 Weak transcranial direct current stimulation tDCS induces persisting excitability changes in the human motor cortex. this effect depends on the stimulation polarity and is specific to the site of stimulation. Interacting with cortical activity, by means of cortical stimulation, can positively affect the short-term cognitive performance and improve the rehabilitation potential of neurologic patients. In this respect, preliminary evidence suggests that cortical stimulation may play a role in treating aphasia, unilateral neglect, and other cognitive disorders. 