Effects of Transcranial Direct Current Stimulation (tDCS) Plus Language Therapy for Naming in Subacute Left Hemisphere Stroke

The investigators will study the effects of transcranial direct current (tDCS) stimulation during language therapy for naming in individuals with aphasia in the acute and subacute post stroke period. Naming difficulties are a persistent and common symptom in aphasia after left-hemisphere (LH) stroke. Behavioral therapy (speech and language therapy; SALT) is the mainstay treatment for post stroke aphasia. Transcranial direct cortical stimulation (tDCS) is a promising adjunct to traditional SALT. tDCS is a safe, non-invasive, non-painful electrical stimulation of the brain which modulates cortical excitability by application of weak electrical currents in the form of direct current brain polarization. It is usually administered via saline-soaked surface sponge electrodes attached to the scalp and connected to a direct current stimulator with low intensities. Most studies are conducted in the chronic phase after stroke. Because neuroplasticity is greatest early after stroke, there is reason to believe tDCS might be most effective in the acute-subacute period. However, only two studies have evaluated tDCS paired with language therapy in group studies of acute to subacute aphasic stroke patients and only one of these was sham-controlled. Furthermore, no studies (of which we are aware) have combined tDCS with therapy to facilitate naming in post stroke aphasia, as shown to be effective in studies of chronic stroke. In this study, the investigators will evaluate whether tDCS combined with SALT improves naming in individuals with aphasia in the acute and subacute post stroke period, more than SALT alone in a randomized, double-blind, sham-controlled trial. The investigators will test the hypothesis that anodal tDCS (A-tDCS) over a targeted region and computer-delivered SALT is associated with greater gains in accuracy in naming pictures, compared to sham combined with the same computer-delivered SALT in post stroke aphasia.