Valeriani Massimiliano, Arendt-Nielsen Lars, Le Pera Domenica, Restuccia Domenico, Rosso Tiziana, De Armas Liala, Maiese Toni, Fiaschi Antonio, Tonali Pietro, Tinazzi Michele
Istituto di Neurologia, Università Cattolica del Sacro Cuore, L.go A. Gemelli 8, 00168, Rome, Italy.
Clin Neurophysiol. 2003 Oct;114(10):1879-90. doi: 10.1016/s1388-2457(03)00180-9.
To investigate possible neuroplastic changes induced by pain in cerebral areas devoted to nociceptive input processing.
CO(2) laser-evoked potentials (LEPs) were recorded from 10 healthy subjects after stimulation of the right and left hand dorsum. Acute pain was obtained by topical application of capsaicin on the skin of right hand dorsum. LEPs were recorded after right and left hand stimulation before capsaicin, at the peak pain and 10-20 min after capsaicin removal. Right hand LEPs were evoked by laser stimuli delivered over the zone of secondary hyperalgesia during capsaicin and on both the zones of primary and secondary hyperalgesia after capsaicin removal.
After right hand stimulation, the vertex LEPs, which are generated in the cingulate cortex, were significantly decreased in amplitude during capsaicin application and after capsaicin removal. Moreover, the topography of these potentials was modified after capsaicin removal, shifting from the central toward the parietal region. Dipolar modelling showed that the dipolar source in the anterior cingulate cortex moved backward after capsaicin removal. All these changes were not observed after stimulation of the left hand, contralateral to the application of capsaicin, thus suggesting that functional changes are selective for the painful skin and the adjacent territories.
Our results suggest that acute cutaneous pain may inhibit the neural activity in regions of central nervous system processing nociceptive inputs and cortical representation of these inputs can be rapidly modified in presence of acute pain.
研究疼痛在专门用于伤害性输入处理的脑区所诱发的可能的神经可塑性变化。
对10名健康受试者的右手背和左手背进行刺激后，记录二氧化碳激光诱发电位（LEP）。通过在右手背皮肤局部应用辣椒素来诱发急性疼痛。在应用辣椒素之前、疼痛高峰时以及去除辣椒素后10 - 20分钟，分别对右手和左手进行刺激后记录LEP。在应用辣椒素期间，通过在继发性痛觉过敏区域施加激光刺激诱发右手LEP，在去除辣椒素后，在原发性和继发性痛觉过敏区域均施加激光刺激诱发右手LEP。
右手刺激后，在扣带回皮层产生的头顶LEP，在应用辣椒素期间和去除辣椒素后，其波幅显著降低。此外，去除辣椒素后这些电位的地形图发生改变，从中央区域向顶叶区域转移。偶极子模型显示，去除辣椒素后，前扣带回皮层中的偶极子源向后移动。在对与应用辣椒素的手对侧的左手进行刺激后，未观察到所有这些变化，因此表明功能变化对疼痛皮肤及其相邻区域具有选择性。
我们的结果表明，急性皮肤疼痛可能抑制中枢神经系统处理伤害性输入区域的神经活动，并且在急性疼痛存在时，这些输入的皮层表征可迅速改变。
