Inclusion Criteria:
* Clinical diagnosis of tetraplegia (quadriplegia), brainstem stroke , amyotrophic lateral sclerosis (ALS) or Locked-in Syndrome (LIS)
* Tetraplegia diagnosis, ALS diagnosis, stroke, or LIS etiology onset occurred at least one year prior to enrollment
* Complete or incomplete tetraplegia (quadriplegia), tetraparesis (quadriparesis), or severe ataxia. In addition, these motor impairments may be combined with severe motor-related speech impairment (dysarthria or anarthria), as in LIS.
* 22-70 years
* Meeting surgical safety criteria, including surgical clearance by the participant's primary healthcare provider, study physicians, and any necessary consultants
* Ability to communicate reliably, such as through eye movement
* Willingness and ability to provide informed consent
* Screened by rehabilitation psychologist with a result showing that the participant has a stable psychosocial support system with caregiver capable of monitoring participant throughout the study
* Ability and willingness to travel up to 100 miles to study location up to three days per week for the duration of the study
* Ability to understand and comply with study session instructions
* Participant consents to the study and still wishes to participate at the time of the study
Exclusion Criteria:
* Performance on formal neuropsychological testing that indicates significant psychiatric conditions or cognitive impairments that would interfere with obtaining informed consent or fully participating in study activities.
* Suicide attempt or persistent suicidal ideation within the past 12 months.
* Implanted devices that are incompatible with MRI, which may include pacemakers, cardiac defibrillators, spinal cord or vagal nerve stimulators, deep brain stimulators, and cochlear implants.
* History of substance abuse, narcotic dependence, or alcohol dependence in past 24 months
* Medical conditions contraindicating surgery of a chronically implanted device (e.g. osteomyelitis, diabetes, hepatitis, any autoimmune disease/disorder, epilepsy, skin disorders causing excessive skin sloughing or poor wound healing, blood or cardiac disorder requiring chronic anti-coagulation)
* Other chronic, unstable medical conditions that could interfere with subject participation.
* Presence of pre-surgical findings in anatomical, functional, and/or vascular neuroimaging that makes achieving implant locations within desired risk levels too challenging (to be decided by neurological and neurosurgical team)
* Prior cranioplasty
* Inability to undergo MRI or anticipated need for an MRI during the study period
* Participants with active infections or unexplained fever
* Participants with other morbid conditions making the implantation of the recording elements unsafe; not limited to: significant pulmonary, cardiovascular, metabolic, or renal impairments making the surgical procedure unsafe
* Pregnancy (confirmation through blood test)
* Nursing an infant, planning to become pregnant, or not using adequate birth control
* Corrected vision poorer than 20/100
* HIV or AIDS infection
* Existing scalp lesions or skin breakdown
* Chronic oral or intravenous use of steroids or immunosuppressive therapy
* Active cancer within the past year or requires chemotherapy
* Uncontrolled autonomic dysreflexia within the past 3 months
* Hydrocephalus with or without an implanted ventricular shunt
* Participants in whom it is medically contraindicated to stop anti-coagulant medications during surgery