Inhibitory control and its modification in spider phobia - Study protocol for an antisaccade training trial

OBJECTIVES

Inhibitory control deficits are considered a key pathogenic factor in anxiety disorders. To assess inhibitory control, the antisaccade task is a well-established measure that assesses antisaccade performance via latencies and error rates. The present study follows three aims: (1) to investigate inhibitory control via antisaccade latencies and errors in an antisaccade task, and their associations with multiple measures of fear in patients with spider phobia (SP) versus healthy controls (HC), (2) to investigate the modifiability of antisaccade performance via a fear-specific antisaccade training in patients with SP and HC, and (3) to explore associations between putative training-induced changes in antisaccade performance in SPs and changes in diverse measures of fear.

METHODS

Towards aim 1, we assess antisaccade latencies (primary outcome) and error rates (secondary outcome) in an emotional antisaccade task. Further, the baseline assessment includes assessments of psychophysiological, behavioral, and psychometric indices of fear in patients with SP and HCs. To address aim 2, we compare effects of a fear-specific antisaccade training with effects of a prosaccade training as a control condition. The primary and secondary outcomes are reassessed at a post-1-assessment in both SPs and HCs. Aim 3 employs a cross-over design and is piloted in patients with SP, only. Towards this aim, primary and secondary outcomes, as well as psychophysiological, behavioral, and psychometric measures of fear are reassessed at a post-2-assessment after the second training block.

CONCLUSION

This study aims to better understand inhibitory control processes and their modifiability in spider phobia. If successful, antisaccade training may assist in the treatment of specific phobia by directly targeting the putative underlying inhibitory control deficits. This study has been preregistered with ISRCTN (ID: ISRCTN12918583) on 28th February 2022.

Close(d) to you? Avoidant attachment is associated with attenuated pupil responsivity to social stimuli

Insecure attachment is thought to impair romantic relationships, presumably also contributing to mental health problems. Previous research has suggested a link to biased automatic processing of social information, potentially reflected in pupil dilation responses. To address this hypothesis, 37 adults were presented with attachment-related, emotional pictures of erotic couples, everyday couples, or interpersonal violence after assessment with the Experiences in Close Relationships Scale. Considerable variation in self-reported attachment behaviors regarding both attachment anxiety and avoidance was observed in our sample. Overall, pupil dilation was most pronounced during viewing of erotica and violence-related pictures. Relative to nature pictures as control, attachment avoidance was associated with attenuated pupillary responses to social content. However, this was not significant with erotica. For pictures of violence, this avoidant bias was also evident in reduced subjective arousal. In contrast, attachment anxiety was unrelated to differential pupil dilation. Our findings, although preliminary, suggest that previous attachment-related experiences may bias the processing of social stimuli, which in turn may be reflected in altered patterns of pupillary responses.

Optimal timing of oral metyrapone intake for the suppression of cold-pressor stress-induced cortisol release

BACKGROUND

Pharmacological manipulation of cortisol levels is instrumental in elucidating mechanisms underlying acute stress effects and for distinguishing the physiological and behavioral effects of cortisol from those of the adrenergic system. Administration (oral or IV) of hydrocortisone is a direct and efficient method to elevate cortisol, and thus, frequently used in psychobiological stress research. However, lowering of cortisol (i.e. blockade of stress cortisol) requires a more sophisticated approach, such as the administration of the corticostatic compound metyrapone (MET). However, there is insufficient knowledge about the temporal dynamics of MET for the blocking of stress-induced cortisol reactivity. Thus, the present study aimed to build up an experimental protocol suitable to suppress acute behavioral stress-induced cortisol secretion by MET.

METHODS

50 healthy young men were randomly assigned to one of five treatment groups. They received 750 mg oral MET either 30 (n = 9), 45 (n = 11), or 60 (n = 10) minutes before exposure to a combined cold pressor and mental arithmetic test (stress induction), or were subjected to two different control treatments (placebo 60 min before stress (n = 10) or MET 30 min before non-stressful warm-water condition (n = 10)). Salivary cortisol concentration, hemodynamics, and subjective ratings were assessed.

RESULTS

Suppression of cold stress-induced cortisol release was strongest when MET intake was scheduled 30 min prior to stress onset. Cardiovascular stress-responses and subjective ratings remained unaffected by MET.

CONCLUSION

In healthy young males, 750 mg of MET efficiently block cold stress-induced cortisol release when oral administration is scheduled 30 min prior to stress onset. This finding may guide future research in improving timing of suppression of stress-induced cortisol secretion.

Repressive and vigilant coping styles in stress and relaxation: evidence for physiological and subjective differences at baseline, but not for differential stress or relaxation responses

Introduction

Previous research suggested differential stress reactivity depending on individuals' coping style, e.g., as classified by the model of coping modes. Specifically, stronger physiological reactivity and weaker subjective stress ratings were found for repressors than for sensitizers. However, it remains to be investigated (i) whether these findings, which are largely based on social stress induction protocols, also generalize to other stressors, (ii) whether repressors vs. sensitizers also exhibit differential stress recovery following the application of a relaxation method, and (iii) which stress reactivity and recovery patterns are seen for the two remaining coping styles, i.e., fluctuating, and non-defensive copers. The current study thus examines stress reactivity in physiology and subjective ratings to a non-social stressor and the subsequent ability to relax for the four coping groups of repressors, sensitizers, fluctuating, and non-defensive copers.

Methods

A total of 96 healthy participants took part in a stress induction (Mannheim Multicomponent Stress Test) and a subsequent relaxation intervention. Subjective ratings of stress and relaxation, heart rate (HR), heart rate variability (HRV), and blood pressure were assessed during the experiment. HR and blood pressure are markers of the sympathetic stress response that can be regulated by relaxation, while HRV should increase with relaxation. To investigate long-term relaxation effects, subjective ratings were also assessed on the evening of testing.

Results

Despite successful stress induction, no differential responses (baseline to stress, stress to relaxation) were observed between the different coping groups on any of the measures. In contrast, a strong baseline effect was observed that persisted throughout the experiment: In general, fluctuating copers showed lower HR and higher HRV than non-defensive copers, whereas repressors reported lower subjective stress levels and higher levels of relaxation during all study phases. No differences in subjective ratings were observed in the evening of testing.

Conclusion

Contrary to previous research, no differential stress reactivity pattern was observed between coping groups, which could be due to the non-social type of stressor employed in this study. The novel finding of physiological baseline differences between fluctuating and non-defensive individuals is of interest and should be further investigated in other stressor types in future research.

Associations between hair cortisol and subjective stress measures in a large occupational sample

BACKGROUND

Hair cortisol concentrations (HCC) are commonly used to capture long-term cumulative cortisol secretion in stress research. However, data on associations between HCC and subjective stress measures have been inconsistent. This may partly be due to bias introduced by smaller-sized academic samples. Here, we investigate associations between HCC and (work-) stress-related measures in a large occupational, predominantly male, sample.

METHODS

Demographic, anthropometric, and self-reported data were collected as part of an occupational health assessment for employees of an airplane manufacturing company (N = 1258). Hair samples (3 cm) were obtained and glucocorticoid concentrations (HCC and hair cortisone, HairE) were analyzed using liquid chromatography-tandem mass spectrometry.

RESULTS

HCC and HairE were unrelated to self-report measures of perceived stress, work-related stress (effort-reward imbalance, overcommitment), and other stress-related constructs. Group-based analyses concerning associations with job strain revealed a small effect of individuals with high job strain (n = 281) exhibiting higher HCC than the remaining sample (n = 811).

CONCLUSIONS

Our data replicate previous findings of no consistent associations between hair glucocorticoids and subjective stress-related questionnaire data, besides evidence for elevated HCC in a high job strain group. Further research addressing open methodological questions regarding HCC by means of advanced stress assessment methods is needed.

Pupil dilation tracks divergent learning processes in aware versus unaware Pavlovian conditioning

Evidence regarding unaware differential fear conditioning in humans is mixed and even less is known about the effects of contingency awareness on appetitive conditioning. Phasic pupil dilation responses (PDR) might be more sensitive for capturing implicit learning than other measures, such as skin conductance responses (SCR). Here, we report data from two delay conditioning experiments utilizing PDR (alongside SCR and subjective assessments) to investigate the role of contingency awareness in aversive and appetitive conditioning. In both experiments, valence of unconditioned stimuli (UCS) was varied within participants by administering aversive (mild electric shocks) and appetitive UCSs (monetary rewards). Preceding visual stimuli (CSs) predicted either the reward, the shock (65% reinforcement), or neither UCS. In Exp. 1, participants were fully instructed about CS-UCS contingencies, whereas in Exp. 2, no such information was given. PDR and SCR demonstrated successful differential conditioning in Exp. 1 and in (learned) aware participants in Exp. 2. In non-instructed participants who remained fully unaware of contingencies (Exp. 2), differential modulation of early PDR (immediately after CS onset) by appetitive cues emerged. Associations with model-derived learning parameters further suggest that early PDR in unaware participants mainly reflect implicit learning of expected outcome value, whereas early PDR in aware (instructed/learned-aware) participants presumably index attentional processes (related to uncertainty/prediction error processing). Similar, but less clear results emerged for later PDR (preceding UCS onset). Our data argue in favor of a dual-process account of associative learning, suggesting that value-related processing can take place irrespective of mechanisms involved in conscious memory formation.

Increased pupil and heart-rate responses to sexual stimuli in men after physical exertion

Physical stress has been found to enhance arousability by visual sexual stimuli on a short-term basis, as reflected in higher phasic pupil dilation responses, probably mediated by sympathetic nervous system (SNS)-related processes. However, previous research has not addressed the specificity of this effect in terms of emotional valence, that is, whether it reflects an instance of general excitation transfer or a more specific mechanism. Thus, to further investigate changes in sexual processing after acute stress exposure, 40 male participants underwent either a predominantly sympathetic stressor (3 min sustained handgrip) or similar control procedure. After stress induction, pictures varying in valence as well as sexual versus non-sexual arousal were presented (for 5000 ms each). Using principal component analysis, pupillary responses during picture viewing were dissociated into fast and slow components (early vs. late response phases). In addition, startle eyeblink responses were elicited by bursts of white noise (50 ms, 105 dB) in half of the trials and recorded at the orbicularis oculi via electromyography. Skin conductance and heart rate were co-registered, as well. While affective startle modulation and skin conductance responses to emotional stimuli were unaffected by previous stress exposure, both evoked heart-rate deceleration (but not acceleration) and pupil responses were specifically enhanced with sexually arousing stimuli in stressed participants, and this effect was mediated by blood pressure reactivity as an index of preceding SNS activation. Taken together, our findings provide strong evidence for enhancement of sexual processing by acute stress exposure in men and suggest differential involvement of parasympathetic versus sympathetic mechanisms.

Evaluation and update of the expert consensus guidelines for the assessment of the cortisol awakening response (CAR)

The cortisol awakening response (CAR) is frequently assessed in psychobiological (stress) research. Obtaining reliable CAR data, however, requires careful attention to methodological detail. To promote best practice, expert consensus guidelines on the assessment of the CAR were published (Stalder et al., 2016, PNEC). However, it is unclear whether these highly cited guidelines have resulted in actual methodological improvements. To explore this, the PNEC editorial board invited the present authors to conduct a critical evaluation and update of current CAR methodology, which is reported here. (i) A quantitative evaluation of methodological quality of CAR research published in PNEC before and after the guidelines (2013-2015 vs. 2018-2020) was conducted. Disappointingly, results reveal little improvement in the implementation of central recommendations (especially objective time verification) in recent research. (ii) To enable an update of guidelines, evidence on recent developments in CAR assessment is reviewed, which mostly confirms the accuracy of the majority of the original guidelines. Moreover, recent technological advances, particularly regarding methods for the verification of awakening and sampling times, have emerged and may help to reduce costs in future research. (iii) To aid researchers and increase accessibility, an updated and streamlined version of the CAR consensus guidelines is presented. (iv) Finally, the response of the PNEC editorial board to the present results is described: potential authors of future CAR research to be published in PNEC will be required to submit a methodological checklist (based on the current guidelines) alongside their article. This will increase transparency and enable reviewers to readily assess the quality of the respective CAR data. Combined, it is hoped that these steps will assist researchers and reviewers in assuring higher quality CAR assessments in future research, thus yielding more reliable and reproducible results and helping to further advance this field of study.

Stressed in afterthought: Neuroendocrine effects of social self-threat during physical effort are counteracted by performance feedback after stress exposure

Social self-threat during physical stress, such as exposure to the cold pressor test and isometric handgrip test, has been shown to induce activation of the HPA axis, in addition to autonomic responses. However, previous research has suggested that dysfunctional post-event processing may play a major role in neuroendocrine reactivity at initial as well as subsequent social stress exposure. In the present study, we investigated how the interplay of context (i.e. performance feedback) with state (i.e., self-esteem) as well as trait-like factors (i.e., ruminative tendencies) affects stress responses to repeated, short bouts of physical activity. On two sessions, 1 week apart, 53 participants (27 women) performed an isometric handgrip task for 3 min, during which they were exposed to social-evaluative threat. In addition, participants received fake feedback on their performance immediately after the task, labeling it as either 'above' (positive) or 'below average' (negative). In addition to neuroendocrine (cortisol), cardiovascular (heart rate, blood pressure) and subjective stress reactivity, performance-related and social dimensions of state self-esteem were assessed before and after stress induction. Substantial increases in cardiovascular parameters were found on both days, regardless of feedback condition. However, positive feedback led to significantly diminished neuroendocrine responses on day 1, whereas baseline cortisol on session 2 was significantly higher in the negative feedback group. Conversely, social self-esteem decreased after stress induction on both days only for participants who had received negative feedback. Changes in self-esteem reported on day 1 were associated with increased baseline cortisol at the second session, while interindividual differences in self-reported (trait) rumination were associated with cortisol reactivity at session 1. Taken together, the results suggest that effects of social evaluation during short periods of physical stress rely on post-event processing and might be counteracted by positive appraisal directly after stress exposure. Post-hoc framing (in terms of success vs. failure) may predict subsequent stress-related hormonal effects better than task demands per se, which should be considered as a potential moderator in future acute stress research, but might also be relevant to many practical applications in fields ranging from sports/performance to health psychology.

Pupil dilation as an index of Pavlovian conditioning. A systematic review and meta-analysis

The use of pupillometry to track emotional learning processes in humans is generating an increasing interest. Here, we provide a first systematic review and meta-analysis on the value of pupil dilation as a marker of Pavlovian conditioning, focusing on the roles of UCS valence (aversive vs. appetitive), the time course across trials and response intervals within trials. Based on data from 39 independent samples (total n = 1303), our results revealed strong evidence for the overall validity of conditioned pupil responses, with a trend for larger effects in aversive (average g = 0.73) vs. appetitive conditioning (g = 0.39). Response differentiation increased over the course of acquisition. Substantial differentiation effects were found in both early and late response windows. Moderator analyses revealed a consistent influence of UCS modality on differential conditioning, while evidence for moderation by contingency instructions and length of acquisition phase was mixed. The results highlight pupil dilation as a sensitive and reliable index of Pavlovian conditioning across valence categories and stimulus modalities. Important implications regarding methodological considerations and research goals are discussed.

Combining mental and physical stress: Synergy or interference?

Both cognitive stressors (such as mental arithmetic tasks) and physical stressors (such as the cold pressor test, CP) are among the most widely employed tools in acute stress research, and there is growing evidence for a high degree of stimulus-response specificity, rather than uniformity, in the human stress response. However, little is known about potential synergistic or interfering effects during concurrent administration. While cognitive tasks have been hypothesized to attenuate pain perception during CP, they are also thought to enhance physiological reactivity. Conversely, physical stress might interfere with effective stress induction by cognitive challenges. To address these questions, 56 participants underwent either the CP (3-min ice-water immersion of feet) or a warm-water control condition. In half of the sample, the Paced Auditory Serial Addition Task (PASAT) was performed simultaneously (fully crossed interventions). Salivary cortisol, cardiovascular parameters, and subjective ratings as well as voice pitch (F0) were assessed. Results show that cortisol responses, self-reported pain and subjective arousal were mainly driven by cold exposure, which also led to increased F0. The PASAT incrementally enhanced cardiovascular reactions, but did not affect pain ratings nor cortisol responses to the CP. However, intra-individual concordance between elevated blood pressure and other reactivity measures was enhanced by PASAT administration during the CP. Importantly, performance decrements in the mental-arithmetic task were not associated with diminished stress responses. In conclusion, our results speak against any strong interference when administering cognitive and painful physical stressors simultaneously, pointing rather to specific additive effects, particularly regarding cardiovascular reactivity.

Modulation of startle and heart rate responses by fear of physical activity in patients with heart failure and in healthy adults

Fear of physical activity (FoPA) has been suggested as a barrier to physical activity in patients with heart failure and might be associated with low adherence to exercise regimen despite medical guideline recommendations. The present study examined physiological indicators of FoPA by assessing startle modulation (via EMG at the orbicularis oculi muscle) and heart rate responses (derived from ECG) after affective priming with lexical stimuli of positive, neutral, and negative valence, as well as words related to physical activity as potentially phobic cues. After screening for FoPA in patients with heart failure and healthy adults, twenty participants each were assigned to one of three subsamples: a healthy control group and two cardiac patient groups scoring either low or high on FoPA. The high-FoPA group showed startle potentiation and more pronounced heart rate acceleration (than did controls) in the phobic prime condition, indicating defensive response mobilization. Among the patients, higher FoPA accounted for 30% of the startle potentiation by phobic priming, whereas general anxiety, depression, and disease severity were no significant predictors of startle modulation. These findings suggest that FoPA in patients with heart failure is associated with defensive responses on a physiological level that might be indicative of avoidance behavior, thereby contributing to low adherence to exercise regimen. Thus, FoPA presents a significant target for psychological interventions to foster physical activity in cardiac patients.

Central Sympathetic Nervous System Effects on Cognitive-Motor Performance

Abstract. The intriguing interplay between acute stress physiology and cognitive processes has long been noted. However, while stress-induced release of glucocorticoids has repeatedly been shown to impact brain mechanisms underlying cognition and memory, less experimental research addressed the effects of stress-induced central sympathetic nervous system (SNS) activation on cognitive performance. Moreover, despite the long-standing notion that the way performance is modulated by arousal may crucially depend on task complexity, mechanistic research demonstrating a direct, causal influence of altered SNS activity is scarce. Twelve healthy men participated in a placebo-controlled, pharmacologic dose–response study involving three within-subject assessments (1-week intervals). Subjective and objective indices of SNS activity as well as reaction time (RT) in three different tasks varying in cognitive demand (simple RT, choice RT, and verbal RT in complex mental arithmetic) were assessed during modulation of central SNS tone by intravenous infusions of dexmedetomidine (alpha2-agonist), yohimbine (alpha2-antagonist), and placebo. Cognitive performance was negatively affected by alpha2-agonism in all task conditions. By contrast, administration of yohimbine improved simple RT, while diminishing complex RT, supporting the assumption of a nonlinear way of action depending on task characteristics. Our results highlight the consequences of central (noradrenergic) SNS activation for cognitive-motor performance in RT tasks of varying complexity.

Self-Resemblance Modulates Processing of Socio-Emotional Pictures in a Context-Sensitive Manner

Abstract. Relevance of emotional information varies with self-involvement. The current study was undertaken to test whether subtle facial self-resemblance is sufficient to affect attentional and affective processing of complex socio-emotional pictures. Faces digitally manipulated to resemble the participants’ (final sample: N = 21) own versus unfamiliar control faces (form and color morphs) were presented in pictures of emotionally evocative social interactions, that is, threat versus sex scenes. At stimulus onset asynchronies (SOAs) of either 300 ms or 3,000 ms after picture onset, startle responses were elicited by acoustic white noise bursts (50 ms, 105 dB), and recorded at the orbicularis oculi via electromyography (EMG). The majority of participants remained unaware of the morphing manipulation, and awareness did not affect the principal results. As indexed by inhibition of startle at short lead intervals and by picture-evoked heart rate deceleration, facial self-resemblance modulates effects of motivational salience in a context-sensitive way, increasing prepulse inhibition with threat-related, but not erotic cues. Overall, the present study suggests that visual cues of general motivational significance and of self-relevance are integrated in a fast, presumably automatic manner.

Blunted endocrine response to a combined physical-cognitive stressor in adults with early life adversity

The negative health effects of early life adversity (ELA) continue long into adulthood. Changes in the physiological response to psychosocial stressors have been proposed to mediate this effect. However, many previous studies have come to contradicting conclusions as to whether ELA induces a long-term increase or decrease in stress reactivity. Therefore, we tested the association of ELA exposure and adult stress reactivity in a sample of early life adoptees and controls. Two previously validated stressful elements (bilateral feet CPT and the Paced Auditory Serial Addition Task (PASAT)) were combined in an extended Cold Pressor Test (CPT). This test was performed on 22 participants who had experienced severe ELA (separation from biological parents, institutionalization, and adoption in early childhood), and in 22 age-matched control participants. A prior history of ELA was associated with blunted reactivity of the hypothalamic-pituitary-adrenal (HPA) axis (Cohen´s d = 0.680). Cardiovascular reactivity remained unchanged, and affective reactivity (self-report ratings) were increased in participants exposed to ELA compared to the control group (range Cohen´s d: 0.642-0.879). Our results suggest that the activity of the HPA axis reactivity was inhibited in ELA participants. Importantly, cardiovascular stress responsiveness was not affected by ELA. This separation of the HPA axis and cardiovascular stress responses may best be explained by ELA selectively enhancing central feedback-sensitivity to glucocorticoids, but preserving cardiovascular/ autonomic stress reactivity.

Acute stress enhances pupillary responses to erotic nudes: Evidence for differential effects of sympathetic activation and cortisol

Chronic stress attenuates reproductive behavior in many species, but evidence regarding the impact of acute stress on human sexual arousability is insufficient. Stressor-specific effects might result from divergent roles of both stress response systems. Social self-threat, linked to affiliation-oriented coping, might also influence sexual responsivity. To investigate stress-induced modulation of the processing of sexual cues and its relationship with cortisol, 58 participants underwent either a predominantly sympathetic stressor (3 min sustained handgrip) or similar control procedure. In both conditions, half of the sample was monitored by an opposite-sex person (social evaluation). Pupillary responses to erotic nudes were recorded and dissociated into fast and slow PCA components. Physically stressed participants showed enhanced (slow) dilation to explicit pictures. Cortisol levels after stress negatively predicted rapid responses to opposite-sex and (marginally) explicit stimuli. Our results suggest that acute sympathetic stress exposure facilitates cognitive sexual processing, whereas subsequent HPA-axis activation may induce counteracting effects.

The socially evaluated handgrip test: Introduction of a novel, time-efficient stress protocol

Most widely-used stress-induction procedures (such as the TSST and the Cold Pressor Test) require considerable effort and overhead in terms of preparation, logistics, and staff recruitment. Moreover, while known to reliably induce HPA axis activation, especially when combined with social self-threat, most conventional laboratory stressors cannot be flexibly adapted to elicit either a mainly autonomic or an additional endocrine stress response. Being a promising alternative approach, a new version of the isometric handgrip test enriched by a social-evaluative component was evaluated in the present study. On two consecutive sessions, forty participants (20 women) performed a handgrip task at both 45% (stress) and 10% (control) of maximum voluntary isometric contraction lasting for 3min. During the stress test, continuous visual feedback on performance was given. Participants in the social-evaluative condition (50%) were observed and evaluated by a previously unknown person of the opposite sex, whereas in the standard condition feedback was provided via a computer monitor. Cardiovascular measures (heart rate, blood pressure) as well as additional indices of autonomic reactivity (skin conductance, heart-rate variability) were registered before, during, and after stress induction. Moreover, changes in salivary cortisol and in subjective well-being were assessed. Relative to control, significant increases in cardiovascular and sympathetic activity were found, irrespective of experimental group. Importantly, however, additional social evaluation resulted in elevated cortisol levels. Furthermore, evidence for reduced vagal tone during sustained socially evaluated handgrip emerged. In conclusion, the socially evaluated handgrip test represents a versatile, time-efficient method to induce stress in small laboratory settings.

Startling similarity: Effects of facial self-resemblance and familiarity on the processing of emotional faces

Facial self-resemblance has been associated with positive emotional evaluations, but this effect may be biased by self-face familiarity. Here we report two experiments utilizing startle modulation to investigate how the processing of facial expressions of emotion is affected by subtle resemblance to the self as well as to familiar faces. Participants of the first experiment (I) (N = 39) were presented with morphed faces showing happy, neutral, and fearful expressions which were manipulated to resemble either their own or unknown faces. At SOAs of either 300 ms or 3500–4500 ms after picture onset, startle responses were elicited by binaural bursts of white noise (50 ms, 105 dB), and recorded at the orbicularis oculi via EMG. Manual reaction time was measured in a simple emotion discrimination paradigm. Pictures preceding noise bursts by short SOA inhibited startle (prepulse inhibition, PPI). Both affective modulation and PPI of startle in response to emotional faces was altered by physical similarity to the self. As indexed both by relative facilitation of startle and faster manual responses, self-resemblance apparently induced deeper processing of facial affect, particularly in happy faces. Experiment II (N = 54) produced similar findings using morphs of famous faces, yet showed no impact of mere familiarity on PPI effects (or response time, either). The results are discussed with respect to differential (presumably pre-attentive) effects of self-specific vs. familiar information in face processing.

Filling the gap: Evidence for a spatial differentiation in trace eyeblink conditioning

Trace eyeblink conditioning is used as a translational model of declarative memory but restricted to the temporal domain. Potential spatial aspects have never been experimentally addressed. We employed a spatiotemporal trace eyeblink conditioning paradigm in which a spatial dimension (application side of the unconditioned stimulus) was differentially coded by tone frequency of the conditioned stimulus and recorded conditioned reactions from both eyes. We found more and stronger conditioned reactions at the side predicted by the conditioned stimulus but only in aware participants. Thus, spatial effects are present in trace eyeblink conditioning and may be differentially conditioned depending on the awareness about the spatial relation between conditioned and unconditioned stimulus.

Enhanced startle reflexivity during presentation of visual nurture cues in young adults who experienced parental divorce in early childhood

Adverse childhood experiences (ACE) may influence stress and affective processing in adulthood. Animal and human studies show enhanced startle reflexivity in adult participants with ACE. This study examined the impact of one of the most common ACE, parental divorce, on startle reflexivity in adulthood. Affective modulation of acoustically-elicited startle eye blink was assessed in a group of 23 young adults with self-reported history of parental divorce, compared to an age- and sex-matched control group (n=18). Foreground pictures were either aversive (e.g. mutilation and injury), standard appetitive (e.g. erotic, recreational sport), or nurture pictures (e.g. related to early life, parental care), intermixed with neutral pictures (e.g. household objects), and organized in three valence blocks delivered in a balanced, pseudo-randomized sequence. During picture viewing startle eye blinks were elicited by binaural white noise bursts (50ms, 105 dB) via headphones and recorded at the left orbicularis oculi muscle via EMG. A significant interaction of group×picture valence (p=0.01) was observed. Contrast with controls revealed blunted startle responsiveness of the ACE group during presentation of aversive pictures, but enhanced startle during presentation of nurture-related pictures. No group differences were found during presentation of standard appetitive pictures. ACE participants rated nurture pictures as more arousing (p=0.02) than did control participants. Results suggest that divorce in childhood led to altered affective context information processing in early adulthood. When exposed to unpleasant (vs. neutral) pictures participants with ACE showed less startle potentiation than controls. Nurture context, however, potentiated startle in ACE participants, suggesting visual cuing to activate protective behavioral responses.

Startle eye-blink modulation by facial self-resemblance and current mood

Although salient stimuli are known to modulate startle eye-blink responses, and one's own face is considered of particular salience, effects of facial self-resemblance on startle responsiveness have not been systematically investigated. For the present study, pictures from the FACES database (rated as neutral) were digitally morphed to resemble the participants' (N=37) faces to varying degrees (25-50-75%). Perceptually matched geometrical shapes served as a control condition. At SOAs of either 300ms or 3000ms after picture onset, startle responses were elicited by white noise (50ms, 105dB), and recorded at the orbicularis oculi via EMG. Prior to the experiment, self-reported mood was assessed by means of the PANAS. Relative to non-face stimuli, the presentation of faces reduced startle magnitude at short, but not long, lead intervals. Furthermore, for probes presented at a SOA of 300ms, a linear decrease in startle magnitude with higher levels of self-resemblance was observed, presumably reflecting higher salience of the self-face. The startle modulating effect of self-resembling faces during longer lead intervals was moderated by the participants' current mood: negative affect predicted stronger patterns of attenuation, which might be interpreted as an increase in self-focus resulting from more negative mood.