Variability, regularity and coupling measures distinguish PD tremor from voluntary 5 Hz tremor

Morrison, S., Cortes, N., Newell, K. M., Silburn, P. A. and Kerr, G. (2013) Variability, regularity and coupling measures distinguish PD tremor from voluntary 5 Hz tremor. Neuroscience Letters, 534 1: 69-74. doi:10.1016/j.neulet.2012.11.040

Author Morrison, S.
Cortes, N.
Newell, K. M.
Silburn, P. A.
Kerr, G.
Title Variability, regularity and coupling measures distinguish PD tremor from voluntary 5 Hz tremor
Journal name Neuroscience Letters   Check publisher's open access policy
ISSN 0304-3940
Publication date 2013-02-08
Year available 2012
Sub-type Article (original research)
DOI 10.1016/j.neulet.2012.11.040
Volume 534
Issue 1
Start page 69
End page 74
Total pages 6
Place of publication Ireland
Publisher Elsevier Ireland
Collection year 2014
Language eng
Formatted abstract
A characteristic of Parkinson's disease (PD) is the development of tremor within the 4–6 Hz range. One method used to better understand pathological tremor is to compare the responses to tremor-type actions generated intentionally in healthy adults. This study was designed to investigate the similarities and differences between voluntarily generated 4–6 Hz tremor and PD tremor in regards to their amplitude, frequency and coupling characteristics. Tremor responses for 8 PD individuals (on- and off-medication) and 12 healthy adults were assessed under postural and resting conditions. Results showed that the voluntary and PD tremor were essentially identical with regards to the amplitude and peak frequency. However, differences between the groups were found for the variability (SD of peak frequency, proportional power) and regularity (Approximate Entropy, ApEn) of the tremor signal. Additionally, coherence analysis revealed strong inter-limb coupling during voluntary conditions while no bilateral coupling was seen for the PD persons. Overall, healthy participants were able to produce a 5 Hz tremulous motion indistinguishable to that of PD patients in terms of peak frequency and amplitude. However, differences in the structure of variability and level of inter-limb coupling were found for the tremor responses of the PD and healthy adults. These differences were preserved irrespective of the medication state of the PD persons. The results illustrate the importance of assessing the pattern of signal structure/variability to discriminate between different tremor forms, especially where no differences emerge in standard measures of mean amplitude as traditionally defined.

Highlights ► Young adults were able to produce a tremor similar in frequency to PD tremor. ► PD tremor was more variable and irregular than voluntarily generated 5 Hz tremor. ► Stronger coupling between the arms was seen for voluntary tremor responses. ► Variability measures can be used to discern between different tremor forms.
Keyword Tremor
Parkinson's disease
Bilateral coupling
Physiological tremor
Bimanual coordination
Postural tremor
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Available online 1 December 2012

Document type: Journal Article
Sub-type: Article (original research)
Collections: UQ Centre for Clinical Research Publications
Official 2014 Collection
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Citation counts: TR Web of Science Citation Count  Cited 1 times in Thomson Reuters Web of Science Article | Citations
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