Max Planck Institute for Human Development, D-14195 Berlin, Germany.
Neuroimage. 2013 Dec;83:912-20. doi: 10.1016/j.neuroimage.2013.07.032. Epub 2013 Jul 19.
Trial-to-trial reaction time (RT) variability is consistently higher in children and older adults than in younger adults. Converging evidence also indicates that higher RT variability is (a) associated with lower behavioral performance on complex cognitive tasks, (b) distinguishes patients with neurological deficits from healthy individuals, and also (c) predicts longitudinal cognitive decline in older adults. However, so far the processes underlying increased RT variability are poorly understood. Previous evidence suggests that control signals in the medial frontal cortex (MFC) are reflected in theta band activity and may implicate the coordination of distinct brain areas during performance monitoring. We hypothesized that greater trial-to-trial variability in theta power during performance monitoring may be associated with greater behavioral variability in response latencies. We analyzed event-related theta oscillations assessed during a cued-Go/NoGo task in a lifespan sample covering the age range from middle childhood to old age. Our results show that theta inter-trial coherence during NoGo trials increases from childhood to early adulthood, and decreases from early adulthood to old age. Moreover, in all age groups, individuals with higher variability in medial frontal stimulus-locked theta oscillations showed higher trial-to-trial RT variability behaviorally. Importantly, this effect was strongest at high performance monitoring demands and independent of motor response execution as well as theta power. Taken together, our findings reveal that lower theta inter-trial coherence is related to greater behavioral variability within and across age groups. These results hint at the possibility that more variable MFC control may be associated with greater performance fluctuations.
在儿童和老年人中，试验间反应时间（RT）的变异性始终高于年轻人。越来越多的证据还表明，更高的 RT 变异性与（a）在复杂认知任务上的较低行为表现相关，（b）将神经功能缺损患者与健康个体区分开来，以及（c）预测老年人的纵向认知下降。然而，迄今为止，导致 RT 变异性增加的过程还知之甚少。先前的证据表明，内侧前额叶皮层（MFC）中的控制信号反映在θ波段活动中，并且可能暗示在执行绩效监测期间不同脑区的协调。我们假设，在执行绩效监测期间，θ功率的试验间变异性越大，响应潜伏期的行为变异性可能越大。我们分析了在一个从儿童中期到老年的寿命样本中，在一个提示 Go/NoGo 任务中评估的事件相关θ振荡。我们的结果表明，在 NoGo 试验期间，θ的跨试验相干性从儿童期到成年早期增加，然后从成年早期到老年期减少。此外，在所有年龄组中，内侧前额叶刺激锁定θ振荡的个体在更高的变异性中表现出更高的试验间 RT 变异性行为。重要的是，这种效应在高绩效监测需求时最强，并且与运动反应执行以及θ功率无关。总而言之，我们的研究结果表明，较低的θ跨试验相干性与各年龄段内和跨年龄段的更大行为变异性有关。这些结果暗示，更可变的 MFC 控制可能与更大的性能波动有关。
