Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Martinistr. 52, Building W34, 20248, Hamburg, Germany.
Sci Rep. 2022 Feb 25;12(1):3199. doi: 10.1038/s41598-022-07208-1.
The perception of pain is modulated by different processes such as, for example, expectations and attention regarding the upcoming stimulus. Such processes are initiated prior to the actual stimulus and are reflected in ongoing brain activity. Different processes that are by definition also complex in itself are reflected in pre-stimulus activity and therefore the detection of this activity pattern should benefit from a multivariate approach. To identify specific pre-stimulus EEG activity patterns related to subsequent pain perception in humans, we contrasted painful with non-painful sensations delivered at the individual threshold level during EEG measurements. The results of the multivariate EEG analysis revealed a high level of accuracy (group mean 68%) in predicting the pain categorization solely based on pre-stimulus activity. In particular, fronto-central regions and activity in the higher gamma band (60:120 Hz) were of maximal importance for classification. Additional analyses supported the specific role of the pattern of high gamma band activity prior to the stimulus for predicting the behavioral outcome and demonstrated that the informational value embedded in the pre-stimulus activity is nearly as informative as the post-stimulus processing and reflects a specific preparatory state. Further, a close relation between pre- and post-stimulus processing in the high gamma band was observed. These findings support the important role of a multivariate cognitive state prior to stimulus appearance for the emergence of the subjective perception of pain and the functional role of widespread high gamma band activity.
疼痛的感知受到不同过程的调节，例如对即将到来的刺激的预期和注意力。这些过程在实际刺激之前开始，并反映在正在进行的大脑活动中。不同的过程本身也很复杂，反映在刺激前的活动中，因此这种活动模式的检测应该受益于多元方法。为了在人类中确定与随后的疼痛感知相关的特定的刺激前 EEG 活动模式，我们在 EEG 测量期间在个体阈值水平上对比了疼痛和非疼痛感觉。多元 EEG 分析的结果表明，仅基于刺激前活动，预测疼痛分类的准确性很高（组平均 68%）。特别是，额中央区域和更高伽马频段（60:120 Hz）的活动对分类至关重要。额外的分析支持了刺激前高伽马频段活动模式对于预测行为结果的特定作用，并表明刺激前活动中嵌入的信息价值几乎与刺激后处理一样具有信息量，反映了一种特定的预备状态。此外，在高伽马频段中观察到刺激前和刺激后处理之间的密切关系。这些发现支持了在刺激出现之前的多元认知状态对于主观疼痛感知的出现的重要作用，以及广泛的高伽马频段活动的功能作用。
