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Modulation of the cortical silent period elicited by single- and paired-pulse transcranial magnetic stimulation.
BMC Neurosci. 2013 Apr 02; 14:43.BN

Abstract

BACKGROUND

The cortical silent period (CSP) elicited by transcranial magnetic stimulation (TMS) is affected by changes in TMS intensity. Some studies have shown that CSP is shortened or prolonged by short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF), Those studies, however, used different TMS intensities to adjust the amplitude of the motor evoked potential (MEP). Therefore, it is unclear whether changes in CSP duration are induced by changes in TMS intensities or by SICI and ICF. The purpose of this study was to confirm the effects of muscle contractions and stimulus intensities on MEP amplitude and the duration of CSP induced by single-pulse TMS and to clarify the effects of SICI and ICF on CSP duration.MEP evoked by TMS was detected from the right first dorsal interosseous muscle in 15 healthy subjects. First, MEP and CSP were induced by single-pulse TMS with an intensity of 100% active motor threshold (AMT) at four muscle contraction levels [10%, 30%, 50%, and 70% electromyogram (EMG)]. Next, MEP and CSP were induced by seven TMS intensities (100%, 110%, 120%, 130%, 140%, 150%, and 160% AMT) during muscle contraction of 10% EMG. Finally, SICI and ICF were recorded at the four muscle contraction levels (0%, 10%, 30%, and 50% EMG).

RESULTS

MEP amplitudes increased with increases in muscle contraction and stimulus intensity. However, CSP duration did not differ at different muscle contraction levels and was prolonged with increases in stimulus intensity. CSP was shortened with SICI compared with CSP induced by single-pulse TMS and with ICF at all muscle contraction levels, whereas CSP duration was not significantly changed with ICF.

CONCLUSIONS

We confirmed that CSP duration is affected by TMS intensity but not by the muscle contraction level. This study demonstrated that CSP is shortened with SICI, but it is not altered with ICF. These results indicate that after SICI, CSP duration is affected by the activity of inhibitory intermediate neurons that are activated by the conditioning SICI stimulus.

Authors+Show Affiliations

Graduate school of Health and Welfare, Niigata University of Health and Welfare, Nigata, Japan. hpm11003@nuhw.ac.jpNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

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

Language

eng

PubMed ID

23547559

Citation

Kojima, Sho, et al. "Modulation of the Cortical Silent Period Elicited By Single- and Paired-pulse Transcranial Magnetic Stimulation." BMC Neuroscience, vol. 14, 2013, p. 43.
Kojima S, Onishi H, Sugawara K, et al. Modulation of the cortical silent period elicited by single- and paired-pulse transcranial magnetic stimulation. BMC Neurosci. 2013;14:43.
Kojima, S., Onishi, H., Sugawara, K., Kirimoto, H., Suzuki, M., & Tamaki, H. (2013). Modulation of the cortical silent period elicited by single- and paired-pulse transcranial magnetic stimulation. BMC Neuroscience, 14, 43. https://doi.org/10.1186/1471-2202-14-43
Kojima S, et al. Modulation of the Cortical Silent Period Elicited By Single- and Paired-pulse Transcranial Magnetic Stimulation. BMC Neurosci. 2013 Apr 2;14:43. PubMed PMID: 23547559.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Modulation of the cortical silent period elicited by single- and paired-pulse transcranial magnetic stimulation. AU - Kojima,Sho, AU - Onishi,Hideaki, AU - Sugawara,Kazuhiro, AU - Kirimoto,Hikari, AU - Suzuki,Makoto, AU - Tamaki,Hiroyuki, Y1 - 2013/04/02/ PY - 2012/11/11/received PY - 2013/03/27/accepted PY - 2013/4/4/entrez PY - 2013/4/4/pubmed PY - 2013/8/14/medline SP - 43 EP - 43 JF - BMC neuroscience JO - BMC Neurosci VL - 14 N2 - BACKGROUND: The cortical silent period (CSP) elicited by transcranial magnetic stimulation (TMS) is affected by changes in TMS intensity. Some studies have shown that CSP is shortened or prolonged by short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF), Those studies, however, used different TMS intensities to adjust the amplitude of the motor evoked potential (MEP). Therefore, it is unclear whether changes in CSP duration are induced by changes in TMS intensities or by SICI and ICF. The purpose of this study was to confirm the effects of muscle contractions and stimulus intensities on MEP amplitude and the duration of CSP induced by single-pulse TMS and to clarify the effects of SICI and ICF on CSP duration.MEP evoked by TMS was detected from the right first dorsal interosseous muscle in 15 healthy subjects. First, MEP and CSP were induced by single-pulse TMS with an intensity of 100% active motor threshold (AMT) at four muscle contraction levels [10%, 30%, 50%, and 70% electromyogram (EMG)]. Next, MEP and CSP were induced by seven TMS intensities (100%, 110%, 120%, 130%, 140%, 150%, and 160% AMT) during muscle contraction of 10% EMG. Finally, SICI and ICF were recorded at the four muscle contraction levels (0%, 10%, 30%, and 50% EMG). RESULTS: MEP amplitudes increased with increases in muscle contraction and stimulus intensity. However, CSP duration did not differ at different muscle contraction levels and was prolonged with increases in stimulus intensity. CSP was shortened with SICI compared with CSP induced by single-pulse TMS and with ICF at all muscle contraction levels, whereas CSP duration was not significantly changed with ICF. CONCLUSIONS: We confirmed that CSP duration is affected by TMS intensity but not by the muscle contraction level. This study demonstrated that CSP is shortened with SICI, but it is not altered with ICF. These results indicate that after SICI, CSP duration is affected by the activity of inhibitory intermediate neurons that are activated by the conditioning SICI stimulus. SN - 1471-2202 UR - https://www.unboundmedicine.com/medline/citation/23547559/Modulation_of_the_cortical_silent_period_elicited_by_single__and_paired_pulse_transcranial_magnetic_stimulation_ L2 - https://bmcneurosci.biomedcentral.com/articles/10.1186/1471-2202-14-43 DB - PRIME DP - Unbound Medicine ER -