Schaefer Michael, Flor Herta, Heinze Hans-Jochen, Rotte Michael
Department of Neurology II, Otto-von-Guericke University Magdeburg, 39120 Magdeburg, Germany.
Neuroimage. 2007 Jul 1;36(3):700-5. doi: 10.1016/j.neuroimage.2007.03.046. Epub 2007 Apr 3.
Recent studies suggest that in contrast to traditional views of the body map the topographic representation in primary somatosensory cortex (SI) reflects the perceived rather than the physical aspects of peripheral stimulation. Here, we created a simple illusion of feeling an elongated arm by using the dominance of the visual domain over the tactile sense: employing an artificial hand and arm, which were connected to the body, subjects were given the visual impression that they had an extended arm. Since it is known from animal studies that tactile illusions alter early sensory processing in SI, we expected a modulation of the topography in SI corresponding to this illusion. Behavioral results showed that during the illusion the participants felt that their arm was elongated. Neuromagnetic source imaging of the functional organization in SI revealed that the cortical distance between first (D1) and fifth digit (D5) decreased when subjects felt the arm elongated. Since this modulation was significantly positively correlated with the illusionary feeling of an extended arm, the results suggest an involvement of SI during perceived changes in the size of body parts. We discuss the results as possible top-down modulations of SI by higher order somatosensory areas.
最近的研究表明，与传统的身体图谱观点相反，初级体感皮层（SI）中的拓扑表征反映的是外周刺激的感知方面而非物理方面。在此，我们利用视觉领域对触觉的主导作用，创造了一种感觉手臂变长的简单错觉：使用与身体相连的假手和假臂，让受试者产生他们有一条延长手臂的视觉印象。由于从动物研究中已知触觉错觉会改变SI中的早期感觉处理，我们预期SI中的拓扑结构会对应于这种错觉而发生调制。行为结果表明，在错觉期间，参与者感觉他们的手臂变长了。对SI功能组织的神经磁源成像显示，当受试者感觉手臂变长时，食指（D1）和小指（D5）之间的皮层距离减小。由于这种调制与手臂延长的错觉感觉显著正相关，结果表明在身体部位大小的感知变化过程中SI参与其中。我们将这些结果讨论为高阶体感区域对SI可能的自上而下的调制。
