Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstr. 1A, 04103 Leipzig, Germany.
Brain. 2012 Jan;135(Pt 1):201-15. doi: 10.1093/brain/awr311. Epub 2011 Dec 19.
Executive functions describe a wide variety of higher order cognitive processes that allow the flexible modification of thought and behaviour in response to changing cognitive or environmental contexts. Their impairment is common in neurodegenerative disorders. Executive deficits negatively affect everyday activities and hamper the ability to cope with other deficits, such as memory impairment in Alzheimer's disease or behavioural disorders in frontotemporal lobar degeneration. Our study aimed to characterize the neural correlates of executive functions by relating respective deficits to regional hypometabolism in early dementia. Executive functions were assessed with two classical tests, the Stroop and semantic fluency test and various subtests of the behavioural assessment of the dysexecutive syndrome test battery capturing essential aspects of executive abilities relevant to daily living. Impairments in executive functions were correlated with reductions in brain glucose utilization as measured by [(18)F]fluorodeoxyglucose positron emission tomography and analysed voxelwise using statistical parametric mapping in 54 subjects with early dementia, mainly Alzheimer's disease and frontotemporal lobar degeneration, and its prodromal stages: subjective and mild cognitive impairment. Although the analysis revealed task-specific frontoparietal networks, it consistently showed that hypometabolism in one region in the left lateral prefrontal cortex-the inferior frontal junction area-was related to performance in the various neuropsychological tests. This brain region has recently been related to the three component processes of cognitive control-working memory, task switching and inhibitory control. Group comparisons additionally showed hypometabolism in this area in Alzheimer's disease and frontotemporal lobar degeneration. Our study underlines the importance of the inferior frontal junction area for cognitive control in general and for executive deficits in early dementia.
执行功能描述了广泛的高级认知过程，这些过程允许根据认知或环境变化灵活地修改思维和行为。它们的损伤在神经退行性疾病中很常见。执行功能缺陷会对日常活动产生负面影响，并妨碍应对其他缺陷的能力，例如阿尔茨海默病的记忆障碍或额颞叶变性的行为障碍。我们的研究旨在通过将各自的缺陷与早期痴呆症中的局部低代谢相关联，来描述执行功能的神经相关性。使用两种经典测试，即 Stroop 和语义流畅性测试以及行为评估测试组合的各种子测试来评估执行功能，这些测试涵盖了与日常生活相关的执行能力的基本方面。通过正电子发射断层扫描测量 [(18)F]氟脱氧葡萄糖摄取，并用统计参数映射对 54 名早期痴呆患者（主要为阿尔茨海默病和额颞叶变性及其前驱阶段：主观和轻度认知障碍）进行分析，将执行功能的损伤与大脑葡萄糖利用率的降低相关联。尽管分析显示出任务特异性的额顶网络，但它一致表明，左侧外侧前额皮质（下额连接区）一个区域的低代谢与各种神经心理学测试的表现相关。该脑区最近与认知控制的三个组成部分过程（工作记忆、任务转换和抑制控制）有关。组间比较还显示出该区域在阿尔茨海默病和额颞叶变性中存在低代谢。我们的研究强调了下额连接区对一般认知控制以及早期痴呆症中执行功能缺陷的重要性。
