Individual differences in the functional and morphological architecture of the dorsal and ventral language pathways may explain part of the variability observed in the ability to learn new words in healthy population and in language recovery of persons with aphasia (PWA). The traditional gold-standard of aphasia rehabilitation is speech and language therapy (SLT), yet in many cases its effectiveness is limited and aphasic subjects are left with enduring deficits. More recent studies suggest that benefits of SLT can be boosted by the use of additional therapeutic approaches such as transcranial direct current stimulation (tDCS). The present project seeks to identify brain and cognitive predictors of treatment response that guide the choice of the language pathway (i.e. dorsal or ventral) and hemisphere (left or right) that must be potentiated to maximize individual benefits. For this, the implication of the dorsal and ventral pathways will be modulated with two validated word-learning tasks: phonological word-learning task and contextual word-learning task. Further, the activity of the left or right cerebral hemispheres will be modulated by using 3different tDCS conditions. This project will be implemented through two studies in two different samples: (i) 30 healthy adults, and (ii) 10 PWA. Each subject will participate in 3 sessions separated by a week. In each session, subjects will receive a different tDCS stimulation condition and will be required to perform the two learning tasks. A magnetic resonance imaging session will be acquired at baseline to obtain structural and functional information. The results of this project will provide helpful hints for making decision in the selection of therapeutic algorithms for tDCS as well as for the selection of tailor-made SLT for aphasic individuals.
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