Noninvasive Neuromodulation for Treatment of Symptoms Due to Mild or Moderate Traumatic Brain Injury

Inclusion Criteria: * All candidates will have a balance disorder as a result of a traumatic brain injury (TBI). * All candidates will have a NeuroCom® Sensory Organization Test (SOT) composite score at least 8 points below normal after adjustment for age and height \[based on normative data\]. * All candidates will be between the ages of 18 and 65 (at the time of screening). * If female of childbearing potential, the candidate agrees to use adequate contraception throughout participation in the study (from enrollment to completion). * All candidates must have access to a treadmill. * All candidates will be at least 1 year post-injury. * All candidates will have a neuroradiologic scan and report after their most recent TBI. * All candidates will be ambulatory and able to walk for 20 minutes. * All candidates, if on medications, will not have had any major changes in type or dosage within 3 months of enrollment. * All candidates will have participated in a focused physical rehabilitation program for their TBI and feel that they have reached a plateau. * All candidates will be able to understand and willing to give informed consent. Exclusion Criteria: * All candidates that have oral health problems (e.g. gum disease, active cankers, piercings, oral surgery within the previous 3 months). * All candidates with non-removable metal orthodontic devices (e.g., braces) or oral cavity piercings that could interfere with PoNS™ use. * All candidates who have chronic infectious diseases (e.g. hepatitis, HIV, TB). * All candidates with unmanaged hypertension. * All candidates with unmanaged diabetes, or complications due to diabetes (e.g. retinopathy, neuropathy, renal disease). * All candidates with neurological disorders other than those attributed to their primary diagnosis (e.g., MS, PD, ALS, AD or other dementia, uncontrolled pain). * All candidates with a history of oral cancer. * All candidates who have been treated for any type of cancer other than basal cell carcinoma within the past year. * All candidates who have had a penetrating injury, craniotomy (with the exception of a burr hole \[trephination\] for resolution of acute subdural hematoma), or refractory subdural hematoma. * Exceptions for other abnormalities identified in neuroradiologic scan reports that are asymptomatic and not expected to change may be made on a case by case basis by the Medical Advisor. * All candidates with chronic use of psychoactive or psychostimulant medications that, in the opinion of the investigators, would compromise the subject's ability to comprehend and perform the study activities. * All candidates who have a pacemaker, or are identified as at-risk for cardiovascular events. * All candidates who are pregnant or lactating. * All candidates with a lower extremity biomechanical prosthetic. * All candidates with a history of seizures (except those in the acute or post-acute phases, and are controlled). * All candidates who who experienced a loss of consciousness greater than 24 hours as a result of their TBI. * All candidates with a "severe" score in any of the Attention, Memory, or Executive Functions categories on the Cognitive Linguistic Quick Test (CLQT). * All candidates who, in the opinion of the investigators, are unable to feel the stimulation and successfully complete the device level setting procedure.