Functional connectivity between parietal and temporal lobes mediates internal forward models during speech production

Area of Science:

• Neuroscience
• Cognitive Science
• Speech Production Research

Background:

• Internal forward models explain how the brain predicts action outcomes.
• The cascaded theory suggests the inferior parietal lobe (IPL) relays motor signals to predict auditory speech consequences serially.

Purpose of the Study:

• To investigate the cascaded processing theory of speech production using functional connectivity (FC).
• To examine the role of the inferior parietal lobe (IPL) in converting motor signals to auditory predictions.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was employed.
• Functional connectivity (FC) analyses were performed during three speech tasks: overt articulation (OA), silent articulation (SA), and imagined articulation (IA).

Main Results:

• Connectivity between anterior IPL and superior temporal gyrus (STG) increased in OA vs. SA, indicating task-modulated somatosensory-auditory relationships.
• Stronger connectivity between opercular IFG and posterior IPL, and between posterior IPL and STG, was observed in SA and IA vs. OA.

Conclusions:

• The findings support a cascaded processing model within internal forward models during speech production.
• The inferior parietal lobe (IPL) plays a crucial role as a computational relay in predicting auditory speech consequences.