CNRS (CERCO) UMR Unité 5549, Université Paul Sabatier, Toulouse, France.
Pôle Neurosciences (Neurochirurgie), Centres Hospitalo-Universitaires, Toulouse, France.
J Physiol. 2020 Dec;598(23):5487-5504. doi: 10.1113/JP280156. Epub 2020 Sep 15.
We performed a prospective electrostimulation study of the motor homunculus in 100 patients without motor deficit or brain lesion in the precentral gyrus in order to acquire accurate Montreal Neurological Institute (MNI) coordinates of the functional areas. The analysis of 248 body coordinates in the precentral gyrus showed rare inter-individual variations in the medial-to-lateral somatotopic movement organization with quite similar intensity thresholds. Electrostimulation only induced basic and stereotyped movements. We detected a relative medial-to-lateral somatotopy of the wrist/hand/global/individual fingers, with sometimes different sites for an individual muscle or movement. We found some similarities to, but also substantial differences from, the seminal work of Penfield and colleagues. We propose an updated version of the human motor homunculus and of its correlation with the somatosensory homunculus, previously defined in MNI space with a similar brain mapping technique.
In this prospective electrostimulation study, based on 100 operated patients without motor deficit or brain lesion in the precentral gyrus, we acquired coordinates of the functional areas of the motor homunculus and normalized them to standard MNI space. Among 608 sites stimulated in the precentral gyrus (and 1937 in gyri nearby), 248 positive points (40%) for motor response were detected - 245 in the precentral gyrus. Positive stimulations were detected through the 'on/off' outbreak effect, and only basic movements were detected. We found no significant difference in mean intensity threshold between the motor representations of the fingers (1.94 mA), tongue and lower limbs (both 2.0 mA), or face (2.25 mA). In the precentral gyrus, the evoked body movements displayed a medial-to-lateral somatotopy in very small (often <10 mm ) areas. The hand region displayed multiple areas for a specific movement, with areas inducing either global or single-finger movement (with a relative medial-to-lateral somatotopy). Among these tested patients, the somatotopic organization of the intact motor cortex showed little inter-individual variations. Unlike Penfield and collaborators, we evoked no sensations such as sense of movement or desire to move, and only 2% of motor responses outside the precentral gyrus. We propose a rationalization of the standard drawing of the motor homunculus according to MNI space. We found a somatotopic correlation perpendicular to the central sulcus when matching our motor data to those previously obtained for the somatosensory homunculus.
我们对 100 名无运动缺陷或大脑前中央回损伤的患者进行了运动小人的前瞻性电刺激研究，以获取功能区的准确蒙特利尔神经学研究所 (MNI) 坐标。对前中央回 248 个体表坐标的分析显示，在以中侧为序的躯体组织中，个体间的变化很少，且强度阈值相当相似。电刺激仅引起基本和刻板的运动。我们检测到手/手腕/全局/单个手指的相对中侧躯体组织，有时单个肌肉或运动的部位也不同。我们发现与彭菲尔德及其同事的开创性工作有一些相似之处，但也有很大的不同。我们提出了一种更新的人类运动小人版本及其与体感小人的相关性，该版本以前是使用类似的脑映射技术在 MNI 空间中定义的。
在这项前瞻性的电刺激研究中，我们基于 100 名接受手术且无运动缺陷或大脑前中央回损伤的患者，获取了运动小人功能区的坐标，并将其标准化到标准的 MNI 空间。在前中央回（和附近的 1937 个脑回）刺激了 608 个部位后，检测到 248 个（40%）有运动反应的阳性点 - 前中央回中有 245 个。阳性刺激是通过“开/关”爆发效应检测到的，只检测到基本运动。我们发现手指（1.94 mA）、舌头和下肢（均为 2.0 mA）或面部（2.25 mA）运动代表的平均强度阈值之间没有显著差异。在前中央回，诱发的身体运动在非常小的区域（通常 <10 mm）呈现从中到侧的躯体组织。手部区域显示出特定运动的多个区域，这些区域可引起全局或单个手指运动（具有相对从中到侧的躯体组织）。在这些受测患者中，完整运动皮层的躯体组织组织显示出很小的个体间变化。与彭菲尔德及其同事不同，我们没有诱发运动感觉或运动欲望等感觉，只有 2%的运动反应发生在前中央回之外。我们根据 MNI 空间对运动小人的标准图进行了合理化。当将我们的运动数据与之前获得的体感小人数据相匹配时，我们发现了与中央沟垂直的躯体组织相关性。
