Paired Vagus Nerve Stimulation Mechanisms

Eligibility Criteria

• * Ability to provide signed and dated informed consent form
• * Stated willingness to comply with all study procedures and availability for the duration of the study
• * 22-79 years of age
• * Unilateral supratentorial ischemic stroke that occurred ≥ 12 months prior to enrollment
• * Upper extremity Fugl-Meyer Assessment score of 20 to 50
• * Modified Rankin Score of 2, 3, or 4
• * Meets all clinical criteria for VNS implantation as determined by the PI and clinical care team
• * Intracerebral hemorrhage or traumatic brain injury
• * Deficits in language or attention that interfere with study participation
• * Severe spasticity (Modified Ashworth \> 3)
• * Psychiatric disorders and/or cognitive impairments that would interfere with study participation, as assessed by medical evaluation
• * Receiving any therapy (medication or otherwise) that would interfere with VNS, such as drugs that perturb neurotransmitter action (anticholinergics, adrenergic blockers, etc.)
• * Presence of any other implanted electrical stimulation device
• * Prior injury to vagus nerve
• * Females of childbearing potential who are either pregnant, lactating, heterosexually active, or planning to become pregnant or heterosexually active during study participation; and who are not using, or will not agree to use, the following medically acceptable birth control methods:\* (1) sterilization surgery for women, (2) Surgical Sterilization Implant for Women, (3) sterilization surgery for men, (4) long-acting reversible contraceptives (LARC) - implantable rod and IUD; (5) contraceptive shot/injection every 3 months; (6) oral contraceptives ("The Pill"); (7) contraceptive patch; and (8) vaginal contraceptive ring.
• * Concurrent participation in another interventional clinical trial
• * Ferromagnetic metal in head (except dental work) or torso
• * Persons with a current or past: (a) medical (psychiatric, non-psychiatric) condition, disease, disorder, injury, or disability\*; or (b) non-medical situation or circumstance that, in the opinion of the principal investigator, study participation: may pose a significant or undue risk to the person; make it unlikely the person will complete all the study requirements per protocol; or may adversely impact the integrity of the data or the validity of the study results. \[\*Examples include, but are not limited to, the following types of conditions, diseases or disorders: renal, peripheral vascular, cardiac, endocrinologic (e.g., diabetes), immunologic, psychiatric (e.g., substance use), neurologic (e.g., cognitive), or dysphagia\]
• * Persons with a neck circumference larger than 18.5 inches
• * As determined by the principal investigator, is under current incarceration or legal detention