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Objective: To test the hypothesis that intermittent theta burst stimulation (iTBS) variability depends on the ability to engage specific neurons in the primary motor cortex (M1)., Methods: In a sham-controlled interventional study on 31 healthy volunteers, we used concomitant transcranial magnetic stimulation (TMS) and electroencephalography (EEG). We compared baseline motor evoked potentials (MEPs), M1 iTBS-evoked EEG oscillations, and resting-state EEG (rsEEG) between subjects who did and did not show MEP facilitation following iTBS. We also investigated whether baseline MEP and iTBS-evoked EEG oscillations could explain inter and intraindividual variability in iTBS aftereffects., Results: The facilitation group had smaller baseline MEPs than the no-facilitation group and showed more iTBS-evoked EEG oscillation synchronization in the alpha and beta frequency bands. Resting-state EEG power was similar between groups and iTBS had a similar non-significant effect on rsEEG in both groups. Baseline MEP amplitude and beta iTBS-evoked EEG oscillation power explained both inter and intraindividual variability in MEP modulation following iTBS., Conclusions: The results show that variability in iTBS-associated plasticity depends on baseline corticospinal excitability and on the ability of iTBS to engage M1 beta oscillations., Significance: These observations can be used to optimize iTBS investigational and therapeutic applications., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.)

Objective: To investigate whether the somatosensory temporal discrimination threshold (STDT) is already altered at the clinical onset of Parkinson's disease (PD) and whether STDT abnormalities correlate with disease progression we tested STDT values in patients with different severity of disease., Methods: We prospectively and consecutively enrolled 63 PD patients: 26 drug-naive PD patients with symptom onset no longer than two years prior to inclusion in the study (early-phase), 37 PD patients with varying degrees of disease severity and 51 age-matched healthy subjects. The STDT was tested on the index finger of both hands, and on both sides of the face. Twelve out of 26 early phase PD patients were re-tested two years after the initial diagnosis., Results: PD patients as a whole displayed higher STDT values than healthy subjects. STDT values did not significantly differ between early-phase PD patients and healthy subjects, whereas they were significantly higher in patients with mild/moderate and advanced PD. In early-phase PD patients STDT values at the two years-follow up assessment did not statistically differ from those obtained at baseline. Considering the whole group of PD patients STDT abnormalities significantly correlated with duration and severity of the disease., Conclusions: STDT increases as disease progresses. In early-phase PD patients STDT values are still statistically similar to those of healthy subjects, thus implying that dopaminergic depletion alone may not be sufficient to cause STDT abnormalities., Significance: Our study gives new insight into the sensory abnormalities in PD., (Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.)