tVNS Responsiveness Testing With Pupil Size

Eligibility Criteria

• * 18-60 years old across all races, genders, and ethnicities.
• * Post-stroke subjects will have persistent hemiparesis on the upper extremity (UE) with some residual UE voluntary movement.
• * Younger than 18 years old or older than 60 years old
• * Current or history of cardiac disease
• * Have a vision problem not corrected by glasses or contact lenses
• * Have an implanted device such as a neurostimulator or cochlear implant
• * Current or history of tympanic membrane perforation
• * Had a stroke or lesion (including tumor) in your brain
• * Had a head injury or brain surgery
• * Suffer from frequent or severe headaches
• * Had a fainting spell or syncope
• * Have any metal in the head such as shrapnel, surgical clips, or fragments from welding or metal work
• * Have any implanted device such as cardiac pacemakers, medical pumps, or intra-cardiac lines
• * Had any brain-related conditions (i.e. multiple sclerosis, Parkinson, Alzheimer)
• * Had any illness that caused brain injury (i.e. meningitis, aneurysm, brain tumor)
• * Had any head trauma that was associated with a loss of consciousness or diagnosed as a concussion
• * Being treated for any psychiatric condition (i.e. depression, anxiety, PTSD, schizophrenia)
• * Suspected of pregnancy
• * Younger than 18 years old or older than 60 years old
• * Current or history of cardiac disease
• * Have a vision problem not corrected by glasses or contact lenses
• * Have any implanted devices such as a neurostimulator or cochlear implant
• * Current or history of tympanic membrane perforation
• * No persistent hemiparesis on the right upper extremity (UE)
• * No residual UE voluntary movement
• * A first stroke less than 4 months prior to the participation
• * Hemorrhagic stroke
• * Cerebellar stroke
• * Serious uncontrolled medical conditions
• * Severe apraxia of speech
• * Excessive pain in any joint of the more affected extremity
• * Receiving any anti-spasticity drugs orally at the time of expected participation, 3 months prior, or wish to or is scheduled to receive injections prior to study completion
• * Received phenol injections less than 12 months prior to receiving therapy
• * Unable to stand independently for 2 min., transfer independently to and from the toilet or perform sit-to-stand
• * Suffer from frequent or severe headaches
• * Had a fainting spell or syncope
• * Have any metal in the head such as shrapnel, surgical clips, or fragments from welding or metal work
• * Have any implanted device such as cardiac pacemakers, medical pumps, or intra-cardiac lines
• * Had any illness that caused brain injury\* (i.e. meningitis, aneurysm, brain tumor)
• * Had any head trauma that was associated with a loss of consciousness or diagnosed as a concussion
• * Being treated for any psychiatric condition (i.e. depression, anxiety, PTSD, schizophrenia)
• * Suspected of pregnancy
• * A score of less than 24 on the Folstein Mini-Mental State Examination
• * A score outside of 19-55 on the upper limb portions of the Fugl Meyer Assessment.
• * Clinical judgment of excessive frailty or lack of stamina (e.g., cannot attend to instructions, stay awake, engage in functional activities, etc.)
• * Serious uncontrolled medical conditions
• * Excessive pain in any joint of the more affected extremity that could limit ability to cooperate with the intervention, as judged by the examining clinician