Neural basis of impaired dexterity: a theta burst stimulation study in Parkinson's disease

Contact Persons: Dr. phil. Tim Vanbellingen, Dr. med. Manuel Bertschi
Funding: Swiss National Science Foundation (SNSF), 320030_129668 (PD Dr. med. Stephan Bohlhalter)
Duration: 2010-2014

In this project the pre-motor cortex modulation of fine motor control by repetitive transcranial magnetic stimulation (rTMS) in PD is of interest. Patients with PD often experience dexterous difficulties impeding activities of daily living (ADL). There is controversy concerning the underlying patho-physiological mechanism, others and we suggest the dexterous difficulties may be apraxic in nature (called limb kinetic apraxia, LKA), possibly due to pre-motor cortical involvement (Gebhardt et al. 2008; Vanbellingen et al. 2011). The aim of the present project is to investigate whether the dorsal pre-motor cortex (Pmd) plays a significant role in manual dexterity in PD. For this purpose we are conducting a fMRI-based neuronavigated theta burst stimulation (TBS) study in patients with PD. A repeated measures design is employed with three experimental sessions: sham stimulation, cTBS (continuous theta burst stimulation) and iTBS (intermittent theta burst stimulation). cTBS is known to elicit inhibitory and iTBS excitatory effects on motor behavior. Accordingly, we hypothesize that manual dexterity in PD may further deteriorate with cTBS and may improve with iTBS. After stimulation (real or sham) patients with PD are performing a series of behavioral tasks, such as the coin rotation task. A modified MDS-UPDRS task is included, which measures primary parkinsonian motor symptoms. Furthermore, proprioception and muscle force is tested to control for primary sensory motor functions.

Infra-red camera to be used for neuronavigation

TMS-coil navigated towards target cortical stimulation area