INCLUSION CRITERIA:
We will include HEALTHY VOLUNTEERS under the following circumstances:
1. Age of 18 to 80 years.
2. Written informed consent is given by the participant.
3. Mini-Mental-Status examination greater than 23 points.
4. Handedness as assessed by Edinburgh handedness inventory shows a laterality index (LI) greater than 75 (dexterity) or LI of less than -75 (left-handedness).
5. Ability to concentrate and to perform the tasks required in the present study.
6. Commitment to participate in the long-term follow-up (up to 3 months).
We will include STROKE PATIENTS under the following circumstances:
1. Age of 18 to 80 years.
2. Stroke more than 3 months ago.
3. Single stroke with hemispheric lesions.
4. Stroke that affected one side of the brain (unilateral stroke).
5. Patients with initially severe motor paresis (below MRC grade 2), who subsequently recovered to the point that they have a residual motor deficit but still able to perform the tasks required by the study.
6. Commitment to participate in the long-term follow-up (up to 3 months).
7. Written informed consent is given by the patient.
8. Mini-Mental-Status examination greater than 23 points.
9. Handedness as assessed by Edinburgh handedness inventory shows a laterality index (LI) greater than 75 (dexterity) or LI of less than -75 (left-handedness).
We will include TB1 PATIENTS under the following circumstances:
1. Age of 18 to 80 years
2. Handedness as assessed by Edinburgh handedness inventory showing a laterality index (L1) greater than 75 (dexterity) or L1 of less than -75 (left-handedness)
3. Ability to concentrate on a computer task for up to an hour.
4. Ability to perform dominant hand thumb opposition against resistance.
5. Willingness to commit to tht time involved in teh study.
6. Willingness and ability to give consent.
7. TB1 occurred from non-penetrating blunt, acceleration, or deceleration forces to the head.
8. TB1 is of mild to moderate severity, based on duration of menatl status change (up to 6 hr) or on post-resuscitative GCS score (9-15), as can be ascertained by medical records or patient report.
9. TB1 more than 6 months ago
EXCLUSION CRITERIA:
We will exclude healthy volunteers and stroke patients, and TB1 patients if one of the following conditions applies:
1. Unable to perform the tasks.
2. A history of severe neurological illness, e.g. brain tumor, epilepsy or a history of symptomatic seizures, polyneuropathy etc.
3. A history of severe alcohol or drug abuse, psychiatric illness such as severe depression, poor motivational capacity, or severe language disturbances, particularly of receptive nature or with serious cognitive deficits (defined as equivalent to a mini-mental state exam score of 23 or less).
4. More than moderate uncontrolled medical problems (e.g. active cancer or renal disease, any kind of end-stage pulmonary or cardiovascular disease, hypo/hyperthyroidism, severe diabetes, peripheral arteriopathy, or a deteriorated condition due to age, or other medical conditions as determined by the study physician, that would interfere with participation in this study).
5. Increased intracranial pressure as evaluated by clinical means (presence of papilledema in eye ground exam, compressed sulci/ventricle on MRI scan).
6. Previous implantation of metallic material (e.g., vascular clips, cochlear implant) in the cranium (except in the mouth), pacemaker, implanted medication pumps, neural stimulators.
7. Drug treatment acting primarily on the central nervous system which lowers the seizure threshold such as antipsychotic drugs (chlorpromazine, clozapine) or tricyclic antidepressants (for the TMS component only).
8. Any visual disturbances, especially visual acuity less than 60%.
9. Diseased or damaged skin over the face or scalp.
10. Acute or chronic tendosynovitis, severe rheumatoid arthritis, active joint deformity of arthritic origin, according to the hand.
11. Professionally practiced playing a musical instrument or trained as a typist.
12. Pregnancy (for the MRI component only).
EXCLUSION CRITERIA - FOR STROKE PATIENTS ONLY:
13. Both sides of the brain are affected by the stroke or clear bilateral motor impairment.
EXCLUSION CRITERIA - FOR TB1 PATIENTS ONLY:
14. TB1 from penetrating gunshot or explosive trauma.
15. Post-tramatic seizures
16. No reported changes in both the Glascow Coma Scale and mental status following injury.
17. Active depression of any severity with psychoactive medication changes in the last 2 months.
18. Active psycohosis, disruptive or violent behavior, or poor motivational capacity.
19. Pending litigation regarding the trauma