| 研究実績の概要 |
The objective of this research is to understand mechanisms of neuroplasticity though synchronization of cortical commands and peripheral sensory feedback. Non-invasive brain stimulation was applied as theta burst stimulation (TBS) either via intermittent TBS (iTBS) facilitatory or continuous TBS (cTBS) inhibitory protocols. Afferent networks were activated using neuromuscular electrical stimulation (NMES) of muscles or recruitment of the cervical dorsal roots sensory fibers through transcutaneous spinal cord stimulation (tSCS).
First, iTBS facilitatory or cTBS inhibitory cortical priming was applied before delivery of upper-limb muscle NMES. Our results showed that facilitatory cortical priming using iTBS followed by NMES was most effective in significantly facilitating corticospinal networks. We then showed that short duration iTBS facilitatory activation applied at the same time using synchronized frequencies affects corticospinal excitability immediate after the intervention. Finally, we tested the effects of the duration of concurrent synchronized iTBS-NMES interventions on corticospinal excitably and showed that longer durations interventions could elicit longer-lasting effects.
In parallel, we have been developing a method for activation of cervical spinal dorsal roots through tSCS. We showed both using computer simulations and experimental findings evidence that sensory fibers in the dorsal roots can be activated before motor fibers. Moreover, we showed selectivity and sensitivity of recruitment of upper-limb motor pools with different cervical stimulation locations.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
1: 当初の計画以上に進展している
理由
(1) “Related to the development of an associative stimulation method” - We compared iTBS facilitatory or cTBS inhibitory cortical priming applied before delivery NMES and showed that iTBS-NMES was most effective to affects corticospinal excitability [1]. We then showed that short duration iTBS-NMES activation applied at the same time using synchronized frequencies affects corticospinal excitability immediate after the intervention [2]. Finally, we showed that longer duration iTBS-NMES interventions could elicit longer-lasting effects [3].
(2) “Related to the development cervical tSCS method” - We showed both using computer simulations [4] and experimental findings [5] evidence that sensory fibers in the dorsal roots can be activated before motor fibers during tSCS. Moreover, we showed selectivity and sensitivity of recruitment of upper-limb motor pools with different cervical stimulation locations using computer simulation [6] and experimental data [7], while low intensity and short-duration tSCS was not effective to excite the central nervous system [5].
References: [1] N. Cao, et al. Experimental Brain Research. In press, 2022; [2] N. Cao, et al. To be submitted to Neuroscience Letters; [3]N. Cao, et al. To be submitted to Brain Stimulation; [4] R. M. de Freitas, et al. Journal of Neural Engineering. In press, 2022; [5] A. Sasaki, et al. Journal of Clinical Medicine, vol. 10(16), 3633, 2021; [6] R. M. de Freitas, et al. In review - Artificial Organs; [7] R. M. de Freitas, et al. Journal of Applied Physiology, vol. 131(2), 2021.
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| 今後の研究の推進方策 |
In the future, we will continue to develop a paired associative stimulation method based on Hebbian learning principles. Specifically, the next step will be to work towards comparing the NMES and tSCS afferent recruitment methods and during concurrent cortical facilitatory iTBS application. In parallel, the developed computer simulation model will also be compared to the experimentally obtained data in an effort to work toward validating the simulations data. Overall, the aim is to develop a novel neuromodulation method for facilitation of corticospinal plasticity through optimal activation of cortical and afferent upper-limb networks.
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