Thalamic theta field potentials and EEG: high thalamocortical coherence in patients with neurogenic pain, epilepsy and movement disorders
We simultaneously recorded local field potentials (LFP) in the thalamus and EEG on the scalp of 17 patients suffering from neurogenic pain, epilepsy and movement disorders. The EEG of 11 patients displayed enhanced power in the theta frequency range (4–8Hz). The thalamic LFP of 14 patients peaked in the theta range. The theta coherence between EEG and LFP was significant for 12 patients and reached strengths up to 70%. These findings suggest that enhanced theta rhythmicity occurs in tight functional thalamocortical loops and is a major element in all three diseases investigated.
To investigate second-order phase-coupling between LFP frequency components, we computed the bicoherence and averaged over the group of patients. We found peaks in the theta band and the beta band (14–30Hz), indicating phase correlations of oscillatory events in these frequency ranges with their first harmonic. A further peak indicates that phase coupling occurred also between theta and beta frequencies.This indicates a strong functional interaction between the generators of these oscillations. We also computed the cross-correlation between LFP spectral power at different frequencies. Although this measure is independent of phase, we found good agreement with the bicoherence patterns, pointing again to strong interaction between theta and beta rhythmicity. The overproduction of theta rhythms, the thalamocortical coherence and the correlation of theta with beta rhythms are key elements forthe understanding of thalamocortical dysrhythmia (TCD).
Read the full article here. Front. Surg., 24 January 2019 | https://doi.org/10.3389/fsurg.2019.00002 Background MR-guided focused ultrasound (MRgFUS) offers new perspectives for safe and efficient lesioning inside the brain. The issue of target coverage remains primordial and sub-optimally addressed or solved in the field of functional neurosurgery. Objective To provide an optimized planning and operative […]
Read the full article here. Published online May 25, 2018; DOI: 10.3171/2017.12.JNS172054. OBJECTIVE Since the first clinical application of the incisionless magnetic resonance–guided focused ultrasound (MRgFUS) technology only small series of patients have been reported, and thus only extrapolations of the procedure-related risks could be offered. In this study, the authors analyze side-effects and targeting […]