Department of Linguistics and Languages, McMaster University, Hamilton, Ontario, Canada.
Centre for Advanced Research in Experimental and Applied Linguistics, McMaster University, Hamilton, Ontario, Canada.
PLoS One. 2018 Jul 19;13(7):e0200793. doi: 10.1371/journal.pone.0200793. eCollection 2018.
Generally, prognostication of coma outcome currently combines behavioral, reflex, and possibly neuroimaging tests that are interpreted by an attending physician. Electroencephalography, particularly, event-related brain potentials (ERP) have received attention due to evidence demonstrating the positive predictive value of certain ERP including the mismatch negativity (MMN) and the P3a, for coma emergence. We describe a set of ERP paradigms designed to require and reflect increasing levels of cognitive processing with the added objective of determining the influence of each paradigm's context strength on its ability to elicit ERPs. These paradigms were then used without explicit instructions to participants to attend to the stimuli to determine which paradigms possessed sufficient context "strength" to elicit ERPs in the absence of active participation on the part of the subject; a circumstance often encountered in brain injury patients. These paradigms were then validated on two groups of adults-younger and older, and the difference due to active participation was validated on another group of younger adults. Results show that paradigms with stronger stimulus context features performed better than those with weaker contexts, and that older adults generally had significantly attenuated and delayed responses compared to younger adults. Based on these findings, it is recommended the use of the auditory oddball paradigm that includes novel stimuli to elicit the mismatch negativity and P300, and semantic violation sentences to elicit the N400. These findings also reinforce the procedure of instructing participants about the requirements of a protocol-regardless of the patient's diagnosis or apparent state-in order to help those who are able to attend to show the most robust responses possible.
一般来说，昏迷预后的预测目前结合了行为、反射和可能的神经影像学测试，由主治医生进行解释。脑电图，特别是事件相关电位（ERP），由于证据表明某些 ERP，包括失匹配负波（MMN）和 P3a，对昏迷苏醒具有阳性预测价值，因此受到了关注。我们描述了一组 ERP 范式，旨在要求和反映认知处理的逐渐增加水平，并增加了确定每个范式的上下文强度对其诱发 ERP 的能力的影响的目标。然后，在没有明确指示参与者关注刺激的情况下，使用这些范式来确定哪些范式具有足够的“强度”上下文来在没有受试者主动参与的情况下诱发 ERP；这种情况在脑损伤患者中经常遇到。然后，我们在两组成年人（年轻人和老年人）上验证了这些范式，并在另一组年轻人上验证了主动参与的差异。结果表明，具有更强刺激上下文特征的范式比具有较弱上下文的范式表现更好，而且老年人的反应通常明显减弱和延迟。基于这些发现，建议使用包括新刺激的听觉Oddball 范式来诱发失匹配负波和 P300，以及语义违反句子来诱发 N400。这些发现还加强了告知参与者协议要求的程序的必要性，无论患者的诊断或明显状态如何，以帮助那些能够关注的人尽可能表现出最强大的反应。
