Reactive Inhibitory Control Precedes Overt Stuttering Events

Area of Science:

• Neuroscience
• Cognitive Science
• Speech Science

Background:

• Stuttering research often focuses on speech motor differences between fluent and non-fluent speakers.
• Less attention has been paid to the cognitive processes preceding stuttered speech events.
• Existing research primarily examines speech motor processes, overlooking cognitive contributions.

Purpose of the Study:

• To investigate the hypothesis that reactive inhibitory control is activated before stuttered speech occurs.
• To explore the neurophysiological correlates of cognitive processes leading to stuttered speech.
• To differentiate cognitive processes underlying fluent versus stuttered speech productions.

Main Methods:

• Magnetoencephalography (MEG) was used to record brain activity in 29 stutterers.
• Participants completed a delayed-response task involving cued word production (stuttered or fluent).
• Analysis focused on beta power changes in specific brain regions, particularly the right pre-supplementary motor area (R-preSMA).

Main Results:

• Increased beta power in the R-preSMA was observed preceding stuttered speech compared to fluent speech.
• R-preSMA beta power correlated with stuttering severity and predicted stuttered vs. fluent trials.
• Stuttered trials showed delayed speech onset, potentially linked to inhibitory control mechanisms.

Conclusions:

• Reactive inhibitory control, mediated by the R-preSMA, appears to be triggered prior to stuttered speech.
• These findings provide a neurocognitive explanation for stuttering, highlighting cognitive processes before overt disfluencies.
• Self-perceived anticipation of stuttering is linked to heightened inhibitory control and increased stuttering likelihood.