Nguyen Elizabeth H L, Taylor Janet L, Brooks Jack, Seizova-Cajic Tatjana
Faculty of Health Sciences, University of Sydney, Sydney, Australia;
Neuroscience Research Australia, Sydney, Australia; and University of New South Wales, Sydney, Australia.
J Neurophysiol. 2016 Feb 1;115(2):674-84. doi: 10.1152/jn.00707.2015. Epub 2015 Nov 25.
We investigated the influence of motion context on tactile localization, using a paradigm similar to the cutaneous rabbit or sensory saltation (Geldard FA, Sherrick CE. Science 178: 178-179, 1972). In one of its forms, the rabbit stimulus consists of a tap in one location quickly followed by another tap elsewhere, creating the illusion that the two taps are near each other. Instead of taps, we used position of a halted brush and instead of distance judgment, localization responses. The brush moved across the skin of the left forearm, creating a clear motion signal before and after a rabbitlike leap of 10 cm (at 100 cm/s). Three before-and-after velocities (7.5, 15, or 30 cm/s) were used. Participants (n = 13) pointed with their right arm at the felt location of the brush when it halted either 1 cm before or after the leap. These stops were 12 cm apart, but distances computed from localization responses were only 5.4, 6.5, and 7.5 cm for the three velocities, respectively (F[2,11] = 15.19, P = 0.001). Thus the leap resulted in compressive position shift, as described previously for sensory saltation, but modulated by motion velocity before the leap: the slower the motion, the greater the shift opposite to motion direction. No gap in stimulation was perceived. We propose that velocity extrapolation causes the position shift: extrapolated motion does not have enough time to bridge the real spatial gap and thus assigns a closer location to the skin on the opposite side of the gap.
我们采用一种类似于皮肤兔或感觉跳跃(Geldard FA,Sherrick CE。《科学》178:178 - 179,1972)的范式,研究了运动背景对触觉定位的影响。在其一种形式中,兔刺激由在一个位置的轻敲迅速跟随在其他位置的另一次轻敲组成,产生一种两个轻敲彼此靠近的错觉。我们用静止刷子的位置代替轻敲,并用定位反应代替距离判断。刷子在左前臂皮肤上移动,在类似兔跳跃式的10厘米(速度为100厘米/秒)前后产生清晰的运动信号。使用了三种前后速度(7.5、15或30厘米/秒)。当刷子在跳跃前或跳跃后1厘米处停止时,参与者(n = 13)用右臂指出他们感觉到的刷子位置。这两个停止位置相距12厘米,但根据定位反应计算出的距离对于三种速度分别仅为5.4厘米、6.5厘米和7.5厘米(F[2,11] = 15.19,P = 0.001)。因此,如先前对感觉跳跃所描述的那样,跳跃导致了压缩性位置偏移,但这种偏移受跳跃前运动速度的调节:运动速度越慢,与运动方向相反的偏移越大。没有察觉到刺激间隙。我们提出速度外推导致了位置偏移:外推运动没有足够的时间跨越实际空间间隙,因此将间隙另一侧皮肤上更靠近的位置分配给了它。