Empirically based comparisons of the reliability and validity of common quantification approaches for eyeblink startle potentiation in humans

Effects of cannabidiol on fear conditioning in anxiety disorders: decreased threat expectation during retention, but no enhanced fear re-extinction

RATIONALE

Preclinical research suggests that pharmacologically elevating cannabinoid levels may attenuate fear memory expression and enhance fear extinction.

OBJECTIVES

We studied the effects of cannabidiol (CBD) on fear memory expression and fear re-extinction in 69 patients with panic disorder with agoraphobia or with social anxiety disorder. Moderation by sex, diagnosis, and serotonergic antidepressant (AD) use was explored.

METHODS

A cued fear conditioning paradigm was applied before the first treatment session with 300 mg CBD/placebo augmented exposure therapy. Study medication was administered orally preceding 8 weekly sessions. Fear acquisition and suboptimal extinction took place prior to the first medication ingestion (T0). After the first medication ingestion (T1), we investigated effects on fear memory expression at retention and fear re-extinction. Subjective fear, shock expectancy, skin conductance, and startle responses to conditioned (CS+) and safety stimulus (CS-) were measured.

RESULTS

Across the sample, CBD reduced shock expectancy at retention under low and ambiguous threat of shock, but fear re-extinction at T1 was unaffected by CBD. However, in AD users, re-extinction of subjective fear was impaired in the CBD condition compared to placebo. In female AD users, CBD interfered with safety learning measured with fear-potentiated startle.

CONCLUSIONS

The current findings provide no evidence for enhanced fear re-extinction by CBD. However, CBD acutely decreased threat expectation at retention, without affecting other indices of fear. More studies are needed to elucidate possible interactions with AD use and sex, as well as potential effects of CBD on threat expectancies.

Neigh G, Jovanovic T, Michopoulos V. HIV Interacts with Posttraumatic Stress Disorder to Impact Fear Psychophysiology in Trauma-Exposed Black Women

Background

The prevalence of posttraumatic stress disorder (PTSD) among people living with HIV (PLWH) is higher than in the general population and can impact health behaviors. The influence of HIV on PTSD psychophysiology requires further investigation due to implications for the treatment of PTSD in PLWH.

Objective

Utilizing fear-potentiated startle (FPS), we aimed to interrogate the influence of PTSD and HIV on fear responses.

Materials and Methods

Women (18-65 years of age) recruited from the Women's Interagency HIV Study in Atlanta, GA (n = 70, 26 without HIV and 44 with HIV), provided informed consent and completed a semistructured interview to assess trauma exposure and PTSD symptom severity. Participants also underwent an FPS paradigm to assess fear acquisition and extinction: Psychophysiological indices that measure how individuals learn new fear and then subsequently attempt to suppress this fear.

Results

Women with PTSD, who did not have HIV, exhibited a greater startle response compared to women without PTSD or HIV during late acquisition to both the danger cue, reinforced conditioned stimulus (CS+, p = 0.013)), and the safety cue, non-reinforced conditioned stimulus (CS-, p = 0.046)), whereas women living with HIV (WLH) and PTSD demonstrated blunted fear responses compared to women with PTSD only. During extinction, WLH comorbid with PTSD exhibited an increased fear response during the extinction period in comparison to all other groups (p = 0.023). Women without PTSD demonstrated a reduction in the fear response during extinction regardless of HIV status.

Conclusion

Our findings indicate that HIV further modifies fear psychophysiology in WLH with comorbid PTSD, highlighting the importance of considering HIV status in conjunction with PTSD treatment.

Whose Signals Are Being Amplified? Toward a More Equitable Clinical Psychophysiology

Research using psychophysiological methods holds great promise for refining clinical assessment, identifying risk factors, and informing treatment. Unfortunately, unique methodological features of existing approaches limit inclusive research participation and, consequently, generalizability. This brief overview and commentary provides a snapshot of the current state of representation in clinical psychophysiology, with a focus on the forms and consequences of ongoing exclusion of Black participants. We illustrate issues of inequity and exclusion that are unique to clinical psychophysiology, considering intersections among social constructions of Blackness and biased design of current technology used to measure electroencephalography, skin conductance, and other signals. We then highlight work by groups dedicated to quantifying and addressing these limitations. We discuss the need for reflection and input from a wider variety of stakeholders to develop and refine new technologies, given the risk of further widening disparities. Finally, we provide broad recommendations for clinical psychophysiology research.

Unconditioned response to a naturally aversive stimulus is associated with sensitized defensive responding and self-reported fearful traits in a PTSD sample

Unconditioned responding (UCR) to a naturally aversive stimulus is associated with defensive responding to a conditioned threat cue (CS+) and a conditioned safety cue (CS-) in trauma-exposed individuals during fear acquisition. However, the relationships of UCR with defensive responses during extinction training, posttraumatic stress disorder (PTSD) symptom severity, and fearful traits in trauma-exposed individuals are not known. In a sample of 100 trauma-exposed adults with a continuum of PTSD severity, we recorded startle responses and skin conductance responses (SCR) during fear acquisition and extinction training using a 140 psi, 250-ms air blast to the larynx as the unconditioned stimulus. We explored dimensional associations of two different measures of UCR (unconditioned startle and unconditioned SCR) with conditioned defensive responding to CS+ and CS-, conditioned fear (CS+ minus CS-), PTSD symptom severity, and a measure of fearful traits (composite of fear survey schedule, anxiety sensitivity index, and Connor-Davidson resilience scale). Unconditioned startle was positively associated with startle potentiation to the threat cue and the safety cue across both learning phases (CS+ Acquisition, CS- Acquisition, CS+ Extinction Training, CS- Extinction Training) and with fearful traits. Unconditioned SCR was positively associated with SCR to the CS+ and CS- and SCR difference score during Acquisition. Neither type of UCR was associated with PTSD symptom severity. Our findings suggest that UCR, particularly unconditioned startle to a naturally aversive stimulus, may inform research on biomarkers and treatment targets for symptoms of pervasive and persistent fear in trauma-exposed individuals.

The interactive effects of different facets of threat uncertainty and cognitive load in shaping fear and anxiety responses

A large body of research indicates that exaggerated response to uncertainty of a future threat is at the core of anxiety and related disorders, underscoring the need for a better understanding of the underlying mechanisms. Although behavioral and neuroimaging studies have suggested a close relationship between uncertainty responses and cognitive control, little is known about what elements of uncertainty are more or less vulnerable to cognitive modulation in shaping aversive responses. Leveraging a novel paradigm, an n-back working memory task embedded within a modified threat-of-shock paradigm, we examined how the influences of different facets of uncertainty (i.e., occurrence and timing) on psychophysiological responses were modulated by cognitive load. Psychophysiological responses were assessed using the acoustic startle reflex. Replicating prior work, the effects of cognitive load and temporal unpredictability of threat on startle responses were evident. The effect of occurrence unpredictability appears to depend on other factors. Under low cognitive load, startle response was potentiated when both the occurrence and the timing of threat were predictable. Under high cognitive load, startle response was significantly reduced, especially when a threat context involves uncertainty in both temporal and probability domains. These observations provide a framework for refining the model of fear and anxiety and for understanding the etiology of psychological disorders characterized by maladaptive uncertainty responses.

Pre-Learning Stress That Is Temporally Removed from Acquisition Impairs Fear Learning

Few studies have examined the time-dependent effects of stress on fear learning. Previously, we found that stress immediately before fear conditioning enhanced fear learning. Here, we aimed to extend these findings by assessing the effects of stress 30 min prior to fear conditioning on fear learning and fear generalization. Two hundred and twenty-one healthy adults underwent stress (socially evaluated cold pressor test) or a control manipulation 30 min before completing differential fear conditioning in a fear-potentiated startle paradigm. One visual stimulus (CS+), but not another (CS-), was associated with an aversive airblast to the throat (US) during acquisition. The next day, participants were tested for their fear responses to the CS+, CS-, and several generalization stimuli. Stress impaired the acquisition of fear on Day 1 but had no significant impact on fear generalization. The stress-induced impairment of fear learning was particularly evident in participants who exhibited a robust cortisol response to the stressor. These findings are consistent with the notion that stress administered 30 min before learning impairs memory formation via corticosteroid-related mechanisms and may help us understand how fear memories are altered in stress-related psychological disorders.

Fear-potentiated startle reveals diminished threat extinction in pathological anxiety

BACKGROUND

Major theories propose that perturbed threat learning is central to pathological anxiety, but empirical support is inconsistent. Failures to detect associations with anxiety may reflect limitations in quantifying conditioned responses to anticipated threat, and hinder translation of theory into empirical work. In prior work, we could not detect threat-specific anxiety effects on states of conditioned threat using psychophysiology in a large sample of patients and healthy comparisons. Here, we examine the utility of an alternative fear potentiated startle (FPS) scoring in revealing associations between anxiety and threat conditioning and extinction in this dataset. Secondary analyses further explored associations among conditioned threat responses, subcortical morphometry, and treatment outcomes.

METHODS

Youths and adults with anxiety disorders and healthy comparisons (n = 306; 178 female participants; 8-50 years) previously completed a well-validated differential threat learning paradigm. FPS and skin conductance response (SCR) quantified psychophysiological responses during threat conditioning and extinction. In this report, we examined normalizing raw FPS scores to intertrial intervals (ITI) to address challenges in more common approaches to FPS scoring which could mask group effects. Secondary analyses examined associations between FPS and subcortical morphometry and with response to exposure-based cognitive behavioral therapy in a subsample of patients.

RESULTS

Patients and comparisons showed comparable differential threat conditioning using FPS and SCR. While SCR suggested comparable extinction between groups, FPS revealed stronger retention of threat contingency during extinction in individuals with anxiety disorders. Extinction indexed with FPS was not associated with age, morphometry, or anxiety treatment outcome.

CONCLUSION

ITI-normalized FPS may have utility in detecting difficulties in extinguishing conditioned threat responses in anxiety. These findings provide support for extinction theories of anxiety and encourage continued research on aberrant extinction in pathological anxiety.

Childhood Maltreatment in Females Is Associated with Enhanced Fear Acquisition and an Overgeneralization of Fear

Childhood maltreatment may alter fear neurocircuitry, which results in pathological anxiety and depression. One alteration of fear-related behaviors that has been observed in several psychiatric populations is an overgeneralization of fear. Thus, we examined the association between childhood maltreatment and fear generalization in a non-clinical sample of young adults. Two hundred and ninety-one participants underwent differential fear conditioning in a fear-potentiated startle paradigm. One visual stimulus (CS+), but not another (CS-), was associated with an aversive airblast to the throat (US) during acquisition. The next day, participants were tested for their fear responses to the CS+, CS-, and several generalization stimuli (GS) without the presence of the US. Participants also completed questionnaires that assessed symptoms of childhood maltreatment, anxiety, depression, and post-traumatic stress disorder (PTSD). Participants reporting high childhood maltreatment (n = 71; 23 males, 48 females) exhibited significantly greater anxiety, depression, and symptoms of PTSD than participants reporting low childhood maltreatment (n = 220; 133 males, 87 females). Females reporting high childhood maltreatment demonstrated significantly enhanced fear learning and greater fear generalization, based on their fear-potentiated startle responses. Our findings suggest that childhood maltreatment may sex-dependently influence the development of fear neurocircuitry and result in greater fear generalization in maltreated females.

Alcohol's effects during uncertain and uncontrollable stressors in the laboratory

Alcohol's effects on reactivity to stressors depends on the nature of the stressor and the reactivity being assessed. Research identifying characteristics of stressors that modulate reactivity and clarifies the neurobehavioral, cognitive, and affective components of this reactivity may help prevent, reduce or treat the negative impacts of acute and chronic alcohol use with implications for other psychopathology involving maladaptive reactivity to stressors. We used a novel, multi-measure, cued electric shock stressor paradigm in a greater university community sample of adult recreational drinkers to test how alcohol (N=64), compared to No-alcohol (N=64), effects reactivity to stressors that vary in both their perceived certainty and controllability. Preregistered analyses suggested alcohol significantly dampened subjective anxiety (self-report) and defensive reactivity (startle potentiation) more during uncertain than during certain stressors regardless of controllability, suggesting that stressor uncertainty -but not uncontrollability- may be sufficient to enhance alcohol's stress reactivity dampening and thus negative reinforcement potential.

Continuous Theta Burst Stimulation to the Right Dorsolateral Prefrontal Cortex may increase Potentiated Startle in healthy individuals

Background

Convergent neuroimaging and neuromodulation studies implicate the right dorsolateral prefrontal cortex (dlPFC) as a key region involved in anxiety-cognition interactions. However, neuroimaging data are correlational, and neuromodulation studies often lack appropriate methodological controls. Accordingly, this work was designed to explore the role of right prefrontal cognitive control mechanisms in the expression/regulation of anxiety using continuous theta-burst transcranial magnetic stimulation (cTBS) and threat of unpredictable shock. Based on prior neuromodulation studies, we hypothesized that the right dlPFC contributed to anxiety expression, and that cTBS should downregulate this expression.

Methods

We measured potentiated startle and performance on the Sternberg working memory paradigm in 28 healthy participants before and after 4 sessions (600 pulses/session) of active or sham cTBS. Stimulation was individualized to the right dlPFC site of maximal working memory-related activity and optimized using electric-field modeling.

Results

Compared with sham cTBS, active cTBS, which is thought to induce long-term depression-like synaptic changes, increased startle during threat of shock, but the effect was similar for predictable and unpredictable threat. As a measure of target (dis)engagement, we also showed that active but not sham cTBS decreased accuracy on the Sternberg task.

Conclusions

Counter to our initial hypothesis, cTBS to the right dlPFC made individuals more anxious, rather than less anxious. Although preliminary, these results are unlikely to be due to transient effects of the stimulation, because anxiety was measured 24 hours after cTBS. In addition, these results are unlikely to be due to off-target effects, because target disengagement was evident from the Sternberg performance data.

When the approaching threat is uncertain: Dynamics of defensive motivation and attention in trait anxiety

Uncertainty of threat has been linked to anxiety, but little is known about how neurophysiological responses change as uncertain threats approach and whether trait anxiety modulates these changes. The current study was designed to explore aspects of the dynamics of defensive motivation (startle reflex elicited by acoustic startle probes), attention (probe N100 component of event-related potentials elicited by acoustic startle probes), and autonomic nervous system activity (heart rate) when the approaching threat was certain or uncertain in a variant of the threat probability task. Behavioral results showed that high-trait anxious individuals reported higher levels of anxiety than low-trait anxious individuals only under the uncertain threat condition. Electromyographic data showed that high-trait anxious individuals tended to produce a more pronounced startle reflex, especially when the uncertain threat was proximal. This pattern was not observed in low-trait anxious individuals. By examining early attention engagement through probe N100, we observed a similar pattern in relation to defensive motivation. Moreover, under the uncertain threat condition, high-trait anxious individuals yielded a greater deceleration of heart rate than low-trait anxious individuals. These results indicate a distinct modulation effect of trait anxiety in the dynamics of defensive motivation, attention, and the autonomic nervous system during the anticipation of uncertain threats.

Differential effects of the translocator protein 18 kDa (TSPO) ligand etifoxine and the benzodiazepine alprazolam on startle response to predictable threat in a NPU-threat task after acute and short-term treatment

RATIONALE

Benzodiazepines have been extensively investigated in experimental settings especially after single administration, which mostly revealed effects on unpredictable threat (U-threat) rather than predictable threat (P-threat). Given the need for pharmacological alternatives with a preferable side-effect profile and to better represent clinical conditions, research should cover also other anxiolytics and longer application times.

OBJECTIVES

The present study compared the acute and short-term effects of the translocator protein 18 kDa (TSPO) ligand etifoxine and the benzodiazepine alprazolam on P-threat and U-threat while controlling for sedation.

METHODS

Sixty healthy male volunteers, aged between 18 and 55 years, were randomly assigned to receive a daily dose of either 150 mg etifoxine, 1.5 mg alprazolam, or placebo for 5 days. On days 1 and 5 of intake, they performed a NPU-threat task including neutral (N), predictable (P), and unpredictable (U) conditions, while startle responsivity and self-reports were studied. Sedative effects were assessed using a continuous performance test.

RESULTS

Neither alprazolam nor etifoxine affected startle responsivity to U-threat on any of the testing days. While etifoxine reduced the startle response to P-threat on day 1 of treatment for transformed data, a contrary effect of alprazolam was found for raw values. No effects on self-reports and no evidence of sedation could be observed for either drug.

CONCLUSIONS

None of the anxiolytic substances had an impact on startle potentiation to U-threat even after several days of intake. The effects of the anxiolytics on startle responsivity to P-threat as well as implications for future studies are discussed.

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

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

Cognitive reappraisal is not always successful during pain anticipation: Stimulus-focused and goal-based reappraisal effects on self-reports and peripheral psychophysiology

The present study aims at comparing the effects of two subtypes of cognitive reappraisal (i.e., stimulus-focused vs. goal-based reappraisal) to reduce anticipatory anxiety of pain. Affective ratings, startle reflex, and autonomic measures (electrodermal and heart rate changes) were used as a measure of emotion regulation success. A total of 86 undergraduate students completed an anticipatory task in which they had to regulate their negative emotions or react naturally when faced with the possibility of receiving a painful thermal stimulus. Participants were randomly assigned to two experimental groups to compare the stimulus-focused and goal-based strategies explored here. Our results revealed enhanced self-reported anxiety, electrodermal activity and eyeblink response when participants tried to voluntarily down-regulate their negative emotions, compared to the control instruction. Differences between both cognitive reappraisal groups were not found. These unexpected findings suggest that brief reappraisal instructions may not necessarily be favorable for regulating emotions during anticipation of aversive events. Moreover, these results are further explained in terms of the pain expectation, the painful stimuli modality, and emotion regulation instructions.

Back to Basics: The Importance of Measurement Properties in Biological Psychiatry

Biological psychiatry is a major funding priority for organizations that fund mental health research (e.g., National Institutes of Health). Despite this, some have argued that the field has fallen short of its considerable promise to meaningfully impact the classification, diagnosis, and treatment of psychopathology. This may be attributable in part to a paucity of research about key measurement properties ("physiometrics") of biological variables as they are commonly used in biological psychiatry research. Specifically, study designs informed by physiometrics are more likely to be replicable, avoid poor measurement that results in misestimation, and maximize efficiency in terms of time, money, and the number of analyses conducted. This review describes five key physiometric principles (internal consistency, dimensionality, method-specific variance, temporal stability, and temporal specificity), illustrates how lack of understanding about these characteristics imposes meaningful limitations on research, and reviews examples of physiometric studies featuring a variety of popular biological variables to illustrate how this research can be done and substantive conclusions drawn about the variables of interest.

Covariate effects of resting heart rate variability on affective ratings and startle reflex during cognitive reappraisal of negative emotions

Heart Rate Variability (HRV) has been widely studied in laboratory settings due to its clinical implications, primarily as a potential biomarker of emotion regulation (ER). Studies have reported that individuals with higher resting HRV show more distinct startle reflexes to negative stimuli as compared to those with lower HRV. These responses have been associated with better defense system function when managing the context demands. There is, however, a lack of empirical evidence on the association between resting HRV and eyeblinks during laboratory tasks using instructed ER. This study explored the influence of tonic HRV on voluntary cognitive reappraisal through subjective and startle responses measured during an independent ER task. In total, 122 healthy participants completed a task consisting of attempts to upregulate, downregulate, or react naturally to emotions prompted by unpleasant pictures. Tonic HRV was measured for 5 minutes before the experiment began. Current results did not support the idea that self-reported and eyeblink responses were influenced by resting HRV. These findings suggest that, irrespective of resting HRV, individuals may benefit from strategies such as reappraisal that are useful for managing negative emotions. Experimental studies should further explore the role of individual differences when using ER strategies during laboratory tasks.

Responding to uncertain threat: A potential mediator for the effect of mindfulness on anxiety

Mindfulness-based interventions have gained extensive support for their application in the treatment of anxiety. However, their mechanisms remain largely unexplored. Excessive reactivity to uncertainty plays a central role in anxiety, and may represent a mechanism for the effect of mindfulness on anxiety, as mindfulness training fosters an open and accepting stance towards all aspects of experience. The present study sought to investigate both (i) self-reported intolerance of uncertainty (IU) as well as (ii) physiological and subjective responding to uncertain threat in a threat-of-shock paradigm, the NPU-threat test, as mediators for the relationship between mindfulness and anxiety in a cross-sectional study of healthy participants (N = 53). The results indicated that IU mediated the effect of mindfulness on some anxiety symptoms. In contrast, scores of physiological as well as subjective responses to uncertain threat from the NPU-threat test were largely unrelated to mindfulness, anxiety, or the IU self-report measure. The results provide initial evidence that reactions to uncertainty may play a role in the mindfulness-anxiety relationship and suggest that studies are needed to address how methodological variations of the NPU-threat test affect perceived levels of uncertainty and uncertainty-related anxiety.

Low-frequency parietal repetitive transcranial magnetic stimulation reduces fear and anxiety

Anxiety disorders are the most prevalent mental disorders, with few effective neuropharmacological treatments, making treatments development critical. While noninvasive neuromodulation can successfully treat depression, few treatment targets have been identified specifically for anxiety disorders. Previously, we showed that shock threat increases excitability and connectivity of the intraparietal sulcus (IPS). Here we tested the hypothesis that inhibitory repetitive transcranial magnetic stimulation (rTMS) targeting this region would reduce induced anxiety. Subjects were exposed to neutral, predictable, and unpredictable shock threat, while receiving double-blinded, 1 Hz active or sham IPS rTMS. We used global brain connectivity and electric-field modelling to define the single-subject targets. We assessed subjective anxiety with online ratings and physiological arousal with the startle reflex. Startle stimuli (103 dB white noise) probed fear and anxiety during the predictable (fear-potentiated startle, FPS) and unpredictable (anxiety-potentiated startle, APS) conditions. Active rTMS reduced both FPS and APS relative to both the sham and no stimulation conditions. However, the online anxiety ratings showed no difference between the stimulation conditions. These results were not dependent on the laterality of the stimulation, or the subjects' perception of the stimulation (i.e. active vs. sham). Results suggest that reducing IPS excitability during shock threat is sufficient to reduce physiological arousal related to both fear and anxiety, and are consistent with our previous research showing hyperexcitability in this region during threat. By extension, these results suggest that 1 Hz parietal stimulation may be an effective treatment for clinical anxiety, warranting future work in anxiety patients.

Navigating the garden of forking paths for data exclusions in fear conditioning research

In this report, we illustrate the considerable impact of researcher degrees of freedom with respect to exclusion of participants in paradigms with a learning element. We illustrate this empirically through case examples from human fear conditioning research, in which the exclusion of 'non-learners' and 'non-responders' is common - despite a lack of consensus on how to define these groups. We illustrate the substantial heterogeneity in exclusion criteria identified in a systematic literature search and highlight the potential problems and pitfalls of different definitions through case examples based on re-analyses of existing data sets. On the basis of these studies, we propose a consensus on evidence-based rather than idiosyncratic criteria, including clear guidelines on reporting details. Taken together, we illustrate how flexibility in data collection and analysis can be avoided, which will benefit the robustness and replicability of research findings and can be expected to be applicable to other fields of research that involve a learning element.

Acute prazosin administration does not reduce stressor reactivity in healthy adults

RATIONALE

Norepinephrine plays a critical role in the stress response. Clarifying the psychopharmacological effects of norepinephrine manipulation on stress reactivity in humans has important implications for basic neuroscience and treatment of stress-related psychiatric disorders, such as posttraumatic stress disorder and alcohol use disorders. Preclinical research implicates the norepinephrine alpha-1 receptor in responses to stressors. The No Shock, Predictable Shock, Unpredictable Shock (NPU) task is a human laboratory paradigm that is well positioned to test cross-species neurobiological stress mechanisms and advance experimental therapeutic approaches to clinical trials testing novel treatments for psychiatric disorders.

OBJECTIVES

We hypothesized that acute administration of prazosin, a noradrenergic alpha-1 antagonist, would have a larger effect on reducing stress reactivity during unpredictable, compared to predictable, stressors in the NPU task.

METHODS

We conducted a double-blind, placebo-controlled, crossover randomized controlled trial in which 64 healthy adults (32 female) completed the NPU task at two visits (2 mg prazosin vs. placebo).

RESULTS

A single acute dose of 2 mg prazosin did not reduce stress reactivity in a healthy adult sample. Neither NPU startle potentiation nor self-reported anxiety was reduced by prazosin (vs. placebo) during unpredictable (vs. predictable) stressors.

CONCLUSIONS

Further research is needed to determine whether this failure to translate preclinical neuroscience to human laboratory models is due to methodological factors (e.g., acute vs. chronic drug administration, brain penetration, study population) and/or suggests limited clinical utility of noradrenergic alpha-1 antagonists for treating stress-related psychiatric disorders.

Immediate pre-learning stress enhances baseline startle response and fear acquisition in a fear-potentiated startle paradigm

Extensive work has shown that stress time-dependently influences hippocampus-dependent learning and memory. In particular, stress that is administered immediately before learning enhances long-term memory, while stress that is temporally separated from learning impairs long-term memory. We have extended these findings by examining the impact of immediate, pre-learning stress on an amygdala-dependent fear conditioning task. One hundred and forty-one healthy participants underwent a stress (socially evaluated cold pressor test) or control manipulation immediately before completing differential fear conditioning in a fear-potentiated startle paradigm. Participants then completed extinction and extinction memory testing sessions 24 and 48 h later, respectively. Stress administered immediately before acquisition increased baseline startle responses and enhanced fear learning, as evidenced by greater fear-potentiated startle to the CS + . Although no group differences were observed during extinction training on Day 2, stressed participants exhibited evidence of impaired extinction processes on Day 3, an effect that was driven by group differences in acquisition. Importantly, stressed participants' cortisol responses to the stressor on Day 1 were positively associated with CS discrimination on Days 2 and 3. These findings suggest that stress immediately before fear conditioning strengthens fear memory formation and produces a more enduring fear memory, perhaps via corticosteroid activity. Such a paradigm could be useful for understanding factors that influence traumatic memory formation.

Fear-potentiated startle response as an endophenotype: Evaluating metrics and methods for genetic applications

The modulation of the startle response (SR) by threatening stimuli (fear-potentiated startle; FPS) is a proposed endophenotype for disorders of the fearful-fearlessness spectrum. FPS has failed to show evidence of heritability, raising concerns. However, metrics used to index FPS-and, importantly, other conditional phenotypes that are dependent on a baseline-may not be suitable for the approaches used in genetic epidemiology studies. Here, we evaluated multiple metrics of FPS in a population-based sample of preadolescent twins (N = 569 from 320 twin pairs, M_age = 11.4) who completed a fear-conditioning paradigm with airpuff-elicited SR on two occasions (~1 month apart). We applied univariate and multivariate biometric modeling to estimate the heritability of FPS using several proposed standardization procedures. This was extended with data simulations to evaluate biases in heritability estimates of FPS (and similar metrics) under various scenarios. Consistent with previous studies, results indicated moderate test-retest reliability (r = 0.59) and heritability of the overall SR (h² = 34%) but poor reliability and virtually no unique genetic influences on FPS when considering a raw or standardized differential score that removes baseline SR. Simulations demonstrated that the use of differential scores introduces bias in heritability estimates relative to jointly analyzing baseline SR and FPS in a multivariate model. However, strong dependency of FPS on baseline levels makes unique genetic influences virtually impossible to detect regardless of methodology. These findings indicate that FPS and other conditional phenotypes may not be well suited to serve as endophenotypes unless such codependency can be disentangled.

If or when? Uncertainty's role in anxious anticipation

Uncertainty is often associated with subjective distress and a potentiated anxiety response. Occurrence uncertainty, or the inability to predict if a threat will occur, has rarely been compared experimentally with temporal uncertainty, or the inability to predict when a threat will occur. The current study aimed to (a) directly compare the anxiogenic effects of anticipating these two types of uncertain threat, as indexed by the eyeblink startle response, and (b) assess the relationship between startle response to occurrence and temporal uncertainty and individual differences in self-reported intolerance of uncertainty and anxiety. The findings indicated that anticipation during occurrence uncertainty elicited a larger startle response than anticipating a certain threat, but anticipation during temporal uncertainty was superior at potentiating startle blink overall. Additional analyses of the effects of order and habituation further highlighted temporal uncertainty's superiority in eliciting greater startle responding. This suggests that, while uncertainty is physiologically anxiety provoking, some level of certainty that the threat will occur enhances the robustness of the physiological anxiety response. However, self-reported anxiety was equivalent for temporal and occurrence uncertainty, suggesting that, while defensive responding may be more affected by temporal uncertainty, people perceive both types of uncertainty as anxiogenic. Individual differences in the intolerance of uncertainty and other anxiety measures were not related to anticipatory startle responsivity during any of the conditions.

Individual variation in working memory is associated with fear extinction performance

PTSD has been associated consistently with abnormalities in fear acquisition and extinction learning and retention. Fear acquisition refers to learning to discriminate between threat and safety cues. Extinction learning reflects the formation of a new inhibitory-memory that competes with a previously learned threat-related memory. Adjudicating the competition between threat memory and the new inhibitory memory during extinction may rely, in part, on cognitive processes such as working memory (WM). Despite significant shared neural circuits and signaling pathways the relationship between WM, fear acquisition, and extinction is poorly understood. Here, we analyzed data from a large sample of healthy Marines who underwent an assessment battery including tests of fear acquisition, extinction learning, and WM (N-back). Fear potentiated startle (FPS), fear expectancy ratings, and self-reported anxiety served as the primary dependent variables. High WM ability (N = 192) was associated with greater CS + fear inhibition during the late block of extinction and greater US expectancy change during extinction learning compared to individuals with low WM ability (N = 204). WM ability was not associated with magnitude of fear conditioning/expression. Attention ability was unrelated to fear acquisition or extinction supporting specificity of WM associations with extinction. These results support the conclusion that individual differences in WM may contribute to regulating fear responses.

The role of prefrontal-subcortical circuitry in negative bias in anxiety: Translational, developmental and treatment perspectives

Anxiety disorders are the most common cause of mental ill health in the developed world, but our understanding of symptoms and treatments is not presently grounded in knowledge of the underlying neurobiological mechanisms. In this review, we discuss accumulating work that points to a role for prefrontal-subcortical brain circuitry in driving a core psychological symptom of anxiety disorders - negative affective bias. Specifically, we point to converging work across humans and animal models, suggesting a reciprocal relationship between dorsal and ventral prefrontal-amygdala circuits in promoting and inhibiting negative bias, respectively. We discuss how the developmental trajectory of these circuits may lead to the onset of anxiety during adolescence and, moreover, how effective pharmacological and psychological treatments may serve to shift the balance of activity within this circuitry to ameliorate negative bias symptoms. Together, these findings may bring us closer to a mechanistic, neurobiological understanding of anxiety disorders and their treatment.

Reducing State Anxiety Using Working Memory Maintenance

The purpose of this protocol is to explain how to examine the relationship between working memory processes and anxiety by combining the Sternberg Working Memory (WM) and the threat of shock paradigms. In the Sternberg WM paradigm, subjects are required to maintain a series of letters in the WM for a brief interval and respond by identifying whether the position of a given letter in the series matches a numerical prompt. In the threat of shock paradigm, subjects are exposed to alternating blocks where they are either at risk of receiving unpredictable presentations of a mild electric shock or are safe from the shock. Anxiety is probed throughout the safe and threat blocks using the acoustic startle reflex, which is potentiated under threat (Anxiety-Potentiated Startle (APS)). By conducting the Sternberg WM paradigm during the threat of shock and probing the startle response during either the WM maintenance interval or the intertrial interval, it is possible to determine the effect of WM maintenance on APS.

Computational reproducibility of "Goal relevance and goal conduciveness appraisals lead to differential autonomic reactivity in emotional responding to performance feedback" (Kreibig, Gendolla, & Scherer, 2012): A guide and new evidence

The emerging field of the psychophysiology of motivation bears many new findings, but little replication. Using my own data (Kreibig, Gendolla, & Scherer, 2012), I test the reproducibility of this specific study, provide the necessary materials to make the study reproducible, and instantiate proper reproducibility practices that other researchers can use as a road map toward the same goal. In addition, based on re-analyses of the original data, I report new evidence for the motivational effects of emotional responding to performance feedback. Specifically, greater appraisal of goal relevance amplifies the emotional response to events appraised as conducive (i.e., effort mobilization), but not to those appraised as obstructive to a person's goals (i.e., effort withdrawal). I conclude by providing a ten-step road map of best practices to facilitate computational reproducibility for future studies.

Increased startle potentiation to unpredictable stressors in alcohol dependence: Possible stress neuroadaptation in humans

Stress plays a key role in addiction etiology and relapse. Rodent models posit that following repeated periods of alcohol and other drug intoxication, compensatory allostatic changes occur in the central nervous system (CNS) circuits involved in behavioral and emotional response to stressors. We examine a predicted manifestation of this neuroadaptation in recently abstinent alcohol-dependent humans. Participants completed a translational laboratory task that uses startle potentiation to unpredictable (vs. predictable) stressors implicated in the putative CNS mechanisms that mediate this neuroadaptation. Alcohol-dependent participants displayed significantly greater startle potentiation to unpredictable than predictable stressors relative to nonalcoholic controls. The size of this effect covaried with alcohol-related problems and degree of withdrawal syndrome. This supports the rodent model thesis of a sensitized stress response in abstinent alcoholics. However, this effect could also represent premorbid risk or mark more severe and/or comorbid psychopathology. Regardless, pharmacotherapy and psychological interventions may target unpredictable stressor response to reduce stress-induced relapse. (PsycINFO Database Record

Don't fear 'fear conditioning': Methodological considerations for the design and analysis of studies on human fear acquisition, extinction, and return of fear

The so-called 'replicability crisis' has sparked methodological discussions in many areas of science in general, and in psychology in particular. This has led to recent endeavours to promote the transparency, rigour, and ultimately, replicability of research. Originating from this zeitgeist, the challenge to discuss critical issues on terminology, design, methods, and analysis considerations in fear conditioning research is taken up by this work, which involved representatives from fourteen of the major human fear conditioning laboratories in Europe. This compendium is intended to provide a basis for the development of a common procedural and terminology framework for the field of human fear conditioning. Whenever possible, we give general recommendations. When this is not feasible, we provide evidence-based guidance for methodological decisions on study design, outcome measures, and analyses. Importantly, this work is also intended to raise awareness and initiate discussions on crucial questions with respect to data collection, processing, statistical analyses, the impact of subtle procedural changes, and data reporting specifically tailored to the research on fear conditioning.

How many blinks are necessary for a reliable startle response? A test using the NPU-threat task

Emotion-modulated startle is a frequently used method in affective science. Although there is a growing literature on the reliability of this measure, it is presently unclear how many startle responses are necessary to obtain a reliable signal. The present study therefore evaluated the reliability of startle responding as a function of number of startle responses (NoS) during a widely used threat-of-shock paradigm, the NPU-threat task, in a clinical (N=205) and non-clinical (N=92) sample. In the clinical sample, internal consistency was also examined independently for healthy controls vs. those with panic disorder and/or major depression and retest reliability was assessed as a function of NoS. Although results varied somewhat by diagnosis and for retest reliability, the overall pattern of results suggested that six startle responses per condition were necessary to obtain acceptable reliability in clinical and non-clinical samples during this threat-of-shock paradigm in the present study.

Postauricular reflexes elicited by soft acoustic clicks and loud noise probes: Reliability, prepulse facilitation, and sensitivity to picture contents

The startle blink reflex is facilitated during early picture viewing, then inhibited by attention during pleasant and aversive pictures compared to neutral pictures, and finally potentiated during aversive pictures specifically. However, it is unclear whether the postauricular reflex, which is elicited by the same loud acoustic probe as the startle blink reflex but enhanced by appetitive instead of defensive emotion, has the same pattern and time course of emotional modulation. We examined this issue in a sample of 90 undergraduates using serially presented soft acoustic clicks that elicited postauricular (but not startle blink) reflexes in addition to standard startle probes. Postauricular reflexes elicited by both clicks and probes correlated during food and nurturant contents, during which they were potentiated compared to neutral pictures, suggesting clicks effectively elicit emotionally modulated postauricular reflexes. The postauricular reflex was initially facilitated during the first 500 ms of picture processing but was larger during pleasant than neutral pictures throughout picture processing, with larger effect sizes during the latter half of picture processing. Across reflexes and eliciting stimuli, measures of emotional modulation had higher coefficient alphas than magnitudes during specific picture contents within each valence, indicating that only emotional modulation measures assess higher-order appetitive or defensive processing.

Error-related brain activity is related to aversive potentiation of the startle response in children, but only the ERN is associated with anxiety disorders

Identifying biomarkers that characterize developmental trajectories leading to anxiety disorders will likely improve early intervention strategies as well as increase our understanding of the etiopathogenesis of these disorders. The error-related negativity (ERN), an event-related potential that occurs during error commission, is increased in anxious adults and children-and has been shown to predict the onset of anxiety disorders across childhood. The ERN has therefore been suggested as a biomarker of anxiety. However, it remains unclear what specific processes a potentiated ERN may reflect. We have recently proposed that the ERN may reflect trait-like differences in threat sensitivity; however, very few studies have examined the ERN in relation to other indices of this construct. In the current study, the authors measured the ERN, as well as affective modulation of the startle reflex, in a large sample (N = 155) of children. Children characterized by a large ERN also exhibited greater potentiation of the startle response in the context of unpleasant images, but not in the context of neutral or pleasant images. In addition, the ERN, but not startle response, related to child anxiety disorder status. These results suggest a relationship between error-related brain activity and aversive potentiation of the startle reflex during picture viewing-consistent with the notion that both measures may reflect individual differences in threat sensitivity. However, results suggest the ERN may be a superior biomarker of anxiety in children. (PsycINFO Database Record

Psychometric properties of startle and corrugator response in NPU, affective picture viewing, and resting state tasks

The current study provides a comprehensive evaluation of critical psychometric properties of commonly used psychophysiology laboratory tasks/measures within the NIMH RDoC. Participants (N = 128) completed the no-shock, predictable shock, unpredictable shock (NPU) task, affective picture viewing task, and resting state task at two study visits separated by 1 week. We examined potentiation/modulation scores in NPU (predictable or unpredictable shock vs. no-shock) and affective picture viewing tasks (pleasant or unpleasant vs. neutral pictures) for startle and corrugator responses with two commonly used quantification methods. We quantified startle potentiation/modulation scores with raw and standardized responses. We quantified corrugator potentiation/modulation in the time and frequency domains. We quantified general startle reactivity in the resting state task as the mean raw startle response during the task. For these three tasks, two measures, and two quantification methods, we evaluated effect size robustness and stability, internal consistency (i.e., split-half reliability), and 1-week temporal stability. The psychometric properties of startle potentiation in the NPU task were good, but concerns were noted for corrugator potentiation in this task. Some concerns also were noted for the psychometric properties of both startle and corrugator modulation in the affective picture viewing task, in particular, for pleasant picture modulation. Psychometric properties of general startle reactivity in the resting state task were good. Some salient differences in the psychometric properties of the NPU and affective picture viewing tasks were observed within and across quantification methods.