Changing reference frames during the encoding of tactile events
Changing reference frames during the encoding of tactile events
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DOI：
10.1016/j.cub.2008.06.045
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发表时间：
2008-07-22
期刊：
影响因子：
9.2
通讯作者：
Soto-Faraco, Salvador
中科院分区：
文献类型：
--
作者：
Azanon, Elena;Soto-Faraco, Salvador
用手拍蚊子这种不动脑子的行为对大脑来说是一个巨大的挑战。鉴于初级躯体感觉皮层映射皮肤位置独立于手臂姿势[1，2]，大脑必须重新调整触觉坐标，以定位刺激在外部空间的来源。先前的研究已经强调了这种触摸的外部映射的行为相关性，其结果是将体感输入与关于身体姿势的本体感受和视觉线索相结合[3 - 7]。然而，尽管人们普遍认为存在这种从躯体位置到外部空间的重新映射过程，并且各种研究结果间接表明了其后果[8 - 11]，但缺乏对其变化的时间过程和性质的证明。我们研究了这种多感觉交互的时间过程及其对人类触觉意识的影响，使用跨通道提示范式[12，13]。我们所展示的是，在触觉事件被提到外部位置之前[12 - 15]，一个短暂的、无意识的触觉图像遵守一个躯体位置参考框架规则的表现。我们建议，这种早期的躯体"一瞥"产生于最初的前馈扫描的神经活动的初级躯体感觉皮层，而后来的外部为基础的，有意识的经验反映了活动的躯体感觉网络，涉及经常性的连接，从协会领域。
The mindless act of swatting a mosquito on the hand poses a remarkable challenge for the brain. Given that the primary somatosensory cortex maps skin location independently of arm posture [1, 2], the brain must realign tactile coordinates in order to locate the origin of the stimuli in extrapersonal space. Previous studies have highlighted the behavioral relevance of such an external mapping of touch, which results from combining somatosensory input with proprioceptive and visual cues about body posture [3-7]. However, despite the widely held assumption about the existence of this remapping process from somatotopic to external space and various findings indirectly suggesting its consequences [8-11], a demonstration of its changing time course and nature was lacking. We examined the temporal course of this multisensory interaction and its implications for tactile awareness in humans using a crossmodal cueing paradigm [12, 13]. What we show is that before tactile events are referred to external locations [12-15], a fleeting, unconscious image of the tactile sensation abiding to a somatotopic frame of reference rules performance. We propose that this early somatotopic "glimpse" arises from the initial feed-forward sweep of neural activity to the primary somatosensory cortex, whereas the later externally-based, conscious experience reflects the activity of a somatosensory network involving recurrent connections from association areas.