Unpredictable threat increases early event-related potential amplitudes and cardiac acceleration: A brain-heart coupling study.

In the face of unpredictable threat, rapid processing of external events and behavioral mobilization through early psychophysiological responses are crucial for survival. While unpredictable threat generally enhances early processing, it would seem adaptive to particularly increase sensitivity for unexpected events as they may signal danger. To examine this possibility, n = 77 participants performed an auditory oddball paradigm and received unpredictable shocks in threat but not in safe contexts while a stream of frequent (standard) and infrequent (deviant) tones was presented. We assessed event-related potentials (ERP), heart period (HP), and time-lagged within-subject correlations of single-trial EEG and HP (cardio-EEG covariance tracing, CECT) time-locked to the tones. N1 and P2 ERP amplitudes were generally enhanced under threat. The P3 amplitude was enhanced to deviants versus standards and this effect was reduced in the threat condition. Regarding HP, both threat versus safe and unexpected versus expected tones led to stronger cardiac acceleration, suggesting separate effects of threat and stimulus expectancy on HP. Finally, CECTs revealed two correlation clusters, indicating that single-trial EEG magnitudes in the N1/P2 and P3 time-windows predicted subsequent cardiac acceleration. The current results show that an unpredictable threat context enhances N1 and P2 amplitudes and cardiac acceleration to benign auditory stimuli. They further suggest separable cortical correlates of different effects on cardiac activity: an early N1/P2 correlate associated with threat-effects on HP and a later P3 correlate associated with expectedness-effects. Finally, the results indicate that unpredictable threat attenuates rather than enhances the processing of unexpected benign events during the P3 latency.

Strengthening the US Public Health Lab System: Summary of Coronavirus Disease (COVID-19) After Action Review Workshop.

CONTEXT: The COVID-19 pandemic highlighted the significance of public health laboratories across the United States, while also revealing weaknesses in the laboratory system. OBJECTIVE: To identify actionable recommendations for building a more resilient public health laboratory system based on previously published lessons learned from COVID-19. DESIGN, SETTING, AND PARTICIPANTS: In April 2023, the Association of Public Health Laboratories, in cooperation with RAND , convened a 1.5-day after action review workshop of approximately 30 public health laboratory stakeholders to reevaluate priorities, improve processes, and affect policies. MAIN OUTCOME MEASURES: Analysis of workshop discussions identified 5 priority areas and 19 recommendations related to clarifying laboratories' unique role and promoting workforce capacity/agility, technology, and collaboration with governmental and nongovernmental partners. RESULTS: Within the identified priority areas, workshop participants described how the recommendations would address challenges encountered during COVID-19 and contribute to strengthening the system. CONCLUSIONS: As the risk of novel infectious diseases persists and grows, the importance of maintaining laboratory response capabilities is likely to increase. Addressing the system's weaknesses will require active engagement of laboratories and the many stakeholders who depend on them, along with consistent, adequate funding to strengthen and sustain capabilities.

The influence of psychological traits and prior experience on treatment expectations.

BACKGROUND: Placebo and nocebo responses are modulated by the treatment expectations of participants and patients. However, interindividual differences predicting treatment expectations and placebo responses are unclear. In this large-scale pooled analysis, we aim to investigate the influence of psychological traits and prior experiences on treatment expectations. METHODS: This paper analyses data from six different placebo studies (total n = 748). In all studies, participants' sociodemographic information, treatment expectations and prior treatment experiences and traits relating to stress, somatization, depression and anxiety, the Big Five and behavioral inhibition and approach tendencies were assessed using the same established questionnaires. Correlation coefficients and structural equation models were calculated to investigate the relationship between trait variables and expectations. RESULTS: We found small positive correlations between side effect expectations and improvement expectations (r = 0.187), perceived stress (r = 0.154), somatization (r = 0.115), agitation (r = 0.108), anhedonia (r = 0.118), and dysthymia (r = 0.118). In the structural equation model previous experiences emerged as the strongest predictors of improvement (ß = 0.32, p = .005), worsening (ß = -0.24, p = .005) and side effect expectations (ß = 0.47, p = .005). Traits related to positive affect (ß = - 0.09; p = .007) and negative affect (ß = 0.04; p = .014) were associated with side effect expectations. DISCUSSION: This study is the first large analysis to investigate the relationship between traits, prior experiences and treatment expectations. Exploratory analyses indicate that experiences of symptom improvement are associated with improvement and worsening expectations, while previous negative experiences are only related to side effect expectations. Additionally, a proneness to experience negative affect may be a predictor for side effect expectation and thus mediate the occurrence of nocebo responses.

Alpha-2 Adrenoreceptor Antagonist Yohimbine Potentiates Consolidation of Conditioned Fear.

BACKGROUND: Hyperconsolidation of aversive associations and poor extinction learning have been hypothesized to be crucial in the acquisition of pathological fear. Previous animal and human research points to the potential role of the catecholaminergic system, particularly noradrenaline and dopamine, in acquiring emotional memories. Here, we investigated in a between-participants design with 3 groups whether the noradrenergic alpha-2 adrenoreceptor antagonist yohimbine and the dopaminergic D2-receptor antagonist sulpiride modulate long-term fear conditioning and extinction in humans. METHODS: Fifty-five healthy male students were recruited. The final sample consisted of n = 51 participants who were explicitly aware of the contingencies between conditioned stimuli (CS) and unconditioned stimuli after fear acquisition. The participants were then randomly assigned to 1 of the 3 groups and received either yohimbine (10 mg, n = 17), sulpiride (200 mg, n = 16), or placebo (n = 18) between fear acquisition and extinction. Recall of conditioned (non-extinguished CS+ vs CS-) and extinguished fear (extinguished CS+ vs CS-) was assessed 1 day later, and a 64-channel electroencephalogram was recorded. RESULTS: The yohimbine group showed increased salivary alpha-amylase activity, confirming a successful manipulation of central noradrenergic release. Elevated fear-conditioned bradycardia and larger differential amplitudes of the N170 and late positive potential components in the event-related brain potential indicated that yohimbine treatment (compared with a placebo and sulpiride) enhanced fear recall during day 2. CONCLUSIONS: These results suggest that yohimbine potentiates cardiac and central electrophysiological signatures of fear memory consolidation. They thereby elucidate the key role of noradrenaline in strengthening the consolidation of conditioned fear associations, which may be a key mechanism in the etiology of fear-related disorders.

Learning dynamics of electrophysiological brain signals during human fear conditioning.

Electrophysiological studies in rodents allow recording neural activity during threats with high temporal and spatial precision. Although fMRI has helped translate insights about the anatomy of underlying brain circuits to humans, the temporal dynamics of neural fear processes remain opaque and require EEG. To date, studies on electrophysiological brain signals in humans have helped to elucidate underlying perceptual and attentional processes, but have widely ignored how fear memory traces evolve over time. The low signal-to-noise ratio of EEG demands aggregations across high numbers of trials, which will wash out transient neurobiological processes that are induced by learning and prone to habituation. Here, our goal was to unravel the plasticity and temporal emergence of EEG responses during fear conditioning. To this end, we developed a new sequential-set fear conditioning paradigm that comprises three successive acquisition and extinction phases, each with a novel CS+/CS- set. Each set consists of two different neutral faces on different background colors which serve as CS+ and CS-, respectively. Thereby, this design provides sufficient trials for EEG analyses while tripling the relative amount of trials that tap into more transient neurobiological processes. Consistent with prior studies on ERP components, data-driven topographic EEG analyses revealed that ERP amplitudes were potentiated during time periods from 33-60 ms, 108-200 ms, and 468-820 ms indicating that fear conditioning prioritizes early sensory processing in the brain, but also facilitates neural responding during later attentional and evaluative stages. Importantly, averaging across the three CS+/CS- sets allowed us to probe the temporal evolution of neural processes: Responses during each of the three time windows gradually increased from early to late fear conditioning, while long-latency (460-730 ms) electrocortical responses diminished throughout fear extinction. Our novel paradigm demonstrates how short-, mid-, and long-latency EEG responses change during fear conditioning and extinction, findings that enlighten the learning curve of neurophysiological responses to threat in humans.

Fear Extinction Recall Modulates Human Frontomedial Theta and Amygdala Activity.

Human functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) studies, as well as animal studies, indicate that the amygdala and frontomedial brain regions are critically involved in conditioned fear and that frontomedial oscillations in the theta range (4-8 Hz) may support communication between these brain regions. However, few studies have used a multimodal approach to probe interactions among these key regions in humans. Here, our goal was to bridge the gap between prior human fMRI, EEG, and animal findings. Using simultaneous EEG-fMRI recordings 24 h after fear conditioning and extinction, conditioned stimuli presented (CS+E, CS-E) and not presented during extinction (CS+N, CS-N) were compared to identify effects specific to extinction versus fear recall. Differential (CS+ vs. CS-) electrodermal, frontomedial theta (EEG) and amygdala responses (fMRI) were reduced for extinguished versus nonextinguished stimuli. Importantly, effects on theta power covaried with effects on amygdala activation. Fear and extinction recall as indicated by theta explained 60% of the variance for the analogous effect in the right amygdala. Our findings show for the first time the interplay of amygdala and frontomedial theta activity during fear and extinction recall in humans and provide insight into neural circuits consistently linked with top-down amygdala modulation in rodents.

Aversive Imagery Causes De Novo Fear Conditioning.

In classical fear conditioning, neutral conditioned stimuli that have been paired with aversive physical unconditioned stimuli eventually trigger fear responses. Here, we tested whether aversive mental images systematically paired with a conditioned stimulus also cause de novo fear learning in the absence of any external aversive stimulation. In two experiments (N = 45 and N = 41), participants were first trained to produce aversive, neutral, or no imagery in response to three different visual-imagery cues. In a subsequent imagery-based differential-conditioning paradigm, each of the three cues systematically coterminated with one of three different neutral faces. Although the face that was paired with the aversive-imagery cue was never paired with aversive external stimuli or threat-related instructions, participants rated it as more arousing, unpleasant, and threatening and displayed relative fear bradycardia and fear-potentiated startle. These results could be relevant for the development of fear and related disorders without trauma.

Fearfulness, neuroticism/anxiety, and COMT Val158Met in long-term fear conditioning and extinction.

Individual differences in long-term stability of fear memories are of potential relevance for stable dispositions related to threat processing, such as neuroticism/anxiety and fearfulness. As previous research suggests a prominent role of dopamine for the retention of conditioned and extinguished fear, dopaminergic gene polymorphisms may also relate to individual differences in fear stability. While the COMT Val158Met polymorphism causes individual differences in prefrontal dopamine, its associations with human long-term fear extinction are currently unknown. Here, n = 30/29/28 healthy male Val/Val, Val/Met and Met/Met carriers, respectively, underwent a two-day differential conditioning paradigm with fear acquisition and extinction on Day 1 and a recall test on Day 2 with recordings of EEG and ECG. Fearfulness but not neuroticism/anxiety predicted fear bradycardia (i.e., heart period slowing) during Day 1 fear acquisition while it did not affect extinction or Day 2 fear recall. In contrast, COMT Val158Met significantly modulated Day 2 fear recall as evident in fear bradycardia and Late Positive Potential (LPP) amplitudes while it did not affect Day 1 fear or extinction learning. Furthermore, exploratory analyses revealed that individual differences in fear bradycardia during Day 2 extinction recall depended on Day 1 extinction success. Importantly, this contingency was (a) modulated by COMT Val158Met and (b) significantly reduced in high vs. low neuroticism/anxiety. The present study indicates that (a) individual differences in dopaminergic genotypes may affect the long-term stability of fear memories and (b) fearfulness vs. neuroticism/anxiety might play distinct roles in initial fear reactions vs. long-term stability of fear memories, respectively.

Prefrontal oscillations during recall of conditioned and extinguished fear in humans.

Human neuroimaging studies indicate that the anterior midcingulate cortex (AMC) and the ventromedial prefrontal cortex (vmPFC) play important roles in the expression and extinction of fear, respectively. Electrophysiological rodent studies further indicate that oscillatory neuronal activity in homolog regions (i.e., prelimbic and infralimbic cortices) changes during fear expression and fear extinction recall. Whether similar processes occur in humans remains largely unexplored. By assessing scalp surface EEG in conjunction with LORETA source estimation of CS-related theta and gamma activity, we tested whether a priori defined ROIs in the human AMC and vmPFC similarly modulate their oscillatory activity during fear expression and extinction recall, respectively. To this end, 42 healthy individuals underwent a differential conditioning/differential extinction protocol with a Recall Test on the next day. In the Recall Test, nonextinguished versus extinguished stimuli evoked an increased differential (CS(+) vs CS(-)) response with regard to skin conductance and AMC-localized theta power. Conversely, extinguished versus nonextinguished stimuli evoked an increased differential response with regard to vmPFC-localized gamma power. Finally, individuals who failed to show a suppressed skin conductance response to the extinguished versus nonextinguished CS(+) also failed to show the otherwise observed alterations in vmPFC gamma power to extinguished CS(+). These results indicate that fear expression is associated with AMC theta activity, whereas successful fear extinction recall relates to changes in vmPFC gamma activity. The present work thereby bridges findings from prior rodent electrophysiological research and human neuroimaging studies and indicates that EEG is a valuable tool for future fear extinction research.

EMOTION-PROCESSING BIASES AND RESTING EEG ACTIVITY IN DEPRESSED ADOLESCENTS.

BACKGROUND: Although theorists have posited that adolescent depression is characterized by emotion-processing biases (greater propensity to identify sad than happy facial expressions), findings have been mixed. Additionally, the neural correlates associated with putative emotion-processing biases remain largely unknown. Our aim was to identify emotion-processing biases in depressed adolescents and examine neural abnormalities related to these biases using high-density resting EEG and source localization. METHODS: Healthy (n = 36) and depressed (n = 23) female adolescents, aged 13-18 years, completed a facial recognition task in which they identified happy, sad, fear, and angry expressions across intensities from 10% (low) to 100% (high). Additionally, 128-channel resting (i.e., task-free) EEG was recorded and analyzed using a distributed source localization technique (low-resolution electromagnetic tomography (LORETA)). Given research implicating the dorsolateral prefrontal cortex (DLPFC) in depression and emotion processing, analyses focused on this region. RESULTS: Relative to healthy youth, depressed adolescents were more accurate for sad and less accurate for happy, particularly low-intensity happy faces. No differences emerged for fearful or angry facial expressions. Further, LORETA analyses revealed greater theta and alpha current density (i.e., reduced brain activity) in depressed versus healthy adolescents, particularly in the left DLPFC (BA9/BA46). Theta and alpha current density were positively correlated, and greater current density predicted reduced accuracy for happy faces. CONCLUSION: Depressed female adolescents were characterized by emotion-processing biases in favor of sad emotions and reduced recognition of happiness, especially when cues of happiness were subtle. Blunted recognition of happy was associated with left DLPFC resting hypoactivity.

Potentiated processing of negative feedback in depression is attenuated by anhedonia.

BACKGROUND: Although cognitive theories of depression have postulated enhanced processing of negatively valenced information, previous EEG studies have shown both increased and reduced sensitivity for negative performance feedback in MDD. To reconcile these paradoxical findings, it has been speculated that sensitivity for negative feedback is potentiated in moderate MDD, but reduced in highly anhedonic subjects. The goal of this study was to test this hypothesis by analyzing the feedback-related negativity (FRN), frontomedial theta power (FMT), and source-localized anterior midcingulate cortex (aMCC) activity after negative feedback. METHODS: Fourteen unmedicated participants with Major Depressive Disorder (MDD) and 15 control participants performed a reinforcement learning task while 128-channel Electroencephalogram (EEG) was recorded. FRN, FMT, and LORETA source-localized aMCC activity after negative and positive feedback were compared between groups. RESULTS: The MDD group showed higher FRN amplitudes and aMCC activation to negative feedback than controls. Moreover, aMCC activation to negative feedback was inversely related to self-reported anhedonia. In contrast, self-reported anxiety correlated with feedback-evoked frontomedial theta (FMT) within the depression group. CONCLUSIONS: The present findings suggest that, among depressed and anxious individuals, enhanced processing of negative feedback occurs relatively early in the information processing stream. These results extend prior work and indicate that although moderate depression is associated with elevated sensitivity for negative feedback, high levels of anhedonia may attenuate this effect.

Dopamine modulates frontomedial failure processing of agentic introverts versus extraverts in incentive contexts.

The agency facet of extraversion (aE) describes individual differences in goal-directed behavior and has been linked to dopamine function in incentive contexts. Because dopamine presumably modulates the processing of negative feedback/failure, aE may relate to failure processing in incentive contexts. To test this hypothesis, N = 86 participants performed a virtual ball-catching task. An incentive context was created by displaying potential rewards and subtle manipulations of task performance, which either was (control group) or was not (incentive context group) made explicit. To probe the involvement of dopamine, participants received either placebo or the selective dopamine D2 receptor antagonist sulpiride (200 mg). Failure processing was assessed through negative-feedback-evoked differences in the frontal midline theta electroencephalogram power (DFMT) and in the feedback-related negativity event-related potential component (FRN). Before incentives were introduced, DFMT (but not the FRN) was related to neuroticism/anxiety. Importantly, once incentives were displayed, aE was associated with DFMT, FRN, task performance, and changes in self-reported positive affect, which further depended on incentive context group and/or substance group: In the incentive context group but not in the control group, agentic extraverts showed relatively blunted DFMT after placebo. Sulpiride significantly enhanced DFMT, whereas it reduced FRN amplitudes and performance in agentic extra- versus introverts. These findings provide strong support for current dopamine models of aE and failure processing, and also highlight the importance of task context. Moreover, the dissociations of FRN and DFMT suggest the existence of two nonredundant electrophysiological indices of feedback processing, both relating to dopamine and aE.

Uncertainty of treatment efficacy moderates placebo effects on reinforcement learning.

The placebo-reward hypothesis postulates that positive effects of treatment expectations on health (i.e., placebo effects) and reward processing share common neural underpinnings. Moreover, experiments in humans and animals indicate that reward uncertainty increases striatal dopamine, which is presumably involved in placebo responses and reward learning. Therefore, treatment uncertainty analogously to reward uncertainty may affect updating from rewards after placebo treatment. Here, we address whether different degrees of uncertainty regarding the efficacy of a sham treatment affect reward sensitivity. In an online between-subjects experiment with N = 141 participants, we systematically varied the provided efficacy instructions before participants first received a sham treatment that consisted of listening to binaural beats and then performed a probabilistic reinforcement learning task. We fitted a Q-learning model including two different learning rates for positive (gain) and negative (loss) reward prediction errors and an inverse gain parameter to behavioral decision data in the reinforcement learning task. Our results yielded an inverted-U-relationship between provided treatment efficacy probability and learning rates for gain, such that higher levels of treatment uncertainty, rather than of expected net efficacy, affect presumably dopamine-related reward learning. These findings support the placebo-reward hypothesis and suggest harnessing uncertainty in placebo treatment for recovering reward learning capabilities.

The association of dispositional anxiety with the NoGo N2 under relaxation instruction vs. speed/accuracy instruction.

Prior research suggests that cognitive control, indicated by NoGo N2 amplitudes in Go/NoGo tasks, is associated with dispositional anxiety. This negative association tends to be reduced in anxiety-enhancing experimental conditions. However, anxiety-reducing conditions have not yet been investigated systematically. Thus, the present study compares the effect of a relaxation instruction with the conventional speed/accuracy instruction in a Go/NoGo task on the correlation of the NoGo N2 with two subconstructs of dispositional anxiety, namely anxious apprehension and anxious arousal. As the test of differences between correlations needs considerable statistical power, the present study was included into the multi-lab CoScience Project. The hypotheses, manipulation checks, and the main path of pre-processing and statistical analysis were preregistered. Complete data sets of 777 participants were available for data analysis. Preregistered general linear models revealed that the different instructions of the task (speed/accuracy vs. relaxation) had no effect on the association between dispositional anxiety and the NoGo N2 amplitude in general. This result was supported by Cooperative-Forking-Path analysis. In contrast, a preregistered latent growth model with categorical variables revealed that anxious arousal was a negative predictor of the NoGo N2 intercept and a positive predictor of the NoGo N2 slope. Non-preregistered growth models, allowing for correlations of anxious apprehension with anxious arousal, revealed that higher anxious apprehension scores were associated with more negative NoGo N2 amplitudes with increased relaxation. Results are discussed in the context of the compensatory error monitoring hypothesis and the revised Reinforcement Sensitivity Theory.

Dopamine-d2-receptor blockade reverses the association between trait approach motivation and frontal asymmetry in an approach-motivation context.

Individual differences in the behavioral approach system (BAS)-referred to as trait approach motivation or trait BAS)-have been linked to both frontal electroencephalogram (EEG) alpha asymmetry between left and right hemispheres (frontal alpha asymmetry) and brain dopamine. However, evidence directly linking frontal alpha asymmetry and dopamine is scarce. In the present study, female experimenters recorded EEG data in 181 male participants after double-blind administration of either a placebo or a dopamine D2 blocker. As expected, trait BAS was associated with greater left- than right-frontal cortical activity (i.e., greater right- than left-frontal EEG alpha) in the placebo group, but a reversed association emerged in the dopamine-blocker group. Furthermore, frontal alpha asymmetry was associated with a genetic variant known to modulate prefrontal dopamine levels (the catechol-O-methyltransferase Val158Met polymorphism). Finally, each of these effects was significant only in the subgroup of male participants interacting with female experimenters rated as most attractive; this finding suggests that associations between frontal alpha asymmetry and both dopamine and trait BAS are detectable only in approach-motivation contexts.

Dissociable feedback valence effects on frontal midline theta during reward gain versus threat avoidance learning.

While frontal midline theta (FMθ) has been associated with threat processing, with cognitive control in the context of anxiety, and with reinforcement learning, most reinforcement learning studies on FMθ have used reward rather than threat-related stimuli as reinforcer. Accordingly, the role of FMθ in threat-related reinforcement learning is largely unknown. Here, n = 23 human participants underwent one reward-, and one punishment-, based reversal learning task, which differed only with regard to the kind of reinforcers that feedback was tied to (i.e., monetary gain vs. loud noise burst, respectively). In addition to single-trial EEG, we assessed single-trial feedback expectations based on both a reinforcement learning computational model and trial-by-trial subjective feedback expectation ratings. While participants' performance and feedback expectations were comparable between the reward and punishment tasks, FMθ was more reliably amplified to negative vs. positive feedback in the reward vs. punishment task. Regressions with feedback valence, computationally derived, and self-reported expectations as predictors and FMθ as criterion further revealed that trial-by-trial variations in FMθ specifically relate to reward-related feedback-valence and not to threat-related feedback or to violated expectations/prediction errors. These findings suggest that FMθ as measured in reinforcement learning tasks may be less sensitive to the processing of events with direct relevance for fear and anxiety.

Dopamine effects on human error processing depend on catechol-O-methyltransferase VAL158MET genotype.

Brain dopamine (DA) has been linked to error processing. Because high and low (vs medium) prefrontal cortex (PFC) DA levels may facilitate D2-receptor-related modulations of PFC neural activation patterns, we hypothesized that high and low DA predicts increased error-specific transitions of PFC activity. Male human participants (n = 169) were genotyped for the catechol-O-methyltransferase (COMT) Val158Met polymorphism, associated with low (Val) and medium (Met) PFC DA levels. In addition, DRD2TaqIa and 5-HTTLPR, associated with striatal D(2) receptor density and serotonin uptake, respectively, were assessed. Participants received placebo or a selective DA-D(2) receptor blocker (sulpiride, 200 mg) and performed a Flanker task. EEG was recorded and decomposed into independent brain components (ICs) using independent component analysis. After errors, participants displayed (1) a negative deflection in ICs source-localized to the proximity of the anterior midcingulate cortex [IC-error-related negativity (IC-ERN)], (2) increased midcingulate cortex IC power in the delta/theta frequency range, and (3) slowing in the subsequent trial [posterror slowing (PES)]. Importantly, all, IC-ERN, delta/theta power, and PES were modulated by COMT × Substance interactions such that the Val allele predicted elevated IC-ERN, delta/theta power, and PES after placebo; this association was reversed under sulpiride. Because low doses of sulpiride presumably increase PFC DA levels, the COMT × Substance interaction supports the hypothesis that low (Val, placebo) and high (Met, sulpiride) versus medium (Val, sulpiride; Met, placebo) DA levels elevate reactivity to errors. Consistent with an influence of serotonin on PFC DA, the COMT × Substance interaction was modulated by 5-HTTLPR.

The role of mindful acceptance and lucid dreaming in nightmare frequency and distress.

A theoretical and empirical association between lucid dreaming and mindfulness, as well as lucid dreaming and nightmares has previously been observed; however, the relationship between nightmares and mindfulness has received surprisingly little attention. Here, we present the findings of two studies exploring the relation of nightmare frequency and distress with two components of mindfulness, termed presence and acceptance, as well as lucid dreaming. Study 1 (N = 338) consisted of a low percentage of frequent lucid dreamers whereas Study 2 (N = 187) consisted primarily of frequent lucid dreamers that used lucid dream induction training techniques and meditation. Across studies, nightmare-related variables showed a more robust association with mindful acceptance as opposed to mindful presence. Moreover, individuals with high levels of meditation expertise and practice of lucid dreaming induction techniques reported lower nightmare frequency. Finally, in Study 2, which consisted of frequent lucid dreamers, a positive correlation between lucid dreaming frequency and mindfulness was apparent. The present findings support the notion that wakeful mindfulness is associated with the quality of dreams and extend previous research by suggesting a disentangled role of the two facets of mindfulness in dream variation. This association remains open for experimental manipulation, the result of which could have clinical implications.

Nightmare Distress Questionnaire: associated factors.

STUDY OBJECTIVES: The diagnosis of a nightmare disorder is based on clinically significant distress caused by the nightmares, eg, sleep or mood disturbances during the day. The question what factors might be associated with nightmare distress in addition to nightmares frequency is not well studied. METHODS: Overall, 1,474 persons (893 women, 581 men) completed an online survey. Nightmare distress was measured with the Nightmare Distress Questionnaire. RESULTS: The findings indicated that nightmare distress, measured by the Nightmare Distress Questionnaire, correlated with a variety of factors in addition to nightmare frequency: neuroticism, female sex, low education, extraversion, low agreeableness, and sensation seeking. Moreover, the percentage of replicative trauma-related nightmares was also associated with higher nightmare distress. CONCLUSIONS: A large variety of factors are associated with nightmare distress, a finding that is of clinical importance. The construct harm avoidance, however, was not helpful in explaining interindividual differences in nightmare distress. Furthermore, the relationship between nightmare distress and other factors, eg, education or agreeableness, is not yet understood.

Cardiac response in aversive and appetitive olfactory conditioning: Evidence for a valence-independent CS-elicited bradycardia.

While the examination of conditioned cardiac responses is well established in human fear conditioning research, comparable studies using less-aversive or rather appetitive unconditioned stimuli (UCS) are sparse and results are mixed. Therefore, the aim of this study was a systematic analysis of cardiac reactions in aversive and appetitive conditioning. Olfactory stimuli were used as unconditioned stimuli as they are suitable reinforcers in both an aversive and an appetitive conditioning offering the opportunity for a comparison between conditioned responses. In total, n = 86 participants took part in both an aversive and an appetitive differential conditioning task with a counterbalanced order across participants. Aversive or appetitive odors, respectively, served as UCS and neutral geometrical figures as CS. Subjective ratings, skin conductance response (SCRs), and evoked cardiac reactions were analyzed and compared between tasks. Conditioned responses in subjective ratings could be observed in both aversive conditioning and appetitive conditioning, while SCRs discriminated between CS+ and CS- in aversive conditioning only. Regarding conditioned cardiac responses, the deceleration for the CS+ was longer than for the CS- in both tasks. In addition, a higher deceleration magnitude and a shorter acceleration for the CS+ as compared to the CS- were found in aversive but not in appetitive conditioning. There were medium-size correlations between aversive and appetitive CRs for subjective ratings and none for physiological responses. The results suggest similarities between cardiac response patterns in aversive and appetitive conditioning, which implies that bradycardia in conditioning might not be fear-specific but presents a valence-independent CS-elicited bradycardia.