Separation of trait and state in stuttering

Area of Science:

• Neuroscience
• Speech and Language Pathology
• Cognitive Science

Background:

• Stuttering involves disrupted speech fluency.
• Individuals who stutter exhibit structural and functional abnormalities in speech and motor systems.
• The distinction between persistent traits and transient states in stuttering remains unclear.

Purpose of the Study:

• To differentiate between trait and state effects in stuttering using functional neuroimaging.
• To identify neural indicators associated with general stuttering traits.
• To investigate neural correlates of speech fluency states in people who stutter.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was employed with sparse sampling during overt speech tasks.
• Participants included 17 people who stutter and 16 fluent controls.
• Hierarchical analyses separated general traits, dysfluent speech states, and fluent-dysfluent state differences.

Main Results:

• Reduced activation in left auditory cortex, bilateral inferior frontal cortex, and medial cerebellum were identified as general traits distinguishing people who stutter.
• A subgroup of people who stutter with higher dysfluency showed reduced activation in right subcortical grey matter, left temporo-occipital cortex, cingulate cortex, and medial parieto-occipital cortex.
• During dysfluent speech states, greater activation was observed in bilateral inferior frontal and premotor cortex, extending into the frontal operculum.

Conclusions:

• Trait effects in stuttering include reduced activation in key speech-motor and auditory processing areas.
• State effects related to dysfluency involve altered activation in subcortical and cortical regions.
• Neural differences in stuttering can be attributed to independent trait and state effects.