Graduate School of Science and Technology, Keio University, Kanagawa, Japan.
Department of Rehabilitation Medicine, School of Medicine, Keio University, Tokyo, Japan.
Elife. 2022 Jul 7;11:e76411. doi: 10.7554/eLife.76411.
Human behavior requires inter-regional crosstalk to employ the sensorimotor processes in the brain. Although external neuromodulation techniques have been used to manipulate interhemispheric sensorimotor activity, a central controversy concerns whether this activity can be volitionally controlled. Experimental tools lack the power to up- or down-regulate the state of the targeted hemisphere over a large dynamic range and, therefore, cannot evaluate the possible volitional control of the activity. We addressed this difficulty by using the recently developed method of spatially bivariate electroencephalography (EEG)-neurofeedback to systematically enable the participants to modulate their bilateral sensorimotor activities. Here, we report that participants learn to up- and down-regulate the ipsilateral excitability to the imagined hand while maintaining constant contralateral excitability; this modulates the magnitude of interhemispheric inhibition (IHI) assessed by the paired-pulse transcranial magnetic stimulation (TMS) paradigm. Further physiological analyses revealed that the manipulation capability of IHI magnitude reflected interhemispheric connectivity in EEG and TMS, which was accompanied by intrinsic bilateral cortical oscillatory activities. Our results show an interesting approach for neuromodulation, which might identify new treatment opportunities, e.g., in patients suffering from a stroke.
人类行为需要区域间的串扰，以利用大脑中的感觉运动过程。尽管已经使用外部神经调节技术来操纵大脑两半球间的感觉运动活动，但一个核心争议是这种活动是否可以进行随意控制。实验工具缺乏在大动态范围内上调或下调目标半球状态的能力，因此无法评估活动的可能随意控制。我们通过使用最近开发的空间双变量脑电图（EEG）-神经反馈方法来解决这个困难，该方法可以系统地使参与者调节其双侧感觉运动活动。在这里，我们报告参与者学会了上调和下调对想象中的手的同侧兴奋性，同时保持对侧兴奋性不变；这调制了通过成对脉冲经颅磁刺激（TMS）范式评估的半球间抑制（IHI）的幅度。进一步的生理分析表明，IHI 幅度的操纵能力反映了 EEG 和 TMS 中的半球间连接性，这伴随着内在的双侧皮质振荡活动。我们的结果展示了一种有趣的神经调节方法，它可能为治疗中风等疾病的患者提供新的治疗机会。
