Model-oriented treatment of word production disorders in aphasia

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In this project, we investigate model-oriented treatment of word production disorders in chronic aphasia. Patients receive lexical access training that aims at the underlying lexical deficit in picture naming. Its intensity complies with the principle of massed practice (Pulvermüller et al., 2001). Assessment of the deficit is accomplished by applying a connectionist model to picture naming performance before and after training (see Abel et al., 2005): The interactive activation model of Foygel & Dell (2000) specifies two steps in picture naming - access of lemmas (semantically specified word units) and access of phonemes (sound units). The model is connectionist in nature, i.e. the disorder is simulated by a computer program that automatically attributes the impairment to one or both lexical access steps (connectionist diagnosis). Using a lexical activation fMRIparadigm in which both levels of processing are activated as separately as possible, processing in overt naming can be examined in the normal brain, and in the lesioned brain before and after therapy (for overview, see Indefrey & Levelt, 2000; Grande & Huber, 2005). Therefore, ¿lesions¿ and ¿recovery¿ are analyzed via the cognitive model and the brain, aiming at understanding the processes underlying recovery and trying to link both levels of explanation.