Autti Salla, Hirvi Pauliina, Keitaanniemi Mariia, Mustaniemi Hanna, Kotilahti Kalle, Renvall Hanna, Nissilä Ilkka
Department of Neuroscience and Biomedical Engineering, Aalto University, Espoo, Finland.
BioMag Laboratory, HUS Medical Imaging Center, Aalto University, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
Hum Brain Mapp. 2025 Aug 1;46(11):e70293. doi: 10.1002/hbm.70293.
Simultaneous measurement of electrophysiological and hemodynamic brain signals imposes special requirements on the instrumentation. Here, we developed a high-density fiberoptic probe for concurrent diffuse optical tomography (DOT) and magnetoencephalography (MEG) recordings. Transparent two-component silicone was mixed with carbon black dye to achieve a black, flexible, non-magnetic support for the dense optode arrangement and low (5 mm) probe thickness. The probe was used to record somatosensory responses to electrical right median nerve stimulation at 0.5, 1, 2, and 4 Hz in 18 adult human subjects. Brain activity was simultaneously measured with a commercial whole-head MEG system and with the DOT optode arrangement covering approximately 40 cm over the parietal region in the contralateral left hemisphere. Two correlation-based clustering methods were developed to find regions where the reconstructed time course of total hemoglobin concentration (HbT) changes correlated with the predicted hemodynamic activity based on time-course characteristics of the MEG sources and the canonical hemodynamic response model. Two statistically significant clusters were found based on the correlation between HbT around the postcentral gyrus and MEG primary somatosensory cortical activity at ~35 ms (P35m response). In addition, correlation between HbT and secondary somatosensory cortical activity suggested a statistically significant cluster in the postcentral gyrus and parietal operculum. These results illustrate an improvement in localization over previous DOT studies using sparse optode arrangements, and demonstrate the feasibility of the system for simultaneous HD-DOT-MEG experiments. Furthermore, the techniques described here pave the way for understanding the coupling between hemodynamic and electrophysiological responses. Further research is needed to reveal the neuronal circuits giving rise to the correlating MEG and DOT response features. Significant improvements in the technology are still expected via optimization of the detected light power in the instrumentation.
同时测量脑电生理信号和脑血流动力学信号对仪器设备提出了特殊要求。在此，我们开发了一种高密度光纤探头，用于同步进行扩散光学断层扫描（DOT）和脑磁图（MEG）记录。将透明的双组分硅酮与炭黑染料混合，以获得一种黑色、柔性、非磁性的支撑体，用于密集的光极排列，并使探头厚度较低（5毫米）。该探头用于记录18名成年人类受试者在0.5、1、2和4赫兹时对右侧正中神经电刺激的体感反应。使用商用全头MEG系统以及覆盖对侧左半球顶叶区域约40厘米的DOT光极排列同时测量脑活动。开发了两种基于相关性的聚类方法，以找到总血红蛋白浓度（HbT）变化的重建时间进程与基于MEG源的时间进程特征和典型血流动力学反应模型预测血流动力学活动相关的区域。基于中央后回周围HbT与MEG初级体感皮层活动在约35毫秒时的相关性（P35m反应），发现了两个具有统计学意义的聚类。此外，HbT与次级体感皮层活动之间的相关性表明在中央后回和顶叶岛盖存在一个具有统计学意义的聚类。这些结果说明了相对于先前使用稀疏光极排列的DOT研究，在定位方面有了改进，并证明了该系统用于同步高清DOT-MEG实验的可行性。此外，这里描述的技术为理解血流动力学和电生理反应之间的耦合铺平了道路。需要进一步研究以揭示产生相关MEG和DOT反应特征的神经回路。通过优化仪器中的检测光功率，预计该技术仍将有显著改进。
