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The excitability of human cortical inhibitory circuits responsible for the muscle silent period after transcranial brain stimulation.
Exp Brain Res. 2000 Jun; 132(3):384-9.EB

Abstract

The silent period after transcranial magnetic brain stimulation mainly reflects the activity of inhibitory circuits in the human motor cortex. To assess the excitability of the cortical inhibitory mechanisms responsible for the silent period after transcranial stimulation, we studied, in 15 healthy human subjects, the recovery cycle of the silent period evoked by transcranial and mixed nerve stimulation delivered with a paired stimulation technique. The recovery cycle is defined as the time course of the changes in the size or duration of a conditioned test response when pairs of stimuli (conditioning and test) are used at different conditioning-test intervals. The recovery cycle of the duration of the silent period in the first dorsal interosseous (FDI) muscle during maximum voluntary contraction after transcranial magnetic stimulation was studied by delivering paired magnetic shocks (a conditioning shock and a test shock) at 120% motor-threshold intensity. Conditioning-test intervals ranged from 20-550 ms. The recovery cycle of the silent period in the FDI muscle during maximum voluntary contraction after nerve stimulation was evaluated by paired, supramaximum bipolar electrical stimulation of the ulnar nerve at the wrist (conditioning-test intervals ranging from 20 to 550 ms). Electromyographic activity was recorded by a pair of surface-disk electrodes over the FDI muscle. The recovery cycle of the silent period after transcranial magnetic stimulation delivered through the large round coil showed two phases of facilitation (lengthening of the silent period), one at 20-40 ms and the other at 180-350 ms conditioning-test intervals, with an interposed phase of inhibition (shortening of the silent period) at 80-160 ms. The conditioning magnetic shock left the size of the test motor-evoked potentials statistically unchanged during maximum voluntary contraction. Paired transcranial stimulation with a figure-of-eight coil increased the duration of the test silent period only at short conditioning-test intervals. Conditioning nerve stimulation left the silent period produced by test nerve stimulation unchanged. In conclusion, after a single transcranial magnetic shock, inhibitory circuits in the human motor cortex undergo distinctive short-term changes in their excitability, probably involving different mechanisms.

Authors+Show Affiliations

Dipartimento di Scienze Neurologiche e della Visione, Università di Verona, Italy.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

10883387

Citation

Bertasi, V, et al. "The Excitability of Human Cortical Inhibitory Circuits Responsible for the Muscle Silent Period After Transcranial Brain Stimulation." Experimental Brain Research, vol. 132, no. 3, 2000, pp. 384-9.
Bertasi V, Bertolasi L, Frasson E, et al. The excitability of human cortical inhibitory circuits responsible for the muscle silent period after transcranial brain stimulation. Exp Brain Res. 2000;132(3):384-9.
Bertasi, V., Bertolasi, L., Frasson, E., & Priori, A. (2000). The excitability of human cortical inhibitory circuits responsible for the muscle silent period after transcranial brain stimulation. Experimental Brain Research, 132(3), 384-9.
Bertasi V, et al. The Excitability of Human Cortical Inhibitory Circuits Responsible for the Muscle Silent Period After Transcranial Brain Stimulation. Exp Brain Res. 2000;132(3):384-9. PubMed PMID: 10883387.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The excitability of human cortical inhibitory circuits responsible for the muscle silent period after transcranial brain stimulation. AU - Bertasi,V, AU - Bertolasi,L, AU - Frasson,E, AU - Priori,A, PY - 2000/7/7/pubmed PY - 2000/10/21/medline PY - 2000/7/7/entrez SP - 384 EP - 9 JF - Experimental brain research JO - Exp Brain Res VL - 132 IS - 3 N2 - The silent period after transcranial magnetic brain stimulation mainly reflects the activity of inhibitory circuits in the human motor cortex. To assess the excitability of the cortical inhibitory mechanisms responsible for the silent period after transcranial stimulation, we studied, in 15 healthy human subjects, the recovery cycle of the silent period evoked by transcranial and mixed nerve stimulation delivered with a paired stimulation technique. The recovery cycle is defined as the time course of the changes in the size or duration of a conditioned test response when pairs of stimuli (conditioning and test) are used at different conditioning-test intervals. The recovery cycle of the duration of the silent period in the first dorsal interosseous (FDI) muscle during maximum voluntary contraction after transcranial magnetic stimulation was studied by delivering paired magnetic shocks (a conditioning shock and a test shock) at 120% motor-threshold intensity. Conditioning-test intervals ranged from 20-550 ms. The recovery cycle of the silent period in the FDI muscle during maximum voluntary contraction after nerve stimulation was evaluated by paired, supramaximum bipolar electrical stimulation of the ulnar nerve at the wrist (conditioning-test intervals ranging from 20 to 550 ms). Electromyographic activity was recorded by a pair of surface-disk electrodes over the FDI muscle. The recovery cycle of the silent period after transcranial magnetic stimulation delivered through the large round coil showed two phases of facilitation (lengthening of the silent period), one at 20-40 ms and the other at 180-350 ms conditioning-test intervals, with an interposed phase of inhibition (shortening of the silent period) at 80-160 ms. The conditioning magnetic shock left the size of the test motor-evoked potentials statistically unchanged during maximum voluntary contraction. Paired transcranial stimulation with a figure-of-eight coil increased the duration of the test silent period only at short conditioning-test intervals. Conditioning nerve stimulation left the silent period produced by test nerve stimulation unchanged. In conclusion, after a single transcranial magnetic shock, inhibitory circuits in the human motor cortex undergo distinctive short-term changes in their excitability, probably involving different mechanisms. SN - 0014-4819 UR - https://www.unboundmedicine.com/medline/citation/10883387/The_excitability_of_human_cortical_inhibitory_circuits_responsible_for_the_muscle_silent_period_after_transcranial_brain_stimulation_ L2 - https://dx.doi.org/10.1007/s002210000352 DB - PRIME DP - Unbound Medicine ER -