Communication Disorders Ph.D. Dissertations

Speech Motor Sequence Learning in Parkinson Disease and Normal Aging: Acquisition, Consolidation, and Automatization

Date of Award

2014

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Communication Disorders

First Advisor

Alexander Goberman (Advisor)

Second Advisor

Ronald Scherer (Committee Member)

Third Advisor

Miriam Krause (Committee Member)

Fourth Advisor

Howard Cromwell (Committee Member)

Fifth Advisor

Patricia Sharp (Committee Member)

Abstract

Motor learning relies on the integrity of sensorimotor circuits in the brain, which are largely affected in individuals with Parkinson disease (PD). Additionally, data suggest normal aging can affect various stages of motor learning. Though data are available on the nature of non-speech motor learning, fewer studies have examined how adults with and without motor speech disorders learn speech articulatory sequences. The aim of the current investigation is to examine speech motor sequence learning in normal aging and PD.

A speech motor sequence learning task was developed and implemented to examine acquisition, consolidation, and automatization over two days. On Day 1, participants learned a sequence of six monosyllabic nonwords to examine acquisition. This speech motor sequence was re-tested on Day 2 in single- and dual-task conditions to evaluate consolidation and automatization, respectively. Learning was inferred from gains in speed and accuracy of the speech motor sequence.

There were no observed effects of aging or PD on speech motor sequence acquisition, as all groups exhibited comparable gains in speed and accuracy on Day 1. However, aging and PD were observed to affect speech motor consolidation following night-time sleep. Specifically, at the Day 2 re-test, young adults exhibited offline gains in speed and accuracy, older adults maintained speed and accuracy (without offline gains), and individuals with PD exhibited offline losses in speed. Only younger adults demonstrated automatization, exhibiting negligible dual-task effects when concurrently performing the speech motor sequence with a visuo-motor task. Conversely, both older adults and individuals with PD exhibited significantly poorer performance of the speech motor sequence in the dual-task condition, with individuals with PD experiencing the largest degree of bidirectional dual-task interference.

Overall, the current findings suggest that speech motor learning is affected by both Parkinson Disease and normal aging. Data from the current investigation are largely in line with findings in the non-speech motor sequence learning literature, suggesting that speech and non-speech motor learning may rely on similar neural circuits. As the individuals with PD exhibited deficits in the consolidation and automatization phases of learning, these data may hold important implications for the speech rehabilitation in PD.

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