P103 Functional connectivity changes after bilateral tDCS over the frontal region: Preliminary data from aphasia

Abstract

Introduction Several studies have already shown that transcranial direct current stimulation (tDCS) is an useful tool to enhance recovery in aphasia. However, no reports to date have investigated functional connectivity changes on cortical activity due to tDCS language treatment. Objectives The present study explored whether bilateral tDCS over the frontal regions would improve language performance in a group of aphasic patients. We also wanted to assess the impact of dual tDCS language treatment on functional connectivity reorganization through rs-fMRI. Materials & methods Nine aphasic persons with articulatory disorders underwent an intensive language therapy in two different conditions: bilateral anodic stimulation over the left Broca’s area and cathodic contralesional stimulation over the right homologue of Broca’s area and a sham condition. The language treatment lasted three weeks (Monday to Friday – fifteen daily sessions). In all patients, language measures were collected before (T0) and at the end of treatment (T15). Before and after each treatment condition (real vs.sham), each subject underwent a resting state fMRI (rsfMRI). Results Results showed that, after real stimulation, patients exhibited the greatest recovery not only in terms of better accuracy in articulating the treated stimuli but also for untreated items on different tasks of the language test (picture description, noun and verb naming, word repetition, word reading). Moreover, while after the sham condition connectivity changes were confined into the right brain hemisphere, bilateral stimulation yielded to stronger functional connectivity increase in the left hemisphere. Conclusion In conclusion, our data provide converging evidence from behavioural and functional imaging data that bilateral tDCS determines functional connectivity changes into the lesioned hemisphere enhancing language recovery process in stroke patients.