School of Psychology, University of Nottingham, University Park , Nottingham , United Kingdom.
Department of Psychological Sciences, Birkbeck University of London , London , United Kingdom.
J Neurophysiol. 2019 Jan 1;121(1):336-344. doi: 10.1152/jn.00641.2018. Epub 2018 Dec 21.
Transcranial magnetic stimulation (TMS) over human primary somatosensory cortex (S1) does not produce immediate outputs. Researchers must therefore rely on indirect methods for TMS coil positioning. The "gold standard" is to use individual functional and structural magnetic resonance imaging (MRI) data, but the majority of studies don't do this. The most common method to locate the hand area of S1 (S1-hand) is to move the coil posteriorly from the hand area of primary motor cortex (M1-hand). Yet, S1-hand is not directly posterior to M1-hand. We localized the index finger area of S1-hand (S1-index) experimentally in four ways. First, we reanalyzed functional MRI data from 20 participants who received vibrotactile stimulation to their 10 digits. Second, to assist the localization of S1-hand without MRI data, we constructed a probabilistic atlas of the central sulcus from 100 healthy adult MRIs and measured the likely scalp location of S1-index. Third, we conducted two experiments mapping the effects of TMS across the scalp on tactile discrimination performance. Fourth, we examined all available neuronavigation data from our laboratory on the scalp location of S1-index. Contrary to the prevailing method, and consistent with systematic review evidence, S1-index is close to the C3/C4 electroencephalography (EEG) electrode locations on the scalp, ~7-8 cm lateral to the vertex, and ~2 cm lateral and 0.5 cm posterior to the M1-hand scalp location. These results suggest that an immediate revision to the most commonly used heuristic to locate S1-hand is required. The results of many TMS studies of S1-hand need reassessment. NEW & NOTEWORTHY Noninvasive human brain stimulation requires indirect methods to target particular brain areas. Magnetic stimulation studies of human primary somatosensory cortex have used scalp-based heuristics to find the target, typically locating it 2 cm posterior to the motor cortex. We measured the scalp location of the hand area of primary somatosensory cortex and found that it is ~2 cm lateral to motor cortex. Our results suggest an immediate revision of the prevailing method is required.
经颅磁刺激（TMS）作用于人体初级体感皮层（S1）不会立即产生输出。因此，研究人员必须依靠间接方法来定位 TMS 线圈。“金标准”是使用个体的功能和结构磁共振成像（MRI）数据，但大多数研究都没有这样做。定位 S1 手部区域（S1-hand）最常用的方法是将线圈从初级运动皮层（M1-hand）的手部区域向后移动。然而，S1-hand 并不直接位于 M1-hand 之后。我们通过四种方法实验性地定位了 S1-hand 的食指区域（S1-index）。首先，我们重新分析了 20 名参与者的功能 MRI 数据，这些参与者接受了他们的 10 个手指的振动触觉刺激。其次，为了在没有 MRI 数据的情况下协助 S1-hand 的定位，我们从 100 名健康成人 MRI 中构建了中央沟的概率图谱，并测量了 S1-index 的可能头皮位置。第三，我们进行了两项实验，在头皮上映射 TMS 对触觉辨别性能的影响。第四，我们检查了我们实验室所有可用的神经导航数据，以确定 S1-index 在头皮上的位置。与流行的方法相反，并且与系统评价证据一致，S1-index 接近头皮上的 C3/C4 脑电图（EEG）电极位置，距顶点约 7-8 厘米，距 M1-hand 头皮位置约 2 厘米和 0.5 厘米外侧。这些结果表明，需要立即修改最常用的启发式方法来定位 S1-hand。许多 S1-hand 的 TMS 研究结果需要重新评估。新的和值得注意的非侵入性人脑刺激需要间接方法来靶向特定的大脑区域。对人类初级体感皮层的磁刺激研究使用基于头皮的启发式方法来寻找目标，通常将其定位在运动皮层后 2 厘米处。我们测量了初级体感皮层手部区域的头皮位置，发现它位于运动皮层外侧约 2 厘米处。我们的结果表明，需要立即修改当前的方法。
