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Single word reading in developmental stutterers and fluent speakers.
R Salmelin1, A Schnitzler, F Schmitz
1Brain Research Unit, Helsinki University of Technology, Espoo, Finland. riitta@neuro.hut.fi
Brain : a Journal of Neurology
|May 29, 2000
Summary
Developmental stutterers show reversed brain activation patterns during speech tasks compared to fluent speakers, indicating potential motor programming and connectivity issues. These findings highlight differences in neural networks essential for fluent speech production.
Area of Science:
- Neuroscience
- Speech and Language Sciences
- Cognitive Science
Background:
- Developmental stuttering is a complex speech disorder affecting fluency.
- Previous research suggests neurological differences in individuals who stutter.
- Understanding the neural underpinnings of speech production in stuttering is crucial for developing effective interventions.
Purpose of the Study:
- To investigate and compare cortical activation patterns during speech production in fluent speakers and individuals with developmental stuttering.
- To identify differences in neural timing and network engagement between the two groups.
- To explore the role of specific brain regions, including the inferior frontal cortex and motor cortex, in stuttering.
Main Methods:
- Utilized whole-head magnetoencephalography (MEG) to map cortical activation sequences.
- Recorded brain activity in ten fluent speakers and nine developmental stutterers reading isolated nouns aloud.
- Analyzed evoked responses time-locked to word presentation and mouth movement, as well as task-related suppression of 20-Hz oscillations.
Main Results:
- Fluent speakers showed a left inferior frontal cortex to motor cortex activation sequence.
- Stutterers exhibited a reversed sequence: early left motor cortex activation followed by a delayed inferior frontal signal.
- Differences were observed in right motor/premotor cortex activation and 20-Hz rhythm suppression patterns between groups, suggesting atypical network engagement in stutterers.
Conclusions:
- Stutterers may initiate motor programs before articulatory code preparation, differing from fluent speakers.
- A network involving the left inferior frontal cortex and right motor/premotor cortex appears dysfunctional in developmental stutterers.
- Findings suggest potential issues with functional connectivity and motor representation segregation in the stuttering brain during speech production.