Traumatic Brain Injury (TBI)patients often suffer from loss of muscle strength in the hand and foot, decrease in coordination and high muscle tone (spasticity). In this study, investigators seek to compare how two different training programs can improve the coordination and symptoms of fatigue in individuals with movement deficits secondary to TBI. Using brain imaging, the study will also investigate changes in brain structure and activity associated with hand movement.

Moderate and severe Traumatic Brain Injury (TBI) commonly causes upper extremity physical impairments that persist even after years of injury; these deficits are attributed to damage in brain structure and changes in structural and functional connectivity. Bimanual coordination deficits and muscle weakness have a significant impact on TBI survivors' well-being, and conventional therapy did not provide high success in treating these two issues. The investigators relate this lag in efficiency to two main reasons: 1) absence of outcome measures to quantify these deficits in a clinical setting, and 2) mental and cognitive fatigue and short attention span in TBI survivors, which limits the feasibility to enroll TBI survivors in intensive training protocols.

The investigators long-term goal is to provide effective rehabilitation training to help TBI survivors in regaining proper bimanual coordination of hand movement and higher hand muscles' strength. Mental practice includes motor imagery and action observation, and neural imaging studies have shown that both motor imagery and action observation share similar neural mechanism as movement execution. In addition, interventional studies have shown success in combining physical and mental practice to improve motor function of stroke survivors, and it does not induce muscle fatigue.

Hence, the first aim of this pilot study is to compare the therapeutic efficacy of combining physical practice with mental practice (motor imagery and action observation) (MP) versus physical practice only with action observation (PP) alone to improve hand bimanual coordination and muscle strength of TBI survivors. Twenty subjects will be randomly and equally assigned to either of two training groups. Maximum Voluntary Contraction (MVC), Reaction Time (RT), and Percent of Error in Matching (PEM) a Target will be used as primary outcome measures in addition to functional-based measures (Wolf Motor Function Test WMFT). In addition, activation maps (functional MRI data) will be established for the brain neural networks before and after training. The investigator's second aim is to study if either or both interventions (MP and PP) induce reorganization in brain activity and in functional (at rest) and effective (during a task) connectivity.

Inclusion Criteria:

• between the ages of 20 to 60 years old.
• have been diagnosed with a moderate to severe Traumatic Brain Injury.
• must have had the injury more than 12 months ago.
• have problems controlling my arm movements.
• right handed.
• speak and understand English.
• willing and able to travel to Kessler Foundation in West Orange, NJ for the 3 testing sessions and the 12 sessions of intervention.
• must have stable health with no expected medication changes for the next 4 months.
• able to understand instructions that are part of the testing and intervention.

Exclusion Criteria:

• have had a penetrating Traumatic Brain Injury.
• have severe spasticity (stiffness and tightness in my muscles) as determined by study staff.
• have had other brain injuries or illnesses in addition to the Traumatic Brain Injury (for example, epilepsy, MS).
• use illegal substances at this time, like drugs
• have had a brain injury that was non-traumatic such as a stroke or brain tumor.
• am enrolled in another research study that is likely to affect my participation in this research study.
• have a history of psychiatric illness (for example, bipolar disorder, schizophrenia, or psychosis).