Babiloni Claudio, Capotosto Paolo, Brancucci Alfredo, Del Percio Claudio, Petrini Laura, Buttiglione Maura, Cibelli Giuseppe, Romani Gian Luca, Rossini Paolo Maria, Arendt-Nielsen Lars
Department of Biomedical Sciences, University of Foggia, Foggia, Italy.
J Pain. 2008 Oct;9(10):902-11. doi: 10.1016/j.jpain.2008.05.007. Epub 2008 Jul 10.
We tested whether cortical activation anticipating painful stimuli is reduced more by integrative processes on somatosensory painful and motor information relative to the same hand than when that information refers to different hands. In 3 conditions, visual warning stimuli were followed by visual target stimuli associated with an electrical painful stimulation at left index finger. In the Pain (control) condition, no task was required after the target stimuli. In the "Pain + ipsilateral movement" condition, the subjects had to perform a movement of the left index finger. In the "Pain + contralateral movement" condition, they had to perform a movement of the right index finger. Meanwhile, electroencephalographic data were recorded (n = 18) from 128 scalp electrodes. Off line, these data were spatially enhanced by surface Laplacian transformation. Sensorimotor cortical activation before the painful stimulation was probed by the percentage power reduction of alpha rhythms at approximately 8 to 12 Hz (event-related desynchronization, ERD). Results showed that the subjects perceived a lower stimulus intensity in both "Pain + ipsilateral" and "Pain + contralateral" conditions compared with the control "Pain" condition. Furthermore, wide anticipatory alpha ERD (approximately 10-12 Hz) was lower in amplitude in the "Pain + ipsilateral" than in the "Pain + contralateral" condition. These results suggest that modulation of alpha rhythms is a putative physiological mechanism underlying anticipatory processes preceding the integration of painful and motor information at cortical level. Furthermore, these processes show a marked interference ("gating") when the sensorimotor integration refer to the same hand as opposed to both hands.
We showed that cortical alpha rhythms preceding painful stimulation are influenced by the preparation of contralateral and ipsilateral finger movements. These results motivate further investigation for testing the hypothesis that chronic pain patients might exaggerate the anticipatory activation of sensorimotor cortex to negligible pain stimuli.
我们测试了，相对于信息涉及不同手的情况，当体感疼痛和运动信息关于同一只手时，整合过程对预期疼痛刺激的皮层激活的减少作用是否更大。在3种条件下，视觉警告刺激之后是与左手食指电疼痛刺激相关的视觉目标刺激。在疼痛（对照）条件下，目标刺激之后无需执行任务。在“疼痛+同侧运动”条件下，受试者必须进行左手食指的运动。在“疼痛+对侧运动”条件下，他们必须进行右手食指的运动。同时，从128个头皮电极记录脑电图数据（n = 18）。离线时，这些数据通过表面拉普拉斯变换进行空间增强。通过大约8至12 Hz的α节律功率降低百分比（事件相关去同步化, ERD）来探测疼痛刺激前的感觉运动皮层激活。结果显示，与对照“疼痛”条件相比，受试者在“疼痛+同侧”和“疼痛+对侧”条件下均感觉到较低的刺激强度。此外，“疼痛+同侧”条件下广泛的预期α ERD（约10 - 12 Hz）幅度低于“疼痛+对侧”条件。这些结果表明，α节律的调制是皮层水平上疼痛和运动信息整合之前预期过程的一种假定生理机制。此外，当感觉运动整合涉及同一只手而非两只手时，这些过程表现出明显的干扰（“门控作用”）。
我们表明，疼痛刺激前的皮层α节律受对侧和同侧手指运动准备的影响。这些结果促使进一步研究，以检验慢性疼痛患者可能会将感觉运动皮层对可忽略不计的疼痛刺激的预期激活夸大这一假设。
