Neural mechanisms underlying the after-effects of repetitive paired-pulse TMS with β tACS on the human primary motor cortex
Abstract We previously reported that repetitive paired-pulse transcranial magnetic stimulation (TMS; rPPS) synchronized to the peak phase of transcranial alternating current stimulation (tACS) at the β frequency induced long-lasting after-effects on primary motor cortex (M1) with less inter-individu...
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Nature Portfolio
2025-03-01
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| Online Access: | https://doi.org/10.1038/s41598-025-92444-4 |
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| author | Hisato Nakazono Katsuya Ogata Tsubasa Mitsutake Akinori Takeda Emi Yamada Shozo Tobimatsu |
| author_facet | Hisato Nakazono Katsuya Ogata Tsubasa Mitsutake Akinori Takeda Emi Yamada Shozo Tobimatsu |
| author_sort | Hisato Nakazono |
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| description | Abstract We previously reported that repetitive paired-pulse transcranial magnetic stimulation (TMS; rPPS) synchronized to the peak phase of transcranial alternating current stimulation (tACS) at the β frequency induced long-lasting after-effects on primary motor cortex (M1) with less inter-individual variability compared with rPPS alone. Here, we investigated the plasticity mechanisms underlying combined stimulation effects using paired-pulse TMS paradigms. rPPS was applied to the peak phase of β tACS (rPPS-tACS-peak) or sham tACS (rPPS alone), or tACS was delivered without rPPS (tACS alone). Resting motor threshold (RMT) and motor evoked potentials (MEPs) elicited by single-pulse TMS, short-interval intracortical inhibition (SICI), intracortical facilitation (ICF), short-latency afferent inhibition (SAI), and short-interval intracortical facilitation (SICF) were measured before and after intervention. rPPS-tACS-peak stimulation significantly increased MEPs compared with other conditions after intervention. Although I-wave interaction was expected to be produced by the facilitation effect of rPPS, rPPS-tACS-peak did not change SICF. In contrast, SAI was decreased in rPPS-tACS-peak compared with baseline. In the control experiment, rPPS-tACS-trough did not change MEPs, SAI, and SICF. Therefore, the after-effects of rPPS-tACS-peak on M1 may be caused by a partial reduction in the inhibitory circuit mediated by cholinergic interneurons, rather than an enhancement of the facilitatory effects of rPPS. |
| format | Article |
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| institution | Kabale University |
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| language | English |
| publishDate | 2025-03-01 |
| publisher | Nature Portfolio |
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| series | Scientific Reports |
| spelling | doaj-art-28fd3762a1cf4c338a83bad1842c80382025-08-20T03:41:40ZengNature PortfolioScientific Reports2045-23222025-03-0115111110.1038/s41598-025-92444-4Neural mechanisms underlying the after-effects of repetitive paired-pulse TMS with β tACS on the human primary motor cortexHisato Nakazono0Katsuya Ogata1Tsubasa Mitsutake2Akinori Takeda3Emi Yamada4Shozo Tobimatsu5Department of Occupational Therapy, Faculty of Medical Science, Fukuoka International University of Health and WelfareDepartment of Pharmaceutical Sciences, School of Pharmacy at Fukuoka, International University of Health and WelfareClinical Research Center, Saga University HospitalResearch Center for Brain Communication, Research Institute, Kochi University of TechnologyDepartment of Linguistics, Faculty of Humanities, Kyushu UniversityDepartment of Orthoptics, Faculty of Medical Science, Fukuoka International University of Health and WelfareAbstract We previously reported that repetitive paired-pulse transcranial magnetic stimulation (TMS; rPPS) synchronized to the peak phase of transcranial alternating current stimulation (tACS) at the β frequency induced long-lasting after-effects on primary motor cortex (M1) with less inter-individual variability compared with rPPS alone. Here, we investigated the plasticity mechanisms underlying combined stimulation effects using paired-pulse TMS paradigms. rPPS was applied to the peak phase of β tACS (rPPS-tACS-peak) or sham tACS (rPPS alone), or tACS was delivered without rPPS (tACS alone). Resting motor threshold (RMT) and motor evoked potentials (MEPs) elicited by single-pulse TMS, short-interval intracortical inhibition (SICI), intracortical facilitation (ICF), short-latency afferent inhibition (SAI), and short-interval intracortical facilitation (SICF) were measured before and after intervention. rPPS-tACS-peak stimulation significantly increased MEPs compared with other conditions after intervention. Although I-wave interaction was expected to be produced by the facilitation effect of rPPS, rPPS-tACS-peak did not change SICF. In contrast, SAI was decreased in rPPS-tACS-peak compared with baseline. In the control experiment, rPPS-tACS-trough did not change MEPs, SAI, and SICF. Therefore, the after-effects of rPPS-tACS-peak on M1 may be caused by a partial reduction in the inhibitory circuit mediated by cholinergic interneurons, rather than an enhancement of the facilitatory effects of rPPS.https://doi.org/10.1038/s41598-025-92444-4Transcranial alternating current stimulationRepetitive paired-pulse transcranial magnetic stimulationCombined stimulationPaired-pulse paradigmPhase dependencePrimary motor cortex |
| spellingShingle | Hisato Nakazono Katsuya Ogata Tsubasa Mitsutake Akinori Takeda Emi Yamada Shozo Tobimatsu Neural mechanisms underlying the after-effects of repetitive paired-pulse TMS with β tACS on the human primary motor cortex Scientific Reports Transcranial alternating current stimulation Repetitive paired-pulse transcranial magnetic stimulation Combined stimulation Paired-pulse paradigm Phase dependence Primary motor cortex |
| title | Neural mechanisms underlying the after-effects of repetitive paired-pulse TMS with β tACS on the human primary motor cortex |
| title_full | Neural mechanisms underlying the after-effects of repetitive paired-pulse TMS with β tACS on the human primary motor cortex |
| title_fullStr | Neural mechanisms underlying the after-effects of repetitive paired-pulse TMS with β tACS on the human primary motor cortex |
| title_full_unstemmed | Neural mechanisms underlying the after-effects of repetitive paired-pulse TMS with β tACS on the human primary motor cortex |
| title_short | Neural mechanisms underlying the after-effects of repetitive paired-pulse TMS with β tACS on the human primary motor cortex |
| title_sort | neural mechanisms underlying the after effects of repetitive paired pulse tms with β tacs on the human primary motor cortex |
| topic | Transcranial alternating current stimulation Repetitive paired-pulse transcranial magnetic stimulation Combined stimulation Paired-pulse paradigm Phase dependence Primary motor cortex |
| url | https://doi.org/10.1038/s41598-025-92444-4 |
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