Dennis Maureen, Cirino Paul T, Simic Nevena, Juranek Jenifer, Taylor W Pat, Fletcher Jack M
Program in Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON, Canada.
Department of Surgery, Faculty of Medicine, University of Toronto, Toronto, Canada.
Brain Imaging Behav. 2016 Mar;10(1):238-51. doi: 10.1007/s11682-015-9388-2.
Elevated reaction time (RT) is common in brain disorders. We studied three forms of RT in a neurodevelopmental disorder, spina bifida myelomeningocele (SBM), characterized by regional alterations of both white and grey matter, and typically developing individuals aged 8 to 48 years, in order to establish the nature of the lifespan-relations of RT and brain variables. Cognitive accuracy and RT speed and variability were all impaired in SBM relative to the typically developing group, but the most important effects of SBM on RT are seen on tasks that require a cognitive decision rule. Individuals with SBM are impaired not only in speeded performance, but also in the consistency of their performance on tasks that extend over time, which may contribute to poor performance on a range of cognitive tasks. The group with SBM showed smaller corrected corpus callosum proportions, larger corrected cerebellar white matter proportions, and larger corrected proportions for grey matter in the Central Executive and Salience networks. There were clear negative relations between RT measures and corpus callosum, Central Executive, and Default Mode networks in the group with SBM; relations were not observed in typically developing age peers. Statistical mediation analyses indicated that corpus callosum and Central Executive Network were important mediators. While RT is known to rely heavily on white matter under conditions of typical development and in individuals with adult-onset brain injury, we add the new information that additional involvement of grey matter may be important for a key neuropsychological function in a common neurodevelopmental disorder.
反应时间（RT）延长在脑部疾病中很常见。我们研究了神经发育障碍脊柱裂脊髓脊膜膨出（SBM）患者的三种反应时间形式，其特征是白质和灰质均有局部改变，同时还研究了8至48岁的正常发育个体，以确定反应时间与大脑变量之间寿命关系的本质。与正常发育组相比，SBM患者的认知准确性、反应时间速度和变异性均受损，但SBM对反应时间的最重要影响体现在需要认知决策规则的任务上。患有SBM的个体不仅在快速执行任务方面受损，而且在长时间任务执行的一致性方面也受损，这可能导致一系列认知任务表现不佳。SBM组的胼胝体校正比例较小，小脑白质校正比例较大，中央执行网络和突显网络中的灰质校正比例也较大。在SBM组中，反应时间测量与胼胝体、中央执行网络和默认模式网络之间存在明显的负相关关系；在正常发育的同龄人中未观察到这种关系。统计中介分析表明，胼胝体和中央执行网络是重要的中介因素。虽然已知在正常发育条件下以及患有成人期脑损伤的个体中，反应时间严重依赖白质，但我们补充了新信息，即在一种常见的神经发育障碍中，灰质的额外参与可能对一项关键的神经心理功能很重要。
