Graduate Institute of Brain and Mind Sciences, National Taiwan University College of Medicine, Taipei, Taiwan.
Pain. 2018 Feb;159(2):359-370. doi: 10.1097/j.pain.0000000000001086.
Humans require the ability to discriminate intensities of noxious stimuli to avoid future harm. This discrimination process seems to be biased by an individual's attention to pain and involves modulation of the relative intensity differences between stimuli (ie, Weber fraction). Here, we ask whether attention networks in the brain modulate the discrimination process and investigate the neural correlates reflecting the Weber fraction for pain intensity. In a delayed discrimination task, participants differentiated the intensity of 2 sequentially applied stimuli after a delay interval. Compared with nonpain discrimination, pain discrimination performance was modulated by participants' vigilance to pain, which was reflected by the functional connectivity between the left inferior parietal lobule and the right thalamus. Of note, this vigilance-related functional coupling specifically predicted participants' behavioral ability to differentiate pain intensities. Moreover, unique to pain discrimination tasks, the response in the right superior frontal gyrus linearly represented the Weber fraction for pain intensity, which significantly biased participants' pain discriminability. These findings suggest that pain intensity discrimination in humans relies on vigilance-related enhancement in the parieto-thalamic attention network, thereby allowing the prefrontal cortex to estimate the relative intensity differences between noxious stimuli.
人类需要辨别有害刺激的强度，以避免未来受到伤害。这种辨别过程似乎受到个体对疼痛的注意力的影响，并且涉及到刺激之间相对强度差异的调制（即韦伯分数）。在这里，我们询问大脑中的注意力网络是否调节了辨别过程，并研究反映疼痛强度韦伯分数的神经相关物。在延迟辨别任务中，参与者在延迟间隔后辨别 2 个顺序应用的刺激的强度。与非疼痛辨别相比，疼痛辨别表现受到参与者对疼痛警觉性的调节，这反映在左顶下小叶和右丘脑之间的功能连接上。值得注意的是，这种与警觉性相关的功能耦合特别预测了参与者区分疼痛强度的行为能力。此外，在疼痛辨别任务中特有的是，右额上回的反应线性表示疼痛强度的韦伯分数，这显著地影响了参与者的疼痛辨别能力。这些发现表明，人类的疼痛强度辨别依赖于顶叶-丘脑注意力网络中与警觉性相关的增强，从而使前额叶皮层能够估计有害刺激之间的相对强度差异。
