Issue
EPL
Volume 83, Number 2, July 2008
Article Number 20003
Number of page(s) 6
Section General
DOI http://dx.doi.org/10.1209/0295-5075/83/20003
Published online 10 July 2008
EPL, 83 (2008) 20003
DOI: 10.1209/0295-5075/83/20003

The generation of Parkinsonian tremor as revealed by directional coupling analysis

D. A. Smirnov1, 2, U. B. Barnikol1, 3, 4, T. T. Barnikol1, B. P. Bezruchko1, 2, C. Hauptmann1, C. Bührle1, 3, 4, M. Maarouf1, 3, 4, V. Sturm3, H.-J. Freund1, 3, 4 and P. A. Tass1, 3, 4

1  Institute of Neuroscience and Biophysics 3 - Medicine and Virtual Institute of Neuromodulation, Research Center Jülich - D-52425, Jülich, Germany, EU
2  Saratov Branch of the Institute of RadioEngineering and Electronics of the Russian Academy of Sciences 38 Zelyonaya St., Saratov 410019, Russia
3  Department of Stereotaxic and Functional Neurosurgery, University of Cologne - D-50924 Cologne, Germany, EU
4  Brain Imaging Center West - D-52425 Jülich, Germany, EU

smirnovda@yandex.ru

received 27 February 2008; accepted in final form 6 June 2008; published July 2008
published online 10 July 2008

Abstract
To reveal the dynamic mechanism underlying Parkinsonian resting tremor, we applied a phase dynamics modelling technique to local field potentials and accelerometer signals recorded in three Parkinsonian patients with implanted depth electrodes. We detect a bidirectional coupling between the subcortical oscillation and the tremor. The tremor $\rightarrow $ brain driving is a linear effect with a small delay corresponding to the neural transmission time. In contrast, the brain $\rightarrow $ tremor driving is a nonlinear effect with a long delay in the order of 1-2 mean tremor periods. Our results are well reproduced for an ensemble of 41 tremor epochs in three Parkinsonian patients and confirmed by surrogate data tests and model simulations. The uncovered mechanism of tremor generation suggests to specifically counteract tremor by desynchronizing the subcortical oscillatory neural activity.

PACS
05.45.Xt - Synchronization; coupled oscillators.
05.45.Tp - Time series analysis.
87.19.xp - Motor system disease (Parkinson's, etc.).

© EPLA 2008