Enhancing Locomotor Learning With Motor Imagery and Transcranial Direct Current Stimulation
Phase: NA
Conditions: Motor Learning
Sponsor: Appalachian State University

Enhancing Locomotor Learning with Motor Imagery and Transcranial Direct Current Stimulation: A Pilot 
Randomized Controlled Trial in Young Adults. 
NCT06414213 
09-20-2022 
Study protocol  
Study Design 
The primary goal of this study is to investigate an novel intervention on improvements in walking and 
balance. The design of this study is a randomized, double-blinded clinical trial. The study will use a pilot 
intervention that will utilize a dual strategy combining MI with tDCS ( a non-invasive brain stimulation) 
to activate the frontal/executive networks of the brain to enhance motor learning to increase retention and 
transfer of locomotor learning. Participants, separated by age by age 18-35 and 50 and older, will be 
randomly allocated to experimental (active tDCS) or sham groups and will be assessed at baseline, 
immediately following the intervention, and at 1-week. Outcome measures include cortical activation 
(oxygenated Hemoglobin, HbO2), assessed through functional near-infrared spectroscopy (fNIRS), 
cognitive assessments, and gait and balance assessments. Complete participation will consist of 2 visits to 
the Neuromechanics laboratory at Leon Levine Hall.  
Outcome Measures 
Assessments will be conducted by the experienced examiner(s) blinded to group tDCS assignment and 
will occur at three time points: baseline, post-Intervention, and follow-up (1 week after the baseline 
assessment). Prefrontal cortical activity will be assessed during walking to investigate intervention-
induced prefrontal/executive activity changes. Using a commercially available Functional near infrared 
spectroscopy (fNIRS) monitor (OctaMon by Artinis Medical Systems), changes in oxygenated 
hemoglobin concentration (O2Hb) relative to a baseline task will be measured for the orbitofrontal and 
dorsolateral prefrontal cortex. During walking assessments, we will use fNIRS to measure frontal cortical 
activity. Changes in O2Hb will be assessed at baseline and after the intervention week. All manufacturer 
guidelines will be followed in the collection of fNIRS.  
Time to completion: Participants will walk over a 4-m instrumented walkway mat during the assessments. 
The walkway system is a clinical instrument that allows for objective gait assessment. Spatial and 
temporal gait variables calculated from the walkway system have strong concurrent validity and test-
retest reliability (intra-class coefficients >0.8 for most variables). These measures will allow us to 
determine time to completion and changes in gait quality (stepping characteristics) during pre/post/ and 
follow-up testing. 
Kinesthetic and Visual Imagery Questionnaire (KVIQ): The ability to imagine movements was assessed 
with the KVIQ. This test evaluates the subject’s ability to see (visual imagery) and feel (kinesthetic 
imagery) movements. TheKVIQ consists of 10 items, (5 movements for each scale), each item being a 
separate movement followed by rating the ease or difficulty of generating those self-images on a 5-point 
Likert scale (where 1 = no image or sensation and 5 = Image as clear as seeing or as intense as executing 
the action). Higher scores reflected higher imagery abilities. 
Baseline visit and Intervention 

We will enroll 40 adults age 18 to 35 (n=20) and 50 and older (n=20) without neurological conditions. 
Participants will be randomized to one of the two groups: 1) MI with sham tDCS (‘MI /sham’) and 2) MI 
with active tDCS (‘MI/ active’). 
For Visit One, All participants will undergo fNIRS, Gait assessment, and KVIQ. Additionally, all 
participants will perform the locomotor learning task.  
Locomotor Learning  
Participants will begin in a quiet, standing position with the fNIRS attached to themselves and after a 
period of 30 secs of quiet rest, participants will stand for a period of 30 secs and then begin walking over 
the course. The course is a 10-meter obstacle course containing foam obstacles of various heights and 
widths at their fastest safe pace. Participants will repeat this process 10 times. Participants will be asked 
not to speak and only engage in thinking about the walking course. Rest periods of a minimum of 1 min 
will be permitted to prevent fatigue and standardize the procedures. Time to complete the course will be 
recorded and the change in time to complete the course will be used as an outcome. 
Following the baseline testing and locomotor learning assessment, the participants will engage MI with 
active or sham tDCS intervention. Participants enrolled will receive standardized instructions explaining 
the protocol and undergo the assessment using a 24-in computer to watch video clips. Instructions, 
“Please watch the following video. You will see someone walking over the course you did for the baseline 
visit, which will be repeated several times. Place your focus on each foot as it approaches each obstacle 
and imagine performing the task yourself during the entire period of the video. At the end of the video 
you will be asked to close your eyes and to continue performing 
mentally the task until you hear the stop sign. From time to time, I will encourage you to perform the task. 
Now try to relax and press the spacebar to start the video while concentrating as much as possible on the 
task when you are ready.” This will be implemented to cue participants' visual attention to the obstacles 
and anatomical regions that are fundamental for correctly and safely walking the course, as consistently 
emphasized by physical therapists and gait rehabilitation experts.  This method has been utilized in 
previous investigations and used during the intervention, The anodal electrode will be placed over the 
frontal cortex (F3/4 10:20 location) contralateral to the test side, and the cathode will be placed over the 
supraorbital region ipsilateral to the test leg (opposite side as the anode). Prior to placement of the 
electrodes, the area will be inspected for signs of scalp irritation and the scalp will be cleared with an 
alcohol pad. Electrodes will be secured with an elastic strap around the forehead and top of head 
(EasyStrap, Soterix). A Soterix clinical transcranial electrical stimulator will be placed within a clear 
backpack to be worn by the subject. The investigator will explain the stimulus to the patient (a tingling or 
itching sensation) and provide a pre-stimulus tickle to ensure proper electrode impedance (measured by 
stimulator) and familiarize the subject. The investigator will enter a specific subject code that will initiate 
either a sham current (2-minutes ramp on followed by no stimulation), or a constant 2.0mA current for the 
sham or tDCS groups, respectively. The current (or sham current) will go on for 18-minutes as 
participants perform a movement intervention. tDCS will be performed using a Soterix Clinical Trial 
stimulator and Soterix sponges. All manufacturer guidelines will be followed in its usage. 
The groups will watch a standardized video sequence consisting of five walking trials (5 video clips—
each trial representing 1 clip) over the 10m complex walking course containing the intermittent soft 
surfaces (foam mats). Participants will watch the video first at normal play speed and then in slow motion 
after a short break (30 secs to 1 min). Total training time will be approximately 20 mins, consistent with 
the locomotor intervention's duration and stimulation. Literature dictates that 15 to 30 mins of observation 

is an appropriate duration for observational learning protocols to observe improvements. The model video 
sequence will show a typical pass through the complex walking course by a gender matched model. 
Follow up 
All participants will then return after one week and repeat the baseline assessments. Including the fNIRS,  
Gait assessment, and KVIQ and the locomotor learning task. 
Statistical Design 
Times of the three trials at each test will be averaged to observe any learning effects during the obstacle 
course. ΔO2Hb at each of the 3 trials during each test were averaged. A 2-way factorial ANOVA with a 
between-subjects factor of group (3 levels) and a within-subjects factor of time (3 levels) will be used. In 
the case of significant interactions of main effects, pairwise comparisons using Fisher’s LSD will be used 
post-hoc. Effect sizes will be interpreted from partial eta squared as small=0.01, medium=0.06, and 
large=0.14. Independent samples t-tests will e used to analyze any differences in the MIQ-3, and the tDCS 
sensitivity between groups.