The effect of pulse shape in theta-burst stimulation: Monophasic vs biphasic TMS
Background: Intermittent theta-burst stimulation (i) (TBS) is a transcranial magnetic stimulation (TMS) plasticity protocol. Conventionally, TBS is applied using biphasic pulses due to hardware limitations. However, monophasic pulses are hypothesised to recruit cortical neurons more selectively than...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2023-07-01
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| Series: | Brain Stimulation |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S1935861X23018739 |
| _version_ | 1797737978876919808 |
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| author | Karen Wendt Majid Memarian Sorkhabi Charlotte J. Stagg Melanie K. Fleming Timothy Denison Jacinta O'Shea |
| author_facet | Karen Wendt Majid Memarian Sorkhabi Charlotte J. Stagg Melanie K. Fleming Timothy Denison Jacinta O'Shea |
| author_sort | Karen Wendt |
| collection | DOAJ |
| description | Background: Intermittent theta-burst stimulation (i) (TBS) is a transcranial magnetic stimulation (TMS) plasticity protocol. Conventionally, TBS is applied using biphasic pulses due to hardware limitations. However, monophasic pulses are hypothesised to recruit cortical neurons more selectively than biphasic pulses, predicting stronger plasticity effects. Monophasic and biphasic TBS can be generated using a custom-made pulse-width modulation-based TMS device (pTMS). Objective: Using pTMS, we tested the hypothesis that monophasic iTBS would induce a stronger plasticity effect than biphasic, measured as induced increases in motor corticospinal excitability. Methods: In a repeated-measures design, thirty healthy volunteers participated in three separate sessions, where monophasic and biphasic iTBS was applied to the primary motor cortex (M1 condition) or the vertex (control condition). Plasticity was quantified as increases in motor corticospinal excitability after versus before iTBS, by comparing peak-to-peak amplitudes of motor evoked potentials (MEP) measured at baseline and over 60 min after iTBS. Results: Both monophasic and biphasic M1 iTBS led to significant increases in MEP amplitude. As predicted, linear mixed effects (LME) models showed that the iTBS condition had a significant effect on the MEP amplitude (χ2 (1) = 27.615, p < 0.001) with monophasic iTBS leading to significantly stronger plasticity than biphasic iTBS (t (693) = 2.311, p = 0.021). Control vertex iTBS had no effect. Conclusions: In this study, monophasic iTBS induced a stronger motor corticospinal excitability increase than biphasic within participants. This greater physiological effect suggests that monophasic iTBS may also have potential for greater functional impact, of interest for future fundamental and clinical applications of TBS. |
| first_indexed | 2024-03-12T13:36:16Z |
| format | Article |
| id | doaj.art-4eb92c5576ff4ce18ec3af54cc52b5be |
| institution | Directory Open Access Journal |
| issn | 1935-861X |
| language | English |
| last_indexed | 2024-03-12T13:36:16Z |
| publishDate | 2023-07-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Brain Stimulation |
| spelling | doaj.art-4eb92c5576ff4ce18ec3af54cc52b5be2023-08-24T04:35:01ZengElsevierBrain Stimulation1935-861X2023-07-0116411781185The effect of pulse shape in theta-burst stimulation: Monophasic vs biphasic TMSKaren Wendt0Majid Memarian Sorkhabi1Charlotte J. Stagg2Melanie K. Fleming3Timothy Denison4Jacinta O'Shea5MRC Brain Network Dynamics Unit, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX1 3TH, UK; Department of Engineering Science, University of Oxford, Oxford, OX1 3PJ, UK; Corresponding author. Institute of Biomedical Engineering, Old Road Campus Research Building, Oxford, OX3 7DQ, UK.MRC Brain Network Dynamics Unit, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX1 3TH, UKMRC Brain Network Dynamics Unit, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX1 3TH, UK; Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UKWellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UKMRC Brain Network Dynamics Unit, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX1 3TH, UK; Department of Engineering Science, University of Oxford, Oxford, OX1 3PJ, UKWellcome Centre for Integrative Neuroimaging, Oxford Centre for Human Brain Activity (OHBA), University of Oxford Department of Psychiatry, Warneford Hospital, Warneford Lane, Oxford, UKBackground: Intermittent theta-burst stimulation (i) (TBS) is a transcranial magnetic stimulation (TMS) plasticity protocol. Conventionally, TBS is applied using biphasic pulses due to hardware limitations. However, monophasic pulses are hypothesised to recruit cortical neurons more selectively than biphasic pulses, predicting stronger plasticity effects. Monophasic and biphasic TBS can be generated using a custom-made pulse-width modulation-based TMS device (pTMS). Objective: Using pTMS, we tested the hypothesis that monophasic iTBS would induce a stronger plasticity effect than biphasic, measured as induced increases in motor corticospinal excitability. Methods: In a repeated-measures design, thirty healthy volunteers participated in three separate sessions, where monophasic and biphasic iTBS was applied to the primary motor cortex (M1 condition) or the vertex (control condition). Plasticity was quantified as increases in motor corticospinal excitability after versus before iTBS, by comparing peak-to-peak amplitudes of motor evoked potentials (MEP) measured at baseline and over 60 min after iTBS. Results: Both monophasic and biphasic M1 iTBS led to significant increases in MEP amplitude. As predicted, linear mixed effects (LME) models showed that the iTBS condition had a significant effect on the MEP amplitude (χ2 (1) = 27.615, p < 0.001) with monophasic iTBS leading to significantly stronger plasticity than biphasic iTBS (t (693) = 2.311, p = 0.021). Control vertex iTBS had no effect. Conclusions: In this study, monophasic iTBS induced a stronger motor corticospinal excitability increase than biphasic within participants. This greater physiological effect suggests that monophasic iTBS may also have potential for greater functional impact, of interest for future fundamental and clinical applications of TBS.http://www.sciencedirect.com/science/article/pii/S1935861X23018739Transcranial magnetic stimulation (TMS)Theta burst stimulation (TBS)Pulse-width modulation based TMSTMS pulse shapeMotor plasticity |
| spellingShingle | Karen Wendt Majid Memarian Sorkhabi Charlotte J. Stagg Melanie K. Fleming Timothy Denison Jacinta O'Shea The effect of pulse shape in theta-burst stimulation: Monophasic vs biphasic TMS Brain Stimulation Transcranial magnetic stimulation (TMS) Theta burst stimulation (TBS) Pulse-width modulation based TMS TMS pulse shape Motor plasticity |
| title | The effect of pulse shape in theta-burst stimulation: Monophasic vs biphasic TMS |
| title_full | The effect of pulse shape in theta-burst stimulation: Monophasic vs biphasic TMS |
| title_fullStr | The effect of pulse shape in theta-burst stimulation: Monophasic vs biphasic TMS |
| title_full_unstemmed | The effect of pulse shape in theta-burst stimulation: Monophasic vs biphasic TMS |
| title_short | The effect of pulse shape in theta-burst stimulation: Monophasic vs biphasic TMS |
| title_sort | effect of pulse shape in theta burst stimulation monophasic vs biphasic tms |
| topic | Transcranial magnetic stimulation (TMS) Theta burst stimulation (TBS) Pulse-width modulation based TMS TMS pulse shape Motor plasticity |
| url | http://www.sciencedirect.com/science/article/pii/S1935861X23018739 |
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