Effects of 10 Hz rTMS on spontaneous brain oscillations in non-demented Parkinson's patients: Preliminary results of combined MEG-rTMS study D. Kičić a,b, ⁎ , R. Bikmullina a , P. Lioumis a , J. Nurminen a , S. Kaakkola c , J.P. Mäkelä a , E. Pekkonen c a BioMag Laboratory, Helsinki University Central Hospital, Helsinki, Finland b Laboratory of Biomedical Engineering, Helsinki University of Technology, Espoo, Finland c Department of Neurology, Helsinki University Central Hospital, Helsinki, Finland Abstract. Therapeutic effects of repetitive transcranial magnetic stimulation (rTMS) are extensively studied in patients with Parkinson's disease (PD). rTMS to primary motor cortex (M1) induces dopamine release in the putamen: consequently M1 is an interesting target for rTMS in PD. The rTMS over M1 in PD patients reduces the reaction time, improves the Unified Parkinson's Disease Rating Scale (UPDRS) scores and alleviates bradykinesia and hypokinesia. However, the effects of rTMS on spontaneous brain activity are not known. We investigated whether subthreshold rTMS to M1 modulated spontaneous oscillations recorded with magnetoencephalography (MEG). MEG from nine medicated, non-demented PD patients displayed a significant increase in beta oscillations after rTMS in the stimulated hemisphere. Minimum current estimate calculations revealed an increase of beta oscillatory activity after the rTMS treatment over the Rolandic regions. The rTMS in PD patients alters spontaneous brain activity as seen with MEG, probably by modulating cortico- thalamo-basal ganglia networks. © 2007 Elsevier B.V. All rights reserved. Keywords: Magnetoencephalography; Transcranial magnetic stimulation; Spontaneous oscillations; Parkinson's disease 1. Introduction Parkinson's disease (PD) is caused by a progressive loss of dopaminergic neurons. However, its detailed pathophysiology is still poorly understood. According to the basal International Congress Series 1300 (2007) 717 – 720 www.ics-elsevier.com ⁎ Corresponding author. BioMag Laboratory, Helsinki University Central Hospital, Helsinki, Finland. Tel.: +358 9 47175582; fax: +358 9 47175781. E-mail addresses: dubravko@biomag.hus.fi, dkicic@gmail.com (D. Kičić). 0531-5131/ © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.ics.2007.03.007