Rapid Acquisition of the Transcranial Magnetic Stimulation Stimulus Response Curve

Jonathan P Mathias, Gergely I Barsi, Mark van de Ruit, Michael J Grey

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

BACKGROUND: Transcranial magnetic stimulation is frequently used to construct stimulus response (SR) curves in studies of motor learning and rehabilitation. A drawback of the established method is the time required for data acquisition, which is frequently greater than a participant's ability to maintain attention. The technique is therefore difficult to use in the clinical setting. 

OBJECTIVE: To reduce the time of curve acquisition by determining the minimum acquisition time and number of stimuli required to acquire an SR curve. 

METHODS: SR curves were acquired from first dorsal interosseous (FDI) and abductor digiti minimi (ADM) at 6 interstimulus intervals (ISI) between 1.4 and 4 s in 12 participants. To determine if low-frequency rTMS might affect the SR curve, MEP amplitudes were monitored before and after 3 min of 1 Hz rTMS delivered at 120% of resting motor threshold in 12 participants. Finally, SR curves were acquired from FDI, ADM and Biceps Brachii (BB) in 12 participants, and the minimum number of stimuli was calculated using a sequential MEP elimination process. 

RESULTS: There were no significant differences between curves acquired with 1.4 s ISI and any other ISI. Low frequency rTMS did not significantly depress MEP amplitude (P = 0.87). On average, 61 ± 18 (FDI), 60 ± 16 (ADM) and 59 ± 16 (BB) MEPs were needed to construct a representative SR curve. 

CONCLUSIONS: This study demonstrates that reliable SR curves may be acquired in less than 2 min. At this rate, SR curves become a clinically feasible method for assessing corticospinal excitability in research and rehabilitation settings.

Original languageEnglish
Pages (from-to)59-65
Number of pages7
JournalBrain Stimulation
Volume7
Issue number1
Early online date3 Sep 2013
DOIs
Publication statusPublished - Jan 2014

Keywords

  • Corticospinal excitability
  • rTMS
  • Assessment
  • Neuroplasticity

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