The aim of this study is to examine the effects of transcranial electrical stimulation on processes associated with fear extinction in healthy humans.
Research links the processes of fear conditioning and extinction to the treatment of anxiety and stress-related disorders. Moreover, considerable translational research examines the neural correlates of these processes. However, virtually no research in humans manipulates neural correlates of these processes, which limits basic-clinical integration. The present study aimed to use transcranial electrical stimulation (tES) to modulate processes associated with fear extinction in order to assess the potential utility of tES in enhancing exposure-based treatment. To this end, healthy participants underwent a three-day fear conditioning and extinction paradigm. Participants were randomly assigned into 3 groups, differing in terms of tES applied during the extinction learning phase (Day 2) and targeting the medial prefrontal cortex: 1) direct current (DC) stimulation, aimed at enhancing extinction learning; 2) alternate current (AC) stimulation, aimed at interfering with reconsolidation of the fear memory activated during the extinction phase; and 3) sham stimulation. The outcome measures (outlined next) involve the assessment of extinction recall during a test phase (Day 3). Successful modulation of extinction learning by tES would be reflected in enhanced extinction recall.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
DOUBLE
Enrollment
45
Galvanic Skin Response (GSR)
GSR was measured throughout the task using 2 standard electrodes on the fingers. Measurement units were in micro-Siemens; scores were square-root-transformed (a common method in GSR studies). A higher level of GSR in response to stimuli is taken to reflect greater physiological fear response, and thus worse in the context of the relevance of the study conditions to the treatment of anxiety disorders. Scores were collected in response to presentation of the CS+ (the stimulus conditioned to be associated with an aversive outcome) and the CS- (the stimulus not conditioned to be associated with any outcome).
Time frame: During three-day experimental task
Self-reported Fear Rankings
Participants marked how fearful they are of stimuli used in the task on a single 10-point scale (1=not afraid, 10=extremely afraid). Higher scores therefore reflect greater fear and are worse in the context of treatment for anxiety disorders. Scores were collected in response to presentation of the CS+ (the stimulus conditioned to be associated with an aversive outcome) and the CS- (the stimulus not conditioned to be associated with any outcome).
Time frame: During three-day experimental task
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