Chronic Transcutaneous Stimulation to Promote Motor Function and Recovery in Individuals With Paralysis or Paresis

Healthy Volunteer Inclusion Criteria:

* Individuals between 18 and 75 years of age
* Individuals without physical disabilities or conditions/diseases that may make them incapable of completing the physical study tasks or otherwise places them at a greater risk of harm
* Individuals that are considered English Proficient due to the study requirements to follow verbal commands during sessions
* Individuals that are able to comprehend the study goals and procedures, and are able to provide informed consent for participation
* Individuals that are willing and able to visit the study center for study procedures, which may be up to 5 sessions a week for up to 1 year (at least 2 months) at up to 4 hours per session

Stroke and Spinal Cord Injury Participant Inclusion Criteria:

* Individuals between 18 and 75 years of age
* Individuals with a limited ability to use at least one hand due to a spinal cord injury or stroke
* Individuals that are at least six months from their initial stroke or one year from their initial spinal cord injury
* Individuals that are considered English Proficient due to the study requirements to follow verbal commands during testing sessions
* Individuals that are able to comprehend the study goals and procedures, and are able to provide informed consent for participation
* Individuals that are willing and able to visit the study center for study procedures, which may be up to 5 sessions a week for up to 1 year (at least 2 months) at up to 4 hours per session

Brain or Nerve Injury Participant Inclusion Criteria:

* Individuals between 18 and 75 years of age
* Individuals with a limited ability or no ability to use at least one limb due to a brain or nerve injury such as a traumatic brain injury, brachial plexus injury, peripheral nerve damage, or Parkinson's Disease.
* Individuals that are considered English Proficient due to the study requirements to follow verbal commands during testing sessions
* Individuals that are able to comprehend the study goals and procedures, and are able to provide informed consent for participation
* Individuals that are willing and able to visit the study center for study procedures, which may be up to 5 sessions a week for up to 1 year (at least 2 months) at up to 4 hours per session

Exclusion Criteria for All Study Participants:

* Individuals participating in another study that may affect the conduct or results of this study
* Individuals having or exhibiting any of the following, as specified by self-report:

  * Stage III-IV pressure ulcers that adversely interfere with study involvement (i.e., pressure ulcer on the extremity of interest or prohibits extended bouts of sitting)
  * History of epilepsy
  * Chronically-implanted electronic medical device (e.g. deep brain stimulator, epidural stimulator, cardiac pacemaker, vagus nerve stimulator, or other)
  * Abnormalities of the arms/hands, legs/feet, or spinal column that would prevent electrical stimulation
  * Ventilator dependence
  * History of serious mood or thought disorder
  * Uncontrolled autonomic dysreflexia
  * Severe spasticity in extremities of interest that are uncontrolled by pharmacological methods or prevents electrical stimulation
  * Botulinum toxin injections to the extremity of interest within 3 months
  * Presence of active cancer at or near the areas of transcutaneous stimulation
  * History of heart or kidney disease
  * History of additional neurologic diseases (e.g., multiple strokes, multiple sclerosis, etc.)
  * Presence of other serious infections, diseases, or disorders that could affect ability to participate in this study (e.g., uncontrolled hypertension, uncontrolled diabetes, rheumatic disease, peripheral neuropathy, HIV or AIDS, etc.)
* Individuals with a substance abuse (alcoholism or other) problem
* Pregnant women
* Prisoners