Differentiated effects of deep brain stimulation and medication on somatosensory processing in Parkinson's disease

•MEG study in PD patients receiving median nerve stimulation during DBS ON, medication on and no treatment.•Differentiated effects of treatments on the induced gamma (31-45 Hz) augmentation.•Results suggest differences in the effect mechanisms of DBS and dopaminergic medication.

ObjectivesDeep brain stimulation (DBS) and dopaminergic medication effectively alleviate the motor symptoms in Parkinson's disease (PD) patients, but their effects on the sensory symptoms of PD are still not well understood. To explore early somatosensory processing in PD, we recorded magnetoencephalography (MEG) from thirteen DBS-treated PD patients and ten healthy controls during median nerve stimulation.MethodsPD patients were measured during DBS-treated, untreated and dopaminergic-medicated states. We focused on early cortical somatosensory processing as indexed by N20m, induced gamma augmentation (31-45 Hz and 55-100 Hz) and induced beta suppression (13-30 Hz). PD patients' motor symptoms were assessed by UPDRS-III.ResultsUsing Bayesian statistics, we found positive evidence for differentiated effects of treatments on the induced gamma augmentation (31-45 Hz) with highest gamma in the dopaminergic-medicated state and lowest in the DBS-treated and untreated states. In contrast, UPDRS-III scores showed beneficial effects of both DBS and dopaminergic medication on the patients' motor symptoms. Furthermore, treatments did not affect the amplitude of N20m.ConclusionsOur results suggest differentiated effects of DBS and dopaminergic medication on cortical somatosensory processing in PD patients despite consistent ameliorating effects of both treatments on PD motor symptoms.SignificanceThe differentiated effect suggests differences in the effect mechanisms of the two treatments.