Using unconditioned responses to predict fear acquisition, fear extinction learning, and extinction retention patterns: Sex hormone status matters

Following a traumatic event, fear dysregulation can increase the likelihood of developing post-traumatic stress disorder (PTSD). This psychopathology is twice as prevalent in women than in men. High physiological reactivity following trauma may be an early risk indicator for the development of PTSD. Elevated physiological reactivity and low estradiol levels have individually been associated with higher fear acquisition and/or lower extinction retention. Thus, sex hormone status may also modulate fear regulation abilities. However, it is unknown whether these two vulnerability factors interact to modulate fear learning and regulation. Using a fear conditioning and extinction protocol, we examined whether physiological reactivity to the aversive stimulus during fear acquisition training predicted fear responses during fear learning, extinction learning, and extinction retention. We verified whether these associations differed according to sex hormone status. Seventy-seven non-clinical participants were recruited including oral contraceptive users (n = 18), early follicular women (n = 20, [low estradiol]), mid-cycle women (n = 20, [high estradiol]), and men (n = 19). Participants underwent a three-day fear conditioning and extinction protocol (day 1: fear acquisition training; day 2: extinction training; day 3: retention test). Skin conductance responses were recorded. In early follicular women, physiological reactivity predicted conditioned and extinguished stimulus fear responses during all phases. For the remaining women, this effect was only present during fear learning and extinction learning. These findings highlight the importance of considering physiological reactivity and sex hormone status following a traumatic event. This knowledge could aid in the early identification of those at higher risk of developing PTSD.

Impaired Decision-Making and Skin Conductance Responses Are Associated with Reward and Punishment Sensitivity in Individuals with Severe Alcohol Use Disorder

INTRODUCTION

Individuals with alcohol use disorder (AUD) have difficulties regulating alcohol consumption, despite adverse drinking-related consequences. This may be due to incapacity incorporating previous negative feedback from drinking, resulting in impaired decision-making.

METHODS

We assessed whether decision-making is impaired in participants with AUD related to severity of AUD, indexed by severe negative drinking consequences using the Drinkers Inventory of Consequences (DrInC) and reward and punishment sensitivity with the Behavioural Inhibition System Behavioural Activation System (BIS BAS) scales. 36 treatment-seeking alcohol-dependent participants completed the Iowa gambling task (IGT) with skin conductance responses (SCRs) measured continuously as an index of somatic autonomic arousal to evaluate impaired expectancy of negative outcomes.

RESULTS

Two-thirds of the sample showed behavioural impairment during the IGT, with greater AUD severity related to worse performance. BIS moderated IGT performance according to severity of AUD, with increased anticipatory SCRs for those with fewer reported DrInC severe consequences. Participants with more DrInC severe consequences showed IGT deficits and reduced SCRs regardless of BIS scores. BAS-Reward was associated with increased anticipatory SCRs to disadvantageous deck choices among those with lower AUD severity, while SCRs did not differ related to AUD severity for reward outcomes.

DISCUSSION

Effective decision-making in the IGT and adaptive somatic responses were moderated by punishment sensitivity contingent on severity of AUD in these drinkers, with impairments in expectancy to negative outcomes from risky choices, including reduced somatic responses, resulting in poor decision-making processes that may help explain impaired drinking and worse drinking-related consequences.

Context effects, skin conductance responses and personality traits - Influencing variables on risk-taking within a modified version of the balloon analog risk task

When individuals take risks, they must weigh potential costs and benefits associated with a decision. Differences in risk-taking appear to be influenced by contextual, and inter-individual factors. However, it is still ambiguous to what extent these characteristics jointly influence risk-taking. We investigated how risk-taking varies as function of context effects, incentives, skin conductance responses (SCR), and personality traits such as impulsivity and sensitivity to reward and punishment. Sixty-eight healthy participants conducted a modified version of the Balloon Analogue Risk Task (BART) composed of a gain-framed (G-BART) and loss-framed (L-BART) context with each a low and a high outcome magnitude condition. While the goal in G-BART was to maximize gains, the goal in L-BART was to minimize losses. In both versions, participants can potentially accumulate the same amounts. We conducted trial-by-trial mixed model analyses to account for within- and between-participant effects. Participants showed greater risk-taking when playing L-BART than G-BART; more risk-taking was observed in the high compared to the low outcome magnitude condition. Furthermore, higher SCR were associated with less risk-taking. Lower impulsivity was related to a greater difference in risk-taking in both contexts, with greater risk-taking in L-BART. Likewise, sensitivity to reward was associated with a greater difference in risk-taking in both contexts, with greater risk-taking in G-BART. Finally, greater sensitivity to punishment was related to risk-taking among participants describing themselves as sensitive to rewards. Results support a multidimensional state-trait model of risk-taking suggesting that risk-taking is favored by loss-aversion along with incentives, psychophysiological arousal, and personality traits.

The association between mnemonic discrimination ability and differential fear learning

BACKGROUND AND OBJECTIVES

It is important to be able to learn which stimuli in our surroundings predict aversive outcomes. To maintain emotional well-being, it is similarly important to be able to learn which stimuli predict safety. The ability to discriminate between stimuli that predict danger and safety has been suggested to not only have an emotional component, but also a cognitive one. One such candidate mechanism is mnemonic discrimination (MD), the ability to differentiate between two memories that are similar but not identical. In the present study, we wanted to examine if MD performance helps to explain inter-individual differences in the ability to acquire a differentiated fear response during fear conditioning.

METHODS

Participants performed a task assessing MD ability, and then underwent a fear conditioning procedure. Fear responses were measured using skin conductance responses (SCRs).

RESULTS

Results revealed no support for MD ability being associated with to which degree a differentiated fear response was acquired, or with the time needed to acquire such a response.

LIMITATIONS

Our only outcome measurement was SCRs. Future studies need to include fear ratings, expectancy ratings and neural responses. Future studies also need to examine this using a stimulus material where the conditioned stimulus and the safety stimulus are more difficult to distinguish from each other.

CONCLUSIONS

If MD ability has a role in inhibiting overgeneralization of fear learning, this does not seem to be driven by MD already during the initial learning.

Does the assessment of different combinations of within-phase subjective measures influence electrodermal responding and between-phase subjective ratings during fear conditioning and extinction experiments?

The type and number of dependent measures assessed have varied between fear conditioning and extinction experiments and it remains unclear whether methodological differences influence results. Measuring skin conductance responses (SCRs) and between-phase subjective ratings between four conditions; Con condition had no within-phase ratings; US Exp condition included within-phase US expectancy ratings only; CS Eval condition included within-phase CS evaluations only and All Meas condition included both. All Meas condition exhibited larger SCRs compared to other conditions during acquisition, extinction, and return of differential responding at test. Differential SCRs did not extinguish in CS Eval and Con conditions, and CS Eval condition exhibited smaller CS- SCRs than other conditions throughout phases. US Exp condition revealed differential conditioning, successful extinction, and no return of differential SCRs. Between-phase ratings were not affected by within-phase ratings. Researchers should consider assessing different combinations of within-phase subjective ratings depending on the aims of their research.

The Body-Threat Assessment Battery (BTAB): A new instrument for the quantification of threat-related autonomic affective responses induced via dynamic movie clips

We present a new instrument for the assessment of responses to threat-related imagery directed towards a human body - the Body-Threat Assessment Battery (BTAB). The BTAB consists of a series of high-definition dynamic clips depicting body-threats and matched non-threat baseline behaviours. For body-threat stimuli a perspective manipulation was included to assess the effects of viewing threats from the point-of-view of the observer (POV) or from an external/exocentric perspective (EXO). Green-screen technology was used so that extraneous background information could be removed and standardised in post-production. Categorical normative data for psychological ratings (valence, arousal and pain), psychophysiological, phasic skin conductance responses (SCRs) and tonic skin conductance levels (SCLs) were obtained for all stimuli. Body-threat stimuli evoked significantly higher psychological ratings of arousal and pain, with more negative ratings of valence, relative to baseline stimuli. In addition, threat stimuli also had an increased efficacy at evoking SCRs, and these were significantly stronger relative to baseline stimuli. There were no effects of perspective on psychophysiological or psychological responses to threat imagery. The findings are discussed in the context of the utility and scope of the BTAB for supporting neurocognitive investigations of aversive imagery and body-threats specifically in the study of embodiment, body-processing and self-consciousness.

Subjective and physiological response to emotions in temporal lobe epilepsy and psychogenic non-epileptic seizures

BACKGROUND

Temporal lobe epilepsy (TLE) and psychogenic non-epileptic seizures (PNES) are conditions frequently associated with dysfunction in emotional regulation leading to increased risk of affective disorders. This study investigates emotional processing with an objective measure of emotional reactivity in patients with TLE and patients with PNES.

METHODS

34 patients with TLE and 14 patients with PNES were evaluated on skin conductance responses (SCR) to emotions induced by short films and compared to 34 healthy controls. An attention and a suppression condition were performed while viewing the films.

RESULTS

The both groups of patients disclosed lower SCR to emotions compared to controls, mainly in suppression condition. While TLE patients had lower SCR in attention condition than controls for fear, sadness and happiness, PNES had lower SCR only for happiness. In suppression condition, both had lower SCR than controls except for peacefulness in both groups and sadness in PNES. Subjective evaluations revealed that both patient's groups scored a higher intensity for sadness than controls in attention and lower for in fear and disgust in suppression only in TLE.

LIMITATIONS

The sample size in the PNES group and the lack of a control group with similar levels of mood symptoms limited the interpretation of our results.

CONCLUSION

As no correlation were found between SCR to emotions and scores of affective disorders, this pattern of responses might be underpinned by specific pathophysiological and cognitive mechanisms related to TLE and to PNES. Thus, therapeutic approaches targeting emotional autonomic responses can be of interest in the management of these conditions.

Nicotine exposure leads to deficits in differential cued fear conditioning in mice and humans: A potential role of the anterior cingulate cortex

Stress and anxiety disorders such as posttraumatic stress disorder (PTSD) are characterized by disrupted safety learning. Tobacco smoking has been strongly implicated in stress and anxiety disorder symptomatology, both as a contributing factor and as a vulnerability factor. Rodent studies from our lab have recently shown that acute and chronic nicotine exposure disrupts safety learning. However, it is unknown if these effects of nicotine translate to humans. The present studies addressed this gap by administering a translational differential cued fear conditioning paradigm to both mice and humans. In mice, we found that chronic nicotine exposure reduced discrimination between a conditioned stimulus (CS) that signals for danger (CS+) and another CS that signals for safety (CS-) during both acquisition and testing. We then employed a similar differential cued fear conditioning paradigm in human smokers and non-smokers undergoing functional magnetic resonance imaging (fMRI). Smokers showed reduced CS+/CS- discrimination during fear conditioning compared to non-smokers. Furthermore, using fMRI, we found that subgenual and dorsal anterior cingulate cortex activations were lower in smokers than in non-smokers during differential cued fear conditioning. These results suggest a potential biological mechanism underlying a dysregulated ability to discriminate between danger and safety cues. Our results indicate a clear parallel between the effects of nicotine exposure on safety learning in mice and humans and therefore suggest that smoking might represent a risk factor for inability to process information related to danger and safety related cues.

What our eyes tell us about feelings: Tracking pupillary responses during emotion regulation processes

Emotion regulation is essential for adaptive behavior and mental health. Strategies applied to alter emotions are known to differ in their impact on psychological and physiological aspects of the emotional response. However, emotion regulation outcome has primarily been assessed via self-report, and studies comparing regulation strategies with regard to their peripheral physiological mechanisms are limited in number. In the present study, we therefore aimed to investigate the effects of different emotion regulation strategies on pupil dilation, skin conductance responses, and subjective emotional responses. Thirty healthy females were presented with negative and neutral pictures and asked to maintain or up- and downregulate their upcoming emotional responses through reappraisal or distraction. Pupil dilation and skin conductance responses were significantly enhanced when viewing negative relative to neutral pictures. For the pupil, this emotional arousal effect manifested specifically late during the pupillary response. In accordance with subjective ratings, increasing negative emotions through reappraisal led to the most prominent pupil size enlargements, whereas no consistent effect for downregulation was found. In contrast, early peak dilations were enhanced in all emotion regulation conditions independent of strategy. Skin conductance responses were not further modulated by emotion regulation. These results indicate that pupil diameter is modulated by emotional arousal, but is initially related to the extent of mental effort required to regulate automatic emotional responses. Our data thus provide first evidence that the pupillary response might comprise two distinct temporal components reflecting cognitive emotion regulation effort on the one hand and emotion regulation success on the other hand.

Probing the influence of unconscious fear-conditioned visual stimuli on eye movements

Efficient threat detection from the environment is critical for survival. Accordingly, fear-conditioned stimuli receive prioritized processing and capture overt and covert attention. However, it is unknown whether eye movements are influenced by unconscious fear-conditioned stimuli. We performed a classical fear-conditioning procedure and subsequently recorded participants' eye movements while they were exposed to fear-conditioned stimuli that were rendered invisible using interocular suppression. Chance-level performance in a forced-choice-task demonstrated unawareness of the stimuli. Differential skin conductance responses and a change in participants' fearfulness ratings of the stimuli indicated the effectiveness of conditioning. However, eye movements were not biased towards the fear-conditioned stimulus. Preliminary evidence suggests a relation between the strength of conditioning and the saccadic bias to the fear-conditioned stimulus. Our findings provide no strong evidence for a saccadic bias towards unconscious fear-conditioned stimuli but tentative evidence suggests that such an effect may depend on the strength of the conditioned response.

Sympathetic nerve activity can be estimated from skin conductance responses - a comment on Henderson et al. (2012)

A recent paper by Henderson et al. (2012) claimed that skin sympathetic nerve activity (SSNA) can not be retrieved from skin conductance responses (SCR). Here, I argue that this claim is not supported by the literature, and comment on contemporary approaches of estimating SSNA from SCR using biophysical models.

Testing a neurobiological model of depersonalization disorder using repetitive transcranial magnetic stimulation

Background

Depersonalization disorder (DPD) includes changes in subjective experiencing of self, encompassing emotional numbing. Functional magnetic resonance imaging (fMRI) has pointed to ventrolateral prefrontal cortex (VLPFC) inhibition of insula as a neurocognitive correlate of the disorder.

Objective

We hypothesized that inhibition to right VLPFC using repetitive transcranial magnetic stimulation (rTMS) would lead to increased arousal and reduced symptoms.

Methods

Patients with medication-resistant DSM-IV DPD (N = 17) and controls (N = 20) were randomized to receive one session of right-sided rTMS to VLPFC or temporo-parietal junction (TPJ). 1Hz rTMS was guided using neuronavigation and delivered for 15 min. Co-primary outcomes were: (a) maximum skin conductance capacity, and (b) reduction in depersonalization symptoms (Cambridge Depersonalisation Scale (CDS) [state version]). Secondary outcomes included spontaneous fluctuations (SFs) and event-related skin conductance responses.

Results

In patients with DPD, rTMS to VLPFC led to increased electrodermal capacity, namely maximum skin conductance deflections. Patients but not controls also showed increased SFs post rTMS. Patients who had either VLPFC or TPJ rTMS showed a similar significant reduction in symptoms. Event-related electrodermal activity did not change.

Conclusions

A single session of right-sided rTMS to VLPFC (but not TPJ) significantly increased physiological arousal capacity supporting our model regarding the relevance of increased VLPFC activity to emotional numbing in DPD. rTMS to both sites led to reduced depersonalization scores but since this was independent of physiological arousal, this may be a non-specific effect. TMS is a potential therapeutic option for DPD; modulation of VLPFC, if replicated, is a plausible mechanism.