Neural Account of Social Placebo Effect

The current study aimed to reveal the neural mechanism of social placebo belief formation and belief representation, and also investigated how the brain pattern predict the social behavior performance under placebo manipulation.

Study Overview

• Status: Completed
• Conditions: Control Group; Spray+ Group
• Intervention / Treatment: Behavioral: spray+ manipulation; Behavioral: control manipulation

Detailed Description

Participants were randomly assigned to spray+ group (sprayed with saline but told as "oxytocin") and control group (sprayed with saline but told as "saline"). After 10 min, participants were invited to the resting-state, text viewing task in fMRI scanner.

In resting state session, participants with their eyes open and were instructed to attend to a black fixation cross centrally presented on a grey projection screen for 8 min (240TR).

The Text viewing task employed a mixed block and even-related fMRI design. Participants were asked to judge whether they could understand the stimuli or not by a button press (1=understand; 2=not understand). Three kinds of stimuli were presented in separate block including "oxytocin-function", "oxytocin-knowledge", "robot" related stimuli, each category contained 20 sentences. In each block, the sentence (within one category) was presented pseudo-randomized from 5s to 9s (with mean duration of 7s), then followed by a jittered time interval (interval time = sentence duration - response time; if participants made response within 5s, the sentence would not disappear until its duration reached 5s). There were two sessions with six blocks per session, and there were 5 sentences (trials) per block. The order of blocks and sentences were designed to present in pseudo-random order and were applied to all participants.

• Study Type: Interventional
• Enrollment (Actual): 68
• Phase: Not Applicable

Contacts and Locations

Study Locations

• China
  • Beijing
    • Beijing, Beijing, China, 100000
      • Beijing Normal University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 35 years (Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: Male

Description

Inclusion Criteria:

• All participants had normal or corrected-to-normal vision, and mental healthy.

Exclusion Criteria:

• Participants who reported no history of neurological, endocrine or psychiatric disorders, who majored in psychology in college or recently participated in any other drug study were not recruited.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: spray+ group; In spray+ condition, participants learned oxytocin materials on a self-paced basis and then intranasally administered with saline (but it was told as "oxytocin"). Participants were instructed to refrain from smoking or drinking (except water) for 2 h before the experiment. The spray was administered to each participant three times, and each administration consisted of one inhalation into each nostril. Participants took a rest (they were told it was a time period waiting for treatment to produce effects) for 10min and then performed the experimental tasks.	Behavioral: spray+ manipulation; Participants in spray+ group received placebo manipulation and were told they sprayed was oxytocin (in fact, it was saline);
Placebo Comparator: control group; In control condition, the materials and procedure were same with the spray+ condition except the nasal spray was told as "saline" instead. Oxytocin materials used in current experiments were adopted from previous study	Behavioral: control manipulation; Participants in control group were told they sprayed saline (in fact, it was saline).

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The brain functional connectivity	For functional connectivity estimation, we adopted DLPFC, mPFC and reward related brain regions as the seeds to do whole-brain connectivity analysis. And the conducted two-sample T test to examine whether there would be some differences between spray+ and control groups.	8 mins, 240 TR in scanner
Social brain network properties in resting-state	For the network properties, we chose the social brain network as our target and interested network, then estimated the global efficiency within this network.And the conducted two-sample T test to examine whether there would be some differences between spray+ and control groups.	8 mins, 240 TR in scanner
The brain response pattern for the key concepts about oxytocin	We estimated the beta response trial by trial for each single concept and then investigated the neural representation of all concepts by using representational similarity analysis (RSA).	5.33mins, 160TR in scanner

Collaborators and Investigators

• Sponsor: Beijing Normal University

Study record dates

Study Major Dates

• Study Start (Actual): June 27, 2018
• Primary Completion (Actual): November 2, 2018
• Study Completion (Actual): November 5, 2018

Study Registration Dates

• First Submitted: March 17, 2019
• First Submitted That Met QC Criteria: March 24, 2019
• First Posted (Actual): March 27, 2019

Study Record Updates

• Last Update Posted (Actual): March 27, 2019
• Last Update Submitted That Met QC Criteria: March 24, 2019
• Last Verified: March 1, 2019

More Information

Terms related to this study

• Keywords: fMRI; social placebo effect; neural account
• Other Study ID Numbers: FSPE

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No