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"Spinnentiere"
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Visual sensory discrimination of threatening stimuli presenting different durations: A magnetoencephalographic and behavioral study
•Stimulus duration (33 to 267 ms) does not interact with threat behavioral effects.•MEG showed threat discrimination from 100 ms in visual cortices, from V1 to TE.•This sensory cortex discrimination also does not interact with duration.•Threat discrimination was stronger for stimuli at fixation than at the periphery.•The brain thus acts as an “all-or-nothing”, rather than gradual, threat detector.
Whether time exposure influences visual sensory processing of emotional stimulation is an unexplored issue, despite its relevance to understanding affective processing. We recorded magnetoencephalographic (MEG) activity -concretely event-related magnetic fields (ERFs)- from 25 participants while attending to spiders (emotional stimuli) and wheels (neutral) silhouettes they had to categorize. These stimuli were presented during 33.33, 66.66, 133.33, and 266.66 ms, and could appear at the center of the screen (fixation) or in the lower visual field (periphery). Behavioral performance revealed improved detection of negative emotional stimuli at fixation, and this effect did not interact with exposure time. At the neural level, greater amplitudes for spiders than for wheels were observed when presented at fixation in two visual ERF components, M100 and M150, an effect originating in striate and extrastriate visual cortices, respectively. This effect, ocurring later for stimuli presented at the periphery (M210, estimated in the extrastriate cortex), neither interacted with stimulus duration. This threat detection mechanism in the visual cortex independent of stimulus duration points to an all-or-nothing, rather than gradual, sensory discrimination of emotional cues regarding their exposure time.
Journal Article
Do oral contraceptives modulate the effects of stress induction on one-session exposure efficacy and generalization in women?
Rationale
The administration of glucocorticoids (GC) as an adjunct to exposure represents a promising strategy to improve one-session exposure outcome in anxiety disorders. It remains to be determined whether similar effects can be induced with the use of acute stress. Furthermore, the possible modulation of exposure effects by hormonal factors (e.g., use of oral contraceptives (OCs)) was not explored so far.
Objectives
We investigated whether acute stress prior to one-session exposure for spider fear affects its efficacy in women using oral contraceptives (
OC
) relative to free-cycling (
FC
) women. In addition, effects of stress on generalization of exposure therapy effects towards untreated stimuli were examined.
Methods
Women with fears of spiders and cockroaches were randomly assigned to a
Stress
(n = 24) or
No-Stress
(n = 24) condition prior to one-session exposure. Of these 48 participants, 19 women used OC (n = 9 in the Stress, and n = 10 in the No-Stress group). All
FC
women had a regular menstrual cycle and were tested only in the follicular phase of their menstrual cycle. Pre-exposure stress induction was realized with the socially evaluated cold-pressor test. Exposure-induced changes towards treated and untreated fear stimuli were tested with behavioral approach tests for spiders and cockroaches and subjective fear and self-report measures.
Results
Acute stress did not influence exposure-induced reduction in fear and avoidance of the treated stimuli (spiders). Similarly, stress had no effect on the generalization of exposure-therapy effects towards untreated stimuli (cockroaches). Exposure-induced reduction in subjective fear and self-report measures for treated stimuli was less evident in women using OC specifically after pre-exposure stress. Women using OC had higher levels of subjective fear and scored higher in self-report measures at post-treatment (24 h after exposure) and follow-up (4 weeks after exposure).
Conclusions
OC intake may represent an important confounding factor in augmentation studies using stress or GC.
Journal Article
Individual-Level Prediction of Exposure Therapy Outcome Using Structural and Functional MRI Data in Spider Phobia: A Machine-Learning Study
Adolescent mental health is impacted by a myriad of factors, including the developing brain, socioeconomic conditions and changing social relationships. Studies to date have neglected investigating those factors simultaneously, despite evidence of their interacting effects and distinct profiles for males and females. The current study addressed that gap by applying structural equation modelling to IMAGEN data from adolescents aged 14 years (n = 1950). A multi-group model split by sex was tested with the variables of socioeconomic stress, family support, peer problems, and brain structure as predictors, and emotional symptoms as the main outcome. Findings indicated that, for both sexes, peer problems were positively associated with emotional symptoms, and socioeconomic stress was negatively associated with family support. Additionally, there were sex-specific findings within the full models: ventromedial prefrontal cortex grey matter volume was negatively associated with emotional symptoms for males when corrected for whole brain volume, and socioeconomic stress was negatively associated with whole brain volume for females. This study underscores the importance of the peer environment for early adolescent emotional symptoms in both boys and girls, but goes further to suggest distinct gender associations with socioeconomic factors and brain structure which provides a multi-level view of risk and resilience. Future research could exploit existing IMAGEN longitudinal data to strengthen causal claims and to determine the potential longstanding impact of social environment and brain development on adolescent mental health.
Journal Article
GLUCOCORTICOIDS ENHANCE IN VIVO EXPOSURE-BASED THERAPY OF SPIDER PHOBIA
Background Preclinical and clinical studies indicate that the administration of glucocorticoids may promote fear extinction processes. In particular, it has been shown that glucocorticoids enhance virtual reality based exposure therapy of fear of heights. Here, we investigate whether glucocorticoids enhance the outcome of in vivo exposure‐based group therapy of spider phobia. Methods In a double blind, block‐randomized, placebo‐controlled, between‐subject study design, 22 patients with specific phobia of spiders were treated with two sessions of in vivo exposure‐based group therapy. Cortisol (20 mg) or placebo was orally administered 1 hr before each therapy session. Patients returned for a follow‐up assessment one month after therapy. Results Exposure‐based group therapy led to a significant decrease in phobic symptoms as assessed with the Fear of Spiders Questionnaire (FSQ) from pretreatment to immediate posttreatment and to follow‐up. The administration of cortisol to exposure therapy resulted in increased salivary cortisol concentrations and a significantly greater reduction in fear of spiders (FSQ) as compared to placebo at follow‐up, but not immediately posttreatment. Furthermore, cortisol‐treated patients reported significantly less anxiety during standardized exposure to living spiders at follow‐up than placebo‐treated subjects. Notably, groups did not differ in phobia‐unrelated state‐anxiety before and after the exposure sessions and at follow‐up. Conclusions These findings indicate that adding cortisol to in vivo exposure‐based group therapy of spider phobia enhances treatment outcome.
Journal Article
SPIDER OR NO SPIDER? NEURAL CORRELATES OF SUSTAINED AND PHASIC FEAR IN SPIDER PHOBIA
Background Processes of phasic fear responses to threatening stimuli are thought to be distinct from sustained, anticipatory anxiety toward an unpredicted, potential threat. There is evidence for dissociable neural correlates of phasic fear and sustained anxiety. Whereas increased amygdala activity has been associated with phasic fear, sustained anxiety has been linked with activation of the bed nucleus of stria terminalis (BNST), anterior cingulate cortex (ACC), and the insula. So far, only a few studies have focused on the dissociation of neural processes related to both phasic and sustained fear in specific phobia. We suggested that first, conditions of phasic and sustained fear would involve different neural networks and, second, that overall neural activity would be enhanced in a sample of phobic compared to nonphobic participants. Methods Pictures of spiders and neutral stimuli under conditions of either predicted (phasic) or unpredicted (sustained) fear were presented to 28 subjects with spider phobia and 28 nonphobic control subjects during functional magnetic resonance imaging (fMRI) scanning. Results Phobic patients revealed significantly higher amygdala activation than controls under conditions of phasic fear. Sustained fear processing was significantly related to activation in the insula and ACC, and phobic patients showed a stronger activation than controls of the BNST and the right ACC under conditions of sustained fear. Functional connectivity analysis revealed enhanced connectivity of the BNST and the amygdala in phobic subjects. Conclusions Our findings support the idea of distinct neural correlates of phasic and sustained fear processes. Increased neural activity and functional connectivity in these networks might be crucial for the development and maintenance of anxiety disorders.
Journal Article
Brain dynamics of visual attention during anticipation and encoding of threat- and safe-cues in spider-phobic individuals
This study systematically investigated the sensitivity of the phobic attention system by measuring event-related potentials (ERPs) in spider-phobic and non-phobic volunteers in a context where spider and neutral pictures were presented (phobic threat condition) and in contexts where no phobic but unpleasant and neutral or only neutral pictures were displayed (phobia-irrelevant conditions). In a between-group study, participants were assigned to phobia-irrelevant conditions either before or after the exposure to spider pictures (pre-exposure vs post-exposure participants). Additionally, each picture was preceded by a fixation cross presented in one of three different colors that were informative about the category of an upcoming picture. In the phobic threat condition, spider-phobic participants showed a larger P1 than controls for all pictures and signal cues. Moreover, individuals with spider phobia who were sensitized by the exposure to phobic stimuli (i.e. post-exposure participants) responded with an increased P1 also in phobia-irrelevant conditions. In contrast, no group differences between spider-phobic and non-phobic individuals were observed in the P1-amplitudes during viewing of phobia-irrelevant stimuli in the pre-exposure group. In addition, cues signaling neutral pictures elicited decreased stimulus-preceding negativity (SPN) compared with cues signaling emotional pictures. Moreover, emotional pictures and cues signaling emotional pictures evoked larger early posterior negativity (EPN) and late positive potential (LPP) than neutral stimuli. Spider phobics showed greater selective attention effects than controls for phobia-relevant pictures (increased EPN and LPP) and cues (increased LPP and SPN). Increased sensitization of the attention system observed in spider-phobic individuals might facilitate fear conditioning and promote generalization of fear playing an important role in the maintenance of anxiety disorders.
Journal Article
Weaving the (neuronal) web: Fear learning in spider phobia
Theories of specific phobias consider classical conditioning as a central mechanism in the pathogenesis and maintenance of the disorder. Although the neuronal network underlying human fear conditioning is understood in considerable detail, no study to date has examined the neuronal correlates of fear conditioning directly in patients with specific phobias. Using functional magnet resonance imaging (fMRI) we investigated conditioned responses using phobia-relevant and non-phobia-relevant unconditioned stimuli in patients with specific phobias (n=15) and healthy controls (n=14) by means of a differential picture–picture conditioning paradigm: three neutral geometric figures (conditioned stimuli) were followed by either pictures of spiders, highly aversive scenes or household items (unconditioned stimuli), respectively. Enhanced activations within the fear network (medial prefrontal cortex, anterior cingulate cortex, amygdala, insula and thalamus) were observed in response to the phobia-related conditioned stimulus. Further, spider phobic subjects displayed higher amygdala activation in response to the phobia-related conditioned stimulus than to the non-phobia-related conditioned stimulus. Moreover, no differences between patients and healthy controls emerged regarding the non-phobia-related conditioned stimulus. The results imply that learned phobic fear is based on exaggerated responses in structures belonging to the fear network and emphasize the importance of the amygdala in the processing of phobic fear. Further, altered responding of the fear network in patients was only observed in response to the phobia-related conditioned stimulus but not to the non-phobia-related conditioned stimulus indicating no differences in general conditionability between patients with specific phobias and healthy controls.
►Phobia-relevant CS leads to hyperactivation of fear network in phobics. ►Amygdala activity depends on phobia-relevance of the CS in phobics. ►No differences between phobics and controls in response to non-phobia-relevant CS.
Journal Article
Timing the fearful brain: unspecific hypervigilance and spatial attention in early visual perception
Numerous studies suggest that anxious individuals are more hypervigilant to threat in their environment than nonanxious individuals. In the present event-related potential (ERP) study, we sought to investigate the extent to which afferent cortical processes, as indexed by the earliest visual component C1, are biased in observers high in fear of specific objects. In a visual search paradigm, ERPs were measured while spider-fearful participants and controls searched for discrepant objects (e.g. spiders, butterflies, flowers) in visual arrays. Results showed enhanced C1 amplitudes in response to spatially directed target stimuli in spider-fearful participants only. Furthermore, enhanced C1 amplitudes were observed in response to all discrepant targets and distractors in spider-fearful compared with non-anxious participants, irrespective of fearful and non-fearful target contents. This pattern of results is in line with theoretical notions of heightened sensory sensitivity (hypervigilance) to external stimuli in high-fearful individuals. Specifically, the findings suggest that fear facilitates afferent cortical processing in the human visual cortex in a non-specific and temporally sustained fashion, when observers search for potential threat cues.
Journal Article
Emotion regulation in spider phobia: role of the medial prefrontal cortex
Phobic responses are strong emotional reactions towards phobic objects, which can be described as a deficit in the automatic regulation of emotions. Difficulties in the voluntary cognitive control of these emotions suggest a further phobia-specific deficit in effortful emotion regulation mechanisms. The actual study is based on this emotion regulation conceptualization of specific phobias. The aim is to investigate the neural correlates of these two emotion regulation deficits in spider phobics. Sixteen spider phobic females participated in a functional magnetic resonance imaging (fMRI) study in which they were asked to voluntarily up- and down-regulate their emotions elicited by spider and generally aversive pictures with a reappraisal strategy. In line with the hypothesis concerning an automatic emotion regulation deficit, increased activity in the insula and reduced activity in the ventromedial prefrontal cortex was observed. Furthermore, phobia-specific effortful regulation within phobics was associated with altered activity in medial prefrontal cortex areas. Altogether, these results suggest that spider phobic subjects are indeed characterized by a deficit in the automatic as well as the effortful regulation of emotions elicited by phobic compared with aversive stimuli. These two forms of phobic emotion regulation deficits are associated with altered activity in different medial prefrontal cortex subregions.
Journal Article