In animals, anodal cortical stimulation of 5-30 minutes has been shown to cause excitability increases lasting for hours after the stimulation, primarily through modulation of the resting membrane potential (Terzuolo & Bullock, 1956; Creutzfeldt et al. 1962; Eccles et al. 1962; Bindman et al. 1964; Purpura & McMurtry, 1965; Artola et al. 1990; Malenka & Nicoll, 1999). In humans, 13 min of TDCS resulted in an increase in excitability up to 150% and lasting 90 min (Nitsche & Paulus, 2001). Research with TDCS has revealed that anodal stimulation can induce transient (on the order of 30 minutes) improvements in performance on cognitive, motor and linguistic tasks. For example, Hummel et al. (2005a,b) found that anodal TDCS delivered to the primary motor area in the lesion hemisphere elicited significant improvements in motor control of the paretic limb. The effect lasted for more than 25 minutes after stimulation. In a recent study, Fregni et al (2005a) also verified that anodal TDCS to the affected hemisphere and cathodal TDCS to the contralesional hemisphere improved motor function. Other examples highlighting the efficacy of anodal TDCS include Fregni et al. (2005b) - anodal TDCS to dorsolateral prefrontal cortex elicited an improvement in working memory; Nitsche et al. (2003a) - stimulation to primary motor cortex improved motor learning; Antal et al. (2004) - TDCS delivered to primary motor area or to visual area V5 induced improvements in visuo-motor coordination; Kincses et al. (2004) - anodal stimulation of fronto-polar regions improved probabilistic classification learning; and Lyer et al. (2005) - left prefrontal cortical stimulation lead to increased verbal fluency. These studies attest to the efficacy and safety of TDCS in brain injury patients, as well as its potential for therapeutic applications in brain lesion recovery.