Valmunen Tanja, Pertovaara Antti, Taiminen Tero, Virtanen Arja, Parkkola Riitta, Jääskeläinen Satu K
Department of Clinical Neurophysiology, Turku University Hospital, P.O. Box 52, 20521 Turku, Finland.
Pain. 2009 Mar;142(1-2):149-58. doi: 10.1016/j.pain.2008.12.031. Epub 2009 Feb 6.
Repetitive transcranial magnetic stimulation (rTMS) has had partly incongruous effects on cutaneous sensibility, and there are no systematic studies on the effects of rTMS on facial sensory function. We assessed modulation of thermal sensitivity of facial skin in healthy subjects by navigated rTMS (10 Hz), enabling accurate localization of predefined cortical targets: right primary motor cortex (M1) of facial muscles, primary somatosensory cortex (S1) representing the cheek, dorsolateral prefrontal cortex (DLPFC), and secondary somatosensory cortex (S2); the control site was occipital cortex (OCC). Applying signal detection theory, we investigated whether the rTMS-induced changes in heat-pain threshold (HPT) relate to an alteration in the subject's discriminative capacity (sensory factor) or response criterion (non-sensory factor). HPT increased after stimulation of S2, but also 45 min after stimulation of DLPFC and OCC. S2 stimulation produced the most effective and long-lasting heat hypoalgesia that was associated with a decrease in discriminative capacity and an increase in response criterion. Cold-pain threshold was elevated after S2 stimulation only in men. Stimulation of M1 decreased capacity to discriminate painful heat without influencing HPT; there was large interindividual variation in rTMS effects in the M1/S1 areas. Detection threshold for innocuous warming rose similarly after rTMS of M1, S1, DLPFC, S2 and OCC, whereas sensibility to innocuous cooling transiently improved after rTMS of S1. The results indicate that rTMS applied anatomically accurately to S2 may produce analgesia in the face via multiple mechanisms, partly depending on gender, and involving decreased discriminative capacity and increased response criterion.
重复经颅磁刺激（rTMS）对皮肤感觉的影响部分不一致，且尚无关于rTMS对面部感觉功能影响的系统性研究。我们通过导航rTMS（10Hz）评估了健康受试者面部皮肤热敏感性的调制情况，从而能够精确定位预定义的皮质靶点：面部肌肉的右侧初级运动皮层（M1）、代表脸颊的初级躯体感觉皮层（S1）、背外侧前额叶皮层（DLPFC）和次级躯体感觉皮层（S2）；对照部位为枕叶皮层（OCC）。应用信号检测理论，我们研究了rTMS诱导的热痛阈值（HPT）变化是否与受试者的辨别能力（感觉因素）或反应标准（非感觉因素）的改变有关。刺激S2后HPT升高，刺激DLPFC和OCC后45分钟HPT也升高。S2刺激产生了最有效且持久的热痛觉减退，这与辨别能力下降和反应标准增加有关。仅在男性中，S2刺激后冷痛阈值升高。刺激M1降低了辨别热痛的能力，但不影响HPT；M1/S1区域的rTMS效应存在较大的个体差异。M1、S1、DLPFC、S2和OCC进行rTMS后，无害温热的检测阈值同样升高，而S1进行rTMS后，对无害冷却的敏感性短暂改善。结果表明，在解剖学上精确应用于S2的rTMS可能通过多种机制在面部产生镇痛作用，部分取决于性别，且涉及辨别能力下降和反应标准增加。
