Bonzano Laura, Bortoletto Marta, Zazio Agnese, Iester Costanza, Stango Antonietta, Gasparotti Roberto, Miniussi Carlo, Bove Marco
Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy.
Neurophysiology Laboratory, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy.
Front Neurosci. 2022 Aug 12;16:896746. doi: 10.3389/fnins.2022.896746. eCollection 2022.
In the seed-based method for studying functional connectivity (FC), seed selection is relevant. Here, we propose a new methodological approach for resting-state FC analysis of hand motor networks using the individual hand motor hotspot (hMHS) as seed. Nineteen right-handed healthy volunteers underwent a transcranial magnetic stimulation (TMS) session and resting-state fMRI. For each subject, the hMHS in both hemispheres was identified by TMS with the contralateral abductor pollicis brevis muscle as the target, the site eliciting the highest and most reliable motor-evoked potentials. Seed regions were built on coordinates on the cortex corresponding to the individual left and right hMHSs. For comparison, the left and right Brodmann's area 4 (BA4) masks extracted from a standard atlas were used as seed. The left and right hMHSs showed FC patterns at rest mainly including sensorimotor regions, with a bilateral connectivity only for the left hMHS. The statistical contrast BA4 > hMHS for both hemispheres showed different extension and lateralization of the functionally connected cortical regions. On the contrary, no voxels survived the opposite contrast (hMHS > BA4). This suggests that detection of individual hand motor seeds by TMS allows to identify functionally connected motor networks that are more specific with respect to those obtained starting from the atlas-based identification of the primary motor cortex.
在基于种子点的功能连接（FC）研究方法中，种子点选择至关重要。在此，我们提出一种新的方法，以个体手部运动热点（hMHS）为种子点，对手部运动网络进行静息态FC分析。19名右利手健康志愿者接受了经颅磁刺激（TMS）实验和静息态功能磁共振成像（fMRI）。对于每个受试者，通过TMS以对侧拇短展肌为靶点，确定双侧半球的hMHS，该部位能引出最高且最可靠的运动诱发电位。种子区域基于与个体左右hMHS相对应的皮质坐标构建。为作比较，使用从标准图谱中提取的左右布罗德曼4区（BA4）掩码作为种子点。左右hMHS在静息状态下显示出的FC模式主要包括感觉运动区域，仅左侧hMHS存在双侧连接。两半球的统计学对比BA4 > hMHS显示出功能连接皮质区域的不同范围和偏侧化。相反，反向对比（hMHS > BA4）未发现有存活的体素。这表明通过TMS检测个体手部运动种子点能够识别出比基于图谱识别初级运动皮层所获得的功能连接运动网络更具特异性的网络。
