Arbitration Between Habitual and Goal-directed Behavior in Obsessive-compulsive Disorder: Circuit Dynamics and Effects of Noninvasive Neurostimulation

Study Overview
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Brief Summary
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People utilize two behavioral strategies, goal-directed and habitual, when engaging in value-based decision-making that involves rewarding or punishing outcomes. Accumulating evidence suggests an imbalance between habitual and goal-directed behavior in favor of habitual control in parallel with exaggerated tendency toward compulsive/harm avoidance behavior in OCD. In healthy subjects, an arbitration mechanism has been proposed recently that controls the balance between those two strategies of action selection. Arbitration regions regulate the goal-directed/habitual decision-making balance by selectively downregulating the activity of the habitual regions. This project aims to explore the neurobehavioral characteristics of arbitration mechanism and its relationship with behaviors and clinical phenotypes in OCD by applying computational cognitive neuroscience, clinical task-based functional magnetic resonance imaging (fMRI) and transcranial direct current stimulation (tDCS) method.

Detailed Description
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Investigators will recruit 30 male and female adults (age 18-65) with OCD and 30 age-, sex-, and education-matched healthy (medically, neurologically and psychiatrically) controls for this project. Each participant will come for three sessions. There will be 3-4 days interval between sessions: Session 1 that includes initial clinical assessment and obtaining T1 structural image (needed for neuronavigation analysis and electric field modeling). Session 2 and 3 that include performing two separate decision-making and symptom provocation-avoidance tasks by participants with OCD and healthy controls under two conditions: while scanned inside the MRI scanner (no tDCS) or while receiving neuronavigated tDCS neurostimulation outside the scanner (no fMRI imaging). As participates will perform each task twice, there might be an order effect on task performance. For minimizing the impact of such a potential order effect on imaging and tDCS results, participants will be randomly assigned to undergo scanning in the session 2 and then receive tDCS in the session 3 or in the opposite order (tDCS in session 2 and then imaging in session 3) but in each session only one of imaging or tDCS experiments (for both tasks) will be conducted for each participant. OCD-relevant and aversive picture rating (explained below) will be done always in the session 3 as the last experiment.

Official Title
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Arbitration Between Habitual and Goal-directed Behavior in Obsessive-compulsive Disorder: Circuit Dynamics and Effects of Noninvasive Neurostimulation

Conditions
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OCD, Decision-Making, tDCS, fMRI

Intervention / Treatment
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* Device: transcranial Direct Current Stimulation (tDCS)


Participation Criteria
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Eligibility Criteria
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A) OCD participants inclusion criteria: DSM-5 diagnostic criteria for OCD as primary (most severe) diagnosis (based on the Mini International Neuropsychiatric Interview). Yale-Brown Obsessive-Compulsive Scale (YBOCS) total score is equal or greater than 16. unmediated or being on a stable dose of medication (only SSRIs and clomipramine) for at least 12 weeks prior to the study. fluent English speaker. signed informed consent. B) OCD participants exclusion criteria: IQ greater than 80 on the Wechsler Abbreviated Scales of Intelligence. lifetime DSM-5 diagnosis of mania, psychotic disorder, or substance dependence (per MINI). current DSM-5 diagnosis of MDD if Montgomery-Asberg Depression Scale (MADRS) scores are equal or greater than 35 (severe), or ADHD. taking any psychotropic medication other than SSRIs or clomipramine. severe psychiatric symptom that requires immediate inpatient psychiatric intervention such as suicidality. presence of any serious psychiatric, psychosocial, or neurological condition requiring immediate treatment. C) Healthy control inclusion criteria: 1-males and females age 18-65 years with signed informed consent and IQ greater than 80 on WASI. D) Exclusion criteria for all participants: presence of any MR scan contraindications particularly body metal or positive pregnancy test. medical conditions in which cerebral metabolism might be compromised such as thyroid disorders, diabetes or current tobacco smoking (potential effect on imaging endpoints). any history of seizure disorders.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 65 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: Other
Allocation: Non-Randomized
Intervention Model: Crossover Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Healthy subjects<br> | Device: transcranial Direct Current Stimulation (tDCS)<br>* tDCS is a non-invasive brain stimulation method by which constant low direct current can be delivered to the sculpt for changing the excitability of neuronal structure adjunct to the stimulating electrode.<br>|
| Active Comparator: OCD subjects<br> | Device: transcranial Direct Current Stimulation (tDCS)<br>* tDCS is a non-invasive brain stimulation method by which constant low direct current can be delivered to the sculpt for changing the excitability of neuronal structure adjunct to the stimulating electrode.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Action Selection Ratio | Participants perform a decision-making task in which goal-directed and habitual strategies of decision-making compete to govern the manner of action selection. Action Selection Ratio is the ratio of goal-directed/habitual action selection strategies during the task. Change in Action Selection Ratio will be measured across 3 sessions (baseline, during fMRI and finally tDCS sessions). | At baseline AND twice in two separate sessions with 3-4 days interval. | 
| Activity Level of Arbitration Regions | Activity level of arbitration regions including the right and left inferior lateral prefrontal cortex and right frontopolar cortex in terms of regional BOLD signals during decision-making and symptom provocation-avoidance tasks. | baseline | 
| Arbitration-Habitual Connectivity | The fMRI based functional connectivity between the arbitration regions(the right and left inferior lateral prefrontal cortex and right frontopolar cortex) and habitual regions (putamen, supplementary motor area) measured by psychophysiological interactions method during decision-making and symptom provocationavoidance tasks. | baseline | 
| Change in Timing of Avoidance Behavior | During symptom provocation-avoidance task, OCD-relevant photos will be shown to participants and they will be instructed to push a button to stop the picture presentation when they feel distressed such that they desire to stop viewing the photo. Timing of Avoidance Behavior is the interval between starting time of photo presentation until pushing the stop button. Change in Timing of Avoidance Behavior will be measured across 3 sessions (baseline, during fMRI and finally tDCS sessions). | At baseline but twice in two separate sessions with 3-4 days interval. |