Functional abnormalities in the primary orofacial sensorimotor cortex during speech in Parkinson's disease

Area of Science:

• Neuroscience
• Speech Science
• Neurology

Background:

• Parkinson's disease (PD) significantly impacts speech production, affecting respiration, phonation, and articulation.
• Understanding the neural underpinnings of speech changes in PD is crucial for developing targeted interventions.

Purpose of the Study:

• To investigate the blood oxygen level-dependent (BOLD) response during overt sentence reading in individuals with Parkinson's disease compared to healthy controls.
• To correlate brain activity with specific speech production parameters in PD patients.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to measure BOLD responses during sentence reading in 9 treated female PD patients and 8 age-matched female controls.
• Speech was recorded and analyzed for paralinguistic features (pitch, loudness, rate) and initiation.
• Statistical analyses controlled for age and medication effects (levodopa equivalent).

Main Results:

• PD patients exhibited lower speech loudness compared to controls, even after accounting for age.
• Both groups showed increased BOLD responses in speech production and perception areas.
• PD patients displayed significantly higher BOLD signal in the right orofacial sensorimotor cortex and stronger correlations between speech parameters and BOLD response in the left orofacial sensorimotor cortex.

Conclusions:

• Altered sensorimotor cortex activity in PD patients during speech tasks may reflect compensatory mechanisms or treatment effects.
• Despite measurable differences in loudness and brain activity, overall speech quality in mild to moderate PD patients remained comparable to controls.