High-Definition Transcranial Direct Current Stimulation (HD-tDCS) allows to induce, in a non-invasive way, a transient inhibitory or excitatory neuromodulation of a given cerebral region and to obtain a very focused cortical effect. Previous studies using HD-tDCS have shown the effectiveness of this stimulation technique for enhancing language recovery in patients with aphasia. However, language processes are not determined solely by local neural activity at a single site, but rather by the interaction between neural networks. This is because a large cortical network is involved in language processes and, therefore, the same language disorder may result from lesions at different locations in this network. The investigators hypothesize that anodal HD-tDCS will enhance neural interactions between language areas and, thereby, improve language processing and word learning. The investigators propose to carry out a study on chronic aphasic patients involving HD-tDCS of the Broca region (left inferior frontal gyrus) combined with a verb learning task.