Inclusion Criteria:  diagnosis of a chronic incomplete cervical lesion as defined by the American Spinal Injury Association Impairment scale classification and at least for 6 months post-injury; upper-extremity weakness associated with tetraplegia with minimal residual thumb and index; finger movement sufficient to grip small objects such as marble; no brain injury; no planned alteration in upper-extremity therapy or medication for muscle tone during the course of the study; no contradiction to tDCS; access to internet at home.  Exclusion Criteria:  prior history of seizure; chronic use of neuroactive medication (e.g., neurostimulants, anticonvulsants, or antidepressants); any joint contracture or severe spasticity in the affected upper extremity, as measured by a Modified Ashworth Score ≥ than 3 out of 4.