Noninvasive Brain Stimulation to Enhance Cognition at Home Following a TBI.

This is a single-blind, open-label pilot study to evaluate the feasibility and preliminary efficacy of remotely supervised, at-home delivery of tVNS in individuals with moderate to severe TBI during the post-acute recovery phase. Eligible participants will complete a 2-week tVNS intervention protocol at home. Mixed methods (quantitative and qualitative) will be used to evaluate outcomes. Eligible participants will be invited to initial baseline assessment and tVNS training session (Visit 1). Then, they will complete two weeks of at-home administration period. Lastly, they will return to a post- stimulation assessment (Visit 2). In the assessment sessions participants will complete tasks of set shifting and working memory, core executive functions, as well as complete surveys regarding fatigue, sleep, and overall quality of life.

• Transcutaneous Vagus Nerve Stimulation (tVNS) (Device), also known as Transcutaneous auricular vagus nerve stimulation (taVNS): tVNS stimulation, one hour a day, for 14 days.

Primary outcomes

• Number of participants who successfully completed 75% of the sessions. [Day 15]: Recording the number of participant who completed at least 75% of the sessions out of the number of participants enrolled in the study.
• Participant-Reported Acceptability of Home-Based tVNS Therapy [Day 0 and Day 15]: Completion of the Treatment Acceptability/Adherence Scale at baseline (day 0) and post stimulation assessment (day 15)

Secondary outcomes

• N-Back task [Day 0 Baseline and Day 15 Post Stimulation Assessment]: In the N-Back Task, participants are presented a series of visual stimuli. They are asking for each stimulus whether is matches a stimulus n-trials before. For example, in a 2-back task, in which the trials consist of letters, participants have to decide whether the current letter is the same as the letter in the trial n-2. We will use a computerized version of this task.
• California Verbal Learning Test [Day 0 Baseline and Day 15 Post Stimulation Assessment]: The California Verbal Learning Test evaluates the ability to encode, recall, and recognize verbally presented information across multiple learning trials and delayed recall conditions. Participants are read multiple lists of words and asked to recall specific words at different time allotments.
• Trail Making Test A&B [Day 0 Baseline and Day 15 Post Stimulation Assessment]: Trail Making Part A requires participant to draw a line between circles containing numbers in ascending order. Part B requires participants to alternate drawing a line between ascending letters and numbers. The key measures are the time required to complete and the number of errors made in Part A and Part B. The test measures various aspects of cognition including attention, visual search, motor coordination, reasoning, and task switching.

Sex: All, ages: 18 Years to 75 Years

Inclusion Criteria:

* Age 18-75 years.

  * Formally diagnosed with traumatic brain injury.
  * Ability to independently use a keyboard.
  * Able to understand and communicate in English (according to clinical judgment).
  * Able to independently provide consent to participate.

Exclusion Criteria:

* Acute medical issues requiring close physician or nursing monitoring.

  * Bioelectrical implants, cerebral shunts, including pacemakers.
  * Anyone with sore or diseased skin area in the ear
  * Pregnancy or persons who are lactating.
  * Cardiac arrhythmia.
  * Epilepsy or seizure disorders.
  * Significant gross or fine motor weakness.
  * Significant, ongoing communication or comprehension impairments (such as aphasia) that would affect an individual's ability to complete the required assessments.
  * Severely impaired memory retention (Score lower than 3 in the 3 Word Delayed Recall test attached to this submission).
  * Current major depression diagnosis.