Research Service (151), Veterans Affairs Northern California Health Care System, 150 Muir Rd., Martinez, CA 94553, USA; Department of Neurology, University of California, Davis, CA USA.
Neuropsychologia. 2013 Dec;51(14):3033-40. doi: 10.1016/j.neuropsychologia.2013.10.008. Epub 2013 Oct 21.
The stability of cognitive control processes over time can be indexed by trial-to-trial variability in reaction time (RT). Greater RT variability has been interpreted as an indicator of executive dysfunction, inhibitory inefficiency, and excessive mental noise. Previous studies have demonstrated that combat veterans with post-traumatic stress disorder (PTSD) show substantial impairments in inhibitory control, but no studies have examined response variability in this population. In the current experiment, RT variability in the Go/NoGo response inhibition task was assessed for 45 veterans with PTSD and 34 control veterans using the intra-individual coefficient of variation (ICV) and ex-Gaussian analysis of RT distributions. Despite having mean RTs that were indistinguishable from controls, the PTSD patients had significantly greater RT variability as measured by ICV. More variable RTs were in turn associated with a greater number of false alarm errors in the patients, suggesting that less consistent performers were less successful at inhibiting inappropriate responses. RT variability was also highly correlated with self-reported symptoms of PTSD, depression, and attentional impulsiveness. Furthermore, response variability predicted diagnosis even when controlling for PTSD symptom severity. In turn, PTSD severity was correlated with self-rated attentional impulsiveness. Deficits in the top-down cognitive control processes that cause greater response variability might contribute to the maintenance of PTSD symptomology. Thus, the distractibility issues that cause more variable reaction times might also result in greater distress related to the trauma.
认知控制过程随时间的稳定性可以通过反应时（RT）的trial-to-trial 可变性来衡量。更大的 RT 可变性被解释为执行功能障碍、抑制效率低下和过多精神噪音的指标。先前的研究表明，患有创伤后应激障碍（PTSD）的退伍军人在抑制控制方面存在严重障碍，但没有研究检查过该人群的反应可变性。在当前的实验中，使用个体内变异系数（ICV）和 RT 分布的外高斯分析，评估了 45 名 PTSD 退伍军人和 34 名对照退伍军人在 Go/NoGo 反应抑制任务中的 RT 可变性。尽管 PTSD 患者的平均 RT 与对照组无法区分，但 PTSD 患者的 RT 可变性通过 ICV 测量明显更大。反过来，更可变的 RT 与患者中更多的假警报错误相关，这表明表现一致性较差的患者在抑制不适当反应方面的成功率较低。RT 可变性与 PTSD、抑郁和注意力冲动性的自我报告症状高度相关。此外，即使在控制 PTSD 症状严重程度的情况下，反应可变性也可以预测诊断。反过来，PTSD 严重程度与自我评估的注意力冲动性相关。导致更大反应可变性的自上而下的认知控制过程的缺陷可能导致 PTSD 症状的维持。因此，导致更可变反应时间的分心问题也可能导致与创伤相关的更大痛苦。
