The generation of Parkinsonian tremor as revealed by directional coupling analysis

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

Corresponding author: smirnovda@yandex.ru

Received: 27 February 2008
Accepted: 6 June 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 brain driving is a linear effect with a small delay corresponding to the neural transmission time. In contrast, the brain 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.