Low-intensity repetitive transcranial magnetic stimulation decreases motor cortical excitability in humans

2006 ◽  
Vol 101 (2) ◽  
pp. 500-505 ◽  
Author(s):  
Gabrielle Todd ◽  
Stanley C. Flavel ◽  
Michael C. Ridding
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Cortical Excitability ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Motor Threshold ◽  
Sham Stimulation ◽  
Motor Cortical Excitability ◽  
Resting Motor Threshold ◽  
Active Motor ◽  
Motor Cortical

Repetitive transcranial magnetic stimulation of the motor cortex (rTMS) can be used to modify motor cortical excitability in human subjects. At stimulus intensities near to or above resting motor threshold, low-frequency rTMS (∼1 Hz) decreases motor cortical excitability, whereas high-frequency rTMS (5–20 Hz) can increase excitability. We investigated the effect of 10 min of intermittent rTMS on motor cortical excitability in normal subjects at two frequencies (2 or 6 Hz). Three low intensities of stimulation (70, 80, and 90% of active motor threshold) and sham stimulation were used. The number of stimuli were matched between conditions. Motor cortical excitability was investigated by measurement of the motor-evoked potential (MEP) evoked by single magnetic stimuli in the relaxed first dorsal interosseus muscle. The intensity of the single stimuli was set to evoke baseline MEPs of ∼1 mV in amplitude. Both 2- and 6-Hz stimulation, at 80% of active motor threshold, reduced the magnitude of MEPs for ∼30 min ( P < 0.05). MEPs returned to baseline values after a weak voluntary contraction. Stimulation at 70 and 90% of active motor threshold and sham stimulation did not induce a significant group effect on MEP magnitude. However, the intersubject response to rTMS at 90% of active motor threshold was highly variable, with some subjects showing significant MEP facilitation and others inhibition. These results suggest that, at low stimulus intensities, the intensity of stimulation may be as important as frequency in determining the effect of rTMS on motor cortical excitability.

Repetitive transcranial magnetic stimulation on the modulation of cortical and spinal cord excitability in individuals with spinal cord injury

2021 ◽  
pp. 1-11
Author(s):  
Thyciane Mendonça ◽  
Rodrigo Brito ◽  
Plínio Luna ◽  
Mayara Campêlo ◽  
Lívia Shirahige ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Cortical Excitability ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Sham Stimulation ◽  
Resting Motor Threshold ◽  
Cord Injury ◽  
Spinal Excitability

Background: Repetitive transcranial magnetic stimulation (rTMS) has been applied for modulating cortical excitability and treating spasticity in neurological lesions. However, it is unclear which rTMS frequency is most effective in modulating cortical and spinal excitability in incomplete spinal cord injury (SCI). Objective: To evaluate electrophysiological and clinical repercussions of rTMS compared to sham stimulation when applied to the primary motor cortex (M1) in individuals with incomplete SCI. Methods: A total of 11 subjects (35±12 years) underwent three experimental sessions of rTMS (10 Hz, 1 Hz and sham stimulation) in a randomized order at 90%intensity of the resting motor threshold and interspersed by a seven-day interval between sessions. The following outcome measures were evaluated: M1 and spinal cord excitability and spasticity in the moments before (baseline), immediately after (T0), 30 (T30) and 60 (T60) minutes after rTMS. M1 excitability was obtained through the motor evoked potential (MEP); spinal cord excitability by the Hoffman reflex (H-reflex) and homosynaptic depression (HD); and spasticity by the modified Ashworth scale (MAS). Results: A significant increase in cortical excitability was observed in subjects submitted to 10 Hz rTMS at the T0 moment when compared to sham stimulation (p = 0.008); this increase was also significant at T0 (p = 0.009), T30 (p = 0.005) and T60 (p = 0.005) moments when compared to the baseline condition. No significant differences were observed after the 10 Hz rTMS on spinal excitability or on spasticity. No inter-group differences were detected, or in the time after application of 1 Hz rTMS, or after sham stimulation for any of the assessed outcomes. Conclusions: High-frequency rTMS applied to M1 was able to promote increased cortical excitability in individuals with incomplete SCI for at least 60 minutes; however, it did not modify spinal excitability or spasticity.

Interhemispheric asymmetry of motor cortical excitability in major depression as measured by transcranial magnetic stimulation

2000 ◽  
Vol 177 (2) ◽  
pp. 169-173 ◽  
Author(s):  
Fumiko Maeda ◽  
Julian P. Keenan ◽  
Alvaro Pascual-Leone
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Cortical Excitability ◽  
Motor Threshold ◽  
Major Depressive ◽  
Paired Pulse ◽  
Prefrontal Cortical ◽  
Motor Cortical Excitability ◽  
Motor Cortical ◽  
Normal Controls

BackgroundNeuroimaging studies of major depressive disorder (MDD) indicate interhemispheric differences in prefrontal cortical activity (right greater than left).AimsTo investigate whether there are any interhemispheric differences of motor cortical excitability in MDD.MethodEight patients with treatment-refractory MDD off medication were assessed for the severity of their depression, and transcranial magnetic stimulation studies (bilateral motor threshold and paired-pulse studies) were conducted. Eight normal controls were also studied.ResultsMDD patients showed significant interhemispheric differences in motor threshold and paired-pulse curves, both of which showed lower excitability on the left hemisphere. Such differences were absent in controls.ConclusionsOur findings may aid the further understanding of the neurophysiology underlying MDD.

scholarly journals Comparison of low frequency repetitive transcranial magnetic stimulation parameters on motor cortex excitability in normal subjects

2016 ◽  
Vol 03 (01) ◽  
pp. 002-006
Author(s):  
Lara Schrader ◽  
Sima Sadeghinejad ◽  
Jalleh Sadeghinejad ◽  
Movses Kazanchyan ◽  
Lisa Koski ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Low Frequency ◽  
Motor Threshold ◽  
Motor Cortex Excitability ◽  
Resting Motor Threshold

Abstract Background/objectives Optimal low frequency repetitive transcranial magnetic stimulation (LF-rTMS) parameters for treating epilepsy and other brain disorders are unknown. To address this question, a systematic study of the effects of LF-rTMS frequency and intensity on cortical excitability was performed. Methods Using a four-period crossover design, subjects were scheduled for four LF-rTMS sessions that were at least four weeks apart. LF-rTMS was delivered as 900 pulses directed at primary motor cortex using four protocols: 0.5 Hz at 90% resting motor threshold (RMT), 0.5 Hz at 110% RMT, 1 Hz at 90% RMT, and 1 Hz at 110% RMT. Motor evoked potential (MEP) amplitude, resting motor threshold (RMT), and cortical silent period (CSP) were measured before, immediately after, and 60 min after LF-rTMS. Each of the four protocols was analyzed separately to compare baseline measurements to those after LF-rTMS. Results None of the four LF-rTMS protocols produced a trend or significant change in MEP amplitude, RMT, or CSP. Conclusion The lack of significant effect from the four LF-rTMS protocols indicates that none produced evidence for alteration of cortical excitability. The direct comparison of four LF-rTMS protocols is distinct to this investigation, as most similar studies were exploratory and studied only one or two protocols. The negative result relates only to the methods used in this investigation and does not indicate that LF-rTMS does not alter cortical excitability with other parameters. These results may be useful when designing additional investigations into the effect of LF-rTMS on epilepsy, other disorders, and cortical excitability.

scholarly journals Suppression of Motor Cortical Excitability in Anesthetized Rats by Low Frequency Repetitive Transcranial Magnetic Stimulation

PLoS ONE ◽  
2014 ◽  
Vol 9 (3) ◽  
pp. e91065 ◽  
Author(s):  
Paul A. Muller ◽  
Sameer C. Dhamne ◽  
Andrew M. Vahabzadeh-Hagh ◽  
Alvaro Pascual-Leone ◽  
Frances E. Jensen ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Cortical Excitability ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Low Frequency ◽  
Motor Cortical Excitability ◽  
Anesthetized Rats ◽  
Motor Cortical

scholarly journals Antidepressant effect of repetitive transcranial magnetic stimulation is not impaired by intake of lithium or antiepileptic drugs

2021 ◽  
Author(s):  
T. Hebel ◽  
M. A. Abdelnaim ◽  
M. Deppe ◽  
P. M. Kreuzer ◽  
A. Mohonko ◽  
...  
Keyword(s):  
Valproic Acid ◽  
Transcranial Magnetic Stimulation ◽  
Antiepileptic Drugs ◽  
Magnetic Stimulation ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Factor Group ◽  
Mood Stabilizers ◽  
Motor Threshold ◽  
Chi Square ◽  
Resting Motor Threshold

Abstract Introduction The effect of concomitant medication on repetitive transcranial magnetic stimulation (rTMS) outcomes in depression remains understudied. Recent analyses show attenuation of rTMS effects by antipsychotic medication and benzodiazepines, but data on the effects of antiepileptic drugs and lithium used as mood stabilizers or augmenting agents are sparse despite clinical relevance. Preclinical electrophysiological studies suggest relevant impact of the medication on treatment, but this might not translate into clinical practice. We aimed to investigate the role of lithium (Li), lamotrigine (LTG) and valproic acid (VPA) by analyzing rTMS treatment outcomes in depressed patients. Methods 299 patients with uni- and bipolar depression treated with rTMS were selected for analysis in respect to intake of lithium, lamotrigine and valproic acid. The majority (n = 251) were treated with high-frequency (10–20 Hz) rTMS of the lDLPFC for an average of 17 treatment sessions with a figure-of-8 coil with a MagVenture system aiming for 110% resting motor threshold, and smaller groups of patients were being treated with other protocols including intermittent theta-burst stimulation and bilateral prefrontal and medial prefrontal protocols. For group comparisons, we used analysis of variance with the between-subjects factor group or Chi-Square Test of Independence depending on the scales of measurement. For post-hoc tests, we used least significant difference (LSD). For differences in treatment effects between groups, we used an ANOVA with the between-subjects factor group (groups: no mood stabilizer, Li, LTG, VPA, Li + LTG) the within-subjects factor treatment (pre vs. post treatment with rTMS) and also Chi-Square Tests of independence for response and remission. Results Overall, patients showed an amelioration of symptoms with no significant differences for the main effect of group and for the interaction effect treatment by group. Based on direct comparisons between the single groups taking mood stabilizers against the group taking no mood stabilizers, we see a superior effect of lamotrigine, valproic acid and combination of lithium and lamotrigine for the response and remission rates. Motor threshold was significantly and markedly higher for patients taking valproic acid. Conclusion Being treated with lithium, lamotrigine and valproic acid had no relevant influence on rTMS treatment outcome. The results suggest there is no reason for clinicians to withhold or withdraw these types of medication from patients who are about to undergo a course of rTMS. Prospective controlled work on the subject is encouraged.

Modulation of motor cortical excitability following rapid-rate transcranial magnetic stimulation

2007 ◽  
Vol 118 (1) ◽  
pp. 140-145 ◽  
Author(s):  
Eman M. Khedr ◽  
John C. Rothwell ◽  
Mohamed A. Ahmed ◽  
Ola A. Shawky ◽  
Mona Farouk
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Cortical Excitability ◽  
Rapid Rate ◽  
Motor Cortical Excitability ◽  
Motor Cortical
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