Williams S R, Chapman C E
Centre de Recherche en Sciences Neurologiques, Faculté de Médecine, Université de Montréal, Montreal, Quebec H3C 3J7, Canada.
J Neurophysiol. 2000 Aug;84(2):863-75. doi: 10.1152/jn.2000.84.2.863.
This study examined the effect of systematically varying stimulus intensity on the time course and magnitude of movement-related gating of tactile detection and scaling in 17 human subjects trained to perform a rapid abduction of the right index finger (D2) in response to a visual cue. Electrical stimulation was delivered to D2 at five different intensities. At the lowest intensity, approximately 90% of stimuli were detected at rest (1 x P(90)); four multiples of this intensity were also tested (1.25, 1.5, 1.75, and 2. 0 x P(90)). At all intensities of stimulation, detection of stimuli applied to the moving digit was diminished significantly and in a time-dependent manner, with peak decreases occurring within +/-12 ms of the onset of electromyographic activity in the first dorsal interosseous (25-45 ms before movement onset). Reductions in the proportion of stimuli detected were greatest at the lowest stimulus intensity and progressively smaller at higher intensities. No shift in the timing of the decreases in performance was seen with increasing intensity. Once the weakest intensity at which most stimuli were perceived during movement had been established (2 x P(90)), magnitude estimation experiments were performed using two stimulus intensities, 2 x P(90) (5 subjects) and 3 x P(90) (3 subjects). Significant movement-related decreases in estimated stimulus magnitude were observed at both intensities, the time course of which was similar to the time course of reductions in detection performance. As stimulus intensity increased, the magnitude of the movement-related decrease in scaling diminished. A model of detection performance that accurately described the effect of stimulus intensity and timing on movement-related reductions in detection was created. This model was then combined with a previous model that described the effects of stimulus localization and timing to predict detection performance at a given stimulation site, intensity, and time during movement. Movement-related gating of tactile perception represents the end result of movement-related effects on the transmission and subsequent processing of the stimulus. The combined model clearly defines many of the requirements that proposed physiological mechanisms of movement-related gating will have to fulfill.
本研究考察了在17名接受训练以响应视觉提示而快速外展右手食指（D2）的人类受试者中，系统改变刺激强度对触觉检测和缩放的运动相关门控的时间进程和幅度的影响。以五种不同强度对D2进行电刺激。在最低强度下，静止时约90%的刺激可被检测到（1×P(90)）；还测试了该强度的四倍（1.25、1.5、1.75和2.0×P(90)）。在所有刺激强度下，施加于运动手指的刺激检测均显著减少，且呈时间依赖性，峰值减少出现在第一背侧骨间肌肌电图活动开始后的±12毫秒内（运动开始前25 - 45毫秒）。在最低刺激强度下，检测到的刺激比例下降最大，在较高强度下逐渐减小。随着强度增加，性能下降的时间没有变化。一旦确定了运动期间大多数刺激被感知的最弱强度（2×P(90)），便使用两种刺激强度进行大小估计实验，即2×P(90)（5名受试者）和3×P(90)（3名受试者）。在两种强度下均观察到与运动相关的估计刺激大小显著下降，其时间进程与检测性能下降的时间进程相似。随着刺激强度增加，与运动相关的缩放下降幅度减小。创建了一个准确描述刺激强度和时间对与运动相关的检测减少影响的检测性能模型。然后将该模型与先前描述刺激定位和时间影响的模型相结合，以预测在给定刺激部位、强度和运动期间时间的检测性能。触觉感知的运动相关门控代表了运动对刺激传递和后续处理的影响的最终结果。该组合模型清楚地定义了许多与运动相关门控的拟议生理机制必须满足的要求。
