Priming Expectations and Motor Learning With tDCS

Arizona State University (ASU)

Status: Completed

Conditions: Motor Learning; Expectations

Treatments: Device: Transcranial Direct Current Stimulation

Study type: Interventional

Funder types: Other

Identifiers

NCT06039605

STUDY00015655

Details and patient eligibility

About

The purpose of this study is to test if priming expectations of transcranial Direct Current Stimulation (tDCS) can improve the efficacy of tDCS in enhancing motor learning.

Full 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.

Enrollment: 140 patients

Sex: All

Ages: 18+ years old

Volunteers: Accepts Healthy Volunteers

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?

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Double Blind

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140 participants in 4 patient groups

Control

No Intervention group

Description:

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.

tDCS1

Experimental group

Description:

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.

Treatment:

Device: Transcranial Direct Current Stimulation

tDCS2

Experimental group

Description:

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.

Treatment:

Device: Transcranial Direct Current Stimulation

tDCS3

Experimental group

Description:

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.

Treatment:

Device: Transcranial Direct Current Stimulation