Xin Zonghao, Abe Yoshifumi, Liu Shuang, Tanaka Kenji F, Hosomi Koichi, Saitoh Youichi, Sekino Masaki
School of Engineering, The University of Tokyo.
Department of Neuropsychiatry, Keio University School of Medicine.
Magn Reson Med Sci. 2021 Mar 1;20(1):83-90. doi: 10.2463/mrms.mp.2019-0156. Epub 2020 Apr 17.
Neuropathic pain is a complex and distressing chronic illness in modern medicine. Since 1990s, motor cortex stimulation (MCS) has emerged as a potential treatment for chronic neuropathic pain; however, the precise mechanisms underlying analgesia induced by MCS are not completely understood. The purpose of the present study was to investigate the blood oxygen-level dependent (BOLD) response in the brain during MCS.
We inserted a bipolar tungsten electrode into the primary motor cortex (M1) of adult male Wistar rats. Functional magnetic resonance imaging (fMRI) scans were implemented simultaneously with the electrical stimulation of M1 and the BOLD signals taken from the fMRI were used as an index to reflect the response against MCS.
Our results demonstrated that the bilateral M1, ipsilateral caudate-putamen, and ipsilateral primary somatosensory cortex to the stimulation spot were activated after the onset of MCS. The BOLD signal time courses were analysed in these regions and similar temporal characteristics were found.
By conducting direct cortical stimulation of the rodent brain to investigate its instant effect using fMRI, we identified encephalic regions directly involved in the instant motor cortical stimulation effects in healthy rat models. This result may be essential in establishing a foundation for further research on the underlying neuropathways associated with the MCS effects.
神经病理性疼痛是现代医学中一种复杂且令人痛苦的慢性疾病。自20世纪90年代以来，运动皮层刺激（MCS）已成为慢性神经病理性疼痛的一种潜在治疗方法；然而，MCS诱导镇痛的确切机制尚未完全明确。本研究的目的是调查MCS期间大脑中的血氧水平依赖（BOLD）反应。
我们将一根双极钨电极插入成年雄性Wistar大鼠的初级运动皮层（M1）。在对M1进行电刺激的同时进行功能磁共振成像（fMRI）扫描，并将从fMRI获取的BOLD信号用作反映对MCS反应的指标。
我们的结果表明，MCS开始后，双侧M1、同侧尾状核 - 壳核以及与刺激点同侧的初级体感皮层被激活。对这些区域的BOLD信号时间进程进行了分析，并发现了相似的时间特征。
通过对啮齿动物大脑进行直接皮层刺激，利用fMRI研究其即时效应，我们在健康大鼠模型中确定了直接参与即时运动皮层刺激效应的脑区。这一结果对于进一步研究与MCS效应相关的潜在神经通路奠定基础可能至关重要。
