EP 30. Deep brain stimulation both at 130 Hz and 340 Hz suppresses cortical alpha and beta band activity

Abstract

Introduction Deep brain stimulation (DBS) is an established therapy to treat motor symptoms in movement disorders such as Parkinson’s disease (PD). However, its mechanisms are still poorly understood. Oscillatory activity,on the other hand, plays a crucial role in the pathophysiology of PD. Investigating the effect of DBS on oscillatory activity can help to clarify the neurophysiological mechanisms of DBS. In this study, we aimed at investigating changes of cortical oscillatory activity using magnetoencephalography (MEG) while stimulating the subthalamic nucleus (STN) at two different stimulation frequencies: 130 Hz as the clinical standard stimulation frequency and 340 Hz as being in the range of high frequency oscillations, which have been reported to be associated with motor improvement ( Ozkurt et al., 2011 ). Methods Seventeen PD patients (13 male, mean age 63.4 ± 9.8 y) clinically selected for DBS participated. Recordings were done with a 306-channel, whole head MEG system (Elekta Oy, Helsinki, Finland) and took place the day after electrode implantation and before implanting the stimulator. STN was stimulated with an external stimulator (OSIRIS, inomed, Emmendingen, Germany) using externalized leads (Medtronic Bakken Research Center, Maastricht, the Netherlands) at the two different stimulation frequencies. All patients were off medication during the recording. Patients were seated comfortably in the MEG chair and asked to rest while keeping their eyes open. Recordings started with 180 s DBS OFF followed by 4 intervals of DBS ON (180 s), which were interleaved by further DBS OFF periods (60 s). When possible, the recording was realized both for stimulation frequencies of 130 Hz and 340 Hz (stimulation amplitude 3 mA; pulse width 60 μs, contralateral to the symptom dominant side, contacts 1 vs. 3). Data from eight patients were discarded due to severe movement artefacts. The DBS artefact was removed from MEG data using a methodology based on the combination of independent component analysis (ICA) and mutual information theory ( Abbasi et al., 2015 ). Results Both 130 Hz and 340 Hz DBS led to a widespread suppression of cortical alpha and beta band activity (8–22 Hz) focused over bilateral sensorimotor cortices ( p Discussion Our finding of a widespread suppression of alpha and beta band activity is particularly interesting as Parkinson’s disease is generally associated with abnormally increased beta band activity in the cortico-basal ganglia thalamocortical loop ( Oswal et al., 2013 ). Previously, it has been shown that DBS suppresses beta activity in the STN and results in a decrease of motor-cortical-STN coherence in the beta band ( Kuhn et al., 2008 ). The modulation of cortical oscillatory activity may be a crucial effect of DBS for relieving motor symptoms in PD and might be achieved at different stimulation frequencies.