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目的探讨图形异同判别ERP范式对鉴别伪装认知损害的法医学价值。方法 40例健康志愿者在合作和伪装认知损害两种情境下,进行二项必选数字记忆测验(BFDMT)及图形异同判别ERP范式检测,对照组为20例合作的三级脑外伤者。结果三组被试完成相同、无关、相似图形刺激后引出的ERP波均包括N1、P2、N2、P3和N3五个成分,三组样本组间的N2、P3和N3的潜伏期和波幅均存在差异。其中,伪装组相同图形的N3潜伏期与正常组无显著性差异,明显短于外伤组(P<0.01);伪装组无关图形的N3潜伏期较正常组延长,但短于外伤组,波幅较正常组降低(P<0.05);伪装组相似图形的N3潜伏期较正常组和外伤组缩短(P<0.01),波幅较正常组降低(P<0.01)。以N3潜伏期为指标进行判别分析,探查伪装认知损害的敏感性为81.8%、特异性为76.9%、命中率为79.2%。结论图形异同判别范式可引出稳定的特征性ERP成分,其中N3的波幅和潜伏期有显著的组间差异,对判断伪装认知损害有一定的参考价值。
Objective To explore the forensic value of discriminating the sameness and different patterns of ERP from cognitive impairment of disguised masquerading. Methods Forty healthy volunteers underwent two mandatory digital memory test (BFDMT) and ERP test of pattern discrimination in the two situations of cooperation and camouflage cognitive impairment. The control group was 20 patients with tertiary TBI. Results The three groups of participants completed the same but not related to each other. The ERP wave induced by similar graphical stimuli included five components of N1, P2, N2, P3 and N3. The latency and amplitude of N2, P3 and N3 among the three groups of samples all existed difference. There was no significant difference in the N3 latency of the same pattern in the camouflage group compared with the normal group (P <0.01). The latency of N3 in camouflage-free pattern was longer than that of the normal group, but shorter than that of the normal group (P <0.05). Compared with normal group and traumatic group, the latency of N3 in camouflage group was shorter than that in normal group (P <0.01). Discrimination analysis using N3 latency as an index revealed that the sensitivities of masquerading cognitive impairment were 81.8%, specificity was 76.9%, and hitting rate was 79.2%. Conclusion The discriminant paradigm of pattern discrimination can lead to stable characteristic ERP components. Among them, the amplitude and latency of N3 have significant differences between groups, which is of certain reference value for judging cognitive impairment of camouflage.