Walhovd Kristine B, Fjell Anders M
University of Oslo, Institute of Psychology, POB 1094 Blindern, 0317 Oslo, Norway.
Neuropsychologia. 2007 Jun 11;45(10):2277-84. doi: 10.1016/j.neuropsychologia.2007.02.022. Epub 2007 Mar 4.
Information processing speed is a central concept in cognitive psychology and neuropsychology. Previous studies have mostly focused on mean reaction time (RT), and largely ignored intra-individual differences (the standard deviation of the RT: sdRT). Still, intra-individual inconsistency across trials has been shown to correlate with age, neurological disorders, intelligence, and performance on cognitive tests. However, sdRT has not been correlated with neuroanatomical variables. Such knowledge is important to the understanding of the neurobiological foundation for intra-individual variability. In the present study, white matter (WM) and cortical gray matter (GM) volume obtained from the average of two MR scans of 71 healthy participants (aged 20-88 years) were correlated with sdRT and mean RT obtained from a 3-stimulus visual oddball task. Negative correlations were hypothesized between sdRT and WM and between mean RT and cortical GM volume. These hypotheses were confirmed. The correlation between sdRT and WM volume was significant also independently of effects of age, gender, and mean RT, while there was a trend towards a significant correlation (p=.085) between cortical GM volume and mean RT independently of age. A path model was constructed, showing that age and sdRT gave independent contributions to the variance in performance intelligence, and that WM volume predicted performance score through the influence of sdRT. Further, sdRT was a stronger predictor of performance intelligence than mean RT. It is concluded that sdRT and mean RT may have different neuroanatomical correlates, and that sdRT is related to WM characteristics of the brain.
信息处理速度是认知心理学和神经心理学中的一个核心概念。以往的研究大多集中在平均反应时间（RT）上，而在很大程度上忽略了个体内部差异（RT的标准差：sdRT）。然而，试验间的个体内部不一致性已被证明与年龄、神经障碍、智力以及认知测试表现相关。不过，sdRT尚未与神经解剖学变量相关联。这类知识对于理解个体内部变异性的神经生物学基础很重要。在本研究中，从71名健康参与者（年龄在20 - 88岁之间）的两次磁共振扫描平均值中获取的白质（WM）和皮质灰质（GM）体积，与从三刺激视觉Oddball任务中获得的sdRT和平均RT相关。假设sdRT与WM之间以及平均RT与皮质GM体积之间存在负相关。这些假设得到了证实。sdRT与WM体积之间的相关性在独立于年龄、性别和平均RT的影响时也很显著，而皮质GM体积与平均RT之间在独立于年龄时有显著相关的趋势（p = 0.085）。构建了一个路径模型，表明年龄和sdRT对表现智力的方差有独立贡献，并且WM体积通过sdRT的影响预测表现分数。此外，sdRT比平均RT是表现智力更强的预测指标。结论是，sdRT和平均RT可能具有不同的神经解剖学相关性，并且sdRT与大脑的WM特征相关。
