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71. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC)
9. Joint Meeting mit der Japanischen Gesellschaft für Neurochirurgie

Deutsche Gesellschaft für Neurochirurgie (DGNC) e. V.

21.06. - 24.06.2020

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The impact of functional connectivity of the motor system on the resting motor threshold – a replication study

Der Effekt funktioneller Konnektivität des motorischen Systems auf die Ruhemotorschwelle – eine Replikationsstudie

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  • presenting/speaker Melina Engelhardt - Charité – Universitätsmedizin Berlin, Neurochirurgie, Berlin, Deutschland; Charité – Universitätsmedizin Berlin, Einstein Centre for Neurosciences, Berlin, Deutschland
  • Darko Komnenić - Humboldt-Universität zu Berlin, Berlin School of Mind and Brain, Berlin, Deutschland
  • Lucius Fekonja - Charité – Universitätsmedizin Berlin, Neurochirurgie, Berlin, Deutschland; Humboldt-Universität zu Berlin, Cluster of Excellence Matters of Activity, Berlin, Deutschland
  • Fabia Roth - Charité – Universitätsmedizin Berlin, Neurochirurgie, Berlin, Deutschland
  • Leona Kawelke - Charité – Universitätsmedizin Berlin, Neurochirurgie, Berlin, Deutschland
  • Carsten Finke - Charité – Universitätsmedizin Berlin, Einstein Centre for Neurosciences, Berlin, Deutschland; Humboldt-Universität zu Berlin, Berlin School of Mind and Brain, Berlin, Deutschland
  • Thomas Picht - Charité – Universitätsmedizin Berlin, Neurochirurgie, Berlin, Deutschland; Humboldt-Universität zu Berlin, Cluster of Excellence Matters of Activity, Berlin, Deutschland

Deutsche Gesellschaft für Neurochirurgie. 71. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), 9. Joint Meeting mit der Japanischen Gesellschaft für Neurochirurgie. sine loco [digital], 21.-24.06.2020. Düsseldorf: German Medical Science GMS Publishing House; 2020. DocP107

doi: 10.3205/20dgnc393, urn:nbn:de:0183-20dgnc3935

Published: June 26, 2020

© 2020 Engelhardt et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 License. See license information at http://creativecommons.org/licenses/by/4.0/.

Outline

Text

Objective: Cortical excitability measured with the resting motor threshold (RMT) shows large inter-individual variability. Several anatomical factors contributing to this variability have been suggested, however recent evidence also suggests an impact of functional connectivity of the motor system on the RMT. The aim of this study was to validate findings on the impact of functional connectivity between the primary motor cortex (M1) and dorsal premotor cortex (PMd) as well as other motor areas on the RMT. The impact of the above-mentioned predictors is compared to the coil-to-cortex distance (CCD) as a known predictor of the RMT.

Methods: The RMT was measured bi-hemispherically in 35 healthy right-handed subjects (38.7 ± 13.7 years, 19 females) without any neurological or psychiatric condition using navigated TMS. Resting-state functional connectivity was assessed inter-hemispherically on M1 and intra-hemispherically between M1 in relation to primary somatosensory cortex (S1), dorsal and ventral premotor cortex (PMd, PMv), supplementary motor area (SMA) and pre-SMA. Other factors included in the analysis were age, sex and CCD. The relationship between each predictor and the RMT was assessed with a linear mixed model to account for non-independence of observations within the same subjects. Further, we evaluated the added impact of a combined model.

Results: Functional connectivity between M1 and PMd did not significantly predict the RMT (b = 0.05, t(34) = 0.02, p = 0.99). In addition, functional connectivity between further regions did not predict the RMT either. Singularly CCD showed a significant impact on the RMT (b = 1.64, t(34) = 6.29, p < .001). The model with CCD explained 51% of the variance of the RMT and was advantageous over a simpler model containing only the random effect for subjects (x2(1) = 28.48, p < 0.001). A model containing all variables explained only 56% of the variance and thus, did not prove better than the previous model (x2(9) = 6.60, p = 0.68).

Conclusion: We could not replicate previous findings on the impact of functional connectivity to non-primary motor areas on the RMT in a larger sample. The distance between stimulation coil and cortex remains the most important and well-established predictor for the RMT.