Activation in Right Dorsolateral Prefrontal Cortex Underlies Stuttering Anticipation

Area of Science:

• Neuroscience
• Speech and Language Sciences
• Cognitive Psychology

Background:

• Stuttering involves anticipating speech events, but the underlying neural mechanisms are not well understood.
• Anticipation significantly influences stuttering behaviors, highlighting the need to investigate its neural basis.
• Previous research suggests cognitive control networks may play a role in stuttering.

Purpose of the Study:

• To investigate the neural correlates of stuttering anticipation using functional near-infrared spectroscopy (fNIRS).
• To examine the role of the right dorsolateral prefrontal cortex (R-DLPFC) and frontoparietal network (FPN) in stuttering anticipation.
• To explore differences in brain activity and connectivity between individuals who stutter and those who do not during speech anticipation.

Main Methods:

• A delayed-response task was employed with 22 adult stutterers and 22 controls, identifying anticipated and unanticipated words.
• Hemodynamic activity was measured using fNIRS, focusing on the five-second anticipation phase before speech production.
• Analysis centered on the R-DLPFC and its connectivity with the right supramarginal gyrus (R-SMG), key components of the FPN.

Main Results:

• Anticipated words were linked to increased R-DLPFC activation in all participants.
• Individuals who stutter exhibited greater R-DLPFC activity compared to controls, regardless of anticipation.
• Anticipated words correlated with reduced connectivity between the R-DLPFC and R-SMG.

Conclusions:

• The R-DLPFC and the broader FPN are implicated as neural substrates for stuttering anticipation.
• Findings support theories of error-likelihood monitoring and action-stopping in the context of stuttering anticipation.
• This research opens avenues for future studies and potential clinical interventions, such as targeted neuromodulation.