Figure 1.

The flowchart shows the criteria and key word search terms used to select papers from the PUBMED database. Twenty-one studies were selected, 10 for aphasic patients, 10 for healthy subjects and one study reported data from healthy subjects and patients.⁴⁹ Irrelevant articles include papers on other pathologies, or using different techniques, or investigating functions different from language or are predictions based on computational models. tDCS, transcranial direct current stimulation.