Approximately 80-90% of individuals with Parkinson’s disease (PD) develop motor speech impairments, predominantly in the form of voice dysfunction. It is known that the motor symptoms of PD arise from degeneration of the dopamine producing neurons in the substantia nigra and dysregulation of basal ganglia motor pathways. It is also known that motor cortical activity in PD patients is abnormal during movement. However, it is unclear how the changes in basal ganglia and motor cortical function relate to the speech and voice symptoms of PD. For this dissertation, I conducted three studies to further understand the contributions of the basal ganglia and motor cortices to speech and voice impairment in PD. In the first study (CHAPTER 2), I demonstrate that there are changes in functional cortico-basal ganglia connections that differentiate PD participants with speech impairment from PD participants without speech impairment. In the second study (CHAPTER 3), I demonstrate that performing speech tasks during continuous fMRI scanning elicits the Lombard effect comparably in both older healthy adults and individuals with PD and hypophonia. This study further demonstrates that this is independent of PD medication state (on medication vs. 12-hour withdrawal). In my third study (CHAPTER 4), I demonstrate that individuals with PD and hypophonia have hypoactivation in the dorsal premotor cortex when performing a sustained vowel task, and that activity in the dorsal premotor cortex is correlated with maximum phonation time. My third study also demonstrates spatial differences in the functional representation of the right laryngeal motor cortex between older healthy adults and individuals with PD and hypophonia. Together, the results of these three studies suggest that changes in multiple brain regions are associated with speech and voice impairment in PD. These include changes in the striatum, globus pallidus, laryngeal motor cortex, and dorsal premotor cortex. The work presented in this dissertation adds to our current understanding of the neurological changes involved in PD speech and voice impairment and presents several avenues for future research.

Creator

• Manes, Jordan Leigh

DOI

• https://doi.org/10.21985/n2-1gb1-j363

Subject

• Neurosciences
• Communication

Language

• en

Alternate Identifier

• etdadmin_upload_759611
• http://dissertations.umi.com/northwestern:15211

Keyword

• neuroimaging
• dysarthria
• fMRI
• basal ganglia
• hypophonia
• Parkinson's disease

Date created

• 2020-01-01

Resource type

• Dissertation

Rights statement

• In Copyright