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 Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
SUPPORTIVE_CARE
Masking
DOUBLE
Enrollment
3
University of Minnesota
Minneapolis, Minnesota, United States
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.
Time frame: 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.
Time frame: 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
Time frame: baseline, 15,45 and 75 minutes post-tDCS
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)
Time frame: 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
Time frame: 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
Time frame: baseline, 15, 45 and 75 minutes post stimulation
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