Besle Julien, Sánchez-Panchuelo Rosa-Maria, Bowtell Richard, Francis Susan, Schluppeck Denis
Visual Neuroscience Group, School of Psychology, University of Nottingham, NG7 2RD, Nottingham, United Kingdom.
Hum Brain Mapp. 2014 May;35(5):2027-43. doi: 10.1002/hbm.22310. Epub 2013 Sep 3.
Recent fMRI studies of the human primary somatosensory cortex have been able to differentiate the cortical representations of different fingertips at a single-subject level. These studies did not, however, investigate the expected overlap in cortical activation due to the stimulation of different fingers. Here, we used an event-related design in six subjects at 7 Tesla to explore the overlap in cortical responses elicited in S1 by vibrotactile stimulation of the five fingertips. We found that all parts of S1 show some degree of spatial overlap between the cortical representations of adjacent or even nonadjacent fingertips. In S1, the posterior bank of the central sulcus showed less overlap than regions in the post-central gyrus, which responded to up to five fingertips. The functional properties of these two areas are consistent with the known layout of cytoarchitectonically defined subareas, and we speculate that they correspond to subarea 3b (S1 proper) and subarea 1, respectively. In contrast with previous fMRI studies, however, we did not observe discrete activation clusters that could unequivocally be attributed to different subareas of S1. Venous maps based on T2*-weighted structural images suggest that the observed overlap is not driven by extra-vascular contributions from large veins.
近期对人类初级躯体感觉皮层的功能磁共振成像（fMRI）研究已能够在单受试者水平上区分不同指尖的皮层表征。然而，这些研究并未探究因不同手指受到刺激而在皮层激活方面预期存在的重叠情况。在此，我们采用事件相关设计，对6名受试者在7特斯拉磁场强度下进行研究，以探索通过对五个指尖进行振动触觉刺激在初级体感皮层（S1）引发的皮层反应中的重叠情况。我们发现，初级体感皮层的所有部分在相邻甚至非相邻指尖的皮层表征之间均呈现出一定程度的空间重叠。在初级体感皮层中，中央沟后缘的重叠程度低于中央后回中对多达五个指尖产生反应的区域。这两个区域的功能特性与细胞构筑学定义的子区域的已知布局相符，我们推测它们分别对应于3b区（狭义的初级体感皮层）和1区。然而，与先前的功能磁共振成像研究不同的是，我们并未观察到能够明确归因于初级体感皮层不同子区域的离散激活簇。基于T2 *加权结构图像的静脉图谱表明，观察到的重叠并非由大静脉的血管外贡献所驱动。
