Ruppin Academic Center, Department of Behavioral Sciences, Emek Hefer, Israel.
Department of Psychology, Ben-Gurion University of the Negev, Beer Sheva, Israel.
Cortex. 2023 Oct;167:25-40. doi: 10.1016/j.cortex.2023.06.007. Epub 2023 Jul 10.
Increased intrasubject variability of reaction time (RT) refers to inconsistency in an individual's speed of responding to a task. This increased variability has been suggested as a fundamental feature of attention deficit hyperactivity disorder (ADHD), however, its neural sources are still unclear. In this study, we aimed to examine whether such inconsistency at the behavioral level would be accompanied by inconsistency at the neural level; and whether different types of neural and behavioral variability would be related to ADHD symptomatology. We recorded electroencephalogram (EEG) data from 62 adolescents, who were part of a prospective longitudinal study on the development of ADHD. We examined trial-by-trial neural variability in response to visual stimuli in two cognitive tasks. Adolescents with high ADHD symptomatology exhibited an increased neural variability before the presentation of the stimulus, but when presented with a visual stimulus, this variability decreased to a level that was similar to that exhibited by participants with low ADHD symptomatology. In contrast with our prediction, neural variability was unrelated to the magnitude of behavioral variability. Our findings suggest that adolescents with higher symptoms are characterized by increased neural variability before the stimulation, which might reflect a difficulty in alertness to the forthcoming stimulus; but this increased neural variability does not seem to account for their RT variability.
反应时（RT）的个体内变异性增加是指个体对任务的反应速度不一致。这种变异性增加被认为是注意力缺陷多动障碍（ADHD）的一个基本特征，但其神经来源仍不清楚。在这项研究中，我们旨在检验行为水平上的这种不一致是否会伴随着神经水平上的不一致；以及不同类型的神经和行为变异性是否与 ADHD 症状学有关。我们从参加 ADHD 发展前瞻性纵向研究的 62 名青少年中记录了脑电图（EEG）数据。我们在两个认知任务中检查了对视觉刺激的逐次试验神经变异性。具有高 ADHD 症状的青少年在刺激呈现前表现出神经变异性增加，但当呈现视觉刺激时，这种变异性降低到与 ADHD 症状较低的参与者相似的水平。与我们的预测相反，神经变异性与行为变异性的幅度无关。我们的发现表明，具有较高症状的青少年在刺激前表现出增加的神经变异性，这可能反映了对即将到来的刺激的警觉困难；但这种增加的神经变异性似乎并不能解释他们的 RT 变异性。
