N-of-few Study of Pain Perception

Healthy Clinical Trial

— NOF  

Official title:

Common and Distinct Mechanisms of Expectancy Effects Across Outcomes

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT04664400
• Other study ID #: 230134
• Secondary ID: 5R01MH076136
• Status: Completed
• Phase: N/A
• Start date: January 22, 2021
• Est. completion date: May 24, 2021

Study information

• Verified date: April 2023
• Source: Trustees of Dartmouth College
• Contact: n/a
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

A behavioral study that will examine how pain perception is affected by different types of conditioning and by context, with a few participants and multiple sessions ("N-of-few" design).

Recruitment information / eligibility

• Status: Completed
• Enrollment: 10
• Est. completion date: May 24, 2021
• Est. primary completion date: May 24, 2021
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: All
• Age group: 18 Years to 55 Years

Eligibility

Inclusion Criteria:

• Healthy participants

Exclusion Criteria:

• Cannot tolerate heat pain applied to the forearm/leg, based on a calibration task at the beginning of the experiment

Related Conditions & MeSH terms

• Healthy

Intervention

Behavioral:
• Symbolic conditioning
Participants will learn associations between cues and thermal stimuli with varying temperatures (low vs. high) through symbolic conditioning (no actual heat stimuli, only pictures of thermometers)
• Conditioning
Participants will learn associations between cues and thermal stimuli with varying temperatures (low vs. high) from experience (with actual heat stimuli).
• Instructions
Participants will learn associations between cues and thermal stimuli with varying temperatures (low vs. high) from verbal instructions.
• Counterfactual
Thermal stimuli will be either the better outcome or the worse outcome out of two possible outcomes.

Locations

Country	Name	City	State
United States	Dartmouth College	Hanover	New Hampshire

Sponsors (2)

Lead Sponsor	Collaborator
Trustees of Dartmouth College	National Institute of Mental Health (NIMH)

Country where clinical trial is conducted

United States, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Other	Within Participant Facial Expressions	The investigators will obtain continuous facial video recordings of participants during the pain tasks with a video camera. The investigators will analyze these data according to Facial Action Units (facial expressions) that are known to be related to pain, and compare them across conditions.	Measured continuously during pain stimuli in each of the 10 sessions of the experiment (up to 3 sessions per week, depending on the participants' availability). Averaged and compared across conditions.
Other	Within Participant Thermal Imaging of the Face	The investigators will obtain thermal recordings of participant's face with an infrared camera, and compare the heat signature of the face (the temperature in different parts of the face) across conditions.	Measured continuously during pain stimuli in each of the 10 sessions of the experiment (up to 3 sessions per week, depending on the participants' availability). Averaged and compared across conditions.
Other	Within Participant Changes in Skin Conductance Response Measured With a Biopac MP160 Device	Each session of the experiment includes pain tasks, in which multiple thermal stimuli are delivered. Skin conductance will be measured continuously. The investigators will compare the skin conductance response to pain stimuli within participant across conditions.	Measured continuously during pain stimuli in each of the 10 sessions of the experiment (up to 3 sessions per week, depending on the participants' availability). Averaged and compared across conditions.
Other	Within Participant Changes in Subjective Ratings of Pain Expectations	Each session of the experiment includes pain tasks, in which multiple thermal stimuli are delivered. Before some of the thermal stimuli, participants are asked to rate how painful they expect the next stimulus to be, on a semi-circular computerized scale. Ratings are based on the angle (0-180), with higher angle representing higher expectations ratings. The investigators will compare the expectation ratings within participant across conditions.	Measured repeatedly during pain tasks, in each of the 10 sessions of the experiment (up to 3 sessions per week, depending on the participants' availability), immediately before thermal stimuli. Averaged and compared across conditions.
Primary	Within Participant Subjective Ratings of Acute Thermal Pain Following High Compared to Low Cues (Learned Via Symbolic Learning)	Each session of the experiment includes pain tasks, in which multiple thermal stimuli are delivered. Following each thermal stimulus, participants are asked to rate how painful it was, on a semi-circular computerized scale. Ratings are based on the angle (0-180), with higher angle representing higher pain ratings. In the symbolic learning procedure, cues are conditioned to different temperatures based on pictures of thermometers (instead of actual thermal stimuli as in the conditioning procedure). For the cues that were learned via symbolic learning, the investigators will compare the average rating of pain for stimuli that are preceded by high cues minus the average rating of pain for stimuli that are preceded by low cues (each averaged across sessions), within participant.	Measured repeatedly during pain tasks, in each of the 10 sessions of the experiment (up to 3 sessions per week, depending on the participants' availability), immediately after thermal stimuli. Averaged across sessions and compared across conditions.
Primary	Within Participant Subjective Ratings of Acute Thermal Pain Following High Compared to Low Cues (Learned Via Conditioning)	Each session of the experiment includes pain tasks, in which multiple thermal stimuli are delivered. Following each thermal stimulus, participants are asked to rate how painful it was, on a semi-circular computerized scale. Ratings are based on the angle (0-180), with higher angle representing higher pain ratings. In the conditioning procedure, cues are conditioned to different temperatures by delivering thermal stimuli with different temperatures after cues are presented (higher temperature following high cues and lower temperature following low cues). For the cues that were learned via conditioning, the investigators will compare the average rating of pain for stimuli that are preceded by high cues minus the average rating of pain for stimuli that are preceded by low cues (each averaged across sessions), within participant.	Measured repeatedly during pain tasks, in each of the 10 sessions of the experiment (up to 3 sessions per week, depending on the participants' availability), immediately after thermal stimuli. Averaged across sessions and compared across conditions.
Primary	Within Participant Subjective Ratings of Acute Thermal Pain Following High Compared to Low Cues (Learned Via Instructions Only)	Each session of the experiment includes pain tasks, in which multiple thermal stimuli are delivered. Following each thermal stimulus, participants are asked to rate how painful it was, on a semi-circular computerized scale. Ratings are based on the angle (0-180), with higher angle representing higher pain ratings. In the instructions only condition, cues are learned via verbal suggestion. For the cues that were learned via instructions only, the investigators will compare the average rating of pain for stimuli that are preceded by high cues minus the average rating of pain for stimuli that are preceded by low cues (each averaged across sessions), within participant.	Measured repeatedly during pain tasks, in each of the 10 sessions of the experiment (up to 3 sessions per week, depending on the participants' availability), immediately after thermal stimuli. Averaged across sessions and compared across conditions.
Primary	Within Participant Subjective Ratings of Acute Thermal Pain, When it is the Worse vs. the Better Alternative	In the counterfactual task, participants are presented with two alternatives (either two pain levels, or one pain level and either losing or gaining a certain amount of money). In these pairs of alternatives, the medium level pain is sometimes the better option (i.e., when the alternative is losing money or a more intense pain stimulus) and sometimes the worse option (i.e., when the other alternative is gaining money or a less intense pain stimulus). One of the two options is chosen by the computer (participants have no control on this choice). The investigators will compare the pain ratings (scale 0-180) within participant for the same level pain stimulus (medium intensity) when it is the worse vs. the better option.	Measured repeatedly during pain tasks, in each of the last 4 sessions of the experiment, immediately after thermal stimuli. Averaged across sessions and compared across conditions.