Differential involvement of the left frontal and temporal regions in verb naming: a tDCS treatment study

In aphasic patients, some studies have already emphasized the efficacy of transcranial direct current stimulation (tDCS) during the treatment of noun retrieval deficits. To date, in the same population, there are have been no studies addressing tDCS effects in the recovery of verb retrieval deficits. In this study, we wanted to test the potential of tDCS to improve verb production in a group of aphasic patients. METHODS: Seven chronic subjects participated in an intensive language training for their difficulties in action naming. Each subject was treated with tDCS (20 min., 1 mA) over the left hemisphere in three different conditions: anodic tDCS over Wernicke's area, anodic tDCS and sham stimulation over Broca's area. Each experimental condition was performed in five consecutive daily sessions over three weeks with 6 days of intersession interval. RESULTS: In all patients, results showed a significantly better response accuracy during the anodic tDCS over Broca's area with respect to the other two conditions which still persisted at one month after the end of the treatment suggesting a long-term effect on the recovery of their verb retrieval deficits. CONCLUSION: These findings further confirm that tDCS represents a useful new therapeutic interventions for the rehabilitation of lexical deficits in aphasic patients.