Department of Orthodontics, College of Dentistry, University of Florida, Gainesville, FL 32610, USA.
Brain Res. 2010 Aug 6;1347:58-64. doi: 10.1016/j.brainres.2010.06.006. Epub 2010 Jun 9.
A psychophysical method of response-dependent stimulation presented ascending and descending series of thermal stimulus intensities that maintained an average rating (setpoint) of mild pain (20 on a scale of 0-100) or moderate pain (35). Subjects were presented with alternating series of thermal stimuli that increased until ratings reached or exceeded the setpoint, then decreased until ratings equaled or were less than the setpoint, then increased, etc. Plots of pain intensity ratings differed substantially for series of ascending and descending stimulus intensities. After an ascending series, pain ratings during a descending series were higher than predicted, and after a descending series, pain ratings during an ascending series were lower than predicted. Thus, the nervous system detects and discriminates between ascending and descending trends in stimulus intensity and alters the magnitude of pain sensations in the direction of the trend of increasing or decreasing stimulus intensity. Ascending (sensitizing) trend effects may increase the magnitude of pathological pain in the absence of treatment, and descending (desensitizing) trend effects likely would enhance the efficacy of procedures that reduce pain sensitivity.
一种基于反应依赖的刺激的心理物理学方法呈现出上升和下降的热刺激强度系列，以维持轻度疼痛（20 分，0-100 分制）或中度疼痛（35 分）的平均评分（设定点）。受试者接受交替的热刺激系列，直到评分达到或超过设定点，然后减少，直到评分等于或小于设定点，然后再次增加，等等。上升和下降刺激强度系列的疼痛强度评分图有很大差异。在上升系列之后，下降系列中的疼痛评分高于预测，而在下降系列之后，上升系列中的疼痛评分低于预测。因此，神经系统可以检测到刺激强度的上升和下降趋势，并在刺激强度增加或减少的趋势方向上改变疼痛感觉的幅度。上升（致敏）趋势效应可能会增加无治疗情况下病理性疼痛的程度，而下降（脱敏）趋势效应可能会增强降低疼痛敏感性的程序的疗效。
