Transcranial brain mapping techniques, such as functional near-infrared spectroscopy (fNIRS) and transcranial magnetic stimulation (TMS), have been playing an increasingly important role in studies of human brain functions. Given a brain function of interest, fNIRS probes and TMS coils should be properly placed on the scalp to ensure that the function is effectively measured or modulated. However, since brain activity is inside the skull and invisible to the researcher during placement, this blind targeting may cause the device to partially or completely miss the functional target, resulting in inconsistent experimental results and divergent clinical outcomes, especially when participants' structural MRI data are not available. To address this issue, we propose here a framework for targeting a designated function directly from the scalp. First, a functional brain atlas for the targeted brain function is constructed via a meta-analysis of large-scale functional magnetic resonance imaging datasets. Second, the functional brain atlas is presented on the scalp surface by using a transcranial mapping previously established from an structural MRI dataset (n = 114), resulting in a novel functional transcranial brain atlas (fTBA). Finally, a low-cost, portable scalp-navigation system is used to localize the transcranial device on the individual's scalp with the guidance of the fTBA. To demonstrate the feasibility of the targeting framework, both fNIRS and TMS mapping experiments were conducted. The results show that fTBA-guided fNIRS positioning can detect functional activity with high sensitivity and specificity for working memory and motor systems; Moreover, compared with traditional TMS targeting approaches (e.g. the International 10-20 System and the conventional 5-cm rule), the fTBA suggested motor stimulation site is closesr to both the motor hotspot and the center of gravity of motor evoked potentials (MEP-COG). In summary, the proposed method unblinds the transcranial function targeting process using prior information, providing an effective and straightforward approach to transcranial brain mapping studies, especially those without participants' structural MRI data.

中文翻译：

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从头皮靶向大脑功能：基于大规模 fMRI 数据合成的经颅脑图谱

功能性近红外光谱 (fNIRS) 和经颅磁刺激 (TMS) 等经颅脑绘图技术在人类大脑功能研究中发挥着越来越重要的作用。鉴于感兴趣的大脑功能，fNIRS 探头和 TMS 线圈应正确放置在头皮上，以确保有效测量或调节功能。然而，由于大脑活动在头骨内，研究人员在放置期间是不可见的，这种盲目瞄准可能会导致设备部分或完全错过功能目标，导致实验结果不一致和临床结果不同，尤其是当参与者的结构 MRI 数据不可用。为了解决这个问题，我们在这里提出了一个框架，用于直接从头皮定位指定功能。第一的，通过对大规模功能磁共振成像数据集的荟萃分析，构建了针对目标大脑功能的功能性大脑图谱。其次，通过使用先前从结构 MRI 数据集（n = 114）建立的经颅映射，将功能性脑图谱呈现在头皮表面，从而产生新的功能性经颅脑图谱（fTBA）。最后，在 fTBA 的引导下，使用低成本、便携式头皮导航系统将经颅设备定位在个人头皮上。为了证明靶向框架的可行性，进行了 fNIRS 和 TMS 映射实验。结果表明，fTBA 引导的 fNIRS 定位可以检测功能活动，对工作记忆和运动系统具有高灵敏度和特异性；而且，与传统的 TMS 靶向方法（例如国际 10-20 系统和传统的 5 厘米规则）相比，fTBA 建议的运动刺激部位更靠近运动热点和运动诱发电位 (MEP-COG) 的重心. 总之，所提出的方法使用先验信息对经颅功能靶向过程进行了揭盲，为经颅脑映射研究提供了一种有效且直接的方法，尤其是那些没有参与者结构 MRI 数据的方法。