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Theta Burst Stimulation of the Cerebellum Modifies the TMS-Evoked N100 Potential, a Marker of GABA Inhibition.

Harrington A, Hammond-Tooke GD - PLoS ONE (2015)

Bottom Line: Motor evoked potentials (MEP) and TEP were recorded before and after each treatment, by stimulating the first dorsal interosseus area of the left motor cortex.Analysis of the 13 right handed participants showed that iTBS at 90% of AMT increased the N100 amplitude compared to sham and cTBS, without significantly altering MEP amplitude. cTBS at 80% of active motor threshold decreased the N100 amplitude and cTBS overall reduced resting MEP amplitude.The study demonstrates effects of 30Hz cerebellar TBS on inhibitory cortical networks that may be useful for treatment of neurological conditions associated with dysfunctional intracortical inhibition.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, University of Otago, Dunedin, New Zealand.

ABSTRACT
Theta burst stimulation (TBS) of the cerebellum, a potential therapy for neurological disease, can modulate corticospinal excitability via the dentato-thalamo-cortical pathway, but it is uncertain whether its effects are mediated via inhibitory or facilitatory networks. The aim of this study was to investigate the effects of 30Hz cerebellar TBS on the N100 waveform of the TMS-evoked potential (TEP), a marker of intracortical GABAB-mediated inhibition. 16 healthy participants (aged 18-30 years; 13 right handed and 3 left handed) received 30Hz intermittent TBS (iTBS), continuous TBS (cTBS) or sham stimulation over the right cerebellum, in three separate sessions. The first 8 participants received TBS at a stimulus intensity of 80% of active motor threshold (AMT), while the remainder received 90% of AMT. Motor evoked potentials (MEP) and TEP were recorded before and after each treatment, by stimulating the first dorsal interosseus area of the left motor cortex. Analysis of the 13 right handed participants showed that iTBS at 90% of AMT increased the N100 amplitude compared to sham and cTBS, without significantly altering MEP amplitude. cTBS at 80% of active motor threshold decreased the N100 amplitude and cTBS overall reduced resting MEP amplitude. The study demonstrates effects of 30Hz cerebellar TBS on inhibitory cortical networks that may be useful for treatment of neurological conditions associated with dysfunctional intracortical inhibition.

No MeSH data available.


Related in: MedlinePlus

Effects of cerebellar cTBS, iTBS and Sham TMS on the N100 potential in right handed participants.The post-treatment marginal means for the interaction Treatment x Stimulus Intensity are shown for the N100 amplitude. p values are shown for the post-hoc comparisons, using Bonferroni correction. Error bars show standard errors. Sham = sham treatment with placebo coil; iTBS = intermittent theta burst stimulation; cTBS = continuous theta burst stimulation; μV = microvolts.
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pone.0141284.g005: Effects of cerebellar cTBS, iTBS and Sham TMS on the N100 potential in right handed participants.The post-treatment marginal means for the interaction Treatment x Stimulus Intensity are shown for the N100 amplitude. p values are shown for the post-hoc comparisons, using Bonferroni correction. Error bars show standard errors. Sham = sham treatment with placebo coil; iTBS = intermittent theta burst stimulation; cTBS = continuous theta burst stimulation; μV = microvolts.

Mentions: The TMS-evoked potentials consisted of a series of positive and negative waveforms including the P60, N100 and N180 potentials (Figs 2, 3 and 4). Some of the earlier waveforms were contaminated by residual TMS artefact, despite artefact removal. Mixed ANOVA with factors Treatment x SI x Electrodes, with pre-treatment N100 amplitude as a covariate revealed a significant effect of Treatment on N100 amplitude, F(2,494) = 41.06, p < 0.001. Post-hoc analysis showed that values were significantly higher (more negative) after iTBS than after Sham or cTBS, p < 0.05. There was an effect of SI on N100 amplitude, with higher amplitudes after 90% than 80% SI, F(1,576) = 19.46, p<0.001. There was a significant Treatment x SI interaction, F(2,494) = 7.88, p<0.001. Post-hoc comparisons showed that the mean N100 amplitude after iTBS at 90% SI was higher than sham or cTBS at 90% SI (Fig 5). In contrast, cTBS at 80% resulted in lower mean N100 amplitude than sham treatment or iTBS. There was no significant difference between 80% iTBS and sham. There was no effect of Electrode, and the effects appeared to be generalised, rather than localized to a few electrodes (Fig 3B and 3C). The mean N100 amplitudes for each participant are contained in the supplementary file S1 N100 Data.


Theta Burst Stimulation of the Cerebellum Modifies the TMS-Evoked N100 Potential, a Marker of GABA Inhibition.

Harrington A, Hammond-Tooke GD - PLoS ONE (2015)

Effects of cerebellar cTBS, iTBS and Sham TMS on the N100 potential in right handed participants.The post-treatment marginal means for the interaction Treatment x Stimulus Intensity are shown for the N100 amplitude. p values are shown for the post-hoc comparisons, using Bonferroni correction. Error bars show standard errors. Sham = sham treatment with placebo coil; iTBS = intermittent theta burst stimulation; cTBS = continuous theta burst stimulation; μV = microvolts.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4631469&req=5

pone.0141284.g005: Effects of cerebellar cTBS, iTBS and Sham TMS on the N100 potential in right handed participants.The post-treatment marginal means for the interaction Treatment x Stimulus Intensity are shown for the N100 amplitude. p values are shown for the post-hoc comparisons, using Bonferroni correction. Error bars show standard errors. Sham = sham treatment with placebo coil; iTBS = intermittent theta burst stimulation; cTBS = continuous theta burst stimulation; μV = microvolts.
Mentions: The TMS-evoked potentials consisted of a series of positive and negative waveforms including the P60, N100 and N180 potentials (Figs 2, 3 and 4). Some of the earlier waveforms were contaminated by residual TMS artefact, despite artefact removal. Mixed ANOVA with factors Treatment x SI x Electrodes, with pre-treatment N100 amplitude as a covariate revealed a significant effect of Treatment on N100 amplitude, F(2,494) = 41.06, p < 0.001. Post-hoc analysis showed that values were significantly higher (more negative) after iTBS than after Sham or cTBS, p < 0.05. There was an effect of SI on N100 amplitude, with higher amplitudes after 90% than 80% SI, F(1,576) = 19.46, p<0.001. There was a significant Treatment x SI interaction, F(2,494) = 7.88, p<0.001. Post-hoc comparisons showed that the mean N100 amplitude after iTBS at 90% SI was higher than sham or cTBS at 90% SI (Fig 5). In contrast, cTBS at 80% resulted in lower mean N100 amplitude than sham treatment or iTBS. There was no significant difference between 80% iTBS and sham. There was no effect of Electrode, and the effects appeared to be generalised, rather than localized to a few electrodes (Fig 3B and 3C). The mean N100 amplitudes for each participant are contained in the supplementary file S1 N100 Data.

Bottom Line: Motor evoked potentials (MEP) and TEP were recorded before and after each treatment, by stimulating the first dorsal interosseus area of the left motor cortex.Analysis of the 13 right handed participants showed that iTBS at 90% of AMT increased the N100 amplitude compared to sham and cTBS, without significantly altering MEP amplitude. cTBS at 80% of active motor threshold decreased the N100 amplitude and cTBS overall reduced resting MEP amplitude.The study demonstrates effects of 30Hz cerebellar TBS on inhibitory cortical networks that may be useful for treatment of neurological conditions associated with dysfunctional intracortical inhibition.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, University of Otago, Dunedin, New Zealand.

ABSTRACT
Theta burst stimulation (TBS) of the cerebellum, a potential therapy for neurological disease, can modulate corticospinal excitability via the dentato-thalamo-cortical pathway, but it is uncertain whether its effects are mediated via inhibitory or facilitatory networks. The aim of this study was to investigate the effects of 30Hz cerebellar TBS on the N100 waveform of the TMS-evoked potential (TEP), a marker of intracortical GABAB-mediated inhibition. 16 healthy participants (aged 18-30 years; 13 right handed and 3 left handed) received 30Hz intermittent TBS (iTBS), continuous TBS (cTBS) or sham stimulation over the right cerebellum, in three separate sessions. The first 8 participants received TBS at a stimulus intensity of 80% of active motor threshold (AMT), while the remainder received 90% of AMT. Motor evoked potentials (MEP) and TEP were recorded before and after each treatment, by stimulating the first dorsal interosseus area of the left motor cortex. Analysis of the 13 right handed participants showed that iTBS at 90% of AMT increased the N100 amplitude compared to sham and cTBS, without significantly altering MEP amplitude. cTBS at 80% of active motor threshold decreased the N100 amplitude and cTBS overall reduced resting MEP amplitude. The study demonstrates effects of 30Hz cerebellar TBS on inhibitory cortical networks that may be useful for treatment of neurological conditions associated with dysfunctional intracortical inhibition.

No MeSH data available.


Related in: MedlinePlus