Dowman Robert, Rissacher Daniel, Schuckers Stephanie
Department of Psychology, Clarkson University, Potsdam, NY 13699-5825, USA.
Clin Neurophysiol. 2008 May;119(5):1201-12. doi: 10.1016/j.clinph.2008.01.019. Epub 2008 Mar 11.
To identify EEG features that index pain-related cortical activity, and to identify factors that can mask the pain-related EEG features and/or produce features that can be misinterpreted as pain-specific.
The EEG was recorded during three conditions presented in counterbalanced order: a tonic cold pain condition, and pain anticipation and arithmetic control conditions. The EEG was also recorded while the subjects made a wincing facial expression to estimate the contribution of scalp EMG artifacts to the pain-related EEG features.
Alpha amplitudes decreased over the contralateral temporal scalp and increased over the posterior scalp during the cold pain condition. There was an increase in gamma band activity during the cold pain condition at most electrode locations that was due to EMG artifacts.
The decrease in alpha over the contralateral temporal scalp during cold pain is consistent with pain-related activity in the primary somatosensory cortex and/or the somatosensory association areas located in the parietal operculum and/or insula. This study also identified factors that might mask the pain-related EEG features and/or generate EEG features that could be misinterpreted as being pain-specific. These include (but are not limited to) an increase in alpha generated in the visual cortex that results from attention being drawn towards the pain; the widespread increase in gamma band activity that results from scalp EMG generated by the facial expressions that often accompany pain; and the possibility that non-specific changes in the EEG over time mask the pain-related EEG features when the pain and control conditions are given in the same order across subjects.
This study identified several factors that need to be controlled and/or isolated in order to successfully record EEG features that index pain-related activity in the somatosensory cortices.
识别指示疼痛相关皮层活动的脑电图（EEG）特征，并识别可能掩盖疼痛相关EEG特征和/或产生可能被误解为疼痛特异性特征的因素。
在以平衡顺序呈现的三种条件下记录EEG：强直性冷痛条件、疼痛预期和算术对照条件。还在受试者做出畏缩面部表情时记录EEG，以估计头皮肌电图伪迹对疼痛相关EEG特征的影响。
在冷痛条件下，对侧颞部头皮的α波幅降低，而后部头皮的α波幅增加。在冷痛条件下，大多数电极位置的γ波段活动增加，这是由肌电图伪迹引起的。
冷痛期间对侧颞部头皮α波的降低与初级体感皮层和/或位于顶叶岛盖和/或脑岛的体感联合区的疼痛相关活动一致。本研究还确定了可能掩盖疼痛相关EEG特征和/或产生可能被误解为疼痛特异性的EEG特征的因素。这些因素包括（但不限于）：由于注意力转向疼痛而在视觉皮层中产生的α波增加；由通常伴随疼痛的面部表情产生的头皮肌电图导致的γ波段活动广泛增加；以及当疼痛和对照条件在受试者之间以相同顺序呈现时，EEG随时间的非特异性变化掩盖疼痛相关EEG特征的可能性。
本研究确定了几个需要控制和/或分离的因素，以便成功记录指示体感皮层中疼痛相关活动的EEG特征。
