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%0 Thesis
%A Peters, Elke
%T Unterschiedliche Generierung niedrig- und hochfrequenter Komponenten somatosensorisch evozierter Potenziale (SEP) beim Menschen
%C Aachen
%I Publikationsserver der RWTH Aachen University
%M RWTH-CONV-124099
%P 58 Bl. : Ill., graph. Darst.
%D 2007
%Z Aachen, Techn. Hochsch., Diss., 2007
%X Human median nerve somatosensory evoked potentials (SEP) contain a low-amplitude (< 500 nV) high-frequency (600 Hz) burst of repetitive wavelets (HFOs) which are superimposed onto the primary cortical response 'N20'. This study aimed to further clarify the cortical and subcortical structures involved in the generation of the HFOs. 128-channel recordings were obtained to right median nerve stimulation of 10 right-handed healthy human subjects and in seven of them additional to right ulnar nerve. Data were evaluated by applying principal component analysis and dipole source analysis. The results were that different source evaluation strategies provided converging evidence for a cortical HFO origin, with two different almost orthogonally oriented generators being active in parallel, but with a phase shift of a quarter of their oscillatory period, while the low frequency 'N20' is adequately modelled by one tangential dipole source. Median and ulnar derived low frequency and HFO cortical sources show a somatotopic order. Additionally, generation of the HFOs was localized in subcortical, near thalamic and subthalamic source sites. The near thalamic dipole was located at significantly different sites in HFO and low frequency data. Conclusions: The cortical HFO source constellation points to a “precortical” source in terminals of thalamocortical fibers and a second intracortical HFO origin. Furthermore, HFOs are also generated at subcortical and even subthalamic sites. Near thalamic, the HFO and low frequency signals are generated or modulated by different neuron populations involved in the thalamocortical outflow.
%K Somatosensorisch evozierte Potenziale (SWD)
%K SEP (SWD)
%F PUB:(DE-HGF)11
%9 Dissertation / PhD Thesis
%U https://publications.rwth-aachen.de/record/62535