Colon Elisabeth, Legrain Valéry, Huang Gan, Mouraux André
Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium.
Psychophysiology. 2015 Nov;52(11):1498-510. doi: 10.1111/psyp.12511. Epub 2015 Aug 29.
The sustained periodic modulation of a stimulus induces an entrainment of cortical neurons responding to the stimulus, appearing as a steady-state evoked potential (SS-EP) in the EEG frequency spectrum. Here, we used frequency tagging of SS-EPs to study the crossmodal links in spatial attention between touch and vision. We hypothesized that a visual stimulus approaching the left or right hand orients spatial attention toward the approached hand, and thereby enhances the processing of vibrotactile input originating from that hand. Twenty-five subjects took part in the experiment: 16-s trains of vibrotactile stimuli (4.2 and 7.2 Hz) were applied simultaneously to the left and right hand, concomitantly with a punctate visual stimulus blinking at 9.8 Hz. The visual stimulus was approached toward the left or right hand. The hands were either uncrossed (left and right hands to the left and right of the participant) or crossed (left and right hands to the right and left of the participant). The vibrotactile stimuli elicited two distinct SS-EPs with scalp topographies compatible with activity in the contralateral primary somatosensory cortex. The visual stimulus elicited a third SS-EP with a topography compatible with activity in visual areas. When the visual stimulus was over one of the hands, the amplitude of the vibrotactile SS-EP elicited by stimulation of that hand was enhanced, regardless of whether the hands were uncrossed or crossed. This demonstrates a crossmodal effect of spatial attention between vision and touch, integrating proprioceptive and/or visual information to map the position of the limbs in external space.
对刺激进行持续的周期性调制会诱导对该刺激做出反应的皮质神经元产生同步化，在脑电图频谱中表现为稳态诱发电位（SS-EP）。在此，我们使用SS-EP的频率标记来研究触觉和视觉在空间注意力方面的跨模态联系。我们假设，接近左手或右手的视觉刺激会将空间注意力导向被接近的手，从而增强源自该手的振动触觉输入的处理。25名受试者参与了实验：将16秒的振动触觉刺激序列（4.2赫兹和7.2赫兹）同时施加于左手和右手，同时伴有以9.8赫兹闪烁的点状视觉刺激。视觉刺激朝着左手或右手靠近。手的摆放方式分为不交叉（左手和右手分别位于受试者身体的左侧和右侧）或交叉（左手和右手分别位于受试者身体的右侧和左侧）。振动触觉刺激引发了两个不同的SS-EP，其头皮地形图与对侧初级体感皮层的活动相符。视觉刺激引发了第三个SS-EP，其地形图与视觉区域的活动相符。当视觉刺激位于其中一只手上方时，无论手是不交叉还是交叉，刺激该手所引发的振动触觉SS-EP的幅度都会增强。这证明了视觉和触觉在空间注意力方面的跨模态效应，整合了本体感觉和/或视觉信息以在外部空间中映射肢体的位置。
