Inclusion Criteria:- subjects between the ages of 18 and 100 years for clinical component;
subjects between the ages of 18 and 70 for the MRI component

   - meets the study criteria of chronic pain of either peripheral or central origin

   - male or a non-pregnant, non-lactating female. If females are of reproductive potential
   (i.e., not surgically sterilized and/or not post menopausal), they must be practicing
   an accepted method of birth control, agree to a urine pregnancy test at the start of
   each study session (for patient scheduled through the clinic, this has already been
   addressed by the recommending physician)

   - is not currently on a sodium channel blocking agent, anticonvulsant, or tricyclic
   antidepressant,

   - must be able to comply with any other study requirements and complete experimental
   tasks

   - have no reported substance abuse within the past six months;

Exclusion Criteria:- subject is lactating or pregnant;

   - subject suffers from clinically significant cardiac, pulmonary, renal or liver
   disease;

   - subject allergic to lidocaine.

   - MRI Component: any metal objects (especially surgical clips), devices, or implants or
   any other MRI contraindication