http://brain.oxfordjournals.org/content/134/10/3083.short
+ Author Affiliations
- Correspondence to: Benjamin Stahl, Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstraße 1A, 04103 Leipzig, Germany E-mail: stahl@cbs.mpg.de
- Received June 23, 2011.
- Revision received August 11, 2011.
- Accepted August 15, 2011.
Summary
The question of whether singing may be
helpful for stroke patients with non-fluent aphasia has been debated for
many years.
However, the role of rhythm in speech recovery
appears to have been neglected. In the current lesion study, we aimed to
assess
the relative importance of melody and rhythm for
speech production in 17 non-fluent aphasics. Furthermore, we
systematically
alternated the lyrics to test for the influence of
long-term memory and preserved motor automaticity in formulaic
expressions.
We controlled for vocal frequency variability,
pitch accuracy, rhythmicity, syllable duration, phonetic complexity and
other
relevant factors, such as learning effects or the
acoustic setting. Contrary to some opinion, our data suggest that
singing
may not be decisive for speech production in
non-fluent aphasics. Instead, our results indicate that rhythm may be
crucial,
particularly for patients with lesions including
the basal ganglia. Among the patients we studied, basal ganglia lesions
accounted
for more than 50% of the variance related to
rhythmicity. Our findings therefore suggest that benefits typically
attributed
to melodic intoning in the past could actually have
their roots in rhythm. Moreover, our data indicate that lyric
production
in non-fluent aphasics may be strongly mediated by
long-term memory and motor automaticity, irrespective of whether lyrics
are sung or spoken.
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