A general problem for current empirical aphasia therapies is our poor understanding of their neurophysiological basis, and the consequent lack of a theoretical framework for optimizing them (Raymer et al. 2008). Many essential brain areas for language are predominantly located in the left hemisphere, and most established therapies focus predominantly on training of left- hemispheric functions.
Recently however, successful rehabilitation of expressive language functions has also been described with music-based therapies focusing on training of right- hemisphere-biased functions (e.g. Music Intonation Therapy (MIT), Norton et al. 2009, Schlaug et al. 2009). As with better-established aphasia therapies, the causal basis for this therapeutic success remains poorly understood. These new findings challenge traditionally-held views of music and language as separate modules, occupying non-overlapping brain regions (Peretz, I. & Coltheart 2003) but are in line with recently published data on shared neural resources for music and language.
Multiple brain imaging findings indicate considerable music/language overlap, particularly in structural or "syntactic" processing, and more careful exploration of aphasic patients has revealed subtle but consistent music processing deficits in these language-impaired patients (Patel et al. 2008). Based on these new findings, we predict that more global therapeutic approaches, targeting shared neural resources via both residual left hemispheric brain areas and healthy right-hemispheric circuits, may lead to innovative and more highly effective aphasia therapies.