Developing a means of marking and assessing impairments in the processing of linguistic prosody in Parkinson's Disease

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Awarding institution
  • University of Strathclyde
Date of award
  • 2022
Thesis identifier
  • T16198
Person Identifier (Local)
  • 201269674
Qualification Level
Qualification Name
Department, School or Faculty
  • Introduction People with Parkinson’s disease (PD) may present with an impaired ability to interpret prosody. There are few studies examining perception of non-emotional prosody in PD and fewer still using event-related potentials (ERPs) to do so. ERPS are the electroencephalogram (EEG) response to stimuli. These are typically named as either P (positive) or N (negative) followed by the time at which they occur (e.g. N100, a negative component typically peaking 100ms after a stimulus). The lack of ERP studies examining linguistic prosody may be due to it having many functions and due to its subtle effect meaning the processing of linguistic prosody is difficult to capture on an EEG. The current study presents a means of eliciting markers for the processing of linguistic prosody in healthy persons and people with PD. This has the purpose of providing a means of examining prosodic perception in PD. The protocol was validated by testing on a primary cohort of healthy older persons, a smaller cohort of healthy younger persons and on two people with PD. Method Three cohorts took part in the study, a healthy senior (HS) cohort aged 59 and older (n=36); a younger Pilot cohort, aged 22-30 (n=8); and 2 people with PD (age 81 and 76; Hoehn and Yahr stages 3 and 1) who were analysed as case studies. The HS cohort and participants with PD were screened for dementia and mild cognitive impairment using the ACE-III and depression using the GDS-30. The protocol consisted of an EEG task combined with two behavioural tasks. Adapted from a study by Eckstein and Friederici (2005), intonational phrase boundaries (IPBs) were used to make two forms of incongruous prosody. There was an IPB-2 condition in which two IPBs were present and an IPB-0 condition in which the IPB was absent. The behavioural tasks were an Identification Task and Discrimination Task in which participants listened to utterances and were asked to identify incongruous prosody or say if two utterances heard back to back had the same or different prosody. During the EEG, participants carried out a Probe Task in which they listened to the utterances and then answered if a displayed word was the last word they heard in the sentence. The IPB-2 condition aimed to elicit the attention capture and orientation components the N100, P3a, reorientation negative (RON), and evoked frontal delta. The IPB-0 condition aimed to elicit the prosody reanalysis components the right-anterior negative (RAN) and the prosodic expectancy positive (PEP). Results The Pilot cohort elicited a P3a in the IPB-2 condition and a PEP and RAN in the IPB-0 condition. The HS cohort elicited an N100, P3a, RON, and, evoked delta in the IPB-2 condition. In addition to this they elicited a switch-positive (SP) and parietal alpha suppression due to the task demands. The IPB-0 condition failed to elicit a RAN or PEP in the HS cohort. The two participants with PD performed similarly to the healthy cohort in the behavioural tasks. In the IPB-2 condition one those participants did not elicit any ERP components but did elicit weakly significant increase in delta power at electrode FCz only. The other participant with PD elicited a P3a and a weakly significant SP and RON. In the IPB-0 condition one participant with PD elicited a weakly significant RAN. The other did not elicit a RAN nor PEP. Discussion The current study successfully elicited the full range of attentional components therefore these can be used to mark various stages in the processing of prosody. The prosodic reanalysis components, the PEP and RAN were absent in the HS cohort but were present in the Pilot cohort. There may therefore be an age effect on how the incongruent prosody was interpreted or processed in older persons. If this is confirmed with future work, it would mean they are inappropriate for use in the study of linguistic prosody in older patient groups. Conclusion The current study successfully elicited attentional markers in response to linguistic prosody in a novel way in healthy older persons. Testing in a small number of people with PD gave a preliminary indication that these can be used to examine the perception of linguistic prosody PD. The study failed to elicit the RAN and PEP in healthy older persons and this may be due to an age effect.
Advisor / supervisor
  • Lowit, Anja
  • Lakany, Heba
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