Universität zu Köln

Roos, Daniela, Biermann, Lea, Jarczok, Tomasz A. and Bender, Stephan (2021). Local Differences in Cortical Excitability - A Systematic Mapping Study of the TMS-Evoked N100 Component. Front. Neurosci., 15. LAUSANNE: FRONTIERS MEDIA SA. ISSN 1662-453X

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Abstract

Transcranial magnetic stimulation (TMS) with simultaneous electroencephalography applied to the primary motor cortex provides two parameters for cortical excitability: motor evoked potentials (MEPs) and TMS-evoked potentials (TEPs). This study aimed to evaluate the effects of systematic coil shifts on both the TEP N100 component and MEPs in addition to the relationship between both parameters. In 12 healthy adults, the center of a standardized grid was fixed above the hot spot of the target muscle of the left primary motor cortex. Twelve additional positions were arranged in a quadratic grid with positions between 5 and 10 mm from the hot spot. At each of the 13 positions, TMS single pulses were applied. The topographical maximum of the resulting N100 was located ipsilateral and slightly posterior to the stimulation site. A source analysis revealed an equivalent dipole localized more deeply than standard motor cortex coordinates that could not be explained by a single seeded primary motor cortex dipole. The N100 topography might not only reflect primary motor cortex activation, but also sum activation of the surrounding cortex. N100 amplitude and latency decreased significantly during stimulation anterior-medial to the hot spot although MEP amplitudes were smaller at all other stimulation sites. Therefore, N100 amplitudes might be suitable for detecting differences in local cortical excitability. The N100 topography, with its maximum located posterior to the stimulation site, possibly depends on both anatomical characteristics of the stimulated cortex and differences in local excitability of surrounding cortical areas. The less excitable anterior cortex might contribute to a more posterior maximum. There was no correlation between N100 and MEP amplitudes, but a single-trial analysis revealed a trend toward larger N100 amplitudes in trials with larger MEPs. Thus, functionally efficient cortical excitation might increase the probability of higher N100 amplitudes, but TEPs are also generated in the absence of MEPs.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Roos, Daniela UNSPECIFIED UNSPECIFIED UNSPECIFIED Biermann, Lea UNSPECIFIED UNSPECIFIED UNSPECIFIED Jarczok, Tomasz A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bender, Stephan UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-566578
DOI:	10.3389/fnins.2021.623692
Journal or Publication Title:	Front. Neurosci.
Volume:	15
Date:	2021
Publisher:	FRONTIERS MEDIA SA
Place of Publication:	LAUSANNE
ISSN:	1662-453X
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language Neurosciences Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/56657