How Does Cerebellar tDCS Alter Intracortical Inhibition Over Time?

Combining cortical tDCS with behavioral interventions has been shown to have beneficial outcomes in individuals post-stroke. However, cerebellar tDCS is a fairly new approach for individuals with unilateral cortical stroke and there has not been reports of duration of effect of tDCS applied to the cerebellum in this population.

Information gained from this study will serve to fill knowledge gaps on the duration of effect of cerebellar tDCS and the effects of polarity.

The purpose of this study is to determine the duration of effect of ventro-lateral cerebellar transcranial direct current stimulation (tDCS) in healthy adults through cortical excitability (CE), cognitive, language and motor assessment measures. Primary aim: Compare baseline CE from left motor cortex of first dorsal interosseous (FDI) and orbicularis oris (OO) areas to CE post cerebellar tDCS at 15 minutes, 45 minutes and 75 minutes. Single-pulse and paired-pulse transcranial magnetic stimulation (TMS) will be used to measure and compare stimulus response curve (S/R curve), cortical silent period (CSP) and short-interval intracortical inhibition (SICI) in the hand area and facial area of the left primary motor cortex at each time point.

Secondary aim: Compare baseline performance on cognition, motor learning and language tasks to performance at 15, 45 and 75 minutes after receiving tDCS. Digit Symbol Substitution Test (DSST), Serial Reaction Time Test (SRTT) and Lexical Decision tasks will be presented via a computer interface.

Study Overview

• Status: Terminated
• Conditions: Stroke
• Intervention / Treatment: Procedure: REAL-A; Procedure: REAL-C; Procedure: SHAM

• Study Type: Interventional
• Enrollment (Actual): 3
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Minnesota
    • Minneapolis, Minnesota, United States, 55414
      • University of Minnesota

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Eligible participants must be over the age of 18 years of age
• must be fluent in English
• have adequate vision to see a computer screen from 12-18 inches, fine motor skills to press a key on a computer keyboard and hearing to hear directions and questions provided by the researcher
• Individuals must also be able to read words and phrases

Exclusion Criteria:

• Pregnancy
• history of seizures
• neurologic injury including concussion/head injury or stroke or other neurologic conditions
• History of documented learning disabilities and/or ADHD
• Metal implants in the body (excluding dental fillings), psoriasis or eczema affecting the scalp.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Supportive Care
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Real anodal tDCS group (REAL-A); Participants randomized to REAL-A	Procedure: REAL-A; one session of 2mA for 20 minutes to the right ventro-lateral cerebellum
Experimental: Real cathodal tDCS group (REAL-C); Participants randomized to REAL-C	Procedure: REAL-C; one session of 2mA for 20 minutes to the right ventro-lateral cerebellum
Sham Comparator: Sham group (SHAM); Participants randomized to SHAM group	Procedure: SHAM; one session of sham tDCS for 20 minutes to the right ventro-lateral cerebellum.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
stimulus/response curve (S/R Curve)	change of motor evoked potential (MEP) as reflected in EMG from 1) hand (FDI muscle) and 2) mouth (orbicularis oris muscle).following single pulse transcranial magnetic stimulation (TMS) to the primary motor cortex of varying intensities.	baseline, 15,45 and 75 minutes post-tDCS
Cortical Silent Period (CSP)	Change in silent period of a contracted muscle shown through EMG from 1) hand (FDI muscle) and 2) mouth (orbicularis oris muscle). following a single supra-threshold stimulus pulse to the primary motor cortex using TMS.	baseline, 15,45 and 75 minutes post-tDCS
Short-interval Intracortical Inhibition (SICI).	Change in MEP as reflected in EMG from 1) hand (FDI muscle) and 2) mouth (orbicularis oris muscle). following a subthreshold conditioning pulse followed by a suprathreshold test pulse	baseline, 15,45 and 75 minutes post-tDCS

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Digit Symbol Substitution Test (DSST)	The DSST is a 90-second timed test that evaluates processing speed, working memory, visuospatial processing, and attention. The test involves a subject replacing given numerals (1-9) with the corresponding unique, simple to draw, symbols provided in the key. The subject is instructed to write as many substitutions as possible within the allotted time. The score is determined by counting the correct number of substitutions. No penalty is applied for incorrect answers. The test permits freedom to achieve the task which allows for creativity and refinement to improve one's score. This test was originally a subsection of the Wechsler Adult Intelligence Test (WAIS), used to measure one's intelligence quotient (IQ)	baseline, 15, 45 and 75 minutes post stimulation
Serial Reaction Time Test (SRTT)	The SRTT is a four-choice reaction time task that measures motor learning. In this task, a visual cue can appear at any one of four positions arranged horizontally on a computer screen. Each screen position, designated 1-4, corresponds to a button on a response pad. When a cue appears, at the start of each trial, a participant selects the appropriate response button. The visual cues play out a repeating sequence of positions (for example, 2-3-1-4-3-2-4-1-3-4-2-1). Sequential trials are followed by random trials	baseline, 15, 45 and 75 minutes post stimulation
Lexical Decision Task	The lexical decision task requires the participant to make a decision whether a target letter string is a word or, with equal probability, a pronounceable non-word. The target string is preceded by a prime word that is either associated with the target word or, with equal probability, not associated	baseline, 15, 45 and 75 minutes post stimulation

Collaborators and Investigators

• Sponsor: University of Minnesota
• Investigators: Principal Investigator: Sharyl Samargia-Grivette, University of Minnesota

Study record dates

Study Major Dates

• Study Start (Actual): July 15, 2024
• Primary Completion (Actual): August 10, 2025
• Study Completion (Actual): August 10, 2025

Study Registration Dates

• First Submitted: April 22, 2024
• First Submitted That Met QC Criteria: April 22, 2024
• First Posted (Actual): April 25, 2024

Study Record Updates

• Last Update Posted (Actual): August 24, 2025
• Last Update Submitted That Met QC Criteria: August 18, 2025
• Last Verified: August 1, 2025

More Information

Terms related to this study

• Other Study ID Numbers: STUDY00021475

Drug and device information, study documents

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