emotional states of the person we are interacting with, influence the interaction behavior. We aimed at verifying how specific the effect is of the facial expressions of emotions of an individual (both their valence and relevance/specificity for the purpose of the action) with respect to how the action aimed at the same individual is executed. In addition, we investigated whether and how the effects of emotions on action execution are modulated by participants'' empathic attitudes. We used a kinematic approach to analyze the simulation of feeding others, which consisted of recording the “feeding trajectory” by using a computer mouse. Actors could express different highly arousing emotions, namely happiness, disgust, anger, or a neutral expression. Response time was sensitive to the interaction between valence and relevance/specificity of emotion: disgust caused faster response. In addition, happiness induced slower feeding time and longer time to peak velocity, but only in blocks where it alternated with expressions of disgust. The kinematic profiles described how the effect of the specificity of the emotional context for feeding, namely a modulation of accuracy requirements, occurs. An early acceleration in kinematic relative-to-neutral feeding profiles occurred when actors expressed positive emotions (happiness) in blocks with specific-to-feeding negative emotions (disgust). On the other hand, the end-part of the action was slower when feeding happy with respect to neutral faces, confirming the increase of accuracy requirements and motor control. These kinematic effects were modulated by participants'' empathic attitudes. In conclusion, the social dimension of emotions, that is, their ability to modulate others'' action planning/execution, strictly depends on their relevance and specificity to the purpose of the action. This finding argues against a strict distinction between social and nonsocial emotions.     

Emotions and actions associated with norm-breaking events

Norms have a strong influence on human social interactions, but the emotions and actions associated with norm-breaking events have not been systematically studied. We asked subjects to imagine themselves in a conflict situation and then to report how they would feel, how they would act, and how they would imagine the feelings and actions of their opponent. By altering the fictional scenario that they were asked to imagine (weak vs. strong norm) and the perspective of the subject (norm-breaker vs. the one whose norm has been violated), the emotions and actions associated with norm-breaking events could be examined. We tested the following hypotheses: (1) norms create emotional asymmetries that resolve conflicts in otherwise symmetrical contest situations; (2) sex differences exist in response to norm-breaking events, with males more prone to violence than females; (3) individual differences exist in response to norm-breaking events, along the lines predicted by theoretical models; and (4) emotions and actions attributed to one’s opponent are distorted in ways that can be interpreted as adaptive for the believer. In addition to these basic hypotheses, we address more subtle issues concerning the particular emotions provoked by norm-breaking events, the degree to which emotional response is fine-tuned to the situation, and the degree to which emotional response correlates with anticipated behavioral response. We discuss the relevance of our study to the general study of emotions and the use of fictional scenarios as a research method in addition to the study of norms from an evolutionary perspective.     

Neurophysiological correlates of induced discrete emotions in humans: an individual analysis

The present study addressed EEG pattering during experimentally manipulated emotion. Film clips previously shown to induce happiness,joy, anger, disgust, fear/anxiety, sadness, as well as neutral control films, were presented to 30 university students while a 62-channel EEG was recorded, and a self-reported effect was described. Analyses revealed both emotion-specific and emotion-unspecific EEG pattering for the emotions under study. Induced positive and negative emotions were accompanied by hemispheric activation asymmetries in theta-2, alpha-2, and beta-1 EEG frequency bands. Emotions of joy and disgust induced lateralized a theta-2 power increase in anterior-temporal and frontal regions of the left hemisphere reflecting involvement of cognitive mechanisms in the emotional processing. Negative emotions of disgust and fear/anxiety were characterized by alpha-2 and beta-1 desynchronization of the right temporal-parietal cortex, suggesting its involvement in modulation of the emotion-related arousal.     

Somatosensory cortex excitability changes due to differences in instruction conditions of motor imagery

Purpose Vivid motor imagery appears to be associated with improved motor learning efficiency. However, the practical difficulties in measuring vivid motor imagery warrant new analytical approaches. The present study aimed to determine the instruction conditions for which vividness in motor imagery could be more easily seen and the excitability of the sensory cortex as it relates to the motor image. Materials and methods In total, 15 healthy, right-handed volunteers were instructed to imagine grasping a rubber ball under a verbal-only instruction condition (verbal condition), a verbal?+?visual instruction condition (visual condition), and a verbal?+?execution (physically grasping a real ball) condition (execution condition). We analyzed motor imagery-related changes in somatosensory cortical excitability by comparing somatosensory-evoked potentials in each condition with the rest (control) condition. We also used a visual analogue scale to measure subject-reported vividness of imagery. Results We found the N33 component was significantly lower in the execution condition than in the rest condition (p?Conclusions These data suggest that experiencing a movement through actual motor execution immediately prior to performing mental imagery of that movement enhances the excitability of motor-related cortical areas. It is suggested that the excitability of the motor-related region increased as a result of the motor imagery in the execution condition acting on the corresponding somatosensory cortex.     

The bitter truth about morality: virtue, not vice, makes a bland beverage taste nice

To demonstrate that sensory and emotional states play an important role in moral processing, previous research has induced physical disgust in various sensory modalities (visual, tactile, gustatory, and olfactory modalities, among others) and measured its effects on moral judgment. To further assess the strength of the connection between embodied states and morality, we investigated whether the directionality of the effect could be reversed by exposing participants to different types of moral events prior to rating the same neutral tasting beverage. As expected, reading about moral transgressions, moral virtues, or control events resulted in inducing gustatory disgust, delight, or neutral taste experiences, respectively. Results are discussed in terms of the relation between embodied cognition and processing abstract conceptual representations.     

Individual Differences in the Range of Sensory Modalities Experienced in Dreams.

The present study investigated the relationship between the recalled frequency of sensory modalities experienced in dreams and waking imagery abilities. Five hundred thirty-one undergraduate students completed 4 imagery ability tests and a dream recall questionnaire containing a question on the frequency of experience of the sensory modalities in dreams. A k-means cluster analysis of the Dream Sense Modality Scale indicated that the participants fell into 3 groups: the major modalities group, whose dreams were entirely visual, auditory, and kinesthetic; the all modalities group, who experienced all sense modalities in dreams; and the no modalities group, whose dreams were without sensory content. The participants' scores on the imagery tests in the 3 groups showed significant intergroup differences. The all modalities group showed the highest levels of ability in evoking vivid imagery and controlling visual imagery and the most frequent use of visual imagery compared with the other two groups. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Emotional and social behaviors elicited by electrical stimulation of the insula in the macaque monkey

Evidence from a large number of brain imaging studies has shown that, in humans, the insula, and especially its anterior part, is involved in emotions and emotion recognition. Typically, however, these studies revealed that, besides the insula, a variety of other cortical and subcortical areas are also active. Brain imaging studies are correlative in nature, and, as such, they cannot give indications about the necessary contribution of the different centers involved in emotions. In the present study, we aimed to define more clearly the role of the insula in emotional and social behavior of the monkey by stimulating it electrically. Using this technique, one may determine whether direct activation of the insula can produce specific emotional or social behaviors and exactly which parts of this structure are responsible for these behaviors. The results showed that two emotional behaviors, a basic one (disgust) and a social one (affiliative state), were easily elicited by electrical stimulation of specific parts of the insula. Both behaviors were characterized by specific motor and vegetative responses and by a dramatic change in the monkey's responsiveness to external stimuli.     

Homeliness is in the disgust sensitivity of the beholder: relatively unattractive faces appear especially unattractive to individuals higher in pathogen disgust

Pathogen-relevant variables (e.g., regional variation in pathogen prevalence, individual differences in sensitivity to pathogen disgust) have been found to be associated with judgments and preferences surrounding physical attractiveness, in line with the view that certain morphological features and configurations indicate health and/or immunocompetence. In three studies, we administered the three-domain disgust scale and obtained ratings of attractiveness of faces to examine whether associations emerged between perceivers' disgust sensitivity and their ratings of attractive and/or unattractive targets. The results across the three studies showed that for unattractive targets, perceivers higher in pathogen disgust tended to assign lower attractiveness ratings; for attractive targets, pathogen disgust was uncorrelated with attractiveness ratings. Sexual disgust and moral disgust were not associated with perceptions of unattractive or attractive target faces. These results indicate that disgust-dependent attractiveness perceptions may motivate avoidance of potentially unfit interaction partners.     

Disgust sensitivity predicts sociosexuality across cultures

Restricted sociosexuality has been linked to sexual disgust, suggesting that decreasing sexual behavior may be a pathogen avoidance technique. Using the behavioral immune system framework, which posits that humans experience disgust after exposure to pathogen cues, we replicate and expand on previous studies by analyzing the influence of three domains of disgust (sexual, moral, pathogen) on psychological (desire and attitude) and behavioral domains of sociosexuality (SOI) in four diverse samples: American university students (n = 155), Salvadoran community members (n = 98), a global online sample (n = 359), and a four-country online sample (US, India, Italy, and Brazil; n = 822) collected during the SARS-CoV-2 pandemic. In contrast with previous studies, we account for shared variance in sexual, pathogen, and moral disgust by entering all three in a multiple regression to predict composite SOI. In both large samples, sexual disgust and pathogen disgust had opposing effects on composite SOI; that is, higher sexual disgust and lower pathogen disgust were associated with more restricted composite SOI. Additionally, we constructed a multi-group structural equation model (SEM) to determine the impact of each domain of disgust on each domain of SOI across all our samples simultaneously, while controlling for age and sex. Within this model we also assessed how the psychological domains of SOI – attitude and desire – mediate the relationship between disgust and sociosexual behavior. Pathogen disgust positively predicted SOI attitude and desire, but not behavior, consistently across all groups. SOI behavior was only predicted by pathogen disgust when mediated by SOI attitude, again across all groups, suggesting that behavior seems to be driven largely by the psychological facets of SOI. We discuss these findings in light of the behavioral immune system and the bet-hedging hypothesis, which make opposing predictions on the relationship between infection risk and sexual behavior.     

Rejection of unfair offers can be driven by negative emotions, evidence from modified ultimatum games with anonymity

The rejection of unfair offers can be affected by both negative emotions (e.g. anger and moral disgust) and deliberate cognitive processing of behavioral consequences (e.g. concerns of maintaining social fairness and protecting personal reputation). However, whether negative emotions are sufficient to motivate this behavior is still controversial. With modified ultimatum games, a recent study (Yamagishi T, et al. (2009) Proc Natl Acad Sci USA 106:11520-11523) found that people reject unfair offers even when this behavior increases inequity, and even when they could not communicate to the proposers. Yamagishi suggested that rejection of unfair offers could occur without people's concerning of maintaining social fairness, and could be driven by negative emotions. However, as anonymity was not sufficiently guaranteed in Yamagishi's study, the rejection rates in their experiments may have been influenced by people's concerns of protecting personal reputation (reputational concerns) in addition to negative emotions; thus, it was unclear whether the rejection was driven by negative emotions, or by reputational concerns, or both. In the present study, with specific methods to ensure anonymity, the effect of reputational concerns was successfully ruled out. We found that in a private situation in which rejection could not be driven by reputational concerns, the rejection rates of unfair offers were significantly larger than zero, and in public situations in which rejection rates could be influenced by both negative emotions and reputational concerns, rejection rates were significantly higher than that in the private situation. These results, together with Yamagishi's findings, provided more complete evidence suggesting (a) that the rejection of unfair offers can be driven by negative emotions and (b) that deliberate cognitive processing of the consequences of the behavior can increase the rejection rate, which may benefit social cooperation.     

Neural structures associated with recognition of facial expressions of basic emotions.

People with Huntington''s disease and people suffering from obsessive compulsive disorder show severe deficits in recognizing facial expressions of disgust, whereas people with lesions restricted to the amygdala are especially impaired in recognizing facial expressions of fear. This double dissociation implies that recognition of certain basic emotions may be associated with distinct and non-overlapping neural substrates. Some authors, however, emphasize the general importance of the ventral parts of the frontal cortex in emotion recognition, regardless of the emotion being recognized. In this study, we used functional magnetic resonance imaging to locate neural structures that are critical for recognition of facial expressions of basic emotions by investigating cerebral activation of six healthy adults performing a gender discrimination task on images of faces expressing disgust, fear and anger. Activation in response to these faces was compared with that for faces showing neutral expressions. Disgusted facial expressions activated the right putamen and the left insula cortex, whereas enhanced activity in the posterior part of the right gyrus cinguli and the medial temporal gyrus of the left hemisphere was observed during processing of angry faces. Fearful expressions activated the right fusiform gyrus and the left dorsolateral frontal cortex. For all three emotions investigated, we also found activation of the inferior part of the left frontal cortex (Brodmann area 47). These results support the hypotheses derived from neuropsychological findings, that (i) recognition of disgust, fear and anger is based on separate neural systems, and that (ii) the output of these systems converges on frontal regions for further information processing.     

Disgust sensitivity and the neurophysiology of left-right political orientations

Disgust has been described as the most primitive and central of emotions. Thus, it is not surprising that it shapes behaviors in a variety of organisms and in a variety of contexts--including homo sapien politics. People who believe they would be bothered by a range of hypothetical disgusting situations display an increased likelihood of displaying right-of-center rather than left-of-center political orientations. Given its primal nature and essential value in avoiding pathogens disgust likely has an effect even without registering in conscious beliefs. In this article, we demonstrate that individuals with marked involuntary physiological responses to disgusting images, such as of a man eating a large mouthful of writhing worms, are more likely to self-identify as conservative and, especially, to oppose gay marriage than are individuals with more muted physiological responses to the same images. This relationship holds even when controlling for the degree to which respondents believe themselves to be disgust sensitive and suggests that people's physiological predispositions help to shape their political orientations.     

Functional characterization of three G protein-coupled receptors for pigment dispersing factors in Caenorhabditis elegans

Here, we report the identification, cloning, and functional characterization of three Caenorhabditis elegans G protein-coupled pigment dispersing factor (PDF) receptors, which we designated as Ce_PDFR-1a, -b, and -c. They represent three splice isoforms of the same gene (C13B9.4), which share a high degree of similarity with the Drosophila PDF receptor and are distantly related to the mammalian vasoactive intestinal peptide receptors (VPAC2) and calcitonin receptors. In a reverse pharmacological screen, three bioactive C. elegans neuropeptides, which were recently identified as the Drosophila PDF orthologues, were able to activate these receptors in a dose-dependent manner with nanomolar potency (isoforms a and b). Integrated green fluorescent protein reporter constructs reveal the expression of these PDF receptors in all body wall muscle cells and many head and tail neurons involved in the integration of environmental stimuli and the control of locomotion. Using a custom data analysis system, we demonstrate the involvement of this newly discovered neuropeptide signaling system in the regulation of locomotor behavior. Overexpression of PDF-2 phenocopies the locomotor defects of a PDF-1 null mutant, suggesting that they elicit opposite effects on locomotion through the identified PDF receptors. Our findings strengthen the hypothesis that the PDF signaling system, which imposes the circadian clock rhythm on behavior in Drosophila, has been functionally conserved throughout the protostomian evolutionary lineage.     

No relationship between left ventricular radial wall motion and longitudinal velocity and the extent and severity of noncompaction cardiomyopathy

Background

In studies where cross-sectional images of coronary arteries obtained with different imaging modalities are compared, the importance of correct co-localization and matching of images along the coronary artery longitudinal axis is obvious. However, it appears neglected that correct spatial orientation of the cross-sectional plane may not be obtainable just by rotating the images to ensure co-localization of identifiable landmarks such as sidebranches. A cross-section has two sides, one facing proximally and the other distally, and pairs of images reconstructed corresponding to these opposite points of view are mirror images of each other and not superimposable. This may be difficult if not impossible to recognize and unrecognized it will give rise to flawed results in the development and validation of imaging technologies aimed at plaque characterization (tissue mapping). We determined the imagined point of view for three commercially available intracoronary imaging systems used by invasive cardiologists and illustrate its importance in imaging modality validation.

Methods and Results

We made an asymmetric phantom and investigated it with two different intravascular ultrasound (IVUS) systems and one optical coherence tomography (OCT) system. The asymmetry of the phantom allowed determination of the spatial orientation of the cross-sectional images. On all tested systems, an observer should imagine herself/himself standing proximal to the cross-section when looking at the intravascular images.

Conclusions

The tested intracoronary imaging modalities displayed cross-sectional images with a spatial orientation corresponding to a proximal point of view. Knowledge of the spatial orientation is mandatory when comparing and validating different imaging modalities aimed at plaque characterization.