Cortical Excitability in Post-traumatic Epilepsy

Inclusion Criteria: Group 1 (N=10): * Age 18-70 * Sex: male/female * PTE, defined as acquired epilepsy with seizures that developed within ten years of TBI with no other clear cause * Stable ASM doses for at least 30 days * Epilepsy duration for ≥ 6 months Group 2 (N=10): * Age 18-70 * Sex: male/female * Absent epilepsy, but TBI in the past two years and any of the following: * Multifocal intracerebral hemorrhages (ICH) * depressed skull fracture * Subdural hematoma (SDH) requiring surgery * SDH and ICH * Penetrating wound Group 3 (N=10): * Age 18-70 * Sex: male/female * Absent epilepsy or TBI Exclusion Criteria: 1. Primary generalized epilepsy 2. Non-epileptic seizures 3. Progressive neurological disease including neoplasm, CNS degenerative disorders including Alzheimer's disease, other forms of dementia 4. Any systemic illness or unstable medical condition that might pose additional risk, including renal or liver disease, clinically uncontrolled cardiac disease, other unstable metabolic or endocrine disturbances, and active systemic cancer 5. Change in dose of any antiseizure medication within 30 days prior to enrollment 6. Active drug or alcohol dependence or any other factors that, in the opinion of the site investigators that would interfere with adherence to study requirements; 7. Use of any CNS-active investigational drugs within 1 month of enrollment. 8. Resective epilepsy surgery less than 6 months before study initiation. 9. Implanted electrical device (e.g. vagal nerve stimulator, deep brain stimulator, responsive neurostimulation device, cardiac pacemeaker, etc.)