Targeting Motor Cortex High-excitability States Defined by Functional Connectivity with Real-time EEG-TMS
Overview
Authors
Affiliations
We tested previous post-hoc findings indicating a relationship between functional connectivity (FC) in the motor network and corticospinal excitability (CsE), in a real-time EEG-TMS experiment in healthy participants. We hypothesized that high FC between left and right motor cortex predicts high CsE. FC was quantified in real-time by single-trial phase-locking value (stPLV), and TMS single pulses were delivered based on the current FC. CsE was indexed by motor-evoked potential (MEP) amplitude in a hand muscle. Possible confounding factors (pre-stimulus μ-power and phase, interstimulus interval) were evaluated post hoc. MEPs were significantly larger during high FC compared to low FC. Post hoc analysis revealed that the FC condition showed a significant interaction with μ-power in the stimulated hemisphere. Further, inter-stimulus interval (ISI) interacted with high vs. low FC conditions. In summary, FC was confirmed to be predictive of CsE, but should not be considered in isolation from μ-power and ISI. Moreover, FC was complementary to μ-phase in predicting CsE. Motor network FC is another marker of real-time accessible CsE beyond previously established markers, in particular phase and power of the μ rhythm, and may help define a more robust composite biomarker of high/low excitability states of human motor cortex.
Wansbrough K, Marinovic W, Fujiyama H, Vallence A Front Neurosci. 2024; 18:1425527.
PMID: 39371612 PMC: 11450697. DOI: 10.3389/fnins.2024.1425527.
Marzetti L, Basti A, Guidotti R, Baldassarre A, Metsomaa J, Zrenner C Biomedicines. 2024; 12(5).
PMID: 38790917 PMC: 11118810. DOI: 10.3390/biomedicines12050955.