The Neural Mechanisms of Imaginal Extinction

Study Overview
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Brief Summary
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Imaginal exposure is a widely used and effective psychological treatment technique in which patients are exposed to fearful stimuli and situations using mental imagery. This study examines imaginal extinction, an experimental analogue of imaginal exposure that allows the study of this treatment technique under controlled circumstances. During imaginal extinction, conditioned fear is diminished through repeated exposure to mental imagery of the feared (conditioned) stimulus. The neural underpinnings of imaginal extinction is not known, and hence, this study examines neural activations during imaginal extinction using psychophysiology and brain imaging.

Detailed Description
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In this study, participants undergo threat conditioning to two pictures (CS+, CS-) in order to acquire a conditioned threat response. After this, the conditioned threat response is diminished through imaginal extinction (i.e extinction to the mental imagery of CS+ and CS-). Functional magnetic resonance imaging (7T) is used to measure neural activations during threat conditioning and imaginal extinction. Skin conductance is used to measure arousal response. Subjective fear and mental imagery vividness ratings will also be collected. In this way, this study aims to characterize the neural underpinnings of imaginal extinction. Note that this study employs participants fearful of spiders. This is because data collection is shared with a related study (ClinicalTrials.gov ID 2020-06930a).

Official Title
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Exploring the Neural Mechanisms of Imaginal Extinction Using fMRI and Psychophysiology

Conditions
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Fear of Spiders

Intervention / Treatment
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* Behavioral: Threat conditioning
* Behavioral: Imaginal extinction


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Willing and able to provide informed consent and complete study procedures Fear of spiders (due to data collection together with ID 2020-06930a) Exclusion Criteria: Current psychiatric disorder other than spider phobia. Current use of psychotropic medication. Current neurological conditions. MRI-contraindications (i.e metal implants in skull).

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Imaginal extinction<br>Conditioned fear will be diminished using imaginal extinction. | Behavioral: Threat conditioning<br>* Day 1: The participant is repeatedly shown two stimulus (CS+,CS-), one at a time. CS+ is paired with an electric shock. CS- acts as a control stimulus. The stimuli consist of photos of two different objects. Stimuli will be counterbalanced between participants.<br>Behavioral: Imaginal extinction<br>* Day 1: Participants are repeatedly instructed to produce mental imagery of the two stimuli used during threat conditioning. Imagery is prompted through different written instructions presented in pseudo-randomized order on a screen. No shocks will be delivered.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Blood oxygen level dependent contrast (BOLD-signal) during threat conditioning and imaginal extinction. | BOLD-signal is assessed using functional magnetic resonance imaging. | Day 1 | 
| Physiological arousal response during threat conditioning and imaginal extinction. | Skin conductance responses are used as a measure of physiological arousal response (i.e. event-related rise in electrodermal activity to stimuli). | Day 1 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Task-specific mental imagery vividness during imaginal extinction | Vividness of Imagery (scale:1-5; no image at all - image as clear and vivid as real life) | Day 1 | 
| Ratings of subjective fear experienced during threat conditioning and imaginal extinction. | Scale 0-100; no fear at all - extreme fear | Day 1 | 
| Spielberger State-Trait Anxiety Inventory (STAI-T) | STAI-T is a self-rated questionnaire included assess trait-anxiety in the participants. Scale: 20-80, where higher scores represent higher levels of trait anxiety. | One week after Day 1 | 
| Vividness of visual imagery Questionnaire (VVIQ) | VVIQ is used to measure individual differences in the Vividness of Visual mental Imagery; scale: 16-80 where higher scores represent a higher ability for visual imagery. | One week after Day 1 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Threat conditioning, Extinction, Imaginal Extinction, Mental Imagery