Priming Expectations and Motor Learning With tDCS
Effects of Modulating Expectations About Noninvasive Brain Stimulation on Motor Learning
Study Overview
Status
Conditions
Intervention / Treatment
Detailed Description
Transcranial direct current stimulation (tDCS) is currently being investigated by the scientific community as an intervention to improve motor learning in the context of neurorehabilitation (e.g., recover lost motor function after stroke) and performance enhancement (e.g., improve sports or technical skill training). More importantly, consumers believe that tDCS works. The expectation surrounding the benefits of tDCS for skill enhancement is so pervasive that the technology is sold for less than $200 and highly rated by the general public on Amazon.com. At the same time, there is considerable skepticism within the motor control field regarding the efficacy and mechanism of action of tDCS on motor learning, driven by highly irreproducible and equivocal findings between and even within laboratories.
How effective is tDCS, and could the positive effects of tDCS be attributable in part to a strong placebo effect? Placebo effects (i.e., a positive expectation associated with positive treatment outcomes), are well documented in other interventions like surgeries and pharmaceuticals, but have not been investigated in detail for tDCS, particularly in the motor domain. The lack of knowledge or consideration of the placebo effect may therefore explain why tDCS findings are so inconsistent within motor learning. Thus, the overall aim of this project is to determine whether people's expectations about tDCS change as a function of information about tDCS itself, and whether these changed expectations modulate the effects of tDCS on motor learning.
Transcranial direct current stimulation (tDCS) is a noninvasive, safe cortical stimulation technique that has been effectively used for enhancing and inhibiting sensory and motor performance when applied to the responsible cortical areas in healthy adults. For instance, anodal tDCS of primary motor area can improve motor execution. Recent research has investigated whether it is the expectation of receiving tDCS that has a greater impact on behavioral outcomes compared to the actual application of tDCS. This is important as many domains of science are challenged to reproduce previous research demonstrating a positive effect of tDCS on behavior. Thus, to decipher legitimate effects of tDCS on behavior it is important to quantify and compare how changes in behavior are related to tDCS, a key metric related to strength of the placebo effect, and how malleable these placebo effects are.
Individuals may participate in this study for up to four sessions (up to 3 training sessions and up to 1 follow-up visit, as assigned) in the span of approximately one week. The investigators expect that individuals will spend up to one hour during the training sessions, and (if applicable) around 15 minutes to complete the follow-up visit, if assigned. The follow-up visit would occur one week after the final training session.
This is a double-blind study in which participants will be randomly assigned to specific intervention methods.
Study Type
Enrollment (Actual)
Phase
- Not Applicable
Contacts and Locations
Study Locations
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Arizona
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Tempe, Arizona, United States, 85281
- Arizona State University
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Participation Criteria
Eligibility Criteria
Ages Eligible for Study
- Adult
- Older Adult
Accepts Healthy Volunteers
Description
Inclusion Criteria:
- Must be 18 or older. Right-hand dominant
- Right-hand dominant
Exclusion Criteria:
- Mixed-handed or ambidextrous
- Left-hand dominant
- Seizure(s)
- Head injury resulting in a loss of consciousness that has required further investigation (including neurosurgery)
- Migraines
- Current medical diagnosis of a phycological or neurological condition
- Any metal in head (outside of mouth) such as shrapnel or surgical clips
- Any implanted devices (e.g. cardiac pacemaker, brain stimulator)
- Skin condition on scalp (e.g. psoriasis)
- Head wound that has not completely healed
- Adverse reactions to tDCS or any other brain stimulation technique (e.g. TMS, tRNS)
- Pregnant
- Currently taking prescription medications or are self-medicating (including recreational drug use), other than the contraceptive pill?
Study Plan
How is the study designed?
Design Details
- Primary Purpose: Treatment
- Allocation: Randomized
- Interventional Model: Parallel Assignment
- Masking: Double
Arms and Interventions
Participant Group / Arm |
Intervention / Treatment |
|---|---|
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No Intervention: Control
This group will only receive motor training, which consists of 10 trials of motor training per day across 3 days, followed by a one-week follow-up of 2 trials.
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Experimental: tDCS1
This group will receive motor training concurrent with 20 minutes of either sham or active tDCS.
Sham tDCS will be a 30-second ramp up from 0 to 2 milliamps (MA), then a 30-second ramp-down from 2 mA to 0 mA.
The next 18 minutes will have no stimulation (0 mA), starting at minute 19 with 30-second ramp up from 0 to 2 milliamps (MA), then a 30-second ramp-down from 2 mA to 0 mA.
Active tDCS will ramp up to 2 mA in the first 30 seconds, then stay at 2 mA for 19 minutes, then ramp down to 0 mA.
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Transcranial Direct Current Stimulation (tDCS) is a minimal risk, non-invasive, neuromodulatory technique that involves the emission of a weak electrical current, traditionally via the placement of two electrodes attached to the scalp of a participant.
tDCS is widely used for research purposes, the US FDA considers trials of tDCS as non-significant-risk.
There are several review articles supporting the safety of tDCS usage in controlled human trials.
According to a published meta-analysis , the use of conventional tDCS protocols in human trials (≤40 min, ≤4 mA) has not produced any reports of a Serious Adverse Effect or irreversible injury across over 33,200 sessions.
Other Names:
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Experimental: tDCS2
This group will first read some information about tDCS based on cited studies.
They will then receive the same motor training and tDCS as the tDCS1 arm.
|
Transcranial Direct Current Stimulation (tDCS) is a minimal risk, non-invasive, neuromodulatory technique that involves the emission of a weak electrical current, traditionally via the placement of two electrodes attached to the scalp of a participant.
tDCS is widely used for research purposes, the US FDA considers trials of tDCS as non-significant-risk.
There are several review articles supporting the safety of tDCS usage in controlled human trials.
According to a published meta-analysis , the use of conventional tDCS protocols in human trials (≤40 min, ≤4 mA) has not produced any reports of a Serious Adverse Effect or irreversible injury across over 33,200 sessions.
Other Names:
|
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Experimental: tDCS3
This group will first read some information about tDCS based on cited studies, but different cited studies than the tDCS2 arm.
They will then receive the same motor training and tDCS as the tDCS1 and 2 arms.
|
Transcranial Direct Current Stimulation (tDCS) is a minimal risk, non-invasive, neuromodulatory technique that involves the emission of a weak electrical current, traditionally via the placement of two electrodes attached to the scalp of a participant.
tDCS is widely used for research purposes, the US FDA considers trials of tDCS as non-significant-risk.
There are several review articles supporting the safety of tDCS usage in controlled human trials.
According to a published meta-analysis , the use of conventional tDCS protocols in human trials (≤40 min, ≤4 mA) has not produced any reports of a Serious Adverse Effect or irreversible injury across over 33,200 sessions.
Other Names:
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What is the study measuring?
Primary Outcome Measures
Outcome Measure |
Measure Description |
Time Frame |
|---|---|---|
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Performance on Motor Task One Week After Final Training Session
Time Frame: One-Week Follow-Up visit (Day 10)
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This will be calculated as the average of two trials of the motor task that are completed one week after the last training session.
The motor task is a timed test that requires participants to spoon two beans (kidney, raw) at a time from a center proximal "start" cup to three distal "target" cups as fast as possible.
In short, this task requires multijoint coordination and limb reversal, and performance for each trial is measured in seconds.
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One-Week Follow-Up visit (Day 10)
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Secondary Outcome Measures
Outcome Measure |
Measure Description |
Time Frame |
|---|---|---|
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Change in Motor Performance Over the Course of Training
Time Frame: Day 1, 2, and 3
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This outcome measure will be measured as the slope of the line fitted to the motor task performance across all 30 training trials (this includes Day 1, 2 and 3), when trial is transformed to a logarithmic scale.
This transformation is done to account for the fact that change in performance is non-linear.
The motor task is a timed test that requires participants to spoon two beans (kidney, raw) at a time from a center proximal "start" cup to three distal "target" cups as fast as possible.
In short, this task requires multijoint coordination and limb reversal, and performance for each trial is measured in seconds.
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Day 1, 2, and 3
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Change in tDCS Expectations From Day 1 to Day 10
Time Frame: Day 1 and Follow-Up (Day 10)
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This will be the change (Day 1 minus Day 10) in expectations of tDCS.
The tDCS expectation scores are taken from a 1-item survey adapted from the Expectation Assessment Scale, where scores range from 0 (no expectation) to 8 (high expectations); a score of 4 is considered neutral.
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Day 1 and Follow-Up (Day 10)
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Average Dwell Time
Time Frame: One-Week Follow-Up (Day 10)
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This is the average amount of time spent in the home cup for each repetition, averaged across the two follow-up trials.
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One-Week Follow-Up (Day 10)
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Average Peak Reach Velocity
Time Frame: One-Week Follow-Up (Day 10)
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his is the average peak velocity for the outward portion of each repetition, averaged across the two follow-up trials.
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One-Week Follow-Up (Day 10)
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Variability in Transcranial Direct Current Stimulation Expectations
Time Frame: Days 1, 2, 3, and 10
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This is the coefficient of variation (CV) for tDCS expectation scores.
It is calculated by dividing the standard deviation of the participant's expectations across study days (Days 1, 2, 3, and 10) by the mean expectation of these 4 study days.
The tDCS expectation scores are taken from a 1-item survey adapted from the Expectation Assessment Scale, where scores range from 0 (no expectation) to 8 (high expectations); a score of 4 is considered neutral.
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Days 1, 2, 3, and 10
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Post-tDCS Symptom Questionnaire Score
Time Frame: Days 1, 2, and 3
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This is calculated using a 14-item self-rated questionnaire, with answers for each item ranging from 1 ("absent") to 10 ("severe").
A daily average score (ranging from 1 to 10) was calculated for each participant by averaging the 14 items.
The reported values represent the mean of these daily averages per group.
Higher values represent more severe symptoms (a worse outcome).
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Days 1, 2, and 3
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tDCS Expectation Scores
Time Frame: Days 1, 2, 3, and 10
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The tDCS expectation scores are taken from a 1-item survey adapted from the Expectation Assessment Scale, where scores range from 0 (no expectation) to 8 (high expectations); a score of 4 is considered neutral.
This score was collected for each participant in the experimental group (tDCS1, tDCS2, tDCS3) across study days (Days 1, 2, 3, and 10).
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Days 1, 2, 3, and 10
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Collaborators and Investigators
Sponsor
Investigators
- Principal Investigator: Sydney Schaefer, PhD, Arizona State University
Study record dates
Study Major Dates
Study Start (Actual)
Primary Completion (Actual)
Study Completion (Actual)
Study Registration Dates
First Submitted
First Submitted That Met QC Criteria
First Posted (Actual)
Study Record Updates
Last Update Posted (Actual)
Last Update Submitted That Met QC Criteria
Last Verified
More Information
Terms related to this study
Keywords
Additional Relevant MeSH Terms
Other Study ID Numbers
- STUDY00015655
Plan for Individual participant data (IPD)
Plan to Share Individual Participant Data (IPD)?
IPD Plan Description
Drug and device information, study documents
Studies a U.S. FDA-regulated drug product
Studies a U.S. FDA-regulated device product
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