Inclusion Criteria:

1. History of moderate to severe TBI based on estimated worst Glasgow Coma Scale (GCS) score within first 48 hours of injury (acceptable GCS range = 3-12)
2. Age ≥18 and <75 years at the time of informed consent.
3. At least 24 months from date of TBI injury
4. Fluent in local language and able to independently provide consent
5. Rating of upper moderate disability to lower good recovery on the Glasgow Outcome Scale-Extended (GOSE) at time of enrollment (acceptable GOSE range 5-7)
6. Failure to return to pre-injury level of vocational or educational function
7. Either receiving no CNS stimulants or other medications known to affect cognitive function, or on stable doses of these medications for at least last three months prior to signing consent.

Exclusion Criteria:

1. History of major developmental, neurologic, psychiatric or substance use disorder with evidence of disability prior to onset of TBI
2. Any DSM-5 personality disorder diagnosis, as determined by SCID-5-PD, will exclude the participant.
3. Major medical co-morbidities: end stage renal failure, heart failure, severe congestive heart disease, coagulopathy, severe respiratory problems, liver failure, uncontrolled hypertension or other significant medical co-morbidities.
4. Receiving anti-epileptic medications to control active seizures
5. Have had a documented seizure within 3 months prior to signing consent
6. Malignancy with < 5 years life expectancy.
7. Untreated / uncontrolled (severe at the time of enrollment) depression or other psychiatric disorder.
8. Women of childbearing age who do not regularly use an accepted contraceptive method. Participants who become pregnant after enrollment may be excluded from the study. Those who become pregnant prior to the surgical implantation of the DBS system will be excluded from the study.
9. Inability to stop Coumadin or platelet anti-aggregation therapy before, during and after surgery.
10. Previous DBS or other brain implants
11. Previous ablative intracranial surgery
12. Implantable hardware not compatible with MRI or unwilling to undergo MRI (e.g. claustrophobia)
13. Condition requiring diathermy after DBS implantation
14. Hardware, lesions or other factors limiting placement of electrodes in optimal target location in the judgment of the implanting surgeon
15. Concurrent enrollment in any other clinical trial
16. Any condition that, in the judgment of the PI, significantly increases risk or significantly reduces the likelihood of benefit from DBS