Reduction of corticospinal excitability by magnetic stimulation over the cerebellum in patients with large defects of one cerebellar hemisphere

Meyer, Bernd‐Ulrich; Röricht, Simone; Machetanz, J.

doi:10.1016/0168-5597(94)90125-2

Cited by 43 publications

(12 citation statements)

References 9 publications

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“…Preceding studies with transcranial magnetic stimulation (TMS) have shown that the threshold for the production of motor evoked potentials (MEPs) is elevated in humans with acute unilateral cerebellar lesions. [5][6][7][8] This finding indicates a reduction of corticospinal excitability but does not specifically address the question if cerebellar infarctions modify motor excitability on a cortical level. Today, a combination of different TMS techniques allows to differentiate modulations of inhibitory and facilitatory properties of the motor system.…”

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confidence: 90%

Motor Cortex Excitability After Cerebellar Infarction

Liepert

Kucinski

Tüscher

et al. 2004

Stroke

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Background and Purpose-The cerebellum has an influence on motor excitability. We investigated if the location of a cerebellar infarction was crucial for changes of motor cortex excitability and if the electrophysiological findings were correlated with motor performance. Methods-Transcranial magnetic stimulation was applied to study intracortical inhibition (ICI), intracortical facilitation (ICF), motor thresholds, and corticospinal excitability. Dexterity as a measure of motor performance was tested with the Nine-Hole-Peg Test (9HPT). Ratios (affected/unaffected) were also calculated. Results-ICI and ICF ratios were negatively correlated with 9HPT ratios in all patients (nϭ9). Compared with an age-matched control group, patients with lesions in the territory of the superior cerebellar artery (SCA) (nϭ3) or a lesion rostral of the dentate nucleus (nϭ1) had abnormally enhanced ICI and a loss of ICF (3 patients). Dexterity was impaired in all 4 patients. Motor excitability and motor performance normalized over the subsequent weeks. Patients with an infarct either in the territory of the anterior inferior cerebellar artery (nϭ2) or in the territory of the posterior inferior cerebellar artery (nϭ3) displayed motor excitability and motor performance within the normal range. Conclusion-The superior part of the cerebellum has a strong influence on motor cortex excitability. We suggest that the enhancement of motor inhibition and reduction of motor facilitation is mediated by an impairment of the deep cerebellar nuclei.

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confidence: 90%

Motor Cortex Excitability After Cerebellar Infarction

Liepert

Kucinski

Tüscher

et al. 2004

Stroke

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“…This was done using a paired-pulse technique, where cerebellar stimulation results in subsequent inhibition of the contralateral M1 (Meyer et al, 1994; Ugawa et al, 1995; Pinto and Chen, 2001). We have previously shown that this technique is sensitive to learning in a locomotor adaptation task (Jayaram et al, 2011), and that changes in cerebellar-M1 connectivity are proportional to the adaptive change.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Modulation of Cerebellar Excitability for Abrupt, But Not Gradual, Visuomotor Adaptation

et al. 2012

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The cerebellum is critically important for error driven adaptive motor learning, as evidenced by the fact that cerebellar patients do not adapt well to sudden predictable perturbations. However, recent work has shown that cerebellar patients adapt much better if the perturbation is gradually introduced. Here we explore physiological mechanisms that underlie this distinction between abrupt and gradual motor adaptation in humans. We used Transcranial Magnetic Stimulation (TMS) to evaluate whether neural mechanisms within the cerebellum contribute to either process during a visuomotor reach adaptation. When a visuomotor rotation was introduced abruptly, cerebellar excitability changed early in learning, and approached baseline levels near the end of the adaptation block. However, we observed no modulation of cerebellar excitability when we presented the visuomotor rotation gradually during learning. Similarly, we did not observe cerebellar modulation during trial-by-trial adaptation to random visuomotor displacements or during reaches without perturbations. This suggests that the cerebellum is most active during the early-phases of adaptation when large perturbations are successfully compensated.

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“…Motor responses in the lower facial muscles are generally considered to originate from activation of the cortico-bulbar tract when their onset latency is comprised between 10 and 14 msec (Facchini et al 2002;Meyer et al, 1994;Cocito et al, 1993;Cruccu et al, 1990;Benecke et al, 1988). We discarded participants who displayed muscle responses at short latencies (<8 msec) at stimulation intensities below threshold for excitation of the face-associated motor cortex.…”

Section: Transcranial Magnetic Stimulationmentioning

confidence: 99%

Covert Speech Arrest Induced by rTMS over Both Motor and Nonmotor Left Hemisphere Frontal Sites

Aziz‐Zadeh

Cattaneo

Rochat

et al. 2005

Journal of Cognitive Neuroscience

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Abstract& Blocking the capacity to speak aloud (overt speech arrest, SA) may be induced by repetitive transcranial magnetic stimulation (rTMS). The possibility, however, of blocking internal speech (covert SA) has not been explored. To investigate this issue, we conducted two rTMS experiments. In the first experiment, we stimulated two left frontal lobe sites. The first was a motor site (left posterior site) and the second was a nonmotor site located in correspondence to the posterior part of the inferior frontal gyrus (IFG) (left anterior site). The corresponding right hemisphere nonmotor SA site was stimulated as a control. In the second experiment, we focused on the right hemisphere and stimulated a right hemisphere motor site (right posterior site), and, as control sites, a right hemisphere nonmotor site corresponding to the IFG (right anterior site) and a left hemisphere anteromedial site (left control). For both experiments, participants performed a syllable counting task both covertly and overtly for each stimulation site. Longer latencies in this task imply the occurrence of an overt and/or covert SA.All participants showed significantly longer latencies when stimulation was either over the left posterior or the left anterior site, as compared with the right hemisphere site (Experiment 1). This result was observed for the overt and covert speech task alike. During stimulation of the posterior right hemisphere site, a dissociation for overt and covert speech was observed. An overt SA was observed but there was no evidence for a covert SA (Experiment 2). Taken together, the results show that rTMS can induce a covert SA when applied to areas over the brain that are pertinent to language. Furthermore, both the left posterior/motor site and the left anterior/IFG site appear to be essential to language elaboration even when motor output is not required. &

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Reduction of corticospinal excitability by magnetic stimulation over the cerebellum in patients with large defects of one cerebellar hemisphere

Cited by 43 publications

References 9 publications

Motor Cortex Excitability After Cerebellar Infarction

Motor Cortex Excitability After Cerebellar Infarction

Dynamic Modulation of Cerebellar Excitability for Abrupt, But Not Gradual, Visuomotor Adaptation

Covert Speech Arrest Induced by rTMS over Both Motor and Nonmotor Left Hemisphere Frontal Sites

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