Characterizing and minimizing the contribution of sensory inputs to TMS-evoked potentials
Background: Transcranial magnetic stimulation (TMS) evokes voltage deflections in electroencephalographic (EEG) recordings, known as TMS-evoked potentials (TEPs), which are increasingly used to study brain dynamics. However, the extent to which TEPs reflect activity directly evoked by magnetic rathe...
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doaj-d5bb3b4c7ce745ad83b1f8d46b2255542021-03-19T07:20:38ZengElsevierBrain Stimulation1935-861X2019-11-0112615371552Characterizing and minimizing the contribution of sensory inputs to TMS-evoked potentialsMana Biabani0Alex Fornito1Tuomas P. Mutanen2James Morrow3Nigel C. Rogasch4Brain, Mind and Society Research Hub, School of Psychological Sciences and Turner Institute for Brain and Mental Health, Monash University, Melbourne, Australia; Corresponding author. Monash University, Building 220, Clayton Campus, 770 Blackburn Rd, Clayton, VIC, 3800, Australia.Brain, Mind and Society Research Hub, School of Psychological Sciences and Turner Institute for Brain and Mental Health, Monash University, Melbourne, AustraliaCentre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, G12 8QB, United KingdomBrain, Mind and Society Research Hub, School of Psychological Sciences and Turner Institute for Brain and Mental Health, Monash University, Melbourne, AustraliaBrain, Mind and Society Research Hub, School of Psychological Sciences and Turner Institute for Brain and Mental Health, Monash University, Melbourne, AustraliaBackground: Transcranial magnetic stimulation (TMS) evokes voltage deflections in electroencephalographic (EEG) recordings, known as TMS-evoked potentials (TEPs), which are increasingly used to study brain dynamics. However, the extent to which TEPs reflect activity directly evoked by magnetic rather than sensory stimulation is unclear. Objective: To characterize and minimize the contribution of sensory inputs to TEPs. Methods: Twenty-four healthy participants received TMS over the motor cortex using two different intensities (below and above cortical motor threshold) and waveforms (monophasic, biphasic). TMS was also applied over the shoulder as a multisensory control condition. Common sensory attenuation measures, including coil padding and noise masking, were adopted. We examined spatiotemporal relationships between the EEG responses to the scalp and shoulder stimulations at sensor and source levels. Furthermore, we compared three different filters (independent component analysis, signal-space projection with source informed reconstruction (SSP-SIR) and linear regression) designed to attenuate the impact of sensory inputs on TEPs. Results: The responses to the scalp and shoulder stimulations were correlated in both temporal and spatial domains, especially after ∼60 ms, regardless of the intensity and stimuli waveform. Among the three filters, SSP-SIR showed the best trade-off between removing sensoryrelated signals while preserving data not related to the control condition. Conclusions: The findings demonstrate that TEPs elicited by motor cortex TMS reflect a combination of transcranially and peripherally evoked brain responses despite adopting sensory attenuation methods during experiments, thereby highlighting the importance of adopting sensory control conditions in TMS-EEG studies. Offline filters may help to isolate the transcranial component of the TEP from its peripheral component, but only if these components express different spatiotemporal patterns. More realistic control conditions may help to improve the characterization and attenuation of sensory inputs to TEPs, especially in early responses.http://www.sciencedirect.com/science/article/pii/S1935861X19302931TMSTMS-Evoked potentialTEPsPeripherally-evokedPotentialsPEPs |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Mana Biabani Alex Fornito Tuomas P. Mutanen James Morrow Nigel C. Rogasch |
spellingShingle |
Mana Biabani Alex Fornito Tuomas P. Mutanen James Morrow Nigel C. Rogasch Characterizing and minimizing the contribution of sensory inputs to TMS-evoked potentials Brain Stimulation TMS TMS-Evoked potential TEPs Peripherally-evoked Potentials PEPs |
author_facet |
Mana Biabani Alex Fornito Tuomas P. Mutanen James Morrow Nigel C. Rogasch |
author_sort |
Mana Biabani |
title |
Characterizing and minimizing the contribution of sensory inputs to TMS-evoked potentials |
title_short |
Characterizing and minimizing the contribution of sensory inputs to TMS-evoked potentials |
title_full |
Characterizing and minimizing the contribution of sensory inputs to TMS-evoked potentials |
title_fullStr |
Characterizing and minimizing the contribution of sensory inputs to TMS-evoked potentials |
title_full_unstemmed |
Characterizing and minimizing the contribution of sensory inputs to TMS-evoked potentials |
title_sort |
characterizing and minimizing the contribution of sensory inputs to tms-evoked potentials |
publisher |
Elsevier |
series |
Brain Stimulation |
issn |
1935-861X |
publishDate |
2019-11-01 |
description |
Background: Transcranial magnetic stimulation (TMS) evokes voltage deflections in electroencephalographic (EEG) recordings, known as TMS-evoked potentials (TEPs), which are increasingly used to study brain dynamics. However, the extent to which TEPs reflect activity directly evoked by magnetic rather than sensory stimulation is unclear. Objective: To characterize and minimize the contribution of sensory inputs to TEPs. Methods: Twenty-four healthy participants received TMS over the motor cortex using two different intensities (below and above cortical motor threshold) and waveforms (monophasic, biphasic). TMS was also applied over the shoulder as a multisensory control condition. Common sensory attenuation measures, including coil padding and noise masking, were adopted. We examined spatiotemporal relationships between the EEG responses to the scalp and shoulder stimulations at sensor and source levels. Furthermore, we compared three different filters (independent component analysis, signal-space projection with source informed reconstruction (SSP-SIR) and linear regression) designed to attenuate the impact of sensory inputs on TEPs. Results: The responses to the scalp and shoulder stimulations were correlated in both temporal and spatial domains, especially after ∼60 ms, regardless of the intensity and stimuli waveform. Among the three filters, SSP-SIR showed the best trade-off between removing sensoryrelated signals while preserving data not related to the control condition. Conclusions: The findings demonstrate that TEPs elicited by motor cortex TMS reflect a combination of transcranially and peripherally evoked brain responses despite adopting sensory attenuation methods during experiments, thereby highlighting the importance of adopting sensory control conditions in TMS-EEG studies. Offline filters may help to isolate the transcranial component of the TEP from its peripheral component, but only if these components express different spatiotemporal patterns. More realistic control conditions may help to improve the characterization and attenuation of sensory inputs to TEPs, especially in early responses. |
topic |
TMS TMS-Evoked potential TEPs Peripherally-evoked Potentials PEPs |
url |
http://www.sciencedirect.com/science/article/pii/S1935861X19302931 |
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