Case Study: Differential Effects of Melody and Rhythm in Melodic Intonation Therapy

Evidence has been well accumulated for more than two centuries that a patient with non-fluent, or Broca’s, aphasia secondary to a left hemisphere stroke is able to sing songs and words (e.g., Marina, Pasqualetti, & Carlomagno, 2007; Mills, 1904, Gerstmann, 1964, Stahl, Kotz, Henseler, Turner, & Geyer, 2011). The rationale behind this evidence relies on neuroplasticity that a patient’s intact right hemisphere, known to play an important role in processing steady-state spectral information and slowly changing aspects of the auditory-signal (e.g., prosodic contours and sustained vowels), may stimulate the damaged left hemisphere responsible for integrating auditory information across shorter intervals of time (Naeser & Helm-Estabrooks, 1985; Sparks & Deck, 1994; Zatorre & Belin, 2001; Zipse, Worek, Guarino, & Shattuck-Hufnagel, 2014). This clinical observation has led to a variety of singing-based therapeutic techniques such as Melodic Intonation Therapy (MIT; Albert, Sparks, & Helm, 1973; Helm-Estabrooks, Nicholas, & Morgan, 1989; Sparks, Helm, & Albert, 1974; Wan, Ruber, Hohmann, & Schlaug, 2010). Techniques of MIT include sequentially training a patient to sing The purpose of the current observational study was to explore differential effects of melodyonly condition and rhythmic left-hand tapping-only condition in Melodic Intonation Therapy, when accompanied with formulaic words or phrase and slow rate. The participant included a 77-year-old, monolingual, non-Hispanic, Caucasian male with severe Broca’s aphasia enrolled at a university clinic. The independent variable was the individual component of MIT, with two conditions: (1) melody only and (2) rhythm and left-hand tapping only. The dependent variable was percentage accuracy of the participant’s ability to repeat a list of targets (i.e., pre-selected formulaic words/phrases). An alternating treatment design over two treatment phases was used in the present study. The percentage of nonoverlapping data was calculated by dividing the number of treatment sessions exceeding the highest data point during baseline sessions by the total number of treatment sessions. Results indicated that melody-only condition was a fairly effective treatment while rhythm and left-hand tappingonly condition was an unreliable treatment. The participant had difficulty following rhythm and left-hand tapping possibly due to a rhythm-processing deficit. Motivation and mood effect of singing in unison might positively influence the accuracy of repetitions in the participant. Limitations of the study were discussed.