2020 Fiscal Year Research-status Report
Development of a neuromodulation method for facilitation of corticospinal plasticity
Project/Area Number |
20K19412
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Research Institution | Osaka University |
Principal Investigator |
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Project Period (FY) |
2020-04-01 – 2023-03-31
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Keywords | neuromodulation / theta burst stimulation / spinal cord stimulation / muscle stimulation / neuroplasticity / rehabilitation |
Outline of Annual Research Achievements |
The objective of this research is to understand the mechanisms of neuroplasticity though temporal synchronization of cortical commands and afferent sensory feedback from the muscle. Specifically, a continuous paired associative stimulation method for facilitation of corticospinal plasticity based on Hebbian learning principles will be developed to facilitate synchronization of descending signals using non-invasive transcranial magnetic stimulation of the brain and activation of afferent spinal networks using electrical stimulation. Non-invasive brain stimulation will comprise of delivery of theta burst stimulation (TBS), while afferent networks will be activated using neuromuscular electrical stimulation (NMES) of muscles or recruitment of the cervical dorsal roots through transcutaneous spinal cord stimulation (tSCS). Based on these objectives, we have so far tested how intermittent TBS (iTBS) facilitatory and continuous TBS (cTBS) inhibitory cortical priming followed by NMES of hand muscles affects corticospinal excitability. Specifically, faciliatory priming using iTBS was most effective in significantly facilitating corticospinal networks. In parallel, we have been developing a method for activation of cervical spinal dorsal roots through tSCS. We showed selectivity and sensitivity of recruitment of upper-limb motor pools with different cervical stimulation locations, while low intensity and short-duration stimulation was not effective to change the excitability of the central nervous system after the stimulation.
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Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
In the research related to the development of an associative stimulation method based on Hebbian learning, the first study using cortical priming followed by activation of afferent networks using NMES was completed, and it is currently in preparation for submission to a peer-reviewed journal [1]. In the research related to the development cervical tSCS for activation of dorsal roots of the upper-limb muscles, a study related to sensitivity and selectivity of cervical tSCS was completed and is currently in review in a peer-reviewed journal [2]. Moreover, effects of short-term stimulation of cervical dorsal roots using tSCS was investigated and the findings are in preparation for submission to a peer-review journal [3]. Finally, the theoretical framework of the proposed mechanism of Hebbian associative learning principles through presynaptic activation of cortical networks and postsynaptic activation of afferent circuits was published as a review article in a peer-reviewed journal [4]. References: [1] N. Cao, et al., To be submitted to Brain Stimulation; [2] R. M. de Freitas, et al., In review - Journal of Applied Physiology; [3] A. Sasaki, et al., To be submitted to Journal of Clinical Medicine; [4] M. Milosevic, et al., BioMedical Engineering Online, vol. 19, 81, 2020.
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Strategy for Future Research Activity |
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 test the effects of spike-timing dependent plasticity (STDP), i.e., time delay between presynaptic cortical activation and postsynaptic afferent activation on corticospinal excitability (study 1). Moreover, we will also develop a computer simulations model and validate this model through new experimental studies to confirm activation of dorsal roots (afferent networks) during cervical tSCS (study 2). Finally, a comparison between Hebbian learning-based neuromodulation method using TBS and NMES will be compared to that when TBS and clerical tasks are used (study 3). Overall, the aim will be to develop a neuromodulation method for facilitation of corticospinal plasticity through effective and optimal activation of cortical and afferent upper-limb networks.
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Causes of Carryover |
Travel schedule for collaborative research at the University of Tokyo was re-scheduled due to restrictions related to COVID-19. However, all experiments have been successfully completed according to the proposed schedule so far.
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Research Products
(16 results)