Impaired phonetic learning in Parkinson's Disease

Abstract

Parkinson’s Disease (PD) is a neurodegenerative disorder primarily associated with its motor consequences. However, it also has important implications for cognitive functions, including speech production (Altmann and Troche, 2011), the perception of speech intensity (Richardson and Sussman, 2019), and visual category learning (Shohamy et al., 2008), due to its effects on subcortical brain systems that rely on dopamine. In the present study, we examine the effects of PD on a variety of speech perception tasks: one of non-native phonetic learning, one of learning to comprehend rate-compressed speech, one of learning to understand accented speech, and one probing the use of speech rate to guide word segmentation. People with PD showed significant deficits when compared to young and age-matched controls in their ability to adapt to rate-compressed speech. Within the population of those with PD, participants using levodopa-based medication performed significantly worse on the non-native learning task than a small subset of participants without such medication. This suggests that changes in dopamine regulation and use associated with PD have significant effects on higher-level aspects of speech perception such as speech learning.