New graphical method to measure silent periods evoked by transcranial magnetic stimulation

Garvey, Marjorie A.; Ziemann, Ulf; Becker, Danielle A.; Barker, Christopher A.; Bartko, John J.

doi:10.1016/s1388-2457(01)00581-8

Cited by 157 publications

(114 citation statements)

References 22 publications

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“…Onset and offset latencies of the iSP were determined by using an automated and objective graphical method. 8 Horizontal lines indicate the calculated upper and lower variation limits of the prestimulus EMG. Vertical dashed lines indicate iSP onset and offset.…”

Section: Resultsmentioning

confidence: 99%

“…ISP duration was measured automatically and objectively for each muscle and individual by means of a previously described graphical method. 8 For this purpose, an in-house programmed script for use in MatLab for Windows (version 6.1; The MathWorks, Natick, MA) was employed. The digitized EMG was single-trial rectified and then averaged.…”

Section: Methodsmentioning

confidence: 99%

“…The iSP onset was defined as the first of 5 consecutive data points that fell below the lower variation limit, whereas iSP offset was the first data point exceeding the lower variation limit if more than 50% of data points in the succeeding 5 ms were also above the lower limit. 8 To assess the trial-to-trial variability of the iSP in a given subject, its onset and offset were also estimated visually in the rectified single trials where application of the objective graphical method is not suitable due to the large MCD of the prestimulus EMG in single trials. The single-trial analysis was possible in 16 subjects, whereas in the remaining 4 subjects only the rectified averages were stored.…”

Section: Methodsmentioning

confidence: 99%

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Differences of the ipsilateral silent period in small hand muscles

Jung

Ziemann

2006

Muscle and Nerve

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The ipsilateral silent period (iSP) is thought to depend on activity transmitted by the corpus callosum but ipsilateral corticospinal pathways may also contribute. Because the presence of ipsilateral corticospinal pathways differs between small hand muscles, we compared the iSP in the first dorsal interosseous (FDI) and abductor pollicis brevis (APB) muscles. The iSP was elicited in 20 healthy subjects by focal transcranial magnetic stimulation of one primary motor cortex during maximal voluntary contraction of the ipsilateral target muscle. The iSP duration was significantly longer in the FDI than APB because of an irregularly occurring second phase of inhibition in the FDI that was absent in the APB. Although the first phase of inhibition is transmitted by the corpus callosum, we provide evidence that the second phase is mediated through ipsilateral corticospinal pathways. Therefore, for specific assessment of callosal conduction, the iSP should be measured in the APB rather than FDI.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Differences of the ipsilateral silent period in small hand muscles

Jung

Ziemann

2006

Muscle and Nerve

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“…1A) (Garvey et al 2001). The duration of the silent period was plotted against the corresponding stimulation intensity to produce a silent-period recruitment curve (e.g., Fig.…”

Section: Silent Periodmentioning

confidence: 99%

Increases in Corticospinal Tract Function by Treadmill Training After Incomplete Spinal Cord Injury

Thomas

Gorassini²

2005

Journal of Neurophysiology

238

150

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Thomas, Sarah L. and Monica A. Gorassini. Increases in corticospinal tract function by treadmill training after incomplete spinal cord injury. J Neurophysiol 94: 2844 -2855, 2005 First published July 6 2005. doi:10.1152/jn.00532.2005. In this study, we examined if several months of intensive locomotor training increases the function of spared corticospinal tract pathways after chronic spinal cord injury (SCI) in association with the recovery of locomotor function. Transcranial magnetic stimulation (TMS) at incrementing levels of intensity was applied over the motor cortex supplying either the tibialis anterior or vastus lateralis muscles, and the resulting peak-to-peak amplitude of the motor-evoked potentials (MEPs) were measured to obtain a recruitment curve both before and after training. In the majority of subjects (7/8), 3-5 mo of daily intensive training increased the responses to TMS in at least one of the leg muscles tested (9/13). On average, across all muscles tested MEP max , which was evoked at high stimulation intensities, increased by 46% and MEP h , which was evoked at intermediate stimulation intensities, increased by 45% (both significantly different from 0), indicating an increase in corticospinal tract connectivity from training. The slope of the sigmoid function fit to the recruitment curve increased by 24% after training (significantly different), indicating an expansion and/or increased excitability of corticospinal circuits supplying muscles to the lower leg. We also observed that the average duration of the silent period measured at MEP max increased after training from 130 to 178 ms, suggesting that training had effects on cortical circuits thought to mediate this longlasting inhibition. The percentage increase in MEP max was positively and significantly correlated to the degree of locomotor recovery as assessed by the WISCI II score, the distance a subject could walk in 6 min, and the amplitude of the locomotor EMG activity, suggesting that the corticospinal tract, in part, mediated the functional locomotor recovery produced from training.

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“…Duration of CSP was measured from MEP onset to re-emergence of sustained EMG activity. 16 The entire procedure was done twice to improve quality.…”

Section: Tms Procedures and Data Analysismentioning

confidence: 99%

Abnormality of motor cortex excitability in peripherally induced dystonia

2007

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It is widely accepted that peripheral trauma such as soft tissue injuries can trigger dystonia, although little is known about the underlying mechanism. Because peripheral injury only rarely appears to elicit dystonia, a predisposing vulnerability in cortical motor areas might play a role. Using single and paired-pulse pulse transcranial magnetic stimulation, we evaluated motor cortex excitability of a hand muscle in a patient with peripherally induced foot dystonia, in her brother with craniocervical dystonia, and in her unaffected sister, and compared their results to those from a group of normal subjects. In the patient with peripherally induced dystonia, we found a paradoxical intracortical facilitation at short interstimulus intervals of 3 and 5 milliseconds, at which regular intracortical inhibition (ICI) occurred in healthy subjects. These findings suggest that the foot dystonia may have been precipitated as the result of a preexisting abnormality of motor cortex excitability. Furthermore, the abnormality of ICI in her brother and sister indicates that altered motor excitability may be a hereditary predisposition. The study demonstrates that the paired-pulse technique is a useful tool to assess individual vulnerability, which can be particularly relevant when the causal association between trauma and dystonia is less evident.

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New graphical method to measure silent periods evoked by transcranial magnetic stimulation

Cited by 157 publications

References 22 publications

Differences of the ipsilateral silent period in small hand muscles

Differences of the ipsilateral silent period in small hand muscles

Increases in Corticospinal Tract Function by Treadmill Training After Incomplete Spinal Cord Injury

Abnormality of motor cortex excitability in peripherally induced dystonia

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