Evoked EEG Responses to TMS Targeting Regions Outside the Primary Motor Cortex and Their Test–Retest Reliability

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

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en

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Brain Topography, Volume 37, issue 1, pp. 19-36

Abstract

Transcranial magnetic stimulation (TMS)–evoked electroencephalography (EEG) potentials (TEPs) provide unique insights into cortical excitability and connectivity. However, confounding EEG signals from auditory and somatosensory co-stimulation complicate TEP interpretation. Our optimized sham procedure established with TMS of primary motor cortex (Gordon in JAMA 245:118708, 2021) differentiates direct cortical EEG responses to TMS from those caused by peripheral sensory inputs. Using this approach, this study aimed to investigate TEPs and their test–retest reliability when targeting regions outside the primary motor cortex, specifically the left angular gyrus, supplementary motor area, and medial prefrontal cortex. We conducted three identical TMS–EEG sessions one week apart involving 24 healthy participants. In each session, we targeted the three areas separately using a figure-of-eight TMS coil for active TMS, while a second coil away from the head produced auditory input for sham TMS. Masking noise and electric scalp stimulation were applied in both conditions to achieve matched EEG responses to peripheral sensory inputs. High test–retest reliability was observed in both conditions. However, reliability declined for the ‘cleaned’ TEPs, resulting from the subtraction of evoked EEG response to the sham TMS from those to the active, particularly for latencies > 100 ms following the TMS pulse. Significant EEG differences were found between active and sham TMS at latencies < 90 ms for all targeted areas, exhibiting distinct spatiotemporal characteristics specific to each target. In conclusion, our optimized sham procedure effectively reveals EEG responses to direct cortical activation by TMS in brain areas outside primary motor cortex. Moreover, we demonstrate the impact of peripheral sensory inputs on test–retest reliability of TMS-EEG responses.

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Funding Information: Open Access funding enabled and organized by Projekt DEAL. Y.S. reports funding from the China Scholarship Council (CSC). P.C.G. reports funding from the German Research Foundation (Deutsche Forschungsgemeinschaft—DFG—project number 466 458 984). The work was funded by the European Research Council (ERC Synergy) under the European Union’s Horizon 2020 research and innovation program (ConnectToBrain, grant number 810377). | openaire: EC/H2020/810377/EU//ConnectToBrain

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Song, Y, Gordon, P C, Metsomaa, J, Rostami, M, Belardinelli, P & Ziemann, U 2024, 'Evoked EEG Responses to TMS Targeting Regions Outside the Primary Motor Cortex and Their Test–Retest Reliability', Brain Topography, vol. 37, no. 1, pp. 19-36. https://doi.org/10.1007/s10548-023-01018-y