0.7 Music, biological evolution, and the brain  (Page 16/30)

Humans are deeply social creatures, and thus one important question concerns possible increased benefits of social musical activities on cognitive and emotional function after stroke. That is, active engagement of patients in singing or playing instruments may have greater cognitive, emotional, and motor benefits on neural recovery than passive listening to music. In particular, it would be worth comparing live therapy vs. passive listening in terms of the cognitive and mood measures applied by Särkämö et al. If live therapy is substantially more beneficial, this would provide scientific evidence for the value of live music therapy in the post-stroke period.

4.2 music and the recovery of verbal fluency in aphasia

Aphasia is a language impairment due to central neurological dysfunction. Given the importance of language to human communication, aphasia is a truly debilitating neurological disorder affecting over 100,000 stroke victims each year in the U.S. alone (Schlaug et al., 2008). Nonfluent aphasias generally result from lesions in the frontal lobe and/or its underlying white matter fiber tracts, and are characterized by limited, effortful verbal output, often in the face of otherwise intelligent behavior. Such patients have difficulty retrieving the words they want to say and assembling the words into coherent phrases. Yet a striking phenomenon in many such patients, known for over one hundred years, is that they can sometimes sing familiar songs with great fluency (Racette et al., 2006). This led to the development of a form of aphasia therapy known as melodic intonation therapy, or MIT (Albert et al., 1973), which embeds short phrases (e.g., “I love you”) in “melodic” speech intonation patterns that rely on up-and-down movements between two discrete pitches. Patients practice such utterances intensively and regularly with a therapist, who gradually lengthens the phrases to span more syllables (Norton et al., 2009). The goal of the therapy is to improve fluency for both the trained phrases and for spontaneous, untrained utterances spoken in a normal fashion.

Two features of MIT that distinguish it from non-musical speech therapy are the use of melodic speech intonation and rhythmic tapping (i.e., while speaking the utterance, the patient also taps its rhythm using the hand that was unaffected by the stroke). Schlaug and colleagues have recently begun a set of studies aimed at measuring the efficacy of MIT versus a matched “speech repetition therapy” (SRT) without melodic intonation and tapping. In addition to quantifying MIT’s versus SRT’s effects on post-therapy measures of verbal fluency, the researchers are also measuring changes in brain physiology after the two therapies. Of particular interest in this regard is the extent to which MIT patients shift toward using right hemisphere circuits for speech after therapy. Prior neuroimaging research with normal individuals indicates that song and speech have different hemispheric biases, with song activating several right hemisphere regions not activated by ordinary speech (Callan et al., 2006; cf. Peretz, in press). Hence, one question of interest is the extent to which MIT recruits these regions to compensate for damaged left-hemisphere regions.