Change of neuronal pathways in Chinese speakers with non-fluent aphasia after therapy

Melodic intonation therapy (MIT) has been widely reported as an effective approach for improving speech production in people with non-fluent aphasia. Originally developed for native English speakers with aphasia, few has investigated its cross-linguistic effect in a tonal language, such as Chinese. In addition, despite that some studies have provided accounts for the underlying mechanism of MIT-specific behavioral change, literature on the potential white-matter plasticity elicited by the therapy is limited. Aphasia recovery has been reported to employ the perilesional areas in the left hemisphere and/or the homologous language regions in the right hemisphere. Yet, potential white-matter microstructural alteration in language-related regions in the right hemisphere after MIT received surprisingly little attention. This study demonstrated greater facilitation in recovery of speech production after MIT than conventional speech and language therapy among native Chinese speakers with non-fluent aphasia. Further, using diffusion tensor imaging technique, we revealed therapy induced changes in white-matter volumes in the well-established dorsal and ventral language stream tracts in the right hemisphere. The current study offers two accounts for the finding reported: Right hemisphere advantage for tonal language speakers and the role of formulaic language in recovery from non-fluent aphasia are discussed. (C) 2018 Elsevier B.V. All rights reserved.