The purpose of this study is to examine the feasibility and preliminary efficacy of using transcutaneous auricular vagus nerve stimulation (tVNS) to enhance cognitive recovery in patients with mild-moderate traumatic brain injury (TBI).

Eligible participants will be invited to two sessions, 2-7 days apart. In each session, either active tVNS or sham stimulation will be administered while the participants are performing tasks of executive functions. The order of the sessions (tVNS vs Sham) will be counterbalanced across participants.

Inclusion Criteria:

In inpatient rehabilitation due to recent Traumatic Brain Injury, ages 18-65 years.

Ability to independently use a keyboard. Able to understand and communicate in English (according to clinical judgment). Able to independently provide consent to participate. Orientation to place, time, and situation (two consecutive scores of 25 or more on the Orientation Log(O-Log)40. This scale is routinely administered during acute rehabilitation stay.

Exclusion criteria:

Acute medical issues requiring close physician or nursing monitoring. Bioelectrical implants, including pacemakers. Pregnancy or persons who are lactating. 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.

Acute agitation or behavioral issues, as defined by a last Agitated Behavior Scale Score greater than 21 (routinely administered during acute rehabilitation stay, that would affect an individual's ability to participate in the required assessments.

Severely impaired memory retention (Score lower than 3 in the 3 Word Delayed Recall test, routinely administered during acute rehabilitation stay.

Diagnosis of depression. Active substance abuse.