Rationale: About 80% of stroke patients suffer motor impairments, but current therapies have limited effects on motor recovery. Therefore, investigating new potential therapeutic approaches is crucial. Transcranial Direct Current Stimulation (tDCS) is a form of non-invasive electrical stimulation where a weak current is applied through electrodes over the scalp. This stimulation is known to (1) induce changes in neuronal excitability -which can last up to one day with late LTP-like plasticity protocols- in a polarity and site-specific manner, and (2) facilitate motor learning and stroke recovery. However, it is unknown how the motor cortex excitability changes that follow tDCS relate to the increase in motor learning and recovery potential. The currently upheld hypothesis is that motor learning needs to be synchronized in time with electrical stimulation (paired stimulation), but recent results from our lab suggest that tDCS also increases skill learning after stimulation has ended (unpaired stimulation). If this is true, tDCS has a much larger therapeutic window and is a more valuable clinical tool than currently believed. Therefore, the investigators want to investigate how late LTP-like plasticity tDCS affects the increase in skill learning normally seen with tDCS when applied 24 hours before training. The outcome of this study can provide important guidelines on effective motor therapy during stroke rehabilitation.
Objective: Identify the effect of late LTP-like plasticity tDCS in chronic stroke patients on skill learning 24 hours later.
Study design: Double-blinded, randomized between-subjects trials. Study population: Chronic stroke patients. Main study parameters/endpoints: The main objective of the study is to determine the effect of late LTP-like plasticity tDCS on skill learning 24 hours later. As a motor learning paradigm, the investigators will use a circuit tracking task which chronic stroke patients perform better if tDCS is applied concurrently. During this task, patients have to trace a cursor over a circuit as fast and accurately as possible by moving a computer mouse. Skill will be quantified by calculating a combined speed/ accuracy score and skill improvement compared to baseline (LI; the learning index) will be compared between the sham, conventional unpaired tDCS, conventional paired tDCS groups and the late LTP-like plasticity tDCS groups.
- Sham Device
Intervention Desc: Bihemispheric 1mA Sham protocol: sham - pause - sham ARM 1: Kind: Experimental Label: Sham Description: Day 1: sham stimulation Day 2: sham stimulation
- Conventional Paired tDCS Device
Intervention Desc: Bihemispheric 1mA Sham protocol: sham - pause - sham Conventional Paired tDCS protocol: 20 minutes tDCS - pause - sham ARM 1: Kind: Experimental Label: Conventional Paired tDCS Description: Day 1: sham stimulation Day 2: conventional tDCS
- Conventional Unpaired tDCS Device
Intervention Desc: Bihemispheric 1mA Sham protocol: sham - pause - sham Conventional Unpaired tDCS protocol: 20 minutes tDCS - pause - sham ARM 1: Kind: Experimental Label: Conventional Unpaired tDCS Description: Day 1: conventional tDCS Day 2: sham stimulation
- Late LTP-like Plasticity tDCS Device
Intervention Desc: Bihemispheric 1mA Sham protocol: sham - pause - sham Late LTP-like Plasticity tDCS protocol: 10 minutes tDCS - 25 minutes pause - 10 minutes tDCS ARM 1: Kind: Experimental Label: Late LTP-like Plasticity tDCS Description: Day 1: late LTP-like Plasticity tDCS Day 2: sham stimulation
- Allocation: Randomized
- Masking: Double Blind (Subject, Caregiver, Investigator, Outcomes Assessor)
- Purpose: Treatment
- Endpoint: Efficacy Study
- Intervention: Parallel Assignment
|Type||Measure||Time Frame||Safety Issue|
|Primary||Motor Skill Retention||Day 9||No|
|Secondary||Maximum Grip Force||Day 1 and Day 9||No|
|Secondary||Purdue Pegboard Test||Day 1 and Day 9||No|