Keltner John R, Furst Ansgar, Fan Catherine, Redfern Rick, Inglis Ben, Fields Howard L
Pain Management Center, Department of Anesthesia and Perioperative Care, University of California San Francisco, California 94143, USA.
J Neurosci. 2006 Apr 19;26(16):4437-43. doi: 10.1523/JNEUROSCI.4463-05.2006.
We use a novel balanced experimental design to specifically investigate brain mechanisms underlying the modulating effect of expected pain intensity on afferent nociceptive processing and pain perception. We used two visual cues, each conditioned to one of two noxious thermal stimuli [ approximately 48 degrees C (high) or 47 degrees C (low)]. The visual cues were presented just before and during application of the noxious thermal stimulus. Subjects reported significantly higher pain when the noxious stimulus was preceded by the high-intensity visual cue. To control for expectancy effects, for one-half of the runs, the noxious thermal stimuli were accompanied by the cue conditioned to the other stimulus. Comparing functional magnetic resonance imaging blood oxygenation level-dependent activations produced by the high and low thermal stimulus intensities presented with the high-intensity visual cue showed significant activations in nociceptive regions of the thalamus, second somatosensory cortex, and insular cortex. To isolate the effect of expectancy, we compared activations produced by the two visual cues presented with the high-intensity noxious thermal stimulus; this showed significant differences in the ipsilateral caudal anterior cingulate cortex, the head of the caudate, cerebellum, and the contralateral nucleus cuneiformis (nCF). We propose that pain intensity expectancy modulates activations produced by noxious stimuli through a distinct modulatory network that converges with afferent nociceptive input in the nCF.
我们采用一种新颖的平衡实验设计，专门研究预期疼痛强度对传入性伤害性处理和疼痛感知的调节作用背后的脑机制。我们使用了两种视觉线索，每种线索都与两种有害热刺激之一（约48摄氏度（高强度）或47摄氏度（低强度））相关联。在施加有害热刺激之前和期间呈现视觉线索。当有害刺激之前出现高强度视觉线索时，受试者报告的疼痛明显更高。为了控制预期效应，在一半的实验中，有害热刺激伴随着与另一种刺激相关联的线索。比较在高强度视觉线索呈现下，高低不同热刺激强度所产生的功能磁共振成像血氧水平依赖激活，结果显示在丘脑、第二体感皮层和岛叶皮层的伤害性区域有显著激活。为了分离预期效应，我们比较了在高强度有害热刺激下呈现的两种视觉线索所产生的激活；这显示在同侧尾侧前扣带回皮层、尾状核头部、小脑和对侧楔状核（nCF）存在显著差异。我们提出，疼痛强度预期通过一个独特的调节网络来调节有害刺激所产生的激活，该网络在nCF与传入性伤害性输入汇聚。
