Neural correlates of disgust- and fear-conditioned responses

Neurocognitive mechanisms of mental imagery-based disgust learning

Disgust imagery represents a potential pathological mechanism for disgust-related disorders. However, it remains controversial as to whether disgust can be conditioned with disgust-evoking mental imagery serving as the unconditioned stimulus (US). Therefore, we examined this using a conditioned learning paradigm in combination with event-related potential (ERP) analysis in 35 healthy college students. The results indicated that the initial neutral face (conditioned stimulus, CS+) became more disgust-evoking, unpleasant, and arousing after pairing with disgust-evoking imagery (disgust CS+), compared to pairing with neutral (neutral CS+) and no (CS-) imagery. Moreover, we observed that mental imagery-based disgust conditioning was resistant to extinction. While the disgust CS + evoked larger P3 and late positive potential amplitudes than CS- during acquisition, no significant differences were found between disgust CS+ and neutral CS+, indicating a dissociation between self-reported and neurophysiological responses. Future studies may additionally acquire facial EMG as an implicit index of conditioned disgust. This study provides the first neurobiological evidence that associative disgust learning can occur without aversive physical stimuli, with implications for understanding how disgust-related disorders may manifest or deteriorate without external perceptual aversive experiences, such as in obsessive-compulsive disorder (OCD).

Is disgust more resistant to extinction than fear? A meta-analytic review of laboratory paradigms

Disgust can be acquired via evaluative conditioning; a process by which a neutral stimulus (conditioned stimulus; CS) comes to be evaluated as disgusting due to its pairing with an inherently disgusting stimulus (unconditioned stimulus; US). Research has shown that conditioned disgust responses are resistant to extinction which may have implications for disorders (i.e., contamination-based obsessive-compulsive disorder, specific phobias, and post-traumatic stress disorder) in which heightened disgust has been implicated. Importantly, extinction is the primary mechanism by which exposure therapies are thought to achieve symptom reduction for these disorders. Exposure therapies were originally modeled on fear extinction, whereas disgust extinction was largely overlooked until recently. Accordingly, differences in the degree to which learned disgust and fear can be attenuated via extinction learning remains unclear. The present investigation was a meta-analysis directly comparing the degree of extinction of conditioned disgust (n = 14) and conditioned fear (n = 14) in laboratory paradigms. Extinction was operationalized as the standardized mean difference (SMD) in evaluative ratings between the CS+ (the CS paired with the US) and CS- (the unpaired CS) after extinction training. Results of a subgroup analysis indicated that disgust (SMD = 0.52) was significantly more resistant to extinction than fear (SMD = 0.37). Additionally, a series of meta-regression analyses indicated that extinction was not influenced by important study characteristics (e.g., sex, age, number of conditioning and extinction trials). The findings suggest that extinction-based approaches may be less effective at attenuating learned disgust and research is needed to better optimize treatments for disgust-related disorders.

Conscious knowledge of CS-UCS contingency information affects extinction retrieval of conditioned disgust responses: Findings from an online de novo disgust conditioning task

Objective

The present study aimed to establish and develop an online de novo conditioning paradigm for the measurement of conditioned disgust responses. We further explored the effects of explicit instructions about the CS-UCS contingency on extinction learning and retrieval of conditioned disgust responses.

Method

The study included a sample of 115 healthy participants. Geometric figures served as conditioned stimuli (CS) and disgust-evoking pictures as unconditioned stimuli (UCS). During disgust conditioning, the CS+ was paired with the UCS (66% reinforcement) and the CS- remained unpaired; during extinction and retrieval, no UCS was presented. Half of the participants (n = 54) received instructions prior to the disgust extinction stating that the UCS will not be presented anymore. 1-2 days or 7-8 days later participants performed a retrieval test. CS-UCS contingency, disgust and valence ratings were used as dependent measures.

Results

Successful acquisition of conditioned disgust response was observed on the level of CS-UCS contingency, disgust and valence ratings. While some decline in valence and disgust ratings during the extinction stage was observed, contingency instructions did not significantly affect extinction performance. Retrieval one week later revealed that contingency instructions increased the discrimination of the CSs.

Conclusions

Extinction of conditioned disgust responses is not affected by explicit knowledge of the CS-UCS contingencies. However, contingency instructions prior to extinction seem to have a detrimental effect on long-term extinction retrieval.

Disgust as a transdiagnostic index of mental illness: A narrative review of clinical populations

Disgust is a basic emotion of rejection, providing an ancestral defensive mechanism against illness. Based on research that documents altered experiences of disgust across several psychopathological conditions, we conducted a narrative review to address the hypothesis that altered disgust may serve as a transdiagnostic index of mental illness. Our synthesis of the literature from past decades suggests that, compared to healthy populations, patients with mental disorders exhibit abnormal processing of disgust in at least one of the analyzed dimensions. We also outline evidence of alterations in brain areas relevant to disgust processing, such as the insula and the interconnected limbic network. Overall, we provide preliminary support for the hypothesis that altered disgust processing may serve as a transdiagnostic index of mental illness.

Pavlovian Disgust Conditioning and Generalization: Specificity and Associations With Individual Differences

Although studies have identified differences between fear and disgust conditioning, much less is known about the generalization of conditioned disgust. This is an important gap in the literature given that overgeneralization of conditioned disgust to neutral stimuli may have clinical implications. To address this knowledge gap, female participants (n = 80) completed a Pavlovian conditioning procedure in which one neutral food item (conditioned stimulus; CS+) was followed by disgusting videos of individuals vomiting (unconditioned stimulus; US) and another neutral food item (CS-) was not reinforced with the disgusting video. Following this acquisition phase, there was an extinction phase in which both CSs were presented unreinforced. Importantly, participants also evaluated generalization stimuli (GS+, GS-) that resembled, but were distinct from, the CS after each conditioning phase. As predicted, the CS+ was rated as significantly more disgusting and fear inducing than the CS- after acquisition and this pattern persisted after extinction. However, disgust ratings of the CS+ after acquisition were significantly larger than fear ratings. Participants also rated the GS+ as significantly more disgusting, but not fear inducing, than the GS- after acquisition. However, this effect was not observed after extinction. Disgust proneness did predict a greater increase in disgust and fear ratings of the CS+ relative to the CS- after acquisition and extinction. In contrast, trait anxiety predicted only higher fear ratings to the CS+ relative to the CS- after acquisition and extinction. Disgust proneness nor trait anxiety predicted the greater increase in disgust to the GS+ relative to the GS- after acquisition. These findings suggest that while conditioned disgust can generalize, individual difference variables that predict generalization remain unclear. The implications of these findings for disorders of disgust are discussed.

Common and separable behavioral and neural mechanisms underlie the generalization of fear and disgust

Generalization represents the transfer of a conditioned responses to stimuli that resemble the conditioned stimulus (CS). Previous studies on generalization of defensive avoidance responses have primarily focused on fear and have neglected disgust generalization, which represents a key pathological mechanism in some anxiety disorders. In the present study we examined common and distinct mechanisms of fear and disgust generalization by means of a fear or disgust multi-CS conditioning and generalization paradigm with concomitant event-related potential (ERPs) acquisition in n = 62 subjects. We demonstrate that compared to fear, disgust-relevant generalized stimuli (GS) elicited larger expectancy ratings and longer reaction times (RTs) reflecting stronger ratings of 'risk'. On the electrophysiological level, increased P2 amplitudes were found in response to conditioned CS+ versus CS- across both domains, possibly reflecting higher motivational and attentional salience of aversive conditioned stimuli per se. Contingent negative variation (CNV) amplitude was significantly larger for disgust-CS+ than disgust-CS-, reflecting a stronger preparation of the disgust US. Additionally, we found that the contingent negative variation (CNV) fear generalization gradient, and CNV amplitude were increased with similarity to CS+. In contrast the CNV to disgust-GS did not differ and did not reflect disgust generalization. Together this may indicate that the CNV represents a highly fear-specific index for generalization learning. This study provides the first neurobiological evidence for common and distinct generalization learning in fear versus disgust suggesting that dysregulations in separable defensive avoidance mechanisms may underly different anxiety disorder subtypes.

Behavioral and neural mechanisms of latent inhibition

Fear is an adaptive emotion that serves to protect an organism against potential dangers. It is often studied using classical conditioning paradigms where a conditioned stimulus is paired with an aversive unconditioned stimulus to induce a threat response. Less commonly studied is a phenomenon that is related to this form of conditioning, known as latent inhibition. Latent inhibition (LI) is a paradigm in which a neutral cue is repeatedly presented in the absence of any aversive associations. Subsequent pairing of this pre-exposed cue with an aversive stimulus typically leads to reduced expression of a conditioned fear/threat response. In this article, we review some of the theoretical basis for LI and its behavioral and neural mechanisms. We compare and contrast LI and fear/threat extinction-a process in which a previously conditioned cue is repeatedly presented in the absence of aversive outcomes. We end with highlighting the potential clinical utility of LI. Particularly, we focus on how LI application could be useful for enhancing resilience, especially for individuals who are more prone to continuous exposure to trauma and stressful environments, such as healthcare workers and first responders. The knowledge to be gained from advancing our understanding of neural mechanisms in latent inhibition could be applicable across psychiatric disorders characterized by exaggerated fear responses and impaired emotion regulation.

An implicit priming intervention alters brain and behavioral responses to high-calorie foods: a randomized controlled study

BACKGROUND

Conditioned food cues (e.g., smell, sight) can affect intake of foods associated with those cues, regardless of homeostatic need. As such, altering automatic associations with food cues could support weight loss or maintenance efforts by affecting the salience of those cues and the effort required to resist consumption.

OBJECTIVES

This study investigated neuronal and behavioral effects of an implicit priming (IP) intervention, in which negatively valenced images were paired with high-calorie foods and positively valenced images with low-calorie foods. Priming images were presented immediately before food images, but below conscious perception (20 ms). We hypothesized that this evaluative conditioning approach could alter food cue responses by modifying affective associations.

METHODS

The final sample included 41 adults with BMI ≥25 kg/m2 (n = 22, active IP; n = 19, control IP). In control IP, food images were primed with neutral, scrambled images. Participants completed a visual food cue task during fMRI, both before and after IP. To determine the replicability of prior behavioral findings, food image ratings were completed before and after IP as a secondary outcome.

RESULTS

In a whole-brain analysis, reduced dorsolateral prefrontal cortex (dlPFC) response to high-calorie foods was observed after active compared with control IP (t = 4.93, P = 0.033). With a region of interest analysis, reduced response to high-calorie foods in active compared with control IP was also observed in the striatum (t = 2.40, P = 0.009) and insula (t = 2.38, P = 0.010). Active compared with control IP was associated with reduced high-calorie food ratings (F = 4.70, P = 0.038).

CONCLUSIONS

Reduced insula and striatum response to high-calorie foods after active compared with control IP suggests effectiveness of IP in altering food cue salience. Reduced dlPFC response to high-calorie foods after active compared with control IP may reflect fewer attentional resources being directed to those images and reduced engagement of inhibitory processes.This trial was registered at clinicaltrials.gov as NCT02347527.

Reduction of DNMT3a and RORA in the nucleus accumbens plays a causal role in post-traumatic stress disorder-like behavior: reversal by combinatorial epigenetic therapy

Post-traumatic stress disorder (PTSD) is an incapacitating trauma-related disorder, with no reliable therapy. Although PTSD has been associated with epigenetic alterations in peripheral white blood cells, it is unknown where such changes occur in the brain, and whether they play a causal role in PTSD. Using an animal PTSD model, we show distinct DNA methylation profiles of PTSD susceptibility in the nucleus accumbens (NAc). Data analysis revealed overall hypomethylation of different genomic CG sites in susceptible animals. This was correlated with the reduction in expression levels of the DNA methyltransferase, DNMT3a. Since epigenetic changes in diseases involve different gene pathways, rather than single candidate genes, we next searched for pathways that may be involved in PTSD. Analysis of differentially methylated sites identified enrichment in the RAR activation and LXR/RXR activation pathways that regulate Retinoic Acid Receptor (RAR) Related Orphan Receptor A (RORA) activation. Intra-NAc injection of a lentiviral vector expressing either RORA or DNMT3a reversed PTSD-like behaviors while knockdown of RORA and DNMT3a increased PTSD-like behaviors. To translate our results into a potential pharmacological therapeutic strategy, we tested the effect of systemic treatment with the global methyl donor S-adenosyl methionine (SAM), for supplementing DNA methylation, or retinoic acid, for activating RORA downstream pathways. We found that combined treatment with the methyl donor SAM and retinoic acid reversed PTSD-like behaviors. Thus, our data point to a novel approach to the treatment of PTSD, which is potentially translatable to humans.

Facial Emotion Recognition in Obesity and in Fibromyalgia: A Systematic Review

Facial emotion recognition (FER) is extensively investigated in psychological sciences in healthy individuals and clinical conditions. In this paper, we analyzed those studies in which FER was assessed in the case of obesity or fibromyalgia, in relation to the levels of alexithymia. Crucially, these two conditions frequently co-occur; however, no study has explored FER considering both fibromyalgia and obesity. Studies were identified using the electronic search engine of PubMed. The last research was run on 23 July 2021. Two independent lists were generated for the two clinical conditions. Six records were reviewed about obesity, while three records about fibromyalgia. The evidence relative to FER in obesity was not conclusive, whereas the evidence about an altered FER in fibromyalgia seemed more straightforward. Moreover, the role of alexithymia on FER in these clinical conditions was not extensively investigated. In our discussion, we highlighted those factors that should be carefully addressed in investigating FER in these clinical conditions. Moreover, we underlined methodological criticisms that should be overcome in future research.

Fear conditioning and extinction in obsessive-compulsive disorder: A systematic review

Laboratory experiments using fear conditioning and extinction protocols help lay the groundwork for designing, testing, and optimizing innovative treatments for anxiety-related disorders. Yet, there is limited basic research on fear conditioning and extinction in obsessive-compulsive disorder (OCD). This is surprising because exposure-based treatments based on associative learning principles are among the most popular and effective treatment options for OCD. Here, we systematically review and critically assess existing aversive conditioning and extinction studies of OCD. Across 12 studies, there was moderate evidence that OCD is associated with abnormal acquisition of conditioned responses that differ from comparison groups. There was relatively stronger evidence of OCD's association with impaired extinction processes. This included multiple studies finding elevated conditioned responses during extinction learning and poorer threat/safety discrimination during recall, although a minority of studies yielded results inconsistent with this conclusion. Overall, the conditioning model holds value for OCD research, but more work is necessary to clarify emerging patterns of results and increase clinical translational utility to the level seen in other anxiety-related disorders. We detail limitations in the literature and suggest next steps, including modeling OCD with more complex conditioning methodology (e.g., semantic/conceptual generalization, avoidance) and improving individual-differences assessment with dimensional techniques.

Cognitive effects of rapid-acting treatments for resistant depression: Just adverse, or contributing to clinical efficacy?

Major Depressive Disorder is a major public health problem and has a high rate of treatment resistance. Fear conditioning has been proposed as a potential mechanism sustaining negative affect in mood disorders. With the aim of exploring cognitive effects of rapid-acting antidepressant treatments as a potential mechanism of action that can be targeted by neuromodulation, we performed a narrative review of the extant literature on effects of electroconvulsive therapy, ketamine or esketamine, and sleep deprivation on emotional/fear memory retrieval-reconsolidation. We explore interference with reconsolidation as a potential common pathway that explains in part the efficacy of rapid-acting antidepressant treatments with disparate mechanisms of action. We propose the testable hypothesis that fear learning circuits can be specifically targeted by neuromodulation to attempt rapid amelioration of depressive symptoms (especially repetitive negative thinking) while limiting unspecific, untoward cognitive side effects.

Generalization gradients for fear and disgust in human associative learning

Previous research indicates that excessive fear is a critical feature in anxiety disorders; however, recent studies suggest that disgust may also contribute to the etiology and maintenance of some anxiety disorders. It remains unclear if differences exist between these two threat-related emotions in conditioning and generalization. Evaluating different patterns of fear and disgust learning would facilitate a deeper understanding of how anxiety disorders develop. In this study, 32 college students completed threat conditioning tasks, including conditioned stimuli paired with frightening or disgusting images. Fear and disgust were divided into two randomly ordered blocks to examine differences by recording subjective US expectancy ratings and eye movements in the conditioning and generalization process. During conditioning, differing US expectancy ratings (fear vs. disgust) were found only on CS-, which may demonstrated that fear is associated with inferior discrimination learning. During the generalization test, participants exhibited greater US expectancy ratings to fear-related GS1 (generalized stimulus) and GS2 relative to disgust GS1 and GS2. Fear led to longer reaction times than disgust in both phases, and the pupil size and fixation duration for fear stimuli were larger than for disgust stimuli, suggesting that disgust generalization has a steeper gradient than fear generalization. These findings provide preliminary evidence for differences between fear- and disgust-related stimuli in conditioning and generalization, and suggest insights into treatment for anxiety and other fear- or disgust-related disorders.

Understanding the capture of exogenous attention by disgusting and fearful stimuli: The role of interoceptive accuracy

The aim of the study was to explore the role of interoceptive accuracy (IA) on exogenous attention to disgusting and fearful distractors of a main concurrent task. Participants were thirty university students previously identified as high (N = 16) or normal IA according their performance in a heartbeat detection task. Event-related potentials and behavioural responses were recorded. The results showed that disgusting stimuli capture exogenous attention in a first stage as reflected by the augmented amplitude of the P100 component of the ERPs in high IA participants. Fearful distractors may capture attention in a later moment in all participants as revealed by a marginally significant effect on the amplitude of N200. At behavioural level, disgusting distractors provoked a higher number of errors than neutral in normal IA participants. The time course of the effect of disgust and fearful eliciting distractors on exogenous attention appeared to depend on the individual characteristic of participants.

The Role of Disgust in Eating Disorders

PURPOSE OF REVIEW

In current review, we evaluate the current literature examining the role of disgust in eating disorders (EDs), and provide a theoretical model designed to inform the study and treatment of disgust-based symptoms in EDs.

RECENT FINDINGS

Findings from this review suggest that aberrant disgust-conditioning processes represent promising but understudied mechanisms that may contribute to the risk and maintenance of core eating disorder (ED) psychopathology. In addition, preliminary evidence supports the use of interventions designed to target aversive disgust cues and disrupt maladaptive disgust-based conditioning that may maintain eating pathology. However, experimental studies designed to elucidate the role of disgust and aversive learning processes remain limited. Disgust is a promising risk and maintenance factor in EDs. Future systematic investigation is needed to examine disgust-based processes at a mechanistic level in order to better understand the links between disgust, avoidance behaviors, and EDs. Further investigation of the mechanistic role of disgust in EDs is warranted.

Behavioral, Physiological and EEG Activities Associated with Conditioned Fear as Sensors for Fear and Anxiety

Anxiety disorders impose substantial costs upon public health and productivity in the USA and worldwide. At present, these conditions are quantified by self-report questionnaires that only apply to behaviors that are accessible to consciousness, or by the timing of responses to fear- and anxiety-related words that are indirect since they do not produce fear, e.g., Dot Probe Test and emotional Stroop. We now review the conditioned responses (CRs) to fear produced by a neutral stimulus (conditioned stimulus CS+) when it cues a painful laser unconditioned stimulus (US). These CRs include autonomic (Skin Conductance Response) and ratings of the CS+ unpleasantness, ability to command attention, and the recognition of the association of CS+ with US (expectancy). These CRs are directly related to fear, and some measure behaviors that are minimally accessible to consciousness e.g., economic scales. Fear-related CRs include non-phase-locked phase changes in oscillatory EEG power defined by frequency and time post-stimulus over baseline, and changes in phase-locked visual and laser evoked responses both of which include late potentials reflecting attention or expectancy, like the P300, or contingent negative variation. Increases (ERS) and decreases (ERD) in oscillatory power post-stimulus may be generalizable given their consistency across healthy subjects. ERS and ERD are related to the ratings above as well as to anxious personalities and clinical anxiety and can resolve activity over short time intervals like those for some moods and emotions. These results could be incorporated into an objective instrumented test that measures EEG and CRs of autonomic activity and psychological ratings related to conditioned fear, some of which are subliminal. As in the case of instrumented tests of vigilance, these results could be useful for the direct, objective measurement of multiple aspects of the risk, diagnosis, and monitoring of therapies for anxiety disorders and anxious personalities.

Protocol for a mechanistic study of mindfulness based cognitive therapy during pregnancy

OBJECTIVE

Preventive interventions for postpartum depression (PPD) are critical for women at elevated risk of PPD. Mindfulness based cognitive therapy - perinatal depression (MBCT-PD) is a preventive intervention that has been shown to reduce risk for PPD in women with a prior history of depression. The objective of this clinical trial is to examine two potential mechanisms of action of MBCT-PD, emotion regulation and cognitive control, using behavioral and neuroimaging methods.

METHOD

This baseline protocol describes a randomized control trial (RCT) with two arms, MBCT-PD and treatment as usual (TAU). We plan on enrolling 74 females with a prior history of a major depressive episode, with 37 participants randomized to each arm. Participants in the MBCT-PD arm will receive MBCT-PD during pregnancy, and the TAU group will receive standard prenatal care. All participants will complete the Center for Epidemiological Studies Depression Scale - Revised (CESD-R), Emotion Regulation Questionnaire (ERQ), and classic Stroop task at multiple points from pregnancy through six months postpartum. Participants will also complete an fMRI scan at six weeks postpartum.

RESULTS

All primary outcomes are collected at six weeks postpartum. Primary behavioral outcomes include: depressive symptoms on the CESD-R, cognitive reappraisal on the ERQ, and Stroop task performance. In parallel, the primary neurobiological outcomes include whole-brain activation during fMRI tasks when participants 1) regulate emotional responding and 2) engage cognitive control.

CONCLUSIONS

This results of this innovative RCT will help identify potential behavioral and neurobiological mechanisms of action of preventive interventions for PPD for in-depth examination in larger scale RCTs. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Effects of "Dirty" Information on Disgust Responding to an Unknown Animal in Children: The Moderating Role of Maternal Disgust Proneness

Although research has shown that disgust facilitates avoidance of small animals among adults, much less is known about disgust appraisals of small animals in children as well as the predictors of such appraisals. To address this gap, children (ages 5-13) were exposed to dirt-related and cleanliness-related information about unknown animals. The extent to which these types of information influenced children's feelings of fear, disgust, positivity, and avoidance behavior in relation to the animals was examined. The present study then examined the extent to which child and maternal disgust proneness predicted feelings of disgust to the 'dirty' animal. The findings show that providing dirt-related information resulted in a significant increase in disgust, but not fear, responding to the animal. Dirt-related information also resulted in a significant decrease in positive feelings toward the animal. Conversely, providing cleanliness-related information resulted in a significant decrease in disgust, but not fear, responding to the animal. In addition, providing cleanliness-related information resulted in a significant increase in positive feelings toward the animal. Children also engage in more avoidance of the animal described as dirty compared to the animal described as clean. In addition, subsequent analysis revealed an interaction between child and maternal disgust propensity in predicting learned disgust to the dirty animal such that the highest levels of feelings of disgust to the dirty animal were observed among children with high disgust proneness who also have mothers with high disgust proneness. The implications of these findings for conceptualizing the role of disgust in animal phobias among youth will be discussed.

Linking Pavlovian Disgust Conditioning and Eating Disorder Symptoms: An Analogue Study

Although the experience of disgust is commonly endorsed among women with eating disorders, it remains unclear how to best model this emotion in relation to disordered eating. The present study sought to identify potential disgust conditioning abnormalities that may underlie the development of eating disorder symptoms. Individuals high and low in eating disorder symptoms (HED, n = 19; LED, n = 18) completed a Pavlovian conditioning procedure in which one neutral food item (conditioned stimulus; CS+) was followed by disgusting videos of individuals vomiting (unconditioned stimulus; US) and another neutral food item (CS-) was not reinforced with the disgusting video. Following this acquisition procedure, there was an extinction procedure in which both CSs were presented unreinforced. The results showed that ratings of disgust, fear, and willingness to eat the CS+ and CS- did not significantly vary as a function of the conditioning phase for the LED group. However, the HED group rated the CS+ as significantly more disgusting and fear inducing than the CS- after the acquisition phase and this pattern persisted after extinction. These conditioning effects were also observed to be significantly larger for disgust compared to fear. The HED group also reported being significantly less willing to eat the CS+ compared to the CS- after the acquisition phase and this pattern also persisted after extinction. In the full sample, only discriminant disgust responding after acquisition was associated with the amount of calorie consumption over the 24-hour period after conditioning. These findings suggest that eating disorder symptoms may result from a heightened proneness to associate disgusting outcomes with otherwise neutral food items. This pattern of disgust learning may reinforce food avoidance in eating disorders and appears to be difficult to fully unlearn.

The relationship between neuroticism and appetitive conditioning

Appetitive conditioning is considered a central mechanism for the vulnerability to psychiatric disorders. However, the investigation of individual differences that are related to altered appetitive learning has been almost neglected so far. The aim of this study was to investigate the link between neuroticism and appetitive conditioning processes. 79 subjects participated in a differential conditioning procedure in which a conditioned stimulus (CS+) was paired with a reward (money) after a fast behavioral response, while a second conditioned stimulus (CS-) was never followed by a reward, irrespective of the behavioral response. As a main result, neuroticism correlated negatively with the underlying neural processes of appetitive conditioning in females, but not in males. In detail, higher levels of neuroticism were associated with decreased neural responses in the left (p = .001) and right amygdala (p = .011), left (p = .063) and right (p = .019) nucleus accumbens, and left (p = .002) and right (p = .021) orbitofrontal cortex (all results are family-wise-error-corrected). The present results support previous findings, which also showed an inverse sex-specific effect in the context of neuroticism and emotional processing in females. In addition, the findings suggest that neuroticism is not solely linked to increased amygdala sensitivity during the processing of negative stimuli but also to decreased neural responses when processing rewarding stimuli. Possible explanations for the sex differences and implications are discussed.

Emotional expressions associated with therapeutic inertia in multiple sclerosis care

BACKGROUND

Emotions play a critical role in our daily decisions. However, it remains unclear how and what sort of emotional expressions are associated with therapeutic decisions in multiple sclerosis (MS) care. Our goal was to evaluate the relationship between emotions and affective states (as captured by muscle facial activity and emotional expressions) and TI amongst neurologists caring for MS patients when making therapeutic decisions.

METHODS

38 neurologists with expertise in MS were invited to participate in a face-to-face study across Canada. Participants answered questions regarding their clinical practice, aversion to ambiguity, and the management of 10 simulated case-scenarios. TI was defined as lack of treatment initiation or escalation when there was clear evidence of clinical and radiological disease activity. We recorded facial muscle activations and their associated emotional expressions during the study, while participants made therapeutic choices. We used a validated machine learning algorithm of the AFFDEX software to code for facial muscle activations and a predefined mapping to emotional expressions (disgust, fear, surprise, etc.). Mixed effects models and mediation analyses were used to evaluate the relationship between ambiguity aversion, facial muscle activity/emotional expressions and TI measured as a binary variable and a continuous score.

RESULTS

34 (89.4%) neurologists completed the study. The mean age [standard deviation (SD)] was 44.6 (11.5) years; 38.3% were female and 58.8% self-identified as MS specialists. Overall, 17 (50%) participants showed TI in at least one case-scenario and the mean (SD) TI score was 0.74 (0.90). Nineteen (55.9%) participants had aversion to ambiguity in the financial domain. The multivariate analysis adjusted for age, sex and MS expertise showed that aversion to ambiguity in the financial domain (OR 1.56, 95%CI 1.32-1.86) was associated with TI. Most common muscle activations included mouth open (23.4%), brow furrow (20.9%), brow raise (17.6%), and eye widening (13.1%). Most common emotional expressions included fear (5.1%), disgust (3.2%), sadness (2.9%), and surprise (2.8%). After adjustment for age, sex, and physicians' expertise, the multivariate analysis revealed that brow furrow (OR 1.04; 95%CI 1.003-1.09) and lip suck (OR 1.06; 95%CI 1.01-1.11) were associated with an increase in TI prevalence, whereas upper lip raise (OR 0.30; 95%CI 0.15-0.59), and chin raise (OR 0.90; 95%CI 0.83-0.98) were associated with lower likelihood of TI. Disgust and surprise were associated with a lower TI score (disgust: p < 0.001; surprise: p = 0.008) and lower prevalence of TI (OR_disgust: 0.14, 95%CI 0.03-0.65; OR_surprise: 0.66, 94%CI 0.47-0.92) after adjusting for covariates. The mediation analysis showed that brow furrow was a partial mediator explaining 21.2% (95%CI 14.9%-38.9%) of the association between aversion to ambiguity and TI score, followed by nose wrinkle 12.8% (95%CI 8.9%-23.4%). Similarly, disgust was the single emotional expression (partial mediator) that attenuated (-13.2%, 95%CI -9.2% to -24.3%) the effect of aversion to ambiguity on TI.

CONCLUSIONS

TI was observed in half of participants in at least one case-scenario. Our data suggest that facial metrics (e.g. brow furrow, nose wrinkle) and emotional expressions (e.g. disgust) are associated with physicians' choices and partially mediate the effect of aversion to ambiguity on TI.

Evidence of prefrontal hyperactivation to food-cue reversal learning in adolescents with anorexia nervosa

Food avoidance in anorexia nervosa (AN) has been hypothesized to occur as a result of deficits in reversal learning and altered neuronal processing of food-cue relationships. Extant findings suggest that those with AN may rely on heightened recruitment of prefrontal regions during initial formation of food-cue learning and difficulty extinguishing these relationships may result from elevated insula activity. We tested this hypothesis by comparing behavioral and neuronal responses to food-cue acquisition and reversal between adolescents with AN and healthy controls. Compared to controls, acquisition of a food-cue association and its reversal were associated with elevated prefrontal activation in adolescents with AN. There were no significant differences between groups in insula activation and no behavioral differences in the ability to acquire or reverse the food-cue association. The results suggest that adolescents with AN recruit prefrontal regulatory networks to acquire and alter expectancies to food. This pattern of top-down prefrontal control suggests that clinical interventions that target changes in food-cue relationships and rely on cognitive control may be less effective. Interventions that alter behavior without reliance on this top-down control may have advantages with this population.

Neural correlates of deception: lying about past events and personal beliefs

Although a growing body of literature suggests that cognitive control processes are involved in deception, much about the neural correlates of lying remains unknown. In this study, we tested whether brain activation associated with deception, as measured by functional magnetic resonance imaging (fMRI), can be detected either in preparation for or during the execution of a lie, and whether they depend on the content of the lie. We scanned participants while they lied or told the truth about either their personal experiences (episodic memories) or personal beliefs. Regions in the frontal and parietal cortex showed higher activation when participants lied compared with when they were telling the truth, regardless of whether they were asked about their past experiences or opinions. In contrast, lie-related activation in the right temporal pole, precuneus and the right amygdala differed by the content of the lie. Preparing to lie activated parietal and frontal brain regions that were distinct from those activated while participants executed lies. Our findings concur with previous reports on the involvement of frontal and parietal regions in deception, but specify brain regions involved in the preparation vs execution of deception, and those involved in deceiving about experiences vs opinions.

Selecting pure-emotion materials from the International Affective Picture System (IAPS) by Chinese university students: A study based on intensity-ratings only

There is a need to use selected pictures with pure emotion as stimulation or treatment media for basic and clinical research. Pictures from the widely-used International Affective Picture System (IAPS) contain rich emotions, but no study has clearly stated that an emotion is exclusively expressed in its putative IAPS picture to date. We hypothesize that the IAPS images contain at least pure vectors of disgust, erotism (or erotica), fear, happiness, sadness and neutral emotions. Accordingly, we have selected 108 IAPS images, each with a specific emotion, and invited 219 male and 274 female university students to rate only the intensity of the emotion conveyed in each picture. Their answers were analyzed using exploratory and confirmatory factor analysis. Four first-order factors manifested as disgust-fear, happiness-sadness, erotism, and neutral. Later, ten second-order sub-factors manifested as mutilation-disgust, vomit-disgust, food-disgust, violence-fear, happiness, sadness, couple- erotism, female-erotism, male- erotism, and neutral. Fifty-nine pictures for the ten sub-factors, which had established good model-fit indices, satisfactory sub-factor internal reliabilities, and prominent gender-differences in the picture intensity ratings were ultimately retained. We thus have selected a series of pure-emotion IAPS pictures, which together displayed both satisfactorily convergent and discriminant structure-validities. We did not intend to evaluate all IAPS items, but instead selected some pictures conveying pure emotions, which might help both basic and clinical researches in the future.

Identification and intensity of disgust: Distinguishing visual, linguistic and facial expressions processing in Parkinson disease

OBJECTIVES & METHODS

Most of the studies since now show an impairment for facial displays of disgust recognition in Parkinson disease. A general impairment in disgust processing in patients with Parkinson disease might adversely affect their social interactions, given the relevance of this emotion for human relations. However, despite the importance of faces, disgust is also expressed through other format of visual stimuli such as sentences and visual images. The aim of our study was to explore disgust processing in a sample of patients affected by Parkinson disease, by means of various tests tackling not only facial recognition but also other format of visual stimuli through which disgust can be recognized.

RESULTS

Our results confirm that patients are impaired in recognizing facial displays of disgust. Further analyses show that patients are also impaired and slower for other facial expressions, with the only exception of happiness. Notably however, patients with Parkinson disease processed visual images and sentences as controls.

CONCLUSIONS

Our findings show a dissociation within different formats of visual stimuli of disgust, suggesting that Parkinson disease is not characterized by a general compromising of disgust processing, as often suggested. The involvement of the basal ganglia-frontal cortex system might spare some cognitive components of emotional processing, related to memory and culture, at least for disgust.

Pavlovian disgust conditioning as a model for contamination-based OCD: Evidence from an analogue study

Pavlovian fear conditioning provides a model for anxiety-related disorders, including obsessive-compulsive disorder (OCD). However, disgust is the predominant emotional response to contamination, which is a common theme in OCD. The present study sought to identify disgust conditioning abnormalities that may underlie excessive contamination concerns relevant to OCD. Individuals high and low in contamination concern (HCC, n = 32; LCC, n = 30) completed an associative learning task in which one neutral face (conditioned stimulus; CS+) was followed by a disgusting image (unconditioned stimulus; US) and another neutral face (CS-) was unreinforced. Following this acquisition procedure, there was an extinction procedure in which both CSs were presented unreinforced. The groups did not show significant differences in discriminant responding to the CSs following acquisition. However, following extinction, the HCC group reported less reduction in their expectancy of the US following the CS+, and also reported greater disgust to the CS+, compared to the LCC group. Increased disgust to the CS+ following both acquisition and extinction was correlated with increased symptoms of contamination-based OCD and increased disgust sensitivity. Additionally, disgust sensitivity mediated group differences in disgust responding to the CS+ at acquisition and extinction. Also, failure to adjust US expectancy in response to extinction partially mediated group differences in disgust to the CS+ following extinction. Together, these findings suggest that excessive contamination concerns observed in OCD may be related to difficulty inhibiting acquired disgust, possibly due to elevated disgust sensitivity that characterizes the disorder.

Cognitive emotion regulation modulates the balance of competing influences on ventral striatal aversive prediction error signals

Cognitive emotion regulation (CER) is a critical human ability to face aversive emotional stimuli in a flexible way, via recruitment of specific prefrontal brain circuits. Animal research reveals a central role of ventral striatum in emotional behavior, for both aversive conditioning, with striatum signaling aversive prediction errors (aPE), and for integrating competing influences of distinct striatal inputs from regions such as the prefrontal cortex (PFC), amygdala, hippocampus and ventral tegmental area (VTA). Translating these ventral striatal findings from animal research to human CER, we hypothesized that successful CER would affect the balance of competing influences of striatal afferents on striatal aPE signals, in a way favoring PFC as opposed to 'subcortical' (i.e., non-isocortical) striatal inputs. Using aversive Pavlovian conditioning with and without CER during fMRI, we found that during CER, superior regulators indeed reduced the modulatory impact of 'subcortical' striatal afferents (hippocampus, amygdala and VTA) on ventral striatal aPE signals, while keeping the PFC impact intact. In contrast, inferior regulators showed an opposite pattern. Our results demonstrate that ventral striatal aPE signals and associated competing modulatory inputs are critical mechanisms underlying successful cognitive regulation of aversive emotions in humans.

Neuroticism and extraversion moderate neural responses and effective connectivity during appetitive conditioning

Classical appetitive conditioning constitutes a basic learning process through which environmental stimuli can be associated with reward. Previous studies showed that individual differences in neuroticism and extraversion influence emotional processing and have been shown to modulate neural activity in subcortical and prefrontal areas in response to emotional stimuli. However, the role of individual differences in appetitive conditioning has so far not been investigated in detail. The aim of this study was to assess the association between neuroticism and extraversion with neural activity and connectivity during appetitive conditioning. The conditioned stimulus (CS) was either a picture of a dish or a cup. One stimulus (CS+) was paired with a monetary reward and the other stimulus (CS-) was associated with its absence while hemodynamic activity was measured by means of functional magnetic resonance imaging. A significant negative correlation of neuroticism scores with amygdala activity was observed during appetitive conditioning. Further, extraversion was positively associated with responses in the hippocampus and the thalamus. In addition, effective connectivity between the amygdala as a seed region and the anterior cingulate cortex, the insula, and the thalamus was negatively correlated with neuroticism scores and positively correlated with extraversion scores. The results may indicate a neural correlate for the deficits in appetitive learning in subjects with high neuroticism scores and point to a facilitating effect of extraversion on reward-related learning. Hum Brain Mapp 37:2992-3002, 2016. © 2016 Wiley Periodicals, Inc.

Neural signatures of human fear conditioning: an updated and extended meta-analysis of fMRI studies

Classical Pavlovian fear conditioning remains the most widely employed experimental model of fear and anxiety, and continues to inform contemporary pathophysiological accounts of clinical anxiety disorders. Despite its widespread application in human and animal studies, the neurobiological basis of fear conditioning remains only partially understood. Here we provide a comprehensive meta-analysis of human fear-conditioning studies carried out with functional magnetic resonance imaging (fMRI), yielding a pooled sample of 677 participants from 27 independent studies. As a distinguishing feature of this meta-analysis, original statistical brain maps were obtained from the authors of 13 of these studies. Our primary analyses demonstrate that human fear conditioning is associated with a consistent and robust pattern of neural activation across a hypothesized genuine network of brain regions resembling existing anatomical descriptions of the 'central autonomic-interoceptive network'. This finding is discussed with a particular emphasis on the neural substrates of conscious fear processing. Our associated meta-analysis of functional deactivations-a scarcely addressed dynamic in fMRI fear-conditioning studies-also suggests the existence of a coordinated brain response potentially underlying the 'safety signal' (that is, non-threat) processing. We attempt to provide an integrated summary on these findings with the view that they may inform ongoing studies of fear-conditioning processes both in healthy and clinical populations, as investigated with neuroimaging and other experimental approaches.

Altered Appetitive Conditioning and Neural Connectivity in Subjects With Compulsive Sexual Behavior

INTRODUCTION

There has been growing interest in a better understanding of the etiology of compulsive sexual behavior (CSB). It is assumed that facilitated appetitive conditioning might be an important mechanism for the development and maintenance of CSB, but no study thus far has investigated these processes.

AIM

To explore group differences in neural activity associated with appetitive conditioning and connectivity in subjects with CSB and a healthy control group.

METHODS

Two groups (20 subjects with CSB and 20 controls) were exposed to an appetitive conditioning paradigm during a functional magnetic resonance imaging experiment, in which a neutral stimulus (CS+) predicted visual sexual stimuli and a second stimulus (CS-) did not.

MAIN OUTCOME MEASURES

Blood oxygen level-dependent responses and psychophysiologic interaction.

RESULTS

As a main result, we found increased amygdala activity during appetitive conditioning for the CS+ vs the CS- and decreased coupling between the ventral striatum and prefrontal cortex in the CSB vs control group.

CONCLUSION

The findings show that neural correlates of appetitive conditioning and neural connectivity are altered in patients with CSB. The increased amygdala activation might reflect facilitated conditioning processes in patients with CSB. In addition, the observed decreased coupling could be interpreted as a marker for impaired emotion regulation success in this group.

Nociceptive Local Field Potentials Recorded from the Human Insula Are Not Specific for Nociception

The insula, particularly its posterior portion, is often regarded as a primary cortex for pain. However, this interpretation is largely based on reverse inference, and a specific involvement of the insula in pain has never been demonstrated. Taking advantage of the high spatiotemporal resolution of direct intracerebral recordings, we investigated whether the human insula exhibits local field potentials (LFPs) specific for pain. Forty-seven insular sites were investigated. Participants received brief stimuli belonging to four different modalities (nociceptive, vibrotactile, auditory, and visual). Both nociceptive stimuli and non-nociceptive vibrotactile, auditory, and visual stimuli elicited consistent LFPs in the posterior and anterior insula, with matching spatial distributions. Furthermore, a blind source separation procedure showed that nociceptive LFPs are largely explained by multimodal neural activity also contributing to non-nociceptive LFPs. By revealing that LFPs elicited by nociceptive stimuli reflect activity unrelated to nociception and pain, our results confute the widespread assumption that these brain responses are a signature for pain perception and its modulation.

Local field potentials elicited in the human insular cortex by painful stimuli reflect cortical activity that is unrelated to pain perception and so cannot be used as an objective measure of pain.

A widely accepted notion is that the insula, especially its posterior portion, plays a specific role in the perception of pain. This has led a number of researchers to consider activity recorded from this so-called “ouch zone” as an objective correlate of pain perception. We provide compelling evidence to the contrary. Using direct intracerebral recordings, we demonstrate that painful and nonpainful stimuli elicit very similar responses throughout the human insula. This observation argues against the notion that these responses reflect the brain activity through which pain emerges from nociception in the human brain. These findings have implications for basic theories, as well as for the development of diagnostic tests and the identification of therapeutic targets for the treatment of chronic pain. They question the use of these insular responses to assess the effects of pharmacological treatment or to assess pain in patients unable to communicate. Furthermore, they have legal implications, as they contradict the proposal that these responses could be used to determine unequivocally whether plaintiffs are truly experiencing the pain for which they are seeking redress. Finally, they undermine the rationale for neurosurgical procedures aiming at alleviating pain by targeting the posterior insula.

SPIDER OR NO SPIDER? NEURAL CORRELATES OF SUSTAINED AND PHASIC FEAR IN SPIDER PHOBIA

BACKGROUND

Processes of phasic fear responses to threatening stimuli are thought to be distinct from sustained, anticipatory anxiety toward an unpredicted, potential threat. There is evidence for dissociable neural correlates of phasic fear and sustained anxiety. Whereas increased amygdala activity has been associated with phasic fear, sustained anxiety has been linked with activation of the bed nucleus of stria terminalis (BNST), anterior cingulate cortex (ACC), and the insula. So far, only a few studies have focused on the dissociation of neural processes related to both phasic and sustained fear in specific phobia. We suggested that first, conditions of phasic and sustained fear would involve different neural networks and, second, that overall neural activity would be enhanced in a sample of phobic compared to nonphobic participants.

METHODS

Pictures of spiders and neutral stimuli under conditions of either predicted (phasic) or unpredicted (sustained) fear were presented to 28 subjects with spider phobia and 28 nonphobic control subjects during functional magnetic resonance imaging (fMRI) scanning.

RESULTS

Phobic patients revealed significantly higher amygdala activation than controls under conditions of phasic fear. Sustained fear processing was significantly related to activation in the insula and ACC, and phobic patients showed a stronger activation than controls of the BNST and the right ACC under conditions of sustained fear. Functional connectivity analysis revealed enhanced connectivity of the BNST and the amygdala in phobic subjects.

CONCLUSIONS

Our findings support the idea of distinct neural correlates of phasic and sustained fear processes. Increased neural activity and functional connectivity in these networks might be crucial for the development and maintenance of anxiety disorders.

A multi-pathway hypothesis for human visual fear signaling

A hypothesis is proposed for five visual fear signaling pathways in humans, based on an analysis of anatomical connectivity from primate studies and human functional connectvity and tractography from brain imaging studies. Earlier work has identified possible subcortical and cortical fear pathways known as the "low road" and "high road," which arrive at the amygdala independently. In addition to a subcortical pathway, we propose four cortical signaling pathways in humans along the visual ventral stream. All four of these traverse through the LGN to the visual cortex (VC) and branching off at the inferior temporal area, with one projection directly to the amygdala; another traversing the orbitofrontal cortex; and two others passing through the parietal and then prefrontal cortex, one excitatory pathway via the ventral-medial area and one regulatory pathway via the ventral-lateral area. These pathways have progressively longer propagation latencies and may have progressively evolved with brain development to take advantage of higher-level processing. Using the anatomical path lengths and latency estimates for each of these five pathways, predictions are made for the relative processing times at selective ROIs and arrival at the amygdala, based on the presentation of a fear-relevant visual stimulus. Partial verification of the temporal dynamics of this hypothesis might be accomplished using experimental MEG analysis. Possible experimental protocols are suggested.

Increased skin conductance responses and neural activity during fear conditioning are associated with a repressive coping style

The investigation of individual differences in coping styles in response to fear conditioning is an important issue for a better understanding of the etiology and treatment of psychiatric disorders. It has been assumed that an avoidant (repressive) coping style is characterized by increased emotion regulation efforts in context of fear stimuli as compared to a more vigilant coping style. However, no study so far has investigated the neural correlates of fear conditioning of repressors and sensitizers. In the present fMRI study, 76 participants were classified as repressors or as sensitizers and were exposed to a fear conditioning paradigm, in which the CS+ predicted electrical stimulation, while another neutral stimulus (CS-) did not. In addition, skin conductance responses (SCRs) were measured continuously. As the main findings, we found increased neural activity in repressors as compared to sensitizers in the ventromedial prefrontal cortex and the anterior cingulate cortex (ACC) during fear conditioning. In addition, elevated activity to the CS+ in amygdala, insula, occipital, and orbitofrontal cortex (OFC) as well as elevated conditioned SCRs were found in repressors. The present results demonstrate increased neural activations in structures linked to emotion down-regulation mechanisms like the ventromedial prefrontal cortex, which may reflect the increased coping effort in repressors. At the same time, repressors showed increased activations in arousal and evaluation-associated structures like the amygdala, the occipital cortex (OCC), and the OFC, which was mirrored in increased SCRs. The present results support recent assumptions about a two-process model of repression postulating a fast vigilant response to fear stimuli, and a second process associated with the down-regulation of emotional responses.

The association between the 5-HTTLPR and neural correlates of fear conditioning and connectivity

Strong evidence links the 5-HTTLPR genotype to the modulation of amygdala reactivity during fear conditioning, which is considered to convey the increased vulnerability for anxiety disorders in s-allele carriers. In addition to amygdala reactivity, the 5-HTTLPR has been shown to be related to alterations in structural and effective connectivity. The aim of this study was to investigate the effects of 5-HTTLPR genotype on amygdala reactivity and effective connectivity during fear conditioning, as well as structural connectivity [as measured by diffusion tensor imaging (DTI)]. To integrate different classification strategies, we used the bi-allelic (s-allele vs l/l-allele group) as well as the tri-allelic (low-functioning vs high-functioning) classification approach. S-allele carriers showed exaggerated amygdala reactivity and elevated amygdala-insula coupling during fear conditioning (CS + > CS-) compared with the l/l-allele group. In addition, DTI analysis showed increased fractional anisotropy values in s-allele carriers within the uncinate fasciculus. Using the tri-allelic classification approach, increased amygdala reactivity and amygdala insula coupling were observed in the low-functioning compared with the high-functioning group. No significant differences between the two groups were found in structural connectivity. The present results add to the current debate on the influence of the 5-HTTLPR on brain functioning. These differences between s-allele and l/l-allele carriers may contribute to altered vulnerability for psychiatric disorders.

Toward sophisticated basal ganglia neuromodulation: Review on basal ganglia deep brain stimulation

This review presents state-of-the-art knowledge about the roles of the basal ganglia (BG) in action-selection, cognition, and motivation, and how this knowledge has been used to improve deep brain stimulation (DBS) treatment of neurological and psychiatric disorders. Such pathological conditions include Parkinson's disease, Huntington's disease, Tourette syndrome, depression, and obsessive-compulsive disorder. The first section presents evidence supporting current hypotheses of how the cortico-BG circuitry works to select motor and emotional actions, and how defects in this circuitry can cause symptoms of the BG diseases. Emphasis is given to the role of striatal dopamine on motor performance, motivated behaviors and learning of procedural memories. Next, the use of cutting-edge electrochemical techniques in animal and human studies of BG functioning under normal and disease conditions is discussed. Finally, functional neuroimaging studies are reviewed; these works have shown the relationship between cortico-BG structures activated during DBS and improvement of disease symptoms.

Brain activation associated with pride and shame

BACKGROUND

Self-referential emotions such as shame/guilt and pride provide evaluative information about persons themselves. In addition to emotional aspects, social and self-referential processes play a role in self-referential emotions. Prior studies have rather focused on comparing self-referential and other-referential processes of one valence, triggered mostly by external stimuli. In the current study, we aimed at investigating the valence-specific neural correlates of shame/guilt and pride, evoked by the remembrance of a corresponding autobiographical event during functional magnetic resonance imaging.

METHOD

A total of 25 healthy volunteers were studied. The task comprised a negative (shame/guilt), a positive (pride) and a neutral condition (expecting the distractor). Each condition was initiated by a simple cue, followed by the remembrance and finished by a distracting picture.

RESULTS

Pride and shame/guilt conditions both activated typical emotion-processing circuits including the amygdala, insula and ventral striatum, as well as self-referential brain regions such as the bilateral dorsomedial prefrontal cortex. Comparing the two emotional conditions, emotion-processing circuits were more activated by pride than by shame, possibly due to either hedonic experiences or stronger involvement of the participants in positive self-referential emotions due to a self-positivity bias. However, the ventral striatum was similarly activated by pride and shame/guilt. In the whole-brain analysis, both self-referential emotion conditions activated medial prefrontal and posterior cingulate regions, corresponding to the self-referential aspect and the autobiographical evocation of the respective emotions.

CONCLUSION

Autobiographically evoked self-referential emotions activated basic emotional as well as self-referential circuits. Except for the ventral striatum, emotional circuits were more active with pride than with shame.

Impact of COMT Val158Met-polymorphism on appetitive conditioning and amygdala/prefrontal effective connectivity

Appetitive conditioning is an important mechanism for the development, maintenance, and treatment of psychiatric disorders like substance abuse. Therefore, it is important to identify genetic variations, which impact appetitive conditioning. It has been suggested that the Val(158) Met-polymorphism in the Catechol-O-Methyl-Transferase (COMT) is associated with the alteration of neural processes of appetitive conditioning due to the central role of the dopaminergic system in reward processing. However, no study has so far investigated the relationship between variations in the COMT Val(158) Met-polymorphism and appetitive conditioning. In this fMRI study, an appetitive conditioning paradigm was applied, in which one neutral stimulus (CS+) predicted appetitive stimuli (UCS) while a second neutral stimulus (CS-) was never paired with the UCS. As a main result, we observed a significant association between the COMT Val(158) Met-genotype and appetitive conditioning: skin conductance responses (SCRs) revealed a significant difference between CS+ and CS- in Val/Val-allele carriers but not in the other genotype groups. Val/Val-allele carriers showed increased hemodynamic responses in the amygdala compared with the Met/Met-allele group in the contrast CS+ > CS-. In addition, psychophysiological-interaction analysis revealed increased effective amygdala/ventromedial prefrontal cortex connectivity in Met/Met-allele carriers. The increased amygdala activity points to facilitated appetitive conditioning in Val/Val-allele carriers while the amygdala/prefrontal connectivity results could be regarded as a marker for altered emotion regulation during conditioning, which potentially impacts appetitive learning sensitivity. The SCRs finding indicates a stronger conditioned response in the Val/Val-allele group and dovetails with the neural differences between the groups. These findings contribute to the current research on COMT in emotional processing.

Hemodynamic Response Pattern of Spatial Cueing is Different for Social and Symbolic Cues

Directional social gaze and symbolic arrow cues both serve as spatial cues, causing seemingly reflexive shifts of an observer's attention. However, the underlying neural substrates remain a point at issue. The present study specifically addressed the differences in the activation patterns associated with non-predictive gaze and arrow cues, placing special emphasis on brain regions known to be involved in the processing of social information [superior temporal sulcus (STS), fusiform gyrus (FFG)]. Additionally, the functional connectivity of these brain regions with other areas involved in gaze processing and spatial attention was investigated. Results indicate that gaze and arrow cues recruit several brain regions differently, with gaze cues increasing activation in occipito-temporal regions and arrow cues increasing activation in occipito-parietal regions. Specifically, gaze cues in contrast to arrow cues enhanced activation in the FFG and the STS. Functional connectivity analysis revealed that during gaze cueing the STS was more strongly connected to the intraparietal sulcus (IPS) and the frontal eye fields, whereas the FFG was more strongly connected to the IPS and the amygdala.

Excessive disgust caused by brain lesions or temporary inactivations: mapping hotspots of the nucleus accumbens and ventral pallidum

Disgust is a prototypical type of negative affect. In animal models of excessive disgust, only a few brain sites are known in which localized dysfunction (lesions or neural inactivations) can induce intense 'disgust reactions' (e.g. gapes) to a normally pleasant sensation such as sweetness. Here, we aimed to map forebrain candidates more precisely, to identify where either local neuronal damage (excitotoxin lesions) or local pharmacological inactivation (muscimol/baclofen microinjections) caused rats to show excessive sensory disgust reactions to sucrose. Our study compared subregions of the nucleus accumbens shell, ventral pallidum, lateral hypothalamus, and adjacent extended amygdala. The results indicated that the posterior half of the ventral pallidum was the only forebrain site where intense sensory disgust gapes in response to sucrose were induced by both lesions and temporary inactivations (this site was previously identified as a hedonic hotspot for enhancements of sweetness 'liking'). By comparison, for the nucleus accumbens, temporary GABA inactivations in the caudal half of the medial shell also generated sensory disgust, but lesions never did at any site. Furthermore, even inactivations failed to induce disgust in the rostral half of the accumbens shell (which also contains a hedonic hotspot). In other structures, neither lesions nor inactivations induced disgust as long as the posterior ventral pallidum remained spared. We conclude that the posterior ventral pallidum is an especially crucial hotspot for producing excessive sensory disgust by local pharmacological/lesion dysfunction. By comparison, the nucleus accumbens appears to segregate sites for pharmacological disgust induction and hedonic enhancement into separate posterior and rostral halves of the medial shell.

Taste and olfactory status in a gourmand with a right amygdala lesion

In a patient with a lesion of the right amygdala and temporal pole who had the characteristics of the gourmand syndrome, sensory and hedonic testing was performed to examine the processing of taste, olfactory, and some emotional stimuli. The gourmand syndrome describes a preoccupation with food and a preference for fine eating and is associated with right anterior lesions. It was found that the taste thresholds for sweet, salt, bitter, and sour were normal; that the patient did not dislike the taste of salt (NaCl) at low and moderate concentrations as much as age-matched controls; that this also occurred for monosodium glutamate (MSG); that there were some olfactory differences from normal controls; and that there was a marked reduction in the ability to detect face expressions of disgust.

Neural network underlying ictal pouting ("chapeau de gendarme") in frontal lobe epilepsy

In order to determine the anatomical neural network underlying ictal pouting (IP), with the mouth turned down like a "chapeau de gendarme", in frontal lobe epilepsy (FLE), we reviewed the video-EEG recordings of 36 patients with FLE who became seizure-free after surgery. We selected the cases presenting IP, defined as a symmetrical and sustained (>5s) lowering of labial commissures with contraction of chin, mimicking an expression of fear, disgust, or menace. Ictal pouting was identified in 11 patients (8 males; 16-48 years old). We analyzed the clinical semiology, imaging, and electrophysiological data associated with IP, including FDG-PET in 10 and SEEG in 9 cases. In 37 analyzed seizures (2-7/patient), IP was an early symptom, occurring during the first 10s in 9 cases. The main associated features consisted of fear, anguish, vegetative disturbances, behavioral disorders (sudden agitation, insults, and fighting), tonic posturing, and complex motor activities. The epileptogenic zone assessed by SEEG involved the mesial frontal areas, especially the anterior cingulate cortex (ACC) in 8 patients, whereas lateral frontal onset with an early spread to the ACC was seen in the other patient. Ictal pouting associated with emotional changes and hypermotor behavior had high localizing value for rostroventral "affective" ACC, whereas less intense facial expressions were related to the dorsal "cognitive" ACC. Fluorodeoxyglucose positron emission tomography demonstrated the involvement of both the ACC and lateral cortex including the anterior insula in all cases. We propose that IP is sustained by reciprocal mesial and lateral frontal interactions involved in emotional and cognitive processes, in which the ACC plays a pivotal role.

Neural responses to subliminally presented cannabis and other emotionally evocative cues in cannabis-dependent individuals

RATIONALE

Addiction theories posit that drug-related cues maintain and contribute to drug use and relapse. Indeed, our recent study in cocaine-dependent patients demonstrated that subliminally presented cocaine-related stimuli activate reward neurocircuitry without being consciously perceived. Activation of reward neurocircuitry may provoke craving and perhaps prime an individual for subsequent drug-seeking behaviors.

OBJECTIVES

Using an equivalent paradigm, we tested whether cannabis cues activate reward neurocircuitry in treatment-seeking, cannabis-dependent individuals and whether activation was associated with relevant behavioral anchors: baseline cannabis craving (drug-seeking behavior) and duration of use (degree of conditioning).

METHODS

Twenty treatment-seeking, cannabis-dependent individuals (12 males) underwent event-related blood oxygen level-dependent functional magnetic resonance imaging during exposure to 33-ms cannabis, sexual, and aversive cues presented in a backward-masking paradigm. Drug use history and cannabis craving were assessed prior to imaging.

RESULTS

Participants showed increased activity to backward-masked cannabis cues in regions supporting reward detection and interoception, including the left anterior insula, left ventral striatum/amygdala, and right ventral striatum. Cannabis cue-related activity in the bilateral insula and perigenual anterior cingulate cortex was positively associated with baseline cannabis craving, and cannabis cue-related activity in the medial orbitofrontal cortex was positively correlated with years of cannabis use. Neural responses to backward-masked sexual cues were similar to those observed during cannabis cue exposure, while activation to aversive cues was observed only in the left anterior insula and perigenual anterior cingulate cortex.

CONCLUSIONS

These data highlight the sensitivity of the brain to subliminal reward signals and support hypotheses promoting a common pathway of appetitive motivation.

Learning to like disgust: neuronal correlates of counterconditioning

Converging lines of research suggest that exaggerated disgust responses play a crucial role in the development and maintenance of certain anxiety disorders. One strategy that might effectively alter disgust responses is counterconditioning. In this study, we used functional magnetic resonance imaging (fMRI) to examine if the neuronal bases of disgust responses are altered through a counterconditioning procedure. One disgust picture (conditioned stimulus: CS+_disg) announced a monetary reward, while a second disgust picture (CS-_disg) was never paired with the reward. Two neutral control pictures (CS+_con/CS-_con) were conditioned in the same manner. Analyses of evaluative conditioning showed that both CS+ were rated significantly more positive after conditioning as compared to the corresponding CS−. Thereby, the CS+_disg and the CS+_con received an equal increase in valence ratings. Regarding the fMRI data, ANOVA results showed main effects of the conditioning procedure (i.e., CS+ vs. CS−) in the dorsal anterior cingulate cortex. Further, main effects of the picture category (disgust vs. control) were found in the bilateral insula and the orbitofrontal cortex. No interaction effects were detected. In conclusion, the results imply that learning and anticipation of reward was not significantly influenced by the disgust content of the CS pictures. This suggests that the affect induced by the disgust pictures and the affect created by the anticipation of reward may not influence the processing of each other.