Sadibolova Renata, Tamè Luigi, Walsh Eamonn, Longo Matthew R
Department of Psychological Sciences, Birkbeck, University of London, London, United Kingdom.
Institute of Psychiatry, Psychology, and Neuroscience, King's College London, London, United Kingdom.
Front Hum Neurosci. 2018 Feb 13;12:55. doi: 10.3389/fnhum.2018.00055. eCollection 2018.
In this study, we aimed to relate the findings from two predominantly separate streams of literature, one reporting on the localization of single touches on the skin, and the other on the distance perception of dual touches. Participants were touched with two points, delivered either simultaneously or separated by a short delay to various locations on their left hand dorsum. They then indicated on a size-matched hand silhouette the perceived locations of tactile stimuli. We quantified the deviations between the actual stimulus grid and the corresponding perceptual map which was constructed from the perceived tactile locations, and we calculated the precision of tactile localization (i.e., the variability across localization attempts). The evidence showed that the dual touches, akin to single touch stimulations, were mislocalized distally and that their variable localization error was reduced near joints, particularly near knuckles. However, contrary to single-touch localization literature, we observed for the dual touches to be mislocalized towards the ulnar side of the hand, particularly when they were presented sequentially. Further, the touches presented in a sequential order were slightly "repelled" from each other and their perceived distance increased, while the simultaneous tactile pairs were localized closer to each other and their distance was compressed. Whereas the sequential touches may have been localized with reference to the body, the compression of tactile perceptual space for simultaneous touches was related in the previous literature to signal summation and inhibition and the low-level factors, including the innervation density and properties of receptive fields (RFs) of somatosensory neurons.
在本研究中，我们旨在关联来自两个主要独立文献流的研究结果，一个报告关于皮肤上单点触摸的定位，另一个报告关于双点触摸的距离感知。用两个点触摸参与者，这两个点要么同时施加，要么相隔很短的延迟，施加于他们左手背的不同位置。然后，他们在一个尺寸匹配的手部轮廓图上指出触觉刺激的感知位置。我们对实际刺激网格与根据感知到的触觉位置构建的相应感知图之间的偏差进行了量化，并计算了触觉定位的精度（即定位尝试之间的变异性）。证据表明，与单点触摸刺激类似，双点触摸在远端被错误定位，并且它们的可变定位误差在关节附近，特别是指关节附近减小。然而，与单点触摸定位文献相反，我们观察到双点触摸在手的尺侧被错误定位，特别是当它们依次呈现时。此外，依次呈现的触摸彼此之间略有“排斥”，它们感知到的距离增加，而同时呈现的触觉对彼此定位得更近，它们的距离被压缩。虽然依次触摸可能是参照身体进行定位的，但在先前的文献中，同时触摸时触觉感知空间的压缩与信号总和与抑制以及包括体感神经元的神经支配密度和感受野（RF）特性在内的低层次因素有关。
