Mobascher A, Brinkmeyer J, Warbrick T, Musso F, Wittsack H J, Stoermer R, Saleh A, Schnitzler A, Winterer G
Department of Psychiatry, Neuropsychiatric Research Laboratory, Heinrich-Heine University, Duesseldorf, Germany.
Neuroimage. 2009 Feb 1;44(3):1081-92. doi: 10.1016/j.neuroimage.2008.09.004. Epub 2008 Sep 20.
Pain is a complex experience with sensory, emotional and cognitive aspects. It also includes a sympathetic response that can be captured by measuring the electrodermal activity (EDA). The present study was performed to investigate which brain areas are associated with sympathetic activation in experimental pain; an issue that has not been addressed with fMRI (functional magnetic resonance imaging) thus far. Twelve healthy subjects received painful laser stimulation to the left hand. The event-related fMRI BOLD (blood oxygen level dependent) response was measured together with simultaneous EEG (electroencephalography) and EDA recordings. Laser stimuli induced the expected EDA response, evoked EEG potentials and BOLD responses. Single trial EDA amplitudes were used to guide further analysis of fMRI and EEG data. We found significantly higher BOLD responses in trials with high EDA vs. low EDA trials, predominantly in the insula and somatosensory cortex (S1/S2). Likewise, in the EEG we found the N2 laser evoked potentials to have significantly higher amplitudes in trials with high vs. low EDA. Furthermore EDA-informed BOLD modeling explained additional signal variance in sensory areas and yielded higher group level activation. We conclude that the sympathetic response to pain is associated with activation in pain-processing brain regions, predominantly in sensory areas and that single trial (EDA)-information can add to BOLD modeling by taking some of the response variability across trials and subjects into account. Thus, EDA is a useful additional, objective index when pain is studied with fMRI/EEG which might be of particular relevance in the context of genetic- and pharmacoimaging.
疼痛是一种具有感觉、情感和认知等多方面的复杂体验。它还包括一种交感神经反应，这种反应可通过测量皮肤电活动（EDA）来捕捉。本研究旨在探究在实验性疼痛中哪些脑区与交感神经激活相关；这一问题迄今为止尚未通过功能磁共振成像（fMRI）进行研究。12名健康受试者的左手接受了疼痛性激光刺激。在测量事件相关功能磁共振成像血氧水平依赖（BOLD）反应的同时，同步记录脑电图（EEG）和皮肤电活动。激光刺激诱发了预期的皮肤电活动反应、诱发脑电图电位和BOLD反应。单次试验的皮肤电活动幅度用于指导对功能磁共振成像和脑电图数据的进一步分析。我们发现，与低皮肤电活动试验相比，高皮肤电活动试验中的BOLD反应显著更高，主要集中在脑岛和躯体感觉皮层（S1/S2）。同样，在脑电图中，我们发现N2激光诱发电位在高皮肤电活动试验中的幅度显著高于低皮肤电活动试验。此外，基于皮肤电活动的BOLD建模解释了感觉区域中额外的信号方差，并产生了更高的组水平激活。我们得出结论，对疼痛的交感神经反应与疼痛处理脑区的激活相关，主要是在感觉区域，并且单次试验（皮肤电活动）信息可以通过考虑不同试验和受试者之间的一些反应变异性来增加BOLD建模。因此，在使用功能磁共振成像/脑电图研究疼痛时，皮肤电活动是一个有用的额外客观指标，这在基因成像和药物成像的背景下可能具有特别的相关性。
