Inclusion Criteria

• Adults (18-65 years of age)
• Meet criteria for one of four groups
  1. persistent post-traumatic headache (i.e. Persistent headaches following a concussion);
  2. chronic migraine without history of head trauma/concussion;
  3. healthy people with no history of migraine or head trauma/concussion;
  4. concussion with no history of migraine and no persistent post-traumatic headaches.

Exclusion Criteria

• Structural abnormalities that might suggest moderate or severe traumatic brain injury 
• Other structural brain damage as interpreted by a board certified neuroradiologist
• History of any significant head trauma in Chronic Migraine and healthy control subjects
• Attempts will be made to enroll subjects who are not taking headache prevention medications, antidepressant medications, and other medications that could potentially impact imaging findings
• Have both PPTH and a history of a primary headache disorder such as migraine