The Neurobiology of Expectancy and Pain Perception

Study Overview
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Brief Summary
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This study will use using fMRI (functional Magnetic Resonance Imaging) to elucidate how contextual learning/expectation relieves or aggravates pain experience in the same cohort of subjects and the same study session.

Official Title
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A Brain Imaging Study of the Analgesic Effect of Lidocaine and the Hyperalgesic Effect of Capsaicin

Conditions
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Pain

Intervention / Treatment
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* Device: Heat pain applied using TSA or CHEPS


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: a) Healthy male and female adults aged 21-50 b) No contraindications to fMRI scanning c) Right handed Exclusion Criteria: a) Current or past history of major medical, neurological, or psychiatric illness b) Pregnancy or breast feeding, menopause, and irregular menstrual cycles (length of cycle must be within 26 to 32 days) c) Claustrophobia d) History of head trauma e) History of impaired elimination f) Instability of responses to experimental pain (see Study Procedures Section) g) Use of psychotropic drugs, hormone treatments (including hormonal birth control) within 1 year h) Non-fluent speaker of English

Ages Eligible for Study
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Minimum Age: 21 Years
Maximum Age: 50 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
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Arm 1<br>There is only one cohort in this study. All subjects receive the same intervention, the application of heat pain using TSA or CHEPS. | Device: Heat pain applied using TSA or CHEPS<br>* TSA-2001 Thermal Sensory Analyzer (Medoc LTD Advanced Medical Systems) or the Pathway Medoc (CHEPS model, Contact Heat-Evoked Potential Stimulator, Medoc LTD Advanced Medical Systems)<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Subjective Response to Pain (0-20 Visual Analogue Scale) | Subjects received heat pain before and after the application of a neutral cream (told one application of neutral cream was lidocaine, one was capsaicin, and one was neutral) and rated pain intensity on a 0-20 Visual Analogue Scale (0-no pain, 20-intolerable pain). We only measure this outcome measure in session 3. The pain intensity for each cream was averaged amongst all participants for both the pre and post treatment in session 3. Subjects have up to 3 weeks to complete the 3 sessions. | Weeks 1-3 | 
| fMRI Signal Changes in the Dorsal Anterior Cingulate Cortex | We used fMRI to investigate the signal changes associated with administration of identical pain stimuli before (pre) and after the treatment (post) with different creams in session 3. It is important to note that the subjects had multiple weeks to complete the study, but this measure was only taken during one session. The change was calculated from two time points as the value at the later time point (post treatment) minus the value at the earlier time point (pre treatment). | Week 4 |