Please select the eligibility criteria that correspond to the clinical trial below.
Title: N/A
Brief Summary: 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.


Options:
A: Inclusion Criteria:

* Subacute stroke (within 1-4 weeks post stroke)
* Acute hemiparesis (Fugl-Meyer Stage \< IV) with single thromboembolic non-hemorrhagic infarction documented by a neurologist
* Aged 18-79

Exclusion Criteria:

* Absence of voluntary movement (Fugl-Meyer Stage \< III)
* Head injury or the presence of intracranial metal or intracranial lesions
* History of cranial irradiation
* History of epilepsy
* Presence of a pacemaker
* Taking anticonvulsant or neuroleptic medication
* Substance abuse
* Inability to understand instructions
B: Inclusion Criteria:

* Chronic (\> 6 months) stroke patient
* Aged 18-79 years
* Motor deficit in the upper limb due to the stroke

Exclusion Criteria:

* Absence of recordable MEPs from the ADM after TMS
* Absence of voluntary movement (Fugl-Meyer \< III)
* Head injury or the presence of intracranial metal or intracranial lesions
* History of cranial irradiation
* History of epilepsy
* Presence of a pacemaker
* Taking anticonvulsant or neuroleptic medication
* Substance abuse
* Inability to understand instructions
* History of psychiatric disorders
C: Inclusion Criteria:

* First time clinical ischemic or hemorrhagic cerebrovascular accident (radiologically confirmed)
* Demonstrates adequate balance while wearing a hand restraint on the unaffected arm
* Ability to stand from a sitting position and ability to stand with or without upper extremity support
* Stroke onset at least 6 months prior to study enrollment

Exclusion Criteria:

* Significant pre-stroke disability
* Any substantial decrease in alertness, language reception, or attention that might interfere with understanding instructions for motor testing
* Excessive pain in any joint of the paretic extremity
* A terminal medical diagnosis consistent with survival of less than 1 year
* Advanced liver, kidney, cardiac, or pulmonary disease
* Coexistent major neurological or psychiatric disease (including epilepsy)
* A history of significant alcohol or drug abuse in the prior 3 years
* Use of neuropsychotropic drugs - such as antidepressants
* Patients may not be actively enrolled in a separate intervention study targeting stroke recovery
* Patients may not have already received constraint-induced movement therapy and/or tDCS treatment for stroke
D: Inclusion Criteria:

* Participant is willing and able to give informed consent for participation in the study.
* Male or Female, aged 18-85
* At least one month post ischaemic or haemorrhagic stroke or brain damage to the right hemisphere
* Diagnosis of neglect confirmed by evidence of neglect on at least one of the tests in the battery of neglect tests administered during the Recruitment Interview

Absolute contraindications to participation in any part of the study:

* Anyone who does not have adequate understanding of English, sufficient to give informed consent
* Limited verbal communication in the form of dysphasia
* Any person who has a history of drug abuse as the data collected may be influenced by their condition
* Any person who has a history of dementia or any other psychiatric illness as the data collected may be influenced by their condition

Absolute contraindications to participation in the tDCS part of the study:

* Anyone who has a previous personal history of epilepsy, seizures, febrile convulsions as a child or recurrent fainting fits will be excluded from the tDCS part of the study
* Any metallic implant in the neck, head, or eye that is situated within the path of the tDCS current, and anyone with any implanted electrical devices, would be excluded as there is a risk of heating with tDCS
* Pregnant women are excluded as a precaution as there are no data on the effect on maternal tDCS or MRI on the foetus

Absolute contraindications to participation in the MRI part of the study:

* People who suffer from claustrophobia will be excluded from the MRI part of the study if they state they are unable to tolerate the scanner environment
* Anyone with a metal implant or implantable device that is found to be unsafe or unknown for MRI following investigations by named researchers and staff radiographers would be excluded.
* Pregnant women are excluded as a precaution as there are no data on the effect on maternal tDCS or MRI on the foetus

Potential contraindications to participation in the tDCS part of the study:

* Participants on some prescription medications such as anti-depressants or pain medication may be excluded as they may be at an increased risk of seizure
* Individuals who have a family history of epilepsy or seizure may be excluded as this may increase the individual's personal risk of susceptibility to seizures

Potential contraindications to participation in the MRI part of the study:

• An individual with a previous history of a surgical procedure may be excluded, depending on whether a metallic implant was used in their operation and whether the MRI-safety status of the implanted materials can be adequately assessed after requesting the medical/surgical notes (with patient consent) and/or post-surgical imaging and consulting with the staff radiographers who are legally responsible for determining participant safety in advance of any scanning.

Answer: B