The Edmond and Lily Safra Center for Brain Sciences and Medical Neurobiology Department of Institute for Medical Research Israel-Canada and The Hebrew University of Jerusalem Medical School, 91220.
Hebrew University of Jerusalem, Jerusalem 91220, Israel.
J Neurosci. 2019 Oct 2;39(40):7882-7892. doi: 10.1523/JNEUROSCI.0727-18.2019. Epub 2019 Aug 12.
In 1954, Penfield and Jasper's findings based on electric stimulation of epileptic patients led them to hypothesize that a sensory representation of the body should be found in the precuneus. They termed this representation the "supplementary sensory" area and emphasized that the exact form of this homunculus could not be specified on the basis of their results. In the decades that followed, their prediction was neglected. The precuneus was found to be involved in numerous motor, cognitive and visual processes, but no work was done on its somatotopic organization. Here, we used a periodic experimental design in which 16 human subjects (eight women) moved 20 body parts to investigate the possible body part topography of the precuneus. We found an anterior-to-posterior, dorsal-to-ventral, toes-to-tongue gradient in a mirror orientation to the SMA. When inspecting body-part-specific functional connectivity, we found differential connectivity patterns for the different body parts to the primary and secondary motor areas and parietal and visual areas, and a shared connectivity to the extrastriate body area, another topographically organized area. We suggest that a whole-body gradient can be found in the precuneus and is connected to multiple brain areas with different connectivity for different body parts. Its exact role and relations to the other known functions of the precuneus such as self-processing, motor imagery, reaching, visuomotor and other body-mind functions should be investigated. Using fMRI, as well as sensitive spectral analysis, we found a new homunculus in the precuneus: an anterior-to-posterior, dorsal-to-ventral, toes-to-tongue somatotopic gradient in a mirror orientation to the SMA. When inspecting body-part-specific functional connectivity, we found differential connectivity patterns for the different body parts to the primary and secondary motor areas, parietal and visual areas, and a shared connectivity to the extrastriate body area, another topographically organized area. We suggest that a whole-body gradient can be found in the precuneus and is connected to multiple brain areas in a body-part-specific manner.
1954 年，彭菲尔德（Penfield）和贾斯珀（Jasper）基于对癫痫患者的电刺激研究结果，提出假设认为，在楔前叶中应该可以找到身体的感觉代表区。他们将这一代表区命名为“补充感觉”区，并强调基于他们的结果，无法确定这个小人模型的确切形式。在接下来的几十年中，他们的预测被忽视了。虽然已经发现楔前叶参与了许多运动、认知和视觉过程，但没有人研究过其躯体感觉组织形式。在这里，我们使用周期性实验设计，让 16 名受试者（8 名女性）移动 20 个身体部位，以研究楔前叶可能的身体部位拓扑结构。我们发现了一个从前向后、从背侧向腹侧、从脚趾到舌头的镜像排列的梯度，与 SMA 相反。当检查特定身体部位的功能连接时，我们发现不同身体部位与初级和次级运动区、顶叶和视觉区的连接存在差异模式，以及与外侧体区的共享连接，外侧体区也是一个具有拓扑组织的区域。我们认为，楔前叶中可以找到一个全身梯度，与具有不同连接模式的多个大脑区域相连，不同的身体部位连接不同的大脑区域。它的确切作用及其与楔前叶的其他已知功能（如自我加工、运动想象、伸手、视动和其他身心功能）的关系，都应该进行研究。使用 fMRI 以及敏感的频谱分析，我们在楔前叶中发现了一个新的小人模型：一个从前向后、从背侧向腹侧、从脚趾到舌头的镜像排列的躯体感觉梯度，与 SMA 相反。当检查特定身体部位的功能连接时，我们发现不同身体部位与初级和次级运动区、顶叶和视觉区的连接存在差异模式，以及与外侧体区的共享连接，外侧体区也是一个具有拓扑组织的区域。我们认为，楔前叶中可以找到一个全身梯度，并且以特定于身体部位的方式与多个大脑区域相连。
