Evidence for thalamic involvement in the thermal grill illusion: an FMRI study.
Evidence for thalamic involvement in the thermal grill illusion: an FMRI study.
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DOI：
10.1371/journal.pone.0027075
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发表时间：
2011
期刊：
影响因子：
3.7
通讯作者：
Ingvar M
中科院分区：
文献类型：
--
作者：
Lindstedt F;Johansson B;Martinsen S;Kosek E;Fransson P;Ingvar M
知觉错觉在解开意识现象背后的神经机制方面发挥着重要作用。热烧烤错觉(TGI)被认为是探索神经病理性疼痛知觉的一种很有前途的模型，如冷痛(因接触无害的寒冷而产生的疼痛)。TGI是一种因触摸并列的寒冷和温暖的棒而产生的不适/痛苦的感觉，温度无害。开发一种与MRI兼容的TGI单元，并使用功能磁共振成像在一组健康志愿者中探索错觉的棘上相关性。我们构建了TGI热模式，允许在功能磁共振成像环境中快速呈现热(41°C)、冷(18°C)和交错(41°C+18°C = TGI)温度。20名志愿者接受了测试。对每个刺激物的情感-动机(“不愉快”)和感觉-刺激(“疼痛-强度”)维度进行了评级。对功能图像进行校正后的α水平分析。TGI被评为明显比在每种组成温度下的刺激更令人不快和痛苦。此外，TGI被评为明显不愉快而不是痛苦。热刺激与中性基线相比，显示双侧前岛和额顶区的激活。与其组成温度不同，TGI表现出右侧(对侧)丘脑的强烈激活。在稍微更自由的阈值水平上的探索性对比也显示了右侧岛中/前岛的TGI激活，这与不愉快的评级相关(Rho = 0.31)。据我们所知，这是第一次对TGI进行功能磁共振研究。前脑岛的激活与该区域在处理内稳态相关感觉状态中的假定作用是一致的。我们的结果构成了丘脑参与TGI的第一个神经生理学证据。在中枢神经病理性疼痛的患者中，也曾观察到类似的丘脑活动。我们的结果进一步加深了对TGI现象的棘上相关性的理解，并为未来探讨它是否以及如何与神经病理性疼痛相关铺平了道路。
Perceptual illusions play an important role in untangling neural mechanisms underlying conscious phenomena. The thermal grill illusion (TGI) has been suggested as a promising model for exploring percepts involved in neuropathic pain, such as cold-allodynia (pain arising from contact with innocuous cold). The TGI is an unpleasant/painful sensation from touching juxtapositioned bars of cold and warm innocuous temperatures. To develop an MRI-compatible TGI-unit and explore the supraspinal correlates of the illusion, using fMRI, in a group of healthy volunteers. We constructed a TGI-thermode allowing the rapid presentation of warm(41°C), cold(18°C) and interleaved(41°C+18°C = TGI) temperatures in an fMRI-environment. Twenty volunteers were tested. The affective-motivational (“unpleasantness”) and sensory-disciminatory (“pain-intensity”) dimensions of each respective stimulus were rated. Functional images were analyzed at a corrected α-level <0.05. The TGI was rated as significantly more unpleasant and painful than stimulation with each of its constituent temperatures. Also, the TGI was rated as significantly more unpleasant than painful. Thermal stimulation versus neutral baseline revealed bilateral activations of the anterior insulae and fronto-parietal regions. Unlike its constituent temperatures the TGI displayed a strong activation of the right (contralateral) thalamus. Exploratory contrasts at a slightly more liberal threshold-level also revealed a TGI-activation of the right mid/anterior insula, correlating with ratings of unpleasantness(rho = 0.31). To the best of our knowledge, this is the first fMRI-study of the TGI. The activation of the anterior insula is consistent with this region's putative role in processing of homeostatically relevant feeling-states. Our results constitute the first neurophysiologic evidence of thalamic involvement in the TGI. Similar thalamic activity has previously been observed during evoked cold-allodynia in patients with central neuropathic pain. Our results further the understanding of the supraspinal correlates of the TGI-phenomenon and pave the way for future inquiries into if and how it may relate to neuropathic pain.
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