Department of Neurology, Otto-von-Guericke University Magdeburg, Magdeburg, Germany.
PLoS One. 2012;7(8):e42308. doi: 10.1371/journal.pone.0042308. Epub 2012 Aug 17.
An increasing body of evidence has demonstrated that in contrast to the classic understanding the primary somatosensory cortex (SI) reflects merely seen touch (in the absence of any real touch on the own body). Based on these results it has been discussed that SI may play a role in understanding touch seen on other bodies. In order to further examine this understanding of observed touch, the current study aimed to test if mirror-like responses in SI are affected by the perspective of the seen touch. Thus, we presented touch on a hand and close to the hand either in first-person-perspective or in third-person-perspective.
Results of functional magnetic resonance imaging (fMRI) revealed stronger vicarious brain responses in SI/BA2 for touch seen in first-person-perspective. Surprisingly, the third-person viewpoint revealed activation in SI both when subjects viewed a hand being stimulated as well as when the space close to the hand was being touched.
CONCLUSIONS/SIGNIFICANCE: Based on these results we conclude that vicarious somatosensory responses in SI/BA2 are affected by the viewpoint of the seen hand. Furthermore, we argue that mirror-like responses in SI do not only reflect seen touch, but also the peripersonal space surrounding this body (in third-person-perspective). We discuss these findings with recent studies on mirror responses for action observation in peripersonal space.
越来越多的证据表明，与经典理解相反，初级体感皮层（SI）不仅反映了所见的触觉（在自身身体没有任何实际触摸的情况下）。基于这些结果，有人讨论说，SI 可能在理解其他身体上看到的触觉中发挥作用。为了进一步研究对观察到的触觉的这种理解，本研究旨在测试 SI 中的镜像反应是否受到所看到的触觉视角的影响。因此，我们在手和手附近以第一人称视角或第三人称视角呈现触觉。
功能磁共振成像（fMRI）的结果显示，在第一人称视角下看到的触觉在 SI/BA2 中引起了更强的替代性大脑反应。令人惊讶的是，当被试观察到手被刺激时，以及当手附近的空间被触摸时，第三人称视角在 SI 中也显示出了激活。
结论/意义：基于这些结果，我们得出结论，SI/BA2 中的替代性体感反应受到所看到的手的视角的影响。此外，我们认为 SI 中的镜像反应不仅反映了所见的触觉，还反映了身体周围的近体空间（在第三人称视角下）。我们将这些发现与最近关于近体空间中动作观察的镜像反应的研究进行了讨论。
