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Mechanisms underlying long-interval cortical inhibition in the human motor cortex: a TMS-EEG study.
J Neurophysiol 2013; 109(1):89-98JN

Abstract

Long-interval cortical inhibition (LICI) refers to suppression of neuronal activity following paired-pulse transcranial magnetic stimulation (TMS) with interstimulus intervals (ISIs) between 50 and 200 ms. LICI can be measured either from motor-evoked potentials (MEPs) in small hand muscles or directly from the cortex using concurrent electroencephalography (EEG). However, it remains unclear whether EEG inhibition reflects similar mechanisms to MEP inhibition. Eight healthy participants received single- and paired-pulse TMS (ISI = 100 ms) over the motor cortex. MEPs were measured from a small hand muscle (first dorsal interosseus), whereas early (P30, P60) and late (N100) TMS-evoked cortical potentials (TEPs) were measured over the motor cortex using EEG. Conditioning and test TMS intensities were altered, and modulation of LICI strength was measured using both methods. LICI of MEPs and both P30 and P60 TEPs increased in strength with increasing conditioning intensities and decreased with increasing test intensities. LICI of N100 TEPs remained unchanged across all conditions. In addition, MEP and P30 LICI strength correlated with the slope of the N100 evoked by the conditioning pulse. LICI of early and late TEP components was differentially modulated with altered TMS intensities, suggesting independent underlying mechanisms. LICI of P30 is consistent with inhibition of cortical excitation similar to MEPs, whereas LICI of N100 may reflect presynaptic autoinhibition of inhibitory interneurons. The N100 evoked by the conditioning pulse is consistent with the mechanism responsible for LICI, most likely GABA(B)-mediated inhibition of cortical activity.

Authors+Show Affiliations

Monash Alfred Psychiatry Research Centre, Alfred and Monash University Central Clinical School, Melbourne, Australia.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

23100139

Citation

Rogasch, Nigel C., et al. "Mechanisms Underlying Long-interval Cortical Inhibition in the Human Motor Cortex: a TMS-EEG Study." Journal of Neurophysiology, vol. 109, no. 1, 2013, pp. 89-98.
Rogasch NC, Daskalakis ZJ, Fitzgerald PB. Mechanisms underlying long-interval cortical inhibition in the human motor cortex: a TMS-EEG study. J Neurophysiol. 2013;109(1):89-98.
Rogasch, N. C., Daskalakis, Z. J., & Fitzgerald, P. B. (2013). Mechanisms underlying long-interval cortical inhibition in the human motor cortex: a TMS-EEG study. Journal of Neurophysiology, 109(1), pp. 89-98. doi:10.1152/jn.00762.2012.
Rogasch NC, Daskalakis ZJ, Fitzgerald PB. Mechanisms Underlying Long-interval Cortical Inhibition in the Human Motor Cortex: a TMS-EEG Study. J Neurophysiol. 2013;109(1):89-98. PubMed PMID: 23100139.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Mechanisms underlying long-interval cortical inhibition in the human motor cortex: a TMS-EEG study. AU - Rogasch,Nigel C, AU - Daskalakis,Zafiris J, AU - Fitzgerald,Paul B, Y1 - 2012/10/24/ PY - 2012/10/27/entrez PY - 2012/10/27/pubmed PY - 2013/6/6/medline SP - 89 EP - 98 JF - Journal of neurophysiology JO - J. Neurophysiol. VL - 109 IS - 1 N2 - Long-interval cortical inhibition (LICI) refers to suppression of neuronal activity following paired-pulse transcranial magnetic stimulation (TMS) with interstimulus intervals (ISIs) between 50 and 200 ms. LICI can be measured either from motor-evoked potentials (MEPs) in small hand muscles or directly from the cortex using concurrent electroencephalography (EEG). However, it remains unclear whether EEG inhibition reflects similar mechanisms to MEP inhibition. Eight healthy participants received single- and paired-pulse TMS (ISI = 100 ms) over the motor cortex. MEPs were measured from a small hand muscle (first dorsal interosseus), whereas early (P30, P60) and late (N100) TMS-evoked cortical potentials (TEPs) were measured over the motor cortex using EEG. Conditioning and test TMS intensities were altered, and modulation of LICI strength was measured using both methods. LICI of MEPs and both P30 and P60 TEPs increased in strength with increasing conditioning intensities and decreased with increasing test intensities. LICI of N100 TEPs remained unchanged across all conditions. In addition, MEP and P30 LICI strength correlated with the slope of the N100 evoked by the conditioning pulse. LICI of early and late TEP components was differentially modulated with altered TMS intensities, suggesting independent underlying mechanisms. LICI of P30 is consistent with inhibition of cortical excitation similar to MEPs, whereas LICI of N100 may reflect presynaptic autoinhibition of inhibitory interneurons. The N100 evoked by the conditioning pulse is consistent with the mechanism responsible for LICI, most likely GABA(B)-mediated inhibition of cortical activity. SN - 1522-1598 UR - https://www.unboundmedicine.com/medline/citation/23100139/Mechanisms_underlying_long_interval_cortical_inhibition_in_the_human_motor_cortex:_a_TMS_EEG_study_ L2 - http://www.physiology.org/doi/full/10.1152/jn.00762.2012?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -