Facilitatory effect of thinking about movement on motor evoked potentials to transcranial magnetic stimulation of the brain

Shin ichi Izumi, Thomas W. Findley, Tetsuo Ikai, John Andrews, Naoichi Chino

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Abstract

Surface electromyographic responses were recorded from 9 human abductor policies brevis muscles in response to transcranial magnetic stimulation of the brain with 100% of maximal stimulator output, the subject being at rest, contracting with 10% of the maximal muscle activity of APB, and thinking about thumb abduction but with no detectable EMG activity. Stimulation was delivered at the scalp location where 75 or 85% output evoked the largest muscle response. Threshold was determined as the smallest stimulator output to produce at least 4 motor responses (50 μV and over) out of 8 stimuli. The thresholds ranged from 65 to 85% output, and averaged 73%. Thus, relative stimulus intensity of 100% output to threshold ranged from 118 to 167% threshold, and averaged 137 %threshold. Following magnetic stimulation with 100% output, median amplitude of evoked responses during thinking about the movement was approximately twice larger than at rest (p=0.0077), and a half of that during voluntary contraction (p=0.0077). To standardize the degree of facilitation, the amplitude ratios of response during thinking, and voluntary contraction to that at rest were calculated. The thinking/rest ratios ranged from 1.1 to 6.3, and averaged 2.2. The contraction/rest ratios ranged from 2.3 to 18.6, and averaged 7.4. These findings show that thinking about the movement has a facilitatory effect on the evoked potentials to magnetic stimulation of the brain, and that the degree of facilitation in thinking is smaller than in voluntary contraction.

Original languageEnglish
Title of host publication1993 IEEE 19th Annual Northeasrt Bioengineering Conference
PublisherPubl by IEEE
Pages28-30
Number of pages3
ISBN (Print)0780309251
Publication statusPublished - 1993 Jan 1
Externally publishedYes
EventProceedings of the 1993 IEEE 19th Annual Northeast Bioengineering Conference - Newark, NJ, USA
Duration: 1993 Mar 181993 Mar 19

Publication series

NameBioengineering, Proceedings of the Northeast Conference

Other

OtherProceedings of the 1993 IEEE 19th Annual Northeast Bioengineering Conference
CityNewark, NJ, USA
Period93/3/1893/3/19

ASJC Scopus subject areas

  • Bioengineering

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