No trace of phase: Corticomotor excitability is not tuned by phase of pericentral mu-rhythm

Madsen, Kristoffer Hougaard; Karabanov, Anke Ninija; Krohne, Lærke Gebser; Safeldt, Mads Gylling; Tomasevic, L.; Siebner, H. R.

doi:10.1101/513390

Cited by 10 publications

(28 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Larger MEP amplitudes were found when TMS was administered at the trough compared to when it was administered at the peak of the mu-oscillation [31][32][33] (but see ref. 34 ). Others investigated the role of mu-power on MEP amplitude, suggesting that sensorimotor mu-power may reflect a net facilitation or disinhibition of M1 35 .…”

Section: Discussionmentioning

confidence: 99%

Concurrent human TMS-EEG-fMRI enables monitoring of oscillatory brain state-dependent gating of cortico-subcortical network activity

et al. 2020

View full text Add to dashboard Cite

Despite growing interest, the causal mechanisms underlying human neural network dynamics remain elusive. Transcranial Magnetic Stimulation (TMS) allows to noninvasively probe neural excitability, while concurrent fMRI can log the induced activity propagation through connected network nodes. However, this approach ignores ongoing oscillatory fluctuations which strongly affect network excitability and concomitant behavior. Here, we show that concurrent TMS-EEG-fMRI enables precise and direct monitoring of causal dependencies between oscillatory states and signal propagation throughout cortico-subcortical networks. To demonstrate the utility of this multimodal triad, we assessed how pre-TMS EEG power fluctuations influenced motor network activations induced by subthreshold TMS to right dorsal premotor cortex. In participants with adequate motor network reactivity, strong pre-TMS alpha power reduced TMS-evoked hemodynamic activations throughout the bilateral cortico-subcortical motor system (including striatum and thalamus), suggesting shunted network connectivity. Concurrent TMS-EEG-fMRI opens an exciting noninvasive avenue of subject-tailored network research into dynamic cognitive circuits and their dysfunction.

show abstract

Section: Discussionmentioning

confidence: 99%

Concurrent human TMS-EEG-fMRI enables monitoring of oscillatory brain state-dependent gating of cortico-subcortical network activity

et al. 2020

View full text Add to dashboard Cite

show abstract

“…The corticospinal response (measured by MEP) elicited by single-pulse TMS on M1 varies between trials[27–30]. Recent studies have shown that this variability is associated with neural oscillation power[31–37], phase[26,38,39], or their interaction[40], although one study failed to replicate these findings[41]. In our study, we showed that pre-stimulus mu-rhythm oscillatory power was correlated with the modulation of cortical and corticospinal excitability (Fig.…”

Section: Discussionmentioning

confidence: 99%

Pinging the Brain with Transcranial Magnetic Stimulation Reveals Cortical Reactivity in Time and Space

Ahn

Fröhlich

2019

Preprint

View full text Add to dashboard Cite

17 Single-pulse transcranial magnetic stimulation (TMS) elicits an evoked 18 electroencephalography (EEG) potential (TMS-evoked potential, TEP), which is interpreted 19 as direct evidence of cortical reactivity to TMS. Thus, combining TMS with EEG may enable 20 the mechanistic investigation of how TMS treatment paradigms engage network targets in 21 the brain. However, there remains a central controversy about whether the TEP is a genuine 22 marker of cortical reactivity to TMS or the TEP is contaminated by responses to peripheral 23 somatosensory and auditory inputs. Resolving this controversy is of great significance for 24 the field and will validate TMS as a tool to probe networks of interest in cognitive and clinical 25 neuroscience. Here, we delineated the TEP's cortical origins by localizing successive TEP 26 components in time and space and modulating them subsequently with transcranial direct 27 current stimulation (tDCS). We collected both motor evoked potentials (MEPs) and TEPs 28 elicited by suprathreshold single-pulse TMS to the left primary motor cortex (M1). We found 29 that the earliest TEP component (P25) was localized on the TMS target location (left M1) 30 and the following TEP components (N45 and P60) largely were localized on the primary 31 somatosensory cortex, which may reflect afferent input by hand-muscle twitches. The later 32 TEP components (N100, P180, and N280) largely were localized to the auditory cortex. To 33 casually test that these components reflect cortical and corticospinal excitability, we applied 34 tDCS to the left M1. As hypothesized, we found that tDCS modulated cortical and 35 corticospinal excitability selectively by modulating the pre-stimulus mu-rhythm oscillatory 36 power. Together, our findings provide causal evidence that the early TEP components 37 reflect cortical reactivity to TMS. 38 39 tDCS 3 41 Introduction 42 Combined transcranial magnetic stimulation (TMS) and electroencephalography (EEG) 43 provide an opportunity to quantify brain network dynamics by pinging them with TMS[1]. The 44 TMS-evoked potential (TEP), which is considered a reflection of cortical reactivity to TMS, 45 has been shown to have diagnostic value in a variety of neurological and psychiatric 46 disorders[2]. However, there is ongoing controversy about the origin of the TEP. A recent 47 study claimed that the stimulation of peripheral nerves and the TMS coil's loud clicking 48 sound may confound the TEP amplitude[3]. Specifically, sham TMS elicited EEG potentials 49 that were correlated highly with those by real TMS, despite the use of sophisticated 50 procedures to attenuate the somatosensory and auditory confounds. In rebuttal of this 51 publication, it was suggested that insufficient TMS intensity and incomplete auditory 52 masking may explain the sensory-dominant evoked potentials in the experiment[4]. 53 Nonetheless, residual auditory input is unavoidable in TMS studies[5] because of air and 54 bone conduction from the TMS clicking sound[6,7]. Thus, it continues to be debated whether...

show abstract

“…Early studies seem to support the gating-through-inhibition hypothesis and report associations between low mu-power and higher MEP amplitudes [13e15], but these findings could not be replicated by a number of often better-powered studies [16e21] (See Ref. [22] for a detailed, tabular report of studies grouping MEPs according to prestimulus power). Real-time EEG-triggered stimulation systems makes it possible to assess the relationship between mu-oscillatory activity and MEP amplitude more effectively through online targeting of specific oscillation states [13e15].…”

Section: Introductionmentioning

confidence: 99%

Does pericentral mu-rhythm “power” corticomotor excitability? – A matter of EEG perspective

et al. 2021

Self Cite

View full text Add to dashboard Cite

Background: Electroencephalography (EEG) and single-pulse transcranial magnetic stimulation (spTMS) of the primary motor hand area (M1-HAND) have been combined to explore whether the instantaneous expression of pericentral mu-rhythm drives fluctuations in corticomotor excitability, but this line of research has yielded diverging results. Objectives: To re-assess the relationship between the mu-rhythm power expressed in left pericentral cortex and the amplitude of motor potentials (MEP) evoked with spTMS in left M1-HAND. Methods: 15 non-preselected healthy young participants received spTMS to the motor hot spot of left M1-HAND. Regional expression of mu-rhythm was estimated online based on a radial source at motor hotspot and informed the timing of spTMS which was applied either during epochs belonging to the highest or lowest quartile of regionally expressed mu-power. Using MEP amplitude as dependent variable, we computed a linear mixed-effects model, which included mu-power and mu-phase at the time of stimulation and the inter-stimulus interval (ISI) as fixed effects and subject as a random effect. Mu-phase was estimated by post-hoc sorting of trials into four discrete phase bins. We performed a follow-up analysis on the same EEG-triggered MEP data set in which we isolated mu-power at the sensor level using a Laplacian montage centered on the electrode above the M1-HAND. Results: Pericentral mu-power traced as radial source at motor hot spot did not significantly modulate the MEP, but mu-power determined by the surface Laplacian did, showing a positive relation between mu-power and MEP amplitude. In neither case, there was an effect of mu-phase on MEP amplitude. Conclusion:The relationship between cortical oscillatory activity and cortical excitability is complex and minor differences in the methodological choices may critically affect sensitivity.

show abstract

No trace of phase: Corticomotor excitability is not tuned by phase of pericentral mu-rhythm

Cited by 10 publications

References 47 publications

Concurrent human TMS-EEG-fMRI enables monitoring of oscillatory brain state-dependent gating of cortico-subcortical network activity

Concurrent human TMS-EEG-fMRI enables monitoring of oscillatory brain state-dependent gating of cortico-subcortical network activity

Pinging the Brain with Transcranial Magnetic Stimulation Reveals Cortical Reactivity in Time and Space

Does pericentral mu-rhythm “power” corticomotor excitability? – A matter of EEG perspective

Contact Info

Product

Resources

About