Effects of Posterior Parietal Cortex and Cerebellum Anodal tDCS on Ankle Tracking Visuomotor Adaptation

Study Overview
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Brief Summary
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Motor adaptation is guided by state estimation, a dynamic prediction of the interaction consequences between body and environment in the sensorimotor system. Previous studies have shown that the posterior parietal cortex (PPC) and cerebellum are potential candidates for state estimators. However, neither direct evidence linking neural substrates of state estimation and motor adaptation nor the differences in state estimation in these two brain areas was presented. A comparison of neuromodulation effects over PPC and cerebellum in motor adaptation tasks could provide direct evidence to solve the knowledge gap. Objective: This study aims to provide direct evidence to link state estimation and motor adaptation, and the neuromodulation effects of PPC and cerebellum in motor adaptation by using anodal transcranial direct current stimulation.

Detailed Description
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This was a single-blind, sham-controlled study. All participants were randomized to the PPC, cerebellum, and sham stimulation group. The ankle tracking system was used to record the ankle tracking visuomotor task during the motor learning phase, motor adaptation phase, and motor re-adaptation phase. Normalized root-mean squared error (RMSE) and RMSE reduction rate were measured as the performance outcome. A 20-minute atDCS at 2 mA anodal tDCS was given during the motor adaptation phase. The immediate effect and after effect of tDCS were seen in the motor adaptation phase and motor re-adaptation phase, respectively.

Official Title
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Investigating How Cortical Modulation of the Cerebellum and Posterior Parietal Cortex Using Anodal tDCS Influences Ankle Motor Adaptation After Motor Learning

Conditions
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Transcranial Direct Current Stimulation

Intervention / Treatment
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* Device: Transcranial direct current stimulation (Anodal)
* Device: Transcranial direct current stimulation (Sham)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: age between 20 29 years old normal ankle range of motion and muscle strength intact cognitive function (Mini-mental State Examination (MMSE) >27) corrected vision > 0.9. Exclusion Criteria: any neurologic or psychiatric disease history musculoskeletal disease that interferes lower extremities movement severe cardiopulmonary or systematic disease (e.g. unstable angina, severe arrhythmia, heart failure, hypertrophic cardiomyopathy, aortic stenosis, pulmonary embolism, kidney failure) paresthesia seizure history brain surgery, meningitis, encephalitis history drainage tube on the head metal or other insertion in the brain insertion of electric medical device (e.g. pacemaker, cochlear implant) pregnancy taking central nervous system medication (e.g. antidepressants, anxiolytic) alcoholic addiction or drug abuse open wound, allergy, rash, or other illness that would affect the placement of tDCS headache, disgusting, vomit, or any other severe side effect to the tDCS

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 29 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Posterior parietal cortex (PPC)<br>In the motor adaptation phase, a 20-minute, 2 mA anodal tDCS was delivered through two 5cm x 7cm electrodes using the DC-STIMULATOR MR (neuroConn, Germany). The electrical current gradually ramps up and down in 20 seconds. In the PPC group, the anodal electrode was placed over the P3 or P4 areas on the skull, covering the PPC area on the opposite side of the testing foot (according to the international 10-20 EEG system), and the reference electrode was placed over the supraorbital region on the same side of the testing foot. | Device: Transcranial direct current stimulation (Anodal)<br>* 20-minutes, 2 mA anodal tDCS delivering through two 5 cm x 7 cm electrodes<br>|
| Experimental: Cerebellum<br>In the motor adaptation phase, a 20-minute, 2 mA anodal tDCS was delivered through two 5cm x 7cm electrodes using the DC-STIMULATOR MR (neuroConn, Germany). The electrical current gradually ramps up and down in 20 seconds. In the cerebellum group, the anodal electrode was placed 1 2 cm under and 3 4 cm lateral to the inion on the same side of the testing foot, with the reference electrode placed on the buccinator on the same side of the testing foot. | Device: Transcranial direct current stimulation (Anodal)<br>* 20-minutes, 2 mA anodal tDCS delivering through two 5 cm x 7 cm electrodes<br>|
| Sham Comparator: Sham<br>In the motor adaptation phase, a 20-minute, 0 mA anodal tDCS was delivered through two 5cm x 7cm electrodes using the DC-STIMULATOR MR (neuroConn, Germany) for the sham group. Participants were informed that they might experience itchiness, burning, or mild discomfort during the tDCS period regardless of which group they were assigned to, so they would not use their sensation as a basis for determining whether they received actual stimulation or not. | Device: Transcranial direct current stimulation (Sham)<br>* 20-minutes, 0 mA anodal tDCS delivering through two 5 cm x 7 cm electrodes<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Block root-mean squared error (RMSE) | RMSE is the error between target trajectory and subject cursor trajectory. Every 5 trials of RMSE were averaged into one block. | 2 hours during the time of assessment of the participant | 
| RMSE reduction rate | ΔRMSEi-(i+1) = (RMSEi - RMSEi+1) / RMSEi x 100% | 2 hours during the time of assessment of the participant | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Transcranial Direct Current Stimulation