caa a22 4500 445353325 CHVBK 20180317142851.0 cr unu---uuuuu 170323e20110301xx s 000 0 eng 10.1007/s00221-011-2552-z doi (NATIONALLICENCE)springer-10.1007/s00221-011-2552-z Long-interval intracortical inhibition in a human hand muscle [Elektronische Daten] [Chris McNeil, Peter Martin, Simon Gandevia, Janet Taylor] When two motor cortical stimuli are delivered with an interstimulus interval of 50-200ms, the response (motor evoked potential; MEP) to the second stimulus is typically suppressed. This phenomenon is termed long-interval intracortical inhibition (LICI), although data from one subject suggest that facilitation is possible. Moreover, we recently showed that suppression can be mediated at a spinal level. We characterized LICI more fully by exploring a broad range of contraction strengths and test stimulus intensities. MEPs were evoked in first dorsal interosseous by transcranial magnetic stimulation over the motor cortex. Single test and paired (conditioning-test interval of 100ms) stimuli at intensities of 100-160% resting motor threshold were delivered at rest or during brief contractions of 10, 25, or 100% maximal voluntary force. Inhibition or facilitation was quantified with the standard ratio in which conditioned MEPs were expressed as a percentage of unconditioned MEPs. Inhibition was greatest at weak-moderate contraction strengths and least at rest and during maximal efforts. Both at rest and during maximal efforts, MEPs evoked by strong stimuli were facilitated. In a subset of subjects, cervicomedullary stimulation was used to activate the corticospinal tract to identify possible spinal influences on changes to MEPs. Contraction strength and test stimulus intensity each had different effects on unconditioned and conditioned MEP size, and hence, LICI is highly dependent on both factors. Further, because motoneurons are facilitated during contraction but disfacilitated after a strong conditioning stimulus, the standard ratio of LICI is of questionable validity during voluntary contractions. Springer-Verlag, 2011 LICI nationallicence Motor cortex nationallicence Motor control nationallicence Paired-TMS nationallicence Transcranial magnetic stimulation nationallicence McNeil Chris Neuroscience Research Australia, Barker Street, 2031, Randwick, NSW, Australia aut Martin Peter Neuroscience Research Australia, Barker Street, 2031, Randwick, NSW, Australia aut Gandevia Simon Neuroscience Research Australia, Barker Street, 2031, Randwick, NSW, Australia aut Taylor Janet Neuroscience Research Australia, Barker Street, 2031, Randwick, NSW, Australia aut Experimental Brain Research Springer-Verlag 209/2(2011-03-01), 287-297 0014-4819 209:2<287 2011 209 221 https://doi.org/10.1007/s00221-011-2552-z text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00221-011-2552-z text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- McNeil Chris Neuroscience Research Australia, Barker Street, 2031, Randwick, NSW, Australia aut NATIONALLICENCE 700 1- Martin Peter Neuroscience Research Australia, Barker Street, 2031, Randwick, NSW, Australia aut NATIONALLICENCE 700 1- Gandevia Simon Neuroscience Research Australia, Barker Street, 2031, Randwick, NSW, Australia aut NATIONALLICENCE 700 1- Taylor Janet Neuroscience Research Australia, Barker Street, 2031, Randwick, NSW, Australia aut NATIONALLICENCE 773 0- Experimental Brain Research Springer-Verlag 209/2(2011-03-01), 287-297 0014-4819 209:2<287 2011 209 221 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer